Bass Overdrive Pedals
I've been on an overdrive binge for about a year and a half now. Already having more than 45 of them from various manufacturers, I wanted to see if I could build some clones and modify them to be more suited to what I  look for in an overdrive for use with a bass. This page will take me a while to complete, but I figure that I have to start somewhere ( and will be a continuing work in progress). I'm going to write up a short review of each one and post a soundclip of as many of them as I can. As of today, there are 277 different OD/distortion/fuzz pedals on this page (yes, I've gone nuts with them).  Due to the many soundclips and pics, this page may take a while to load so please be patient. I'll first start with the clones and modified clones that I built, followed by manufactured ones. Each of the clones that I built started out as the exact same circuits as the originals, but if I didn't find one to be great for  BASS, I modified its tone to give it full bass frequency response with no low end loss (which to me, is a MUST!)
NOTE: I built these pedals for myself and they pedals are NOT for sale (however, I can build you one if you just have to own a hand-made pedal or it's a pedal that has been long discontinued.).
Barber Direct Drive - Dave Barber  makes some awesome pedals, and for very reasonable prices. I made this one and modded it for use with a bass giving it more low end, added a fat switch, and a blend control. It's a very natural & smooth sounding overdrive capable of going from a transparent clean boost to a heavy overdrive, but even a stock one sounds great with a bass. It's one of my favorite overdrives for bass.
ZVEX Mastotron - I built this one completely stock (and call mine the 'Blastotron'). This pedal is a actually his famous Wooly Mammoth, but also has a 'relax' control that allows it to be used with any bass, since it's basically an input level so you can trim how hard you want to hit the front end. It can go from a fuzz, to a gated fuzz with HUGE subs, almost synthy. It's not transparent, but isn't supposed to be.
ProCo Rat / BassFace / Dry Rot - This is a heavily modified vintage ProCo RAT clone. I raised the values of all of the coupling caps so it retains all of the low end, added a blend control, plus added an additional boost circuit so it can also be used as a clean boost. When modded and voiced properly for a bass, RAT's can make some really nice  and aggressive dirt pedals and this one is no exception.
Fooltone Mosfet Bossdrive: I changed the name (because the maker threatend to sue me for mentioning it, but you probably know who that is). These have been discontinued but are great sounding bass overdrives with three voices (Comp-cut, flat mids and vintage), a separate gain boost footswitch, plus three types of clipping to choose from (silicon asymmetrical and mosfet). No low end loss, and can go from a clean boost, to mild and wild amounts of OD with no harshness or strange artifacts.
Blackout Effectors Musket Fuzz - This one is a Big Muff variant, but with some really cool additions that make it a popular pedal found on alot of bassist's pedal boards. The "Pre" control lets you adjust how hard you want to hit the front end. A 'focus' control allows you to adjust how much low end you want to clip in the drive section, plus it has a mids control along with the standard tone control, so it can go from any version of a Big Muff, and WAY beyond.
Fooltone OSeeD: Another one from an unfriendly maker that basically ripped off and slightly modded the Voodoo Labs Overdrive and called it his own, but it still didn't thrill me at all with a bass, so I modded it for no low end loss. Now it's a very nice sounding overdrive. It uses a TL082 JFet chip with two 2N7000's Mosfet transistors for the clipping circuit giving it a tube amp-like response. After the mods, it's a great sounding bass overdrive.
Wampler Black '65 - In my opinion, Brian Wampler makes some of the best sounding pedals bar none, and this one is no exception. An all FET pedal, designed to sound and feel like a blackface fender amp and it does exactly that. Plus you can drive it into overdrive/distortion with two different amounts of clipping via the toggle switch. No low end loss and a fat tone is easily achieved with this one, even if used only for tonal enhancement.
Wampler Pinnacle - Another great sounding pedal from Brain Wampler, featuring a mid contour control so you can cut mids without affecting anything else. This is a really nice amp simulation pedal that has TONS of drive/gain on tap with a HUGE low end. I added a true blend circuit to it so I could blend some of my clean signal with the overdriven one. This pedal is capable of sounding very 'produced' and 'sophisticated'.
DAM EZEKIEL 25:17 - This is my exact clone of the famous, now discontinued overdrive/fuzz designed for bassists.  It uses the JRC4562D chip along with four different modes / options for clipping on the rotary (chicken knob) switch. With it's built-in clean blend, this pedal can go for mild to wild, from very subtle, to  a heavy in your face fuzz. Originals are commanding some pretty high prices these days and I can see why, but you can buy one of  my exact of it clones HERE
Catalinbread RAH - Designed to emulate Jimmy Page's Hiwatt from Zepplin's Albert Hall performance in 1970, this one also makes a great bass overdrive. It doesn't have tons of gain/dirt, but this four mosfet based pedal can add thickness and a good dose of grit, all while having a tube amp-like  response to your playing. It basically sounds like a HiWatt amp getting pushed into the sweet spot. BIG and FAT is how I would describe it.
Jordan Bosstone - Direct from the 60's comes the Jordan Bosstone. I've owned many original versions of this pedal (I still have one of them) and this is an exact clone of it, with the exception of adding a three way bass boost switch that goes from stock, to a medium bass boost to a big bass boost with no low end loss. With the bass boost mod, it surprised me at how good these sound with a bass.
DAM Sonic Titan - I call my version the 'Super Sonic' since I added a 3-way bass boost switch. This has a JFet driving an LM386 chip (a headphone amplifier chip) and it makes a nice thick and chunky bass overdrive/ distortion pedal for a bass. In my experience, pedals that use 386 chips make them feel like you're really playing thru an amp rather than thru a pedal.
Prescription Electronics 'Depth Charge' - I call my version the "Deep Charge'. Alot of bass players really love these pedals.. If you like an almost synthy/buzzy fine grit distortion, then this pedal is for you. The original's blend control is not a true blend, so I call it a 'Mix' control on mine, and then added an active true blend as well as a starve switch to make the distortion chunkier. I suppose that I could see heavy metal bass players loving this one,
Zvex Distortron - In my experience, most of Zachary Vex's pedals have a sound of their own and not much of your instrument's real tone comes thru them, but with this one it does. He's releasing a bass verison soon (a 'Basstortion'), but I just couldn't wait for it so I built the Distortron and re-voiced it for use with a bass. This is now a no frills bass overdrive but capable of copping a cranked SVT both in tone and feel.
Fooltone Soul-Mate - TheSoulmate is another one from a famous has two distortion circuits in it that can be used seperately or together. Stock, they don't have much low end, but after modding it with a three-way bass boost, this pedal sounds bitchen' with a bass. The stage two circuit adds a more raw type of grit and has its own led to show you just how hard your driving the stage 2 clipping circuit.
Seamoon Funk machine - I bought an original one of these when they first came out way back in 1974, and it was really innovative for its time Not really an overdrive, but an envelope pedal with some added grit in it's tone. I love these things. On my clone, I added a clean blend to make it even more versatile. This is one of my favorite auto wah/envelope pedals of all time and is capable of some really funky sounds.
114 of my hand made pedal clones. I've now built more than 300 of them!:
Zvex Super Duper 2n1 - The Zvex super duper 2n1 is two SHO's (super hard ons) in one pedal, with a stomp switch for each one. It's very transparent (with no loss of low end) and uses two BS170 mosfet transistors. This pedal is capable of a TON of boost and distortion and is an excellent pedal for use with a bass.
DOD 250 /MXR Distortion + - The DOD 250 and MXR distortion + are so similar in design that I decided to build each one with two completely seperate circuit boards into this pedal so I could select between them. I also added a FAT switch to boost the low end. Now, with the low end boost, in my opinion, these vintage pedals make a surprisingly great bass distortion.
Paul Cochrane-Timmy - Paul Cochrane's pedals are great values since they are inexpensive and some of the best sounding (and most copied) pedals offered. I call mine the 'johnny', but it has NO modifications. In my opinion, this is one of the best sounding & transparent overdrive/distortions ever made and you can't go wrong with this one. Three clipping choices along with bass (pre) and treble controls (post) make it an extremely versatile pedal for bass players.
The Duality - One is one of my own designs with two seperate pedals in one (an FET preamp with treble and bass controls & boost, plus a mild overdrive) that can be used together in series or individually. Both circuits are transparent but can also enhance / fatten your tone with tons of options for clean, over-drive or distortion. The page with much more info on this pedal is HERE
Wampler Ecstasy - Brian has recently renamed this pedal the 'Euphoria', but it's the exact same pedal/circuit. This is one of my top five bass overdrive pedals of all time. Capable of a clean boost and gorgeous sounding overdrive / distortion, if you're looking for a bass overdrive you owe it to yourself to try one. I really don't think that it gets any better than this for bass or guitar.
Catalinbread WiiO - Catalinbread makes great pedals and this is one of my favorites. This is a HiWatt tube amp in a box with a HUGE, FAT low end with excellent touch response. It actually feels and sounds like you're playing thru a HiWatt 100 and has some of the most authentic tube grit overdrive that I've ever experienced in any pedal. In other words, this pedal makes your bass sound BALLSY.
Zvex Wooly Mammoth - I call mine the  "Wooly Bully". A very popular bass distortiuon pedal that is anything but transparent. I ended up adding the Mastotron's sub and relax control to make it more versatile. These have a very distinctive effect and are not for the faint of heart. To me, it's more of a novelty pedal, but alot of bass players use them and swear by them (or is that swear at them?)
Fairfield Circuitry 'The Barbershop' - This is also one of my all time favorites for bass. This pedal emulates a tube amp getting pushed into its sweet spot. If you have a solid state or tube head that's just too loud and clean at the gig, this pedal can dial in the 'pushed' ,'hitting the rails' tone, even at bedroom levels. No low end loss and total touch response are it's best features. IMO, just playing thru one makes your tone more sophisticated and richer. This is my current 'GO TO" pedal for a bass overdrive.
Hermida Zendrive - The Zendrive is a VERY popular, highy acclaimed overdrive for guitarists and rightfully so. Two mosfet transistors and an LM2604 chip make this pedal extremley smooth and gorgeous sounding. The voice and tone controls allow alot of tonal variation. I found the stock pedal to  cut too much low end for use with a bass, so I added a 3 way bass boost switch to get it back. Now I can run it stock, or with two other low end options. I absolutely love this one.
Foxx Tone Machine- From the late 60's -.early 70's comes the Foxx Tone machine. It is a pretty wild sounding distortion pedal. With almost synth-like distortion, as well as octave up settings, this pedal sounds great with guitar or bass. It's not to be used as a clean boost or a slight overdrive, but more of a drastic distortion pedal.
Barber Silver LTD- Another one of Dave Barber's excellent pedals. This one doesn't have a ton of dirt but it sounds awesome. The amp 'engine' is a Jfet TL072 chip with silcon diode clipping. With its tone and mids controls you can get alot of different tones out of it. In my experience, all of Dave's pedals sound smooth and dynamic. They have a certain clarity and complexity to their sound without adding too much color, yet sound very 'rich and produced'.
Lovepedal Silicon Fuzzmaster -This distortion pedal was designed to be basically a tweakable version of a Dallas Arbiter fuzz Face. The blend control isn't a clean blend, but rather  controls what frequencies are distorted, so it acts more like a tone control. It also has a trimmer hole in the back of it so you can dial it in to be more smooth or gated. I think that it sounds nice. My only complaint is that on some settings the decay of the notes can be a bit  fizzy.
Subdecay Liquid Sunshine- I really like this pedal. It has a bass boost switch as well as a treble cut. I modded the bass boost switch for even more low end and I love it. It has TWO drive controls so it has two overdrive circuits in it using all Jfet transistors (with  NO chips for the amplifiers and no diodes for the clipping). It's a very ballsy sounding pedal, capable from adding slight tube grit to heavy overdrive.
Maestro Brassmaster- A clone of a very famous vintage distortion pedal. These are wild and 'brassy' sounding fuzz pedals for bass. It does have  a type of clean blend control, but its fuzz is where it really gets interesting, and is its biggest asset. Back in the day, Chris Squire  used them on some Yes songs. If you do a google search for the Brassmaster, you'll get ALOT more info about it.
Fat-Tone Jr. - This is one of my own pedals based on the Craig Anderton Tube Sound Fuzz circuit using a 4049UBE CMOS chip for the dirt and amplifier stages. It's very touch responsive and capable of tons of grind. I added a starve switch to make it more gritty, a hi/lo for use with guitar or bass and a boost switch to kick it into high gear.
Wampler Tweed '57- Another one of Brain Wampler's pedals designed to emulate a 1957 Fender tweed deluxe amp. Its 5 Jfet transistors simulate a tube amp very well. I love it on guitar and actually it makes a pretty nice overdrive for bass if you adjust the treble mid and bass controls.
The Fat-Tone- When I bought a Greedtone pedal, I loved it (and still do), but I made this pedal with a few improvements to make it more of a dedicated bass overdrive pedal, adding more low end, a starve switch and a two way treble cut switch to tame the highs. These are raw and gnarly overdrive pedals that will not get lost in the mix. For more info you can go HERE.
Vox Tone Bender - An infamous distortion / fuzz  pedal. I've owned several originals in the past (and sold them for really big bucks) so I just had to make a clone of one to keep for myself. It does have some low end loss, so it's not the best pedal for use with a bass, but it's germanium transistors really give it a smooth yet bright vintage and complex fuzz that could be blended in with a blend pedal.
Keeler Pull- I call my version the "Yank" since I modded it for more gain and more low end. To me, stock, this pedal was just 'meh', but now I really dig it. Before the mods, it was kind of dull and lifeless, veiling my bass's tone and punch, but now it's much more like the Fairfield Circuitry Barbershop which is one of my favorites at making it sound like you dialed you amp into its sweet spot on the edge of distortion
Voodoo Labs Sparkle Drive - I wanted one of these for a long time and rightfully so. It's a great sounding bass overdrive, especially since I modded it for more low end retention. I also added a 3 way switch for different clipping options. The built-in clean blend is super nice and allows you to maintain your bass's clean punch and dial in any amount of dirt with it. IMO, this is definitely a pedal to consider adding to you bass pedal board.
Earthbound Audio Supercollider - Another big muff variant.  This popular bassist pedal does just about any year and model of a Big Muff and more. The depth control allows you to vary the level and tone of the distortion. The mids control allows you to boost or cut the mids. I added a three way toggle to choose from three types of clipping to make it even more versatile and later found out that the new ones also have it. If you're into using Big Muffs on bass, then this pedal is for you.
OKKO Diablo- I really wanted to make an OKKO Basstard but couldn't find a schematic for it so I built the Diablo and modded it for bass revoicing the circuit's low end and added a blend control. This pedal came out awesome and I wouldn't be at all surprised if it's the same thing as a Basstard now. Big, fat, rich and complex is how I would describe it, just like a cranked Ampeg SVT. And running it at 18 volts really makes it dynamic
MI Audio Crunch Box - MI Audio's Crunch boxes are very nice distortion pedals for guitar but I found it to be lacking in the bass department so I modded it. It now has a full low end, an outboard presence control (stock it's an internal trimpot) and three way clipping (diodes, green leds, and mosfets). This pedal really rocks for bass use now and I think sounds better for guitar too. I also added a charge pump to run it at 18 volts from 9V power source to make it even more dynamic and punchy.
(Note: You can click on each of the pedal pictures below for a larger view of them in another window.)
Xotic RC Booster - This is a very nice transparent preamp / boost pedal that can also be used as an overdrive. Xotic also makes a bass version which is what I converted mine into.  I also added a two way clipping switch to give it even more  overdrive options. This pedal has a TON of low end if you want it. A JRC4558D with two 2N5088's are at the heart of its circuit and it's quickly becoming one of my 'go-to' pedals.
Xotic BB preamp- Another great sounding pedal for bass.. This is another one that they offer a bass version of, so I also converted this one to the bass model, plus added a 3 way clipping option switch. Not quite as much low end boost as the RC boost, but it's not lacking any lows. It has two JRC4580 chips and two 2N5088 transistors in the circuit and can actually get into a smooth tubescreamer type of overdrive as well as be a clean boost.
Way Huge Red Llama - Another great sounding overdrive/distortion pedal based on Craig Anderton's Tubesound Fuzz / 4049UBE CMOS circuit. I modded it to be a little more bass friendly and give it a little more gain. It's very  touch sensitive and has an amp-like response that cleans up well with your instrument's volume control. There are quite a few pedals that are based on this circuit, like the Helter Skelter/Polish Love, and the Greedtone Overdrive.
Rockbox Boiling Point - These boutique overdrive pedals sell for $389! Are they worth it? I don't know, but they do sound great. I prefer mine with a Burr-Brown OPA2134 chip. It has 3 way clipping options for tons of dirt, plus a bass boost switch. I modded mine for even more low end and it's capable of a a clean boost, a mild overdrive or a full blown fuzz. Here's a link to the owner's manual for more info:              
Electro Harmonix 'Green Russian' Big Muff- Out of all the versions of the Big Muff that EHX has offered over the years, the Green Russian has clearly stood out as the bass player's favorite since it has the most low end. I installed a three way mid switch in mine so it can go from the stock scooped sound, to flat, or a midrange boost. I have to agree that the Green Russian is even better than the EHX Bass Big  Muff that they're currently offering.
Wampler Triple Wreck - If you're looking for the best sounding HEAVY distortion pedal with literally TONS of overdrive/fuzz, then look no further. This pedal sounds awesome, and has a TON of low end to boot. The treble, mid and bass controls offer an extreme dose of flexibility. It can go from bright, to middy, to dark and wooly to scooped and anywhere in between. And if that's not enough, it has a boost circuit with it's own contour control to multiply the gain and tonal options. I love this pedal!
Keeley Fuzz Head -Robert Keeley offers lots of  mods for existing pedals, and the ones of his own design are awesome. His Fuzz Head can be modded for more low end and is also capable of running at 18 volts for more headroom. It has a ridiculous amount of clean boost on tap. Using Darlington transistors plus a vintage germanium AC187, this pedal can get a very 'vintage' type of fuzz. I added an internal 18V charge pump and a master volume to give it even more tonal options. The owner's manual for it can be found HERE.
Crowther Prunes & Custard- This is a very unique sounding pedal that's very popular with guitarists AND bassists.  It can get some conventional distortion tones, but is also capable of an enveloped type of distortion when using the mix control. I love the sound of it both ways and I think that you will too. The  "freq' contour' control works in conjuction with the mix knob and lets you dial in the amount of the enveloped distortion effect. I really haven't heard another pedal like it so it's really one of a kind.
Wampler Paisley Drive - A boutique pedal that Brian Wampler made exclusively for Brad Paisley but now offers them for sale. It has a 3-way mids contour switch working with the tone control that makes it very versatile. Stock, it had a bit of low end loss, until I modded it, and now sounds great used with a bass. It's very smooth and one of the most  touch responsive overdives that I've played thru to date. In my opinion, Brian has another winner with this one. The clip below demonstrates its touch sensitivity.
Wampler Plexi-Drive -As you might be able to tell by now, I love all of Brian Wampler's pedals. Not to be confused with the Paisley Drive, the Plexi Drive emulates a Marshall Plexi amp. The nice thing is that with its bass boost switch, it retains all of  the low end and has a ton of volume and gain on tap. Being an all JFET based design, these pedals sound great as a bass overdrive (and are awesome with a guitar of course). If you get a chance to try a bass thru one, i think that you'll be very impressed.
Barber Dirty Bomb- Another really great pedal for bass from Dave Barber. The Dirty Bomb is a high gain distortion, but it can also be used with lower overdrive settings. This one has it all, 3 Jfet opamps, mosfet clipping (very boutiquey), with treble, bass and a 3 way mid switch control. I moved the internal SUBS control ('lo bass') to be external, and added a 3 way, bright / normal / hi cut switch. Ridiculous amounts of rich, smooth sustain and distortion on tap, and this one can actually  BOOST your low end! I love this pedal!
COMING SOON (already built and tested, but not boxed yet):
Clones: Bearfoot CANDY APPLE FUZZ GOLD, Wattkins RF DRIVE, Mr. Black OVERDRIVER, Runoffgroove 22/7, Roger Mayer STONE FUZZ, Colorsound OCTIVIDER, Durham CRAZY HORSE, Carllin COMP/FUZZ, Catalinbread FORMULA no5, Electro Harmonix HOT TUBES, Fred Briggs E11even, Divided by 13 JOYRIDE,  Lotus Pedals SNOWJOB, Sadowsky PREAMP, BJFE FOLK FUZZ 3.5%, Tone Factor CREAM PIE DELUXE, Sam Ash FUZZ-TAIN,  Monolith Effects ORACLE, Roland AD-50 DOUBLE BEAT FUZZ, Modded BAZZ FUSS, Roger Mayer OCTAVIA, Roger Mayer PAGE 1, Emerson EM-DRIVE, Maestro MFZ-1, Brett Robinson's HIDROSIS (modified MFZ-1), Soulsonic HUNNY BUNNY, Roger Mayer SPITFIRE,  Devi Ever Electric BROWN, Devi Ever DARK BOOST and HYPERION dual pedal, Creepy Fingers SI FUZZ FACE (modded), Mictester's BUZZAROUND-ALIKE, Xotic EP BOOSTER, D*A*M RED ROOSTER, Shin Ei FUZZ COMPANION FY-2, Catalinbread  SAGRADO POBLANO PICOSO, Wolf COMPUTER FUZZ, Catalinbread SUPER CHARGED OVERDRIVE (SCOD), Death by Audio FUZZ WAR V2 (4 transistor version), Death by Audio FUZZ WAR (7 transistor version), Creepy Fingers DOOMIDRIVE, Malekko SLOIKA, and many more.................

Manufactured pedals:
Gaussmarkov Dr. Boogie Dual Rectifier - This is a DIY boutique pedal build from Gaussmarkov. Using five JFETS (J201's) it's intended to sound like a mesa Boogie Dual Rectifier (which it really does!) but I revoiced mine for bass and changed the freqs on the tone stack more to my liking. It can go from a medium overdrive to ridiculous amounts of sustaining fuzz/distortion. With no low end loss (now), it can also be bright, dark, mid scooped or mid bumped and anything in between,
Krank Distortus Maximus -Another LM386 based distortion pedal. I modified this one's tone stack for use with a bass and experimented with 6 different types of 386 chips until  found the one that offered the best tone and distortion. I really like this one now, especially for heavily fuzzed tones, but it's also capable of  clean and slightly overdriven  sounds as well.
Fender Blender- This one was released back in to 70's with a mixed 'appreciation' of it's unique fuzz sounds. It's a heavy voiced fuzz with an upper octave effect. I modded mine to be able to turn the upper octave on and off and modded the 'boost' tone stack as well. It does have  a very nice clean blend so you can mix your clean tone back in with the distortion.
Ampeg Scrambler- Word has it that Ampeg only made 800-1000 of these very rare and little known fuzz tones. The gain of the fuzz is preset but it does have a nice clean blend. The originals only have two knobs (texture and balance) but I added a master volume as well as a switchable clean boost. The texture control  goes from a fairly conventional heavy distortion to an octave up mode. It also has a bit of octave down in it. IMO, it's not an 'everyday' dirt pedal, but I do love it's 'one of a kind' type of distortion.
Runoffgroove Flipster-: I love JFet based pedals and this one is no exception. It was designed to sound like the vintage Ampeg 'Fliptop' amps, and I think that it does so in spades. The original schematic had way too much gain so I experimented with different transistors to tame it and it has become one of my top 10 favorites now.
Dwarfcraft Great Destroyer- This one's a really crazy pedal! It can be somewhat 'tamed' and is capable of a zillion different types of dirt, from a  conventional vintage sounding distortion, to a self oscillating hell bent fuzztone. It's super interactive with a bass's volume and tone controls
Runoffgroove Ginger- This pedal was designed to replace the 'Flipster', and to me, it's easily just as good (some like it even better) since it has a bit different tone than its predecessor. There's more mids and mid bass in it and actually sounds more like an SVT (clean or dirty) than a fliptop amp. I really love this one too!
Xotic AC Booster- Another one from Xotic. The AC booster is supposed to yield an AC30 type of tone, but it really didn't do that for me. I ended up modding mine to allow more low end thru it and added an mosfet clipping option, which I actually later changed to an LED clipper. It's a very nice sounding pedal now, but out of Xotic's AC, RC and BB, I  prefer the RC over the other two.
Clark Gainster- A really cool sounding opamp overdrive distortion pedal. I'm running a JRC4558D in mine and this pedal has plenty of low end with no mods Dave Barber offered these for a short time, and in my opinion, any pedal that Barber puts his name on is always good and worth considering. I believe that Clark has now started production of them again.
Pigtronix Philosopher's Twin- This one isn't really an overdrive, but it's rather a compressor, however is does have a germanium distortion circuit in it (switchable via the second footswitch) and I really like it's overdive and its compressor's tone. It's capable of infinite sustain, with or without distortion and can be used as a compressor, a distortion, or both.
Viva Analog 360+ pedal- This pedal is available pre-built or as a pcb. I bought the pcb. It is an exact clone of the early Acoustic 360 preamps from the late 60's and includes a germanium fuzz circuit with a blend control,  I even used an original 1.5H inductor in the vari-amp circuit, but the opamp based one in the Viva Analog circuit sounds great too. It features a mute switch as well as a pad for basses with hot pickups.
Emma Transmorgrifier- This one is actually a compressor (and IMO, a great sounding one at that), but it's also capable of adding heavily overdriven tones. I've been able to quickly dial in the sound of an SVT at the point of clipping (and way beyond), or you can run it at unity gain or as a clean boost.
Marshall Guv'nor- This is my version of the Marshall Guv'nor with the bass,mids and treble tone stack. I modded the freq's for use with a bass as well as the input and output coupling caps. I also added a clean blend with a phase reverse switch since the stock pedal reverses the phase of the original signal. IMO, it's an excellent sounding overdrive/distortion/fuzz pedal for bass now.
Emma Reezafratzitz- The Reezafratzitz is actually a guitar distortion, but I modded mine for bass (more low end), added a clean blend and made it switchable to run on 9 or 18 volts for more headroom with an internal charge pump. IMO, it's a very nice  sounding OD/distortion but it is  just a little noisier (hissy) than most of my other pedals.
BlackArts Pharaoh:   The Pharaoh is another incarnation based on the Big Muff, but with a few twists. It has selectable silicon or germanium clipping diodes for more variable distortion, a Hi/Lo input switch for more or less gain, plus a treble control along with the standard tone control. I prefer it over an EHX Bass Big Muff or a Green Russian by quite a bit since it can be set cleaner and retain more of your instrument's original tone.
BlueTube 903 Bass Driver - The Tubeworks BlueTube was designed by BK Butler. It uses a 12AX7A (i'm using a 12AU7A in mine) to get real tube overdrive/distortion. It can be used as a clean boost all the way to a heavy overdrive. The treble, mids and bass controls are basically a Fender tone stack, and IMO, it's a great sounding bass overdrive. It's extremely touch sensitive and has ALOT of balls. IMO, these should be a lot more popular for bass players than they seem to be.
ToneCzar Openhaus: With more than 100 components on the circuit board (with 8 amp stages!), it just barely fit in a 1590BB enclosure. I found it to be lacking a bit of low end so I modded it for no low end loss, and it's now capable of boosting it. The original pedal was also a little dark so I gave it more top end. It's a awesome sounding pedal now for a high gain distortion-/fuzz. It runs on 18V (internal charge pump), selectable mids freq switch (boost & cut),phase switch, 3 distortion voices, and an expression pedal input.
Earthquaker Devices Speaker Cranker- This pedal was designed to simulate pushing a speaker cabinet into moderate distortion, and it does it very well. It also provides a slight amount of boost when cranked up. It's an excellent sounding pedal if you're looking fo something to give your bass and amp a slightly edgier, and more growly tone.
Blackstone Appliances Mosfet Overdrive:  I really dig this one ALOT. It's two overdrive voices in one pedal via channel switch  with a master mid cut/boost control. A great sounding CMOS overdrive pedal that can be run with or without the internal buffer on the front end. Internal trim pots allow control of the overall top end and adjustment of the gain for the red channel. It can go from clean and transparent to heavily saturated dirt.
Homebrew Electronics Hematoma Bass Overdrive:  HBE's Hematoma is two pedals in one. It contains a clean bass preamp and a bass overdrive. which can be used seperately or together. I found the stock pedal to be a bit too dark for my taste so I modified it for more top end. IMO, it's a great sounding OD/distortion pedal now.
Tronographic RustyBox:  This pedal is a actually the exact circuit Traynor TS50B bass amp's preamp (I used the Traynor schematic to build it). It runs on a bipolar 15 volt power supply. Featuring an input pad for basses with hot pickups and a boost switch for more gain. IMO, it's a good sounding pedal and capable of alot of tonal variation. I find the distorted tones a little nasty (and don't care for them) if I crank the gain too much, but if I keep the gain at moderate levels it is extremely punchy.
Pete Cornish SS2: Cornish pedals go for HUGE bucks these days so I just had to build one to see what all the hype is about. After building it, I can certainly see why. It's an awesome overdrive with excellent touch response, smooth grit, tons of harmonics and great sustain.  I slightly changed mine's tone to make it more suitable for bass and added an additional Cornish buffer for a clean blend. Playing thru it is a very inspiring experience so this one has made it into my top ten favorite overdrives of all time.
Custom JFET Marshall Super Bass Preamp: This one is a five JFET Marshall Super Bass preamp emulator. Just like the real amp, it can go anywhere from clean to very overdriven/distorted. I also added an internal charge pump so I can run it on either 9 volts or 18 volts off of a standard 9V wall wart for more punch, less compression and more headroom.
Tubeworks Bluetube No 2: I built another Bluetube Driver, but this time in a smaller, more conventional enclosure. I also slightly modded the tone stack for a little more low end in this one just so it's a bit different than my first one. Since I've built two of them now, I guess that you can tell that  I really dig these pedals.
Vemuram Jan Ray: Here's an OD pedal that guitarists have been going nuts over lately for it's transparency and smooth distortion. They're pretty expensive at $375. There's zero low end loss and it has an internal trimmer for setting how much gain you want it to have. In all actuality, this pedal is a very slightly modified Paul Cochrane Timmy and sounds  just like one, so if you're thinking about getting one, I'd recommend saving $240 and getting a Timmy.instead. That said, it IS a great sounding pedal.
Way Huge Swollen Pickle: I first built this one stock but then slightly modded it to be more to my liking. I love it now. It's another variation of a Big Muff but with ALOT of differences. The original has 5 external (and two internal) controls, but I mounted all of mine externally. Since mine is not an exact clone anymore, I renamed it the 'Phat Gerkin'. It has tons of low end and now can go from almost clean to a heavy fuzz. This one has so many tonal options that it's going to be impossible to show all of them in a single clip.
Zeibek/Electronix Submarine: Not really an overdrive but rather an FET bass preamp, but it is capable of being a clean boost. Designed by Albert Kreuzer, this discontinued pedal is loved by bassists for its rich harmonic tones. Mine has the three way mids switch that goes from flat, scooped or boosted mids. IMO, it's a nice pedal for 'enhancing ' your tone.
Fooltone RT Overdriver: The RTO is just a modified Tubescreamer circuit without the input buffer, although I find it to sound ALOT better than a tubescreamer, especially on bass. Stock, it makes a nice bass overdrive, but I added and additional bass control on mine so I could boost the low end. I also added a clip select switch to go from the stock 1N4005/1N4148 clipping diodes to a mosfet/Schottkey clipper. This is a very smooth and dynamic overdrive and I prefer it over the OSeeD but quite a large margin.
Colorsound Bass Fuzz: I really like this one, and it's extremely simple to get a great tone out of it.  Three gain stages of BC549C transistors with diode clipping. It has a TON of low end. I added an additional switch to select from the 1N4148 diode clipping to twin LED clipping for an extra clipping 'voice'.  It can go anywhere from nearly perfectly clean to a heavy fuzz.
Roger Mayer Voodoo Bass: Roger Mayer has been designing pedals as long as anyone (since the 60's) and really came up with a winner with this one. It's super fat and punchy, has a thick and heavy distortion/fuzz on tap, but can also be run clean, or have just a hair of dirt/overdrive. He also offers a VooDoo Bass 2 which has treble and bass controls as well as a clean blend balance and output.
BJFE Blueberry Bass Overdrive (BBBOD) : The blueberry OD was designed to be a light to medium overdrive simulating a tube bass amp pushed into distortion. It can actually be run clean, but its overdrive tones are where it shines. Mad Professor has released a PCB version of it that also sounds very nice.. The tone control controls the feedback that changes what frequency the distortion is applied. Uising two JFETS with a CA3130 chip, it's a very dynamic and fat sounding overdrive with zero low end loss.
Interfax Harmonic Perculator: Created by Ed Giese in the 70's and highly sought after. Using a silicon NPN transistor and a germanium PNP transistor it passes even order harmonics while suppressing the odd order ones. I used the exact same (&  rare) transistors, 1N695 diodes, silver mica and tantalum capacitors in mine to make it nearly a perfect clone of the original. Stock, this pedal doesn't have alot of output so I added a clean boost on its output so it can now go way past unity gain. A very interesting and unique sounding fuzz/distortion pedal that adds both subs and highs at the same time.
Madbean FatPants: This pedal was designed to sound like a Maestro Echoplex's preamp section and it really does. It also has a 'body' switch to boost the mids and low end. It really doesn't offer much in the way of overdrive/distortion, but it does fatten up your tone and make it punchier. It can also be used as a clean boost. Using two J201 JFets along with an internal charge pump, it runs on 18 volts to give it more dynamics and headroom. This is a great sounding circuit if you're looking to just enhance and boost your overall tone and give it more thickness and presence.
OKKO Dominator : OKKO uses HUGE status LED's in their pedals, so I used one in my clone too. With an internal charge pump and 15V regulator, this one uses two BF245A Jfets as the input buffer going into a Burr-Brown OPA2604 for the distortion (there's no diode clipping in this one!) From there, two TL072 opamps are used for the EQ section and output buffer. This is a high gain distortion pedal  with bass, treble and a 3 way selectable mids control. As dirty as this pedal can get, it's still very smooth and BIG sounding and works great on both guitar & bass.
BJFE Little Green Wonder (LGW) : Another great sounding overdrive for bass. This one is similar to a tubescreamer circuit, but again, it doesn't sound anything like one. The newer ones use a TLC272 CMOS chip but I went with the earlier version LF353N chip for more headroom. The 'body' control is super cool, going from a fat, slightly scooped high gain drive (fully CCW), to a darker mid emphasized with less gain in the middle positions, to a brighter tone but still with alot of low end (fully CW). it can go from being clean to heavily overdriven. I also added a little more low end to mine, but the stock pedal sounds great too.
Nick Greer Ghetto Stomp: I've now built a few of Nick Greer's designs and I really like them. This one has a super simple circuit but it sounds awesome. Using just one 2N3094 NPN transistor and a couple of 1N4148 diodes, I'm amazed at how dynamic and big sounding it is. I also added a Cornish buffer that can be switched in or out which gives it a bit more lows and highs. It's not a super high gain overdrive but it does yield plenty of grit.
Brunetti Mercury Box : From Italy comes the Mercury Box. I first built it completely stock, and it sounded great for guitar, but it lost a little low end for a bass, so I modded it with larger coupling caps. I also found its top end to be a little dark so I changed that too. It's OD/distortion is so smooth that, at higher gain settings, it lost a bit of the clean signal's punch so I also added a clean blend to it and, IMO, it's an awesome OD pedal now.Since it's no longer an exact Mercury I renamed mine the 'Merc' (sInce I've built so many pedals, I generally use their original names on my clones so i can keep track of what they are).
Runoffgroove/OLC Orange Peel MKII: This one is a 5 Jfet (one MPF102 and four J201's) preamp emulator  of an Orange FAC amp. The FAC control is a 6 way rotary switch that selects the input frequency response. On this one, the treble and bass controls are BEFORE the gain/drive stage, effecting the way which frequencies are distorted. I think that it's a nice sounding pedal that is slightly strong on the 'mid voiced' side.
Himmelstrutz Fetto: This one is a highly praised overdrive/disortion pedal for guitarists so I just had to build one. Using 3 SK170GR Jfets, don't let its simple three knob external appearance fool you. Inside of it are 10 DIP switches and two trimpots to adjust it's distortion and tonal variables. It's drive knob can go from completely uncolored clean boost to a heavy distortion and anything in between. If you click on the pic you can see the internals of the pedal. In my opinion, this is an awesome sounding pedal for guitar OR bass.
Black Cat OD-1 : This pedal's circuit has been around under a frew names, but is said to be "created based on the unique properties of the OP275 opamp". I didn't care for this pedal at all before I modded it. It was too dark, and had an ugly fizzy fade on the tail of the notes. So, I tried more than 20 different chips in it. The OPA2604 solved the fizzy fade issue, and then I changed all of the filters in it to brighten it up a bit.  After the mods, it's a very  good sounding overdrive for bass, but I wouldn't recommend a stock one.
Baldwin-Burns Buzzaround: These three germanium transitor fuzz tones are highly sought after and command high prices. I built mine exactly like the original with the exception of adding a master volume since the balance control also affects the drive and tone of the pedal due to it's loading the circuit. I really like this one for it's complex and vintage sounding distortion. It runs on -9V but I added a voltage inverter so i could run mine on a standard +9V power supply.
Crowther Hotcake: Released in 1976 this simple single opamp (LM741) pedal really sounds good on bass, especially if you get the XLF version. Its frequency dependant drive gets darker as you turn up the drive, and at extreme settings it can get muddy and almost uncontrollable, but at lower settings it can go from clean to slightly overdriven. They are well loved by guitarists and bassists alike.
Mad Professor BJF Sky Blue Overdrive : A really nice sounding light to medium to heavy overdrive that's also  capable of full blown heavy distortion. Featuring a 'Z' control to load you pickup's impedance, and a 'Texture' control which varies the amount of the overdrive's compression, this pedal produces a very wide variety of overdriven touch sensitve tones. I slightly modded mine for a little more low end (for use with a bass) and added a master tone control
Orange Bass Preamp #2: This one is based on Paul Nelson's Orange preamp emulator. His design had an FAC control, but I prefer it more without it so I left it out. This one has absolutely NO low end loss (it can actually boost it) and is a much quieter circuit, but is capable of more gain and distortion. The controls are (L-R): Input Volume, Boost, Treble, Bass, and Master Volume. I absolutely love the sound of this preamp, which can go all the way from a clean and transparent boost to a super heavy overdrive/distortion pedal. More info is HERE.
BJFE Honey Bee: An extrmely smooth yet dynamic overdrive with no low end loss. These are very popluar with guitarists, but sound awesome with a bass too. The 'nature' control goes from a heavier, more compressed and saturated drive (counterclockwise), to a brighter and lighter drive (clockwise). This one's excellent touch response makes it feel very 'amp-like' when you're playing thru it.
Prescription Electronics Yardbox: : This one is a sonic duplicate of the vintage Sola Sound Tonebender which is said to be the only fuzz pedal that Jimmy Page used on the first two Zepplin albums. It sounds awesome with  guitar and is also pretty nice on bass. Using 3 NOS PNP germanium transistors and a germanium diode, it has a smooth, vintage tone and is fuller and smoother than the Vox Tonebenders that I've owned. It runs on -9V so I added an inverter circuit to allow it trun on a standard Boss adapter.
EHX Big Muff Opamp: For a very short period (1978-79) Electro harmonix released an opamp version of the Big Muff. I do have an original one, but wanted to make a clone of it with a couple of mods to make it better suited for bass. It came out great and I like it as much or more than the green Russian. it's also the fuzz pedal that was made popular by the Smashing Pumkins. One version had a tone bypass switch so I also included it in this build.
Smallsound Bigsound Sparkle Motion:SS/BS releasing the schematic on it online is what made me build this one. It's basically a booster pedal (treble or fullrange). The original uses a germanium transistor but I wanted more gain & dirt out of it so I modded it's bias circuit and replaced the stock transistor with one that has more gain (higher hfe). It's now capable of quite a bit of overdrive (as well as a clean boost) and is super punchy used either way.
Fooltone SEVENTY: : A modded version of an early 70's silicon Fuzz Face with an added mids control. I have an original early large one one but wasn't thrilled with it at all so I built this one and modded it by adding a 'bias' (input level control ). I also replaced the first transistor with a high gain NPN germanium one. It sounds great now, and I like it ALOT more than my original stock one.
BJFE Dyna Red Distortion: I'm a really big fan of Bjorn's pedals. The Dyna Red Distortion was designed to sound like a plexi Marshall at full tilt but can also do low overdrive and nearly fully clean tones as well. The original's controls are treble, distortion and volume, but I modded mine for bass, and  added a mid/bass control for even more low end. IMO, it's an awesome sounding distortion pedal for use with a bass now.
BJFE Sea Blue Eq: Another cool BJFE pedal. This one, wasn't designed to be an overdrive but it does add a slight amount of grit on all settings.   The original three knob version has  treble, bass and volume controls, but I added a mid's control to mine to make it even more flexible ( I call mine the 'Deep Blue Eq'). The tone is very 'tube'like' and adds balls to your tone (to see what I mean, just listen to the clip below).
Mad Professor (BJFE Design) Stone Grey Distortion: : A high gain, modern soundng distortion pedal that still retains.note definition, even at extreme distortiion settings. I first built this one completely stock, and it sounded great on guitar, but was light in the low end department for bass so I modified it by changing three caps in it. It's a very smooth distortion that is never harsh soundng  using a CD4069UBE CMOS chip and Fet clipping (2N3819's).
Cornish G-2 : Pete Cornish's G-2 is his take on a Big Muff, with an added buffered input stage. Using five BC549C transistors for the amplifier stages and four germanium diodes for the clipping, as well as different cap and resistor values compared to a standard Big Muff makes it a much smoother, creamier OD/ fuzz. It's tone control is also different in that it's not scooped, and just rolls off the top end. I found it to be a little lacking in the highs and lows for use with a bass so I modded mine for that. IMO, it's a very nice sounding bass overdrive/fuzz  now.
Nick Greer Sucker Punch: This is a great sounding OD for bass with no loss of low end. Using a Jfet (J201) to drive an LM386N (mini amplifier), this is my favorite pedal that uses a 386 chip for the distortion stage. Very amp-like in its response, it's big, fat and ballsy sounding and can also be used as a clean boost.
Catalinbread Dirty Little Secret MKIII: The DLS has undergone quite a few versions and this is the latest one, with treble, bass and mid controls. I firsr built it 100% completely stock, and didn't care for it at all since it was dark, muddy, mushy and had an ugly sounding distortion. I modded the heck out of this one, mounted the presence control externally, added a mids switch and added a boost footswitch as well as a charge pump to switch between 9 and 18 volts. it sounds awesome now!
RetroChannel 'The Fuzz' : This one is a modern day pedal using a somewhat rare CA3046 chip (four transistor array) designed to emulate  germanium Vox Tone Bender and Colorsound fuzzes from the sixties. IMO, it's not a very versatile pedal since it basically goes from a fairly heavy fuzz to even more fuzz, but it does have more low end than a Tone Bender and can sound good for  heavy fuzz bass tones.  I added an input level to allow me to 'tame' its drive a bit and darken its tone.
Skreddy Lunar Module mini deluxe: Skreddy makes some very nice pedals. This one is more of a vintage type fuzz using three BC109C transistors, but with much more control than most vintage fuzz pedals. The 'range' control is a pregain, the body is a pre-distortion bass control, and the brite is post distortion, This pedal can go from nearly clean to thick and very heavy fuzz tones and anywhere in between with no low end loss.
Throbak Overdrive/Boost: This is a great sounding overdrive/distortion pedal for bass with no low end loss (it can actually boost it ALOT). It can be used as a clean boost, an overdrive, or a distortion/fuzz pedal. It's based on the Colorsound overdrive, but is alot more flexible. It also features a pregain footswitch (I mounted the pregain control knob externally) so you can switch between  light or heavy drive thru the circuit. It also has a germanium diode and transistor switch for a more complex &  warmer fuzz tones.
Maxon Overdrive Pro OD820 : Some people refer to this one as the "Klon Killer" and, IMO, it IS an awesome overdrive pedal. It was excellent stock, but I modded my build slightly (just changed one capacitor) for even more low end. It uses a 2SK246 Jfet for an input buffer and then goes into two JRC4558D opamps. It also has an ICL7660S charge pump so the chips actually run on +9 and -9 volts for more headroom. A  dual ganged 250K pot is used for the drive control, and this pedal can go from a clean boost to a heavy but smooooooth overdrive.
KLON Overdrive: The highly praised Klon overdrive is very sought after by guitarists and go for huge bucks these days. It's one of the first 'boutique' pedals and is an original design. I first built mine 100% stock, and while it sounded great for guitar, I wasn't very thrilled with it on bass. I ended up modding it for no low end loss, swapped the two TL072 opamps for Burr-Brown OPA2134's and gave the drive circuit more gain. It's an awesome bass overdrive now that can also be used as a clean boost.
JHS Morning Glory : This is JHS's take on a modified Marshall Bluesbreaker pedal. Stock , IMO, it was just okay, so I modded mine for no low end loss and more gain. It uses an LM833 chip and a 2N5457  JFet for the tone recovery stage. The controls are Volume, Drive, Tone, and a bright cut switch. It's a great distortion pedal for bass now, that still retains the Bluesbreaker's character, but can also do alot more.
Tychobrahe Octavia: Definitely not for the faint of heart, the Octavia is a vintage ('70's) distortion pedal that generates an octave up along with the original frequency. It can almost get synth-like at times. I added a pre-gain control and an octave up on/off swtich to mine, so I can slo use it as a slight overdrive, a heavy fuzz or an octave up fuzz. There's no low end loss with this one completely stock. I used to own the original back in the mid 70's and this one is capable of sounding just like it, and then some.
Analogman King of Tone: Another overdrive based on the Marshall Bluesbreaker that is coveted by guitarists and has about a year waiting list just to get one. This pedal sounds great with a bass stock, but I did  slightly mod it for a little more low end. The two toggles switch different clipping stages in different parts of the circuit. This is an awesome sounding pedal that's super easy to dial in a great overdriven tone. I also made mine the high gain version that you can order as an option from Analogman.
Suhr Riot: A high gain distortion that, again, is based on a heavily modified Marshall Bluesbreaker. Stock, this one really didn't thrill me at all. To me, it was too dull and muddy at low drive settings. It had plenty of low end though, so I modded it for more top end clarity and now can also be used as a pretty transparent clean boost. The 'voice' control is a super cool feature. It switches the clipping between 4 germanium 1N34's, two red leds, or a blue LED with two 51 volt zeners. It's a really nice sounding bass OD/distortion pedal now.
Earthquaker Devices Crimson Drive : A really cool sounding overdrive that sounds great with a bass . It uses a Jfet (J201) driving a germanium AC128 transistor along with two 1N60 diodes for its distortion (no opamps!). This pedal was designed to sound like a cranked Marshall amp and has a very dynamic amp-like response. It's tone is much less compressed and pure than most overdrive pedals.
Mad Professor (BJFE) Sweet Honey Overdrive: Another excellent sounding overdrive pedal from Mad Professor designed by BJFE ( I LOVE his pedals!). Extremely dynamic (its overdrive is variable with how hard you play). Using an OP275 chip with two red leds, two 1N4007's  and a third led, all in different parts of the circuit for its very sensitive and controlled distortion. The focus control adjusts not only it's tone content but also the amount of overdrive and compression.
Johnk LowBallz:This pedal is one of my own. Based on a big muff, but highly modified using a James tone stack (treble & bass), instead of the scooped BMP tone control, and uses a Jfet for the eq recovery stage (w/5 transistors instead of  4). I made it so it can go from a somewhat clean transparent slight boost, to a heavy fuzz with a lot of boost, and can be scooped, flat, dark, bright, or mid boosted. Since it's one of a kind, I gave this one my own name.
Mountainking Electronics Megalith : This one isn't an overdrive. It's a heavy fuzz pedal. There's no adjustment for the distortion other than the 'input' control, but it's extremely fuzzy even at its minimum setting. It has TONS of low end.  The notch control is a three way rotary switch that selects the mids frequency, and the more/heavy control is an added boost. For a heavy fuzz pedal, I think that it actually sounds really good.
Catalinbread CB30/Naga Viper (Galileo): This one is actually two Catalibread pedals in one, a Naga Viper and a CB30 Vox AC30 emulator.  Each of them are pretty cool pedals by themselves, but combined sound awesome with a ton of tonal variations. Catalinbread's 'Galileo' is the same pedal, but without the Naga's 'Heat' and 'Range' controls. There's NO low end loss with this one and it's an extremely touch sensitive overdrive, and each one can be used seperately or together, running the Naga into the CB30 for more dirt if desired.
Zvex Fuzz Factory: Zvex's best selling pedal, the Fuzz Factory is a pretty over the top fuzztone. It can self oscillate, do smooth heavy fuzz, or velco gated fuzz and anything in between. I added a gain switch (with an internal trimpot) so I can tame it, and also run it as a standard overdrive. This one is ALOT of fun to play with and capable of a TON of different tones. It uses one silicon transister and two NOS AC128 germaniums to get it's super fat tone.
The Foundry: I built this pedal by request and it came out reeeally nice! It's a dual overdrive with BJFE blueberry bass overdrive and a Zeibek Submarine bass preamp. They can be used seperately or together. The BBBOD is the first in the chain when both are engaged. Both pedals are great in their own right, but together it's a super sounding overdrive for use with a bass. The sub just adds more harmonics and sparkle to the blueberry's already awesome tone.
Barber Gain Changer: A recent release by Dave Barber that captures the sounds of no less than 3 of his previous popular pedals, the LTD, LTD SR, and the unLimiTeD. The toggle switch on the left is the “EQ switch” ( LTDSR EQ (right), LTDv2 EQ (middle), to a setting that sounds “flat+fat” (left). The “flat+fat” setting is meant to give you a “flat EQ” sound like the LTD SR, but with added fundamentals. The right one selects between heavy distortion (left) and an overdrive (right). It can be run as a clean to low overdrive, a moderate overdrive, a heavy overdrive, all the way up to a heavy distortion. I love this one!.
DOD FX50 Overdrive Preamp: An often overlooked but great sounding vintage overdrive pedal for bass. No low end loss and a great sounding from clean to overdrive to distortion. I added a tone control to mine so I call it the FX50.1 but the stock ones sound great too. It's simple but very effective circuit using a JRC4560 chip for the amplifier stage.
DOD FX91 Bass Overdrive: One of the earliest bass overdrive pedal designs that featured a blend control so you could retain all of your clean punch and mix it with an overdriven tone. I slightly modded mine for a little more low end and added a two way clipping selector to switch between two 1N4148 diodes (stock) to two red 3mm LED's (less dirt/more volume and low mids). IMO, these are really nice sounding overdrive pedals for bass.
MXR Blue Box: I bought one of these when they first came out in the 70's. It's very unique pedal with a pretty unruly heavy distortion. The distortion is set at a fixed amount and there's a TON of it. The blend control blends in another  fuzz 2 octaves down. I modded mine to be able to switch it from two octaves down to 1 octave down, since two octaves down is way to low when used with a bass. It's not a pedal that I would use often but it sure is nice to have when you need an unusual effect.
WMD: WMD stands for Wampler Modified Distortion+(MXR), which is what this pedal is. With the 'comp' (compression),'smooth' (extra germanium and silicon clippers), extended 'bass' (way more low end), and more gain available than the original, it turns a decent pedal into a great one.
Marshall DriveMaster: These are no longer made but are very nice sounding overdrive/distortion pedals. I modded mine for no low end loss ( a verysimple modification) and it sounds awesome now for use with a bass. It's a TL072 based circuit with twin red led clippers and a full treble, middle and bass tonestack. It's gain control can go from clean to heavy distortion. It's tone can be flat, scooped, mid boosted, bright, dark or anywhere in between.
Bogner Ecstasy Amp Simulator: Here's a really nice sounding overdrive/distortion based on Bogner's Ecstasy amp, using 5 JFets with no opamps or clipping diodes. It's very smooth, yet extremely touch responsive. Even with alot of dirt it still maintains the clarity and definition of your notes. This is not the same circuit as the Bogner pedals, but rather an amplifier simulator. It started out as a guitar pedal, but I slightly modded it for more low end for use with a bass.
Seymour Duncan Tweak Fuzz (modified): Duncan's Tweak Fuzz is actually a verbatim silcon fuzz face circuit, only with a variable 6 way input capacitor.selector on the front end. I slightly modded mine to Roger Mayer's fuzz face circuit, changed the transistors to low hfe NOS 2N2926's with an hfe of 70 and 120 and added a tone control so I could tame the top end. It didn't have a lot of output level (just like the original) so I also added a clean volume boost circuit to the output.
Anderton DVFV3: Here's another recent build and it's a wild one. Designed by Craig Anderton in the 70's, it's called the Dual Voiced Filter and it sounds really nice. it's a very tweakable distortion/eq pedal with two sweepable high Q filters plus an overall overdrive/distortion with a clean blend. You can clip each filter individually pre or post eq, or run them clean,  plus it has a master clipper in it as well..It's basically a 'knob tweaker's delight'.
The 'Brat': This one started out as a Landgraff M'OD, which is really a modified rat with three types of clipping (on the mini switch). I then modded it for no low end loss. since it's basically a rat, only modded for bass, I call mine a 'Brat' (short for bass/rat ). This is the best sounding Rat type distortion pedal that I've ever heard on bass and it sounds awesome.
GAMMA BASS OD: Here's a completely new one that I came up with after alot of experimentation, so it is unlike all of the other circuits. With 3 2N5088's and 2 BS170 mosfets, (no opamps), IMO, it sounds very natural and has a very 'pretty' overdriven sound to it. It feels more like an amp than a pedal and has a TON of low end. Mounted in a gamma ray green enclosure, I call it the 'Gamma Bass Overdrive' or GBOD for short. It can go from a clean transparent boost, to a heavy overdrive but still retains all of the dynamics and tone.
Largemouth Bass: This one started out as a Menatone Red Snapper. After modding it for bass, I call mine the 'Largemouth Bass'. The unmodified Red Snapper is actually a very nice sounding pedal, even for bass, but i just felt that it could use a bit more low end. It features the famous JRC4558D opamp, and uses assymetrical diode clipping. Its unique 'bite' control adds more edge to the distortion and the pedal is capable of being a clean transparent boost all the way into a heavy overdrive.
Catalinbread SFT: The Catalinbread SFT was designed to emulate an Ampeg SVT (SFT standing for 'Super Fet Technology'), and IMO, it is capable of doing just that with the correct settings. IMO, these are great sounding OD pedals for bass. I also own the original and after  comparing my clone to it, they sound exactly the same. It uses 8 Jfets in mu-amp stages to voice the circuit like a big, harmonically complex tube amp, and It can be run clean, heavily overdriven or anywhere in between.
You can buy one HERE
Univox SuperFuzz: This is an exact clone of a vintage pedal that goes for pretty big bucks these days. A few newer companys make clones of them too. I added a scoop control as opposed to the stock two way scoop on/off switch so i can adjust the amount of scoop. I also added a switch to select between two scoop frequencies, plus a clean blend. Using six NOS 2SC828 transistors, this pedal is a pretty wild fuzztone with an slightly octave up effect, but also has alot of low end. Rather than try to describe it, I'll post a sound clip of it soon.
Roland BeeBaa AF-100: A very cool vintage Roland Fuzztone with a separate booster. It uses a 2SC644R transistor for the booster and first gain stage and two 2SC828Q's for the fuzz circuit. The fuzz side is not 'mild' at all, but it does retain the low end for use with a bass. The tone select switches between a standard high end rolloff and a scooped midrange. The left switch is the true bypass, and the right one switches between the booster and the fuzz. A bi-color red/green led on the fuzz/boost switch indictaes which mode the pedal is in.
Marshall Shredmaster: Here's a high gain distortion pedal offering from Marshall. It features bass and treble controls along with a 'contour' which is a mid scoop control. The original circuit sounded good with a bass but I modded mine for even more low end retention (no low end loss!), so mine's called the "Bass Shredmaster". I'm really digging this one that uses two TL072 Fet opamps with 1N4148 diodes for the clipping.
Rockett Blue Note OD: The Rockett Blue Note is a low to medium gain overdrive that is pretty transparent. The basic circuit was designed by Brain Wampler and then Rockett tweaked it to their own tonal voicing. Originally, it has a little low end loss but still sounds great with a bass ( of course I ended up modding mine to fix that). The circuit is extremely similar to a Wampler Ecstasy/Euphoria so you can imagine that it's a very nice sounding pedal The' Hot' switch kicks in a bit more mids and gain for cutting thru..
Rockett Animal: Another overdrive/distortion pedal from Rockett. This one is basically identical to the Blue Note but capable of of higher gain (more distortion). IMO, It was kind of redundant to build this one since there's only a couple of resistor values that are different and the gain pot is a higher value. I actually prefer the Animal over the Blue Note, but they are both excellent overdrives.
DOD FX50B: Another super nice sounding vintage DOD overdrive for a bass guitar. My only complaint with this one was that at the lowest drive setting, cranking the volume up all the way still wasn't anywhere near unity gain, so I added a Jfet clean boost to the output to solve that. This is surprisingly a great sounding overdrive, Using an LM1458 and LF353N dual opamps and four 1N4148 clipping diodes in series, it can go from a clean transparent boost to a very heavy overdrive.
Frantone PeachFuzz: This one is a unique and original circuit desined by Fran Blanche using a TL022 opamp for the first stage driving a pair of LM386N power amp chips. It yields a gnarly, thick, yet smooth fuzz with more than enough low end for use with a bass. Fran ceased building pedals in 2009 so if you want to get one, you'll have to find one used.
Maestro FZ1: The first fuzztone ever offered(!), the Maestro FZ1 was first released in 1962. Best known for Keith Richards using it on 'Satisfaction', I've always loved these and have owned four of the originals. I'm very proud of this one since they are very difficult to build to sound like the original.  I modded mine for a little more low end (for bass), but used plug-in caps so I can run it stock too. I also added a pregain control so I can run it at lower 'fuzz' levels, but when the pregain knob is maxxed, it's as if it isn't there. It runs on only -3 volts (two AA's/ positive ground) so I built a highly filtered +9V to -3V convertor into it to simulate the batteries and allow me to run it off of a standard Boss power supply.
Runoffgroove Umble: This  Runoffgroove circuit uses four Jfets (J201's), designed to emulate the famous Dumble overdrive amplifier. I don't know if it really sounds just like a Dumble but it does sound great. It can go from a perfectly clean transparent tone to a super heavily overdriven tone by cranking the input volume. It also has a TON of output. Having the bass, middle and treble tone stack (which is in front of the drive stages) enables a alot of tonal variety and there's NO low end loss with this one.
Boss Blues Driver BD2: Boss's Blues Driver has been around for a very long time now, is still popular, and I've always dug them for guitar. I modded mine for more low end for use with a bass (and call mine the BBD-2). With a summing opamp, 7 transistors (two BJT's and 5 Jfets) this pedal gets it's distortion in a lot of areas of the circuit, and it can go from clean to heavy overdrive/distortion. This one just barely fit in a 1590B enclosure. I also cured the fizzy decay issue that these pedals have by replacing the stock chip with two stacked NE5534 chips.
BJFE Arctic White Fuzz: Yet another one from BJFE. This one is designed to be a vintage sounding fuzz using only two transistors (like a Fuzz Face) to achieve the fuzz. The first amp stage is a BC550C (BJT) and the second stage is a J113 Jfet. The Fuzz control is actually an input level (pre-gain). IMO, it's a great vintage sounding fuzz that's much quieter and consistent than its vintage counterparts. I modded mine for more a bit low end but it also sounded very good stock.
MojoHand Iron Bell: Another Big Muff derivative, but with a few twists. With a guitar, it's said to get the 'David Gilmour tone', and I agree that it does come very close. And it's also a very nice fuzz/overdrive for a bass The gain stages are tweaked differently than a standard BMP, plus has the addition of a 'colour' control that goes from nearly flat (CCW) to boosted mids and midbass (CW). It may have a tiny bit of low end loss, but it more than makes up for it with its thick, fat and smooth distortion,
Morley JD-10 Preamp: This one (designed for Jerry Donahue) is a full blown preamp & amp emulator, complete with a switchable speaker simulator. It has a TON of low end and sounds really good with a bass 100% stock. The classic/rock switch switches between 'normal gain and ultra hi gain for a ton of distortion shoud you want it. It can go from completely clean to mild, to wild amounts of overdrive and distortion with a full BMT tone stack to shape your tone to your preference,
Earthquaker Devices Hoof Fuzz: And yet still another Big Muff derivative, but with quite a few changes to the circuit. Instead of silicon diodes, it uses 4 red leds for the clippers, and the two clipping amp stages uses two germanium transistors. This creates a more overdriven/darker tone with a more 'chunky' distortion. On top of that, a 'Shift' control is added to the tone circuit which changes the effect and range of the tone control. All of those changes make it a really nice pedal for use with a bass.
Zvex Box of Rock: This one is Zvex's take on a Marshall plexi. It sounds really good on bass too. It'sa two channel overdrive/booster capable of 50db of clean  transparent boost. The 'Rock' side of it can do some very nice overdrive by itself, and it's followed by a switchable SHO (zvex Super Hard on) booster. Using four BS170 Mosfet transistors, it is very dynamic and touch responsive to any playing style.
Ibanez TS808 Tube Screamer: One of the most popular overdrive pedals of all time for guitarists, In my opinion, really doesn't make a good bass overdrive since it cuts so much low end. I first built this one exactly like the vintage original, including the earliest version's RC4458P chip. Then I modded it for no low end loss and replaced one of the 1N4148 silicon clipping leds with a green led. I also increased it's overdrive ability. It's an awesome bass overdrive now.
Blackout Effectors Mantra Overdrive: This one is a completely original circuit that sounds great on bass. It uses two Mosfets (2N7000's) followed by two Jfets (J201's). It doesn't use any opamps or diodes for its clipping and includes a Bandaxall Tonestack for its EQ. It works great on guitars as well.
MXR Custom Badass Modified O.D.: MXR's custom modified overdrive sounds great on bass, thanks to its added 100Hz control that allows you to increase or decrease the low end.  Assymetrical diode clipping with two dual opamps driven by a Darlington transistor yields everything from clean to heavy overdrive. It also has a 'bump' switch that increases the lows and low mids.
Gallien Krueger Diesel Dawg: This one is more of a distortion pedal than an overdrive. With 3 Jfets (J113's) and 3 dual opamps (TL072's) it has 9 amplifier stages in it. As a result of that, it can be a bit noisey (hiss) at some settings, but it does have a really nice distortion tone. At high gain levels it can get very compressed, but in a good way. The original unit comes in a HUGE enclosure so I made mine to fit in a 1590BB.
BJFE Pink Purple Fuzz: And yet another super cool sounding one from BJFE, the Purple Pink Fuzz. Not just a fuzz, since it'll actually do anthing from a very slight overdrive to a full out heavy fuzz. It's tone is very 'vintagey', but without the noise and unpredictabilityI it uses a JFet (2N5952), a BJT (BC550C) and a germanium transistor (2N1308) to get it's many voices.
Mosrite FUZZrite (modded): I owned an original Fuzzrite for more than 30 years and I always liked it on guitar. I sold it a few years ago so I just had to build another one, but this time optimized for bass. There are alot of versions/schematic on the web and I build three different versions until I was happy with this one's circuit. I added a pregain, a tone control, raised the value of one of the coupling caps and this thing is a MONSTER fuzz now! It'll still get the tones of the original, but with the added mods, this one does ALOT more.
Prescription Electronics COB: COB stands for Clean Octave Blend. This pedal blends in your clean signal, with a fairly clean to heavily distorted octave up. It also has a lower octave thing going on and it's 100% analog. I really dig it on guitar and bass. With the blend control, you can use it anywhere from a very subtle effect, to a crazy heavy effect. It has a totally unique tone all its own. It can also be used as a clean boost with no low end loss.
HAO Sole Pressure: The Sole Pressure was made to emulate a vintage Fender '59 tweed Bassman. It doesn't have a super high amount of overdrive but IMO, it certainly has more than enough. There's no low end loss with this one so it also makes a great bass overdrive. The toggle at the top has warm, bright and normal modes and they all sound really good.
DAM Meathead Deluxe: This two transistor is a very simple, yet effective overdrive/fuzz circuit. The input first goes thru the filter to determine what frequencies go thru the amplifying and fuzz circuit. it has tons of low end, and if desired can get a heavily fuzzed bass tone. when set properly, It'll do the exact same tones as DAM's popular single knob Meathead, and Dark Meathead but, in my opinion the additonal controls make it more versatile and give you alot more control.
HAO Rust Ride: The HAO Rust ride originally comes with just one volume knob and a three way warm, bright, normal switch and the overdrive/fuzz gain is preset. I modded mine and added a drive control to mine so it can go from clean to very dirty. This is a very smooth overdrive with no low end loss that sounds great and is extremely simple to operate.
BJFE Model G: The Model G stands for "Gibson" but IMO, this pedal is so much more. No low end loss, with a gorgeous overdriven tone, using LEDs and 2N5457 JFets for the clipping. The controls are "C", which affects the mids and top end (kind of like moving a mic around a speaker). "D" = drive adjusts the amount of overdrive. "N" = Nature determines the frequencies that are clipped (CCW lot's of low end, CW thinner/tighter), and Volume. I'm really digging this one.
Roger Mayer Axis Fuzz: I personally dig every pedal that Roger Mayer makes. This one sounds great with a bass and has no low end loss built completely stock. With only two controls, it's very simple to get a great sound out of it, from a light overdrive to a heavy fuzz. It's a vintage design that sounds very 'old school' using two BJT's (a PNP 2N3096 and an NPN 2N3094. For the 2N3904, I used a 2N2222A in mine and I think that it sounds better than the 2N3904.
BJFE Model H:  Another great pedal from Bjorn. The Model H stands for "HiWatt" which is what this pedal was designed to sound like. The Drive control goes from a light overdrive set at minimum, to a fairly heavy overdrive set fully CW The Tone control goes from warm and smooth (CCW) to more mids and highs (CW), but the entire range still retains the low end. This one uses a CA3130EZ chip for the main amplifier and 2N5952 JFets for the buffers and part of the clipping circuit.
LPD MegaDEN Bass Fuzz: This is a pretty obscure Bass fuzz pedal designed by Lawrence Petross that sounds awesome. It actually can be used as a very light overdrive, all the way to a heavy fuzz. It uses a quad Jfet opamp (TL074) for the amplifier stages and two BJT's (2N3904's) with a 1N4148 for the overdrive/fuzz section. It also has a seperate clean level that allows you to blend in your 100% clean tone with the overdrive/fuzz. The fuzz also has it's own tone control for further shaping the pedal's overall tone.
Mad Professor/BJFE Fire Red Fuzz: Since they are all so good, I'll build every one of Bjorn's pedals that I can get the schematics for. This one is Bjorn's take on a Big Muff. It uses different transistors, a Jfet clipping stage (2N3819's), a diode clipping stage (1N4148's) and a JFet output stage 2N5485). No low end loss and the tone can go from dark, to very slighly scooped, to mid humped, to bright and thin.  IMO, it's an awesome sounding fuzz pedal for guitar or bass.
Ibanez BS10 Bass Stack: Ibanez introduced this one in the mid '80's for us bass players. There's no end loss with it and it sounds absolutely great. Some say that it's a Bass Rat but it doesn't sound like a Rat at all to me. It can go from clean, to slightly overdriven to heavy distortion. Its distortion is very smooth. It uses two 2SC1815 BJT's, a 5534 chip and a Jfet for the circuit. Unfortunately, it was discontinued in 1989 so if you can find one used, I highly recommend it.
Boss OD-1 (modded for bass): The Boss OD-1 has been around for a long time, but it doesn't make a very good overdrive for a bass. After building the BYOC modded version, and being completely disappointed with it, I decided to make my own version. It's a very nice sounding overdrive now, with the added bass and treble tone stack, OD level control and a clean blend. I also added an output boost so it can be used as a very transparent clean boost with up to 40db of boost as well.
MXR Custom Badass '78 Distortion: MXR's CBA'78D is based on being a Keeley modded Boss DS-1., and then modded a bit further. It also has a crunch switch that removes an additional pair of 1N4148 clipping diodes for more dynamics/harmonics. Using a TLC2262 opamp instead of the usual JRC4558D, IMO, it's a very nice sounding distortion pedal. It has a little bit of low end loss with a bass but it's still  very thick and fat sounding so I decided to keep this one completely stock
CMATMODS Brownie: AKA as a slightly different GGG BSIABII (Brown Sound in a Box), the Brownie is a high gain distortion pedal using 5 Jfets for it's tone and distortion. I added more low end and a contour control to control the mids. This is a really nice sounding high gainer that's also low noise considering how much distortion you can get out of it.
Fooltone SIXTYNINER (early version): This is simply a modified version of a germanium Fuzz Face. I own a now discontinued original large box version so I built this one to see if I could make an exact clone of it. It was a complete success! I used NOS red dot NKT275 transistors just like the original. IMO, this is a germanium fuzz face that has lots of low end and captures the 1969 Fuzz Face tones, and with the added bias and contour controls can go way beyond it.
Fooltone Sole Blender: A remake of a modified version of a germanium Vox Tone Bender by the a foolish company. The tone control's rotation works in the opposite direction of most tone controls (CW has more bass) and with the tone control all the way up, it has no low end loss. IMO, this is a very gnarly fuzztone for bass that sounds great.
Ampeg A3 Overdrive: The A3 is a very little known and rare overdrive offered from Ampeg during their Japan MTI era. The circuit is also the same as a Rozz R-3, a Westbury W-05 and a Guyatone PS-005. It has plenty of low end, but I found it to be a little mushy so I modded mine for a smoother and more articulate overdrive using a stacked set of NE5532's, and slightly revoiced the frequency response of the drive section.
Pics of 48 of my factory built OD/Distortion/Fuzz pedals below (click on the pics for a larger image and/or a short review)
Brimstone Audio
Source Audio
Creation Audio Labs
Holy Fire
Source Audio
MW Bass Dist. Pro
Seymour Duncan
SFX-11 Tube OD
Way Huge
Pork Loin
Digitech Hardwire CM-2
Red Ripper
Source Audio
Classic Dist Pro
Electro Harmonix
Bass Big Muff
Real Tube
Tube Driver
Dan Electro
Cool Cat
Wave Cannon
Dallas Arbiter
Fuzz Face (ge)
Bad Monkey
Ultimate Octave
Mad Professor
Blueberry Bass OD
Vintage TS9
Ultimate Drive
Made in Japan
Vintage Fuzztone
Electo Harmonix
'78 IC Big Muff
TC Electronics
Nova Drive
Source Audio
SB2 MW Dist.
Fuzzy Drive
VT Bass
Bass Dist. MDI-2
Bass Driver
Full reviews of all of them will be posted as time permits.
James Lomenzo
Dark Driving
Barber Deep Fryer: Dave Barber's pedals are always something special, and I love the sound of every one that he makes. This one is no exception. The Deep Fryer was designed specifically for bass. It has a unique circuit and, IMO, it's drive and overall tone is gorgeous. It's very smooth, yet ballsy. There weren't all that many made (a very limited run) and I believe that this model (V1) was discontinued in 2002 so they're pretty hard to come by. I was fortunate enough to have one sent to me for repair, which after I  got it sorted and heard it, I just had to build one for myself. Now I see why bass players that own one don't sell them. It's that good.
Barber Deep Fryer MODDED: Since I love the Deep Fryer, I located the original schematic of Barber's Tone Pump, and a reverse engineered schematic of Barber's Small Fry, and incorporated their combined features into a Deep Fryer, of which I call my modded version the "Deep Fryer Deluxe EQ". It includes the internal presence and 'note shape' trimmers of the Small Fry, and the external mid and bass controls from the Tone Pump. This is an awesome sounding bass OD/Distortion pedal that I like just as much if not  more than the Deep Fryer V1, and that's saying ALOT!
Click on pic above for review
Click on pic above for review
Click on pic above for review
One of my top 10 favorites of all time!.
Mostly on the 'synthy' side but still very nice.
An excellent sounding bass overdrive..
100% tube audio path that sounds great.
Muddy stock, but after a a single capacitor mod, it's great.
A nice reasonably priced OD for bass.
Decent, but not the best you can do for the money or size.
A cool sounding pedal with mixable enveloped OD
An awesome sounding OD/Dist/Fuzz pedal,  & super versatile!
Another one of my favorites!
Cool for guitar, but IMO, not good for bass.
An awesome fuzz face for bass!
Awful!. Mid scooped, muddy, fizzy with a horrible OD decay
Not the greatest thing that MXR has to offer.
Can be a nice muff if you spend some time with it.
I dig this one. Real Tube feel and sound.
DanE's Timmy clone. Great for the money.
Super nice, versatile and ballsy sounding
Not the best fuzz for bass.
Terrible for bass stock. Okay if modded.
Cool on guitar,. terrible on bass
Another one of my all time favorites. Gnarly!
Not quite as good as the original, but still very nice
Vintage and unique.
Sounds like a cocked wah
Terrible for bass stock. Okay if modded.
OCD clone but  better for bass. BEST BUY!
BDDI exact clone. Lousy stock, decent modified
Simple, crazy Japanese fuzztone.
IC BMP. Not great on bass
Nice OD pedal for bass.
Didn't like it until I modded it.
Mostly on the 'synthy' side but still very nice.
OK with a bass but a bit too fizzy of a decay for me.
I still really like this one if not pushed too hard.
Great sounding but the controls are pretty touchy.
Inexpensive and great sounding. Well worth buying.
IMO, not bad, but nothing to write home about.
Not great, but very good if you spend some time with it.
3BOD/Honey Bee Hybrid only darker. Very nice though.
Click on pic above for review
Alembic F2B Jfet: I built this one to be a Jfet version of the venerable Alembic F2B and it sounds nearly identical to the tube original. I also added an Emerson EM Drive that it switchable in and out to give it some overdrive should I want it. This is more of a tone enhancer that gives my basses more punch, low end and presence. it can also be run as a transparent clean boost or a mild to moderate overdrive. Below is a quick clip showing just some of its various tones.
Bass Driver Preamp: This one started out as a Sansamp BDDI clone but I really don't care for how scooped they are so I made some major mods to it. Instead of a presence control for the already scooped overdrive section, I made it a pregain upper mids control. I also removed one of the  filters in the front end and one of the speaker sim ones in the back end so it would sound more 'natural'. Finally, I completely reworked the fizzy sounding overdrive in it so it's alot smoother. It actually came out to be pretty nice sounding with all of the mods done to it now.
A little low end loss but still very nice for bass.
Supa Nova (a J. Nagy design): This little known pedal sounds great, especially after modding it for more low end. It uses a Mosfet transistor (BS170) to drive two Jfets (J201's) into OD/distortion followed by a BJT (2N5088) to boost it's output. Featuring mid and treble controls as well as a bass boost switch, this pedal is very dynamic and tube amp-like in it's response. Soundclip coming soon.
Fuzzrocious Rat Tail: My clone of this highly modified vintage ProCo Rat distortion pedal using the LM308 chip and a Jfet for the tone recovery amp stage. Along with the standard volume, filter and distortion controls, it has two extra controls named 1 & 2 that control the frequencies that get clipped for more tonal versatility. It also has a 3 way clipping switch that selects between the stock pair of silicon diodes, none, or twin leds.(internal pic of mine). Ryan Has informed me that the new ones use a PCB and are built a lot nicer than his early ones (see pic HERE)
Click on pic above for review
American Sound
MI Audio Tube Zone: Now discontinued, but a really versatile OD/distortion pedal that sounds great with a bass. It uses an LM833 opamp and gets its distortion from a couple of places in the circuit with its dual 50K audio gain pot. The controls allow a ton of tonal variation. 'Character', which is a pre-distortion bass control, 'Mids', 'Bright' (treble) and Tone all have a big effect on its overal sound and on top of that, it has an internal presence trimpot. From clean to heavy distortion, there's no low end loss with this one!
Nobels ODR-S: A really nice overdrive that sounds great with a bass. With a Lo, Mid & Hi tonestack, this pedal can go from  transparent clean to a heavy distortion. It's circuit uses two JRC4558 opamps with a silicon pair of diodes clipping in the first clipping stage, and later a second germanium clipping stage.
Joyo JF-16
British Sound
Another great sounding OD from Joyo..
Skreddy Supa Tone: Skreddy's take on a modified Big Muff. It uses four BC183L lo gain transistors with only one diode clipping stage instead of two. It also has a scoop/flat switch for the tone control. This turns a BMP into more of an overdrive/distortion rather than a fuzz, and the tone circuit has a wider range of tones than a standard biff muff. Skreddy recommends it for guitar or bass so there's little, if any, low end loss with this one.
Nobels ODR-1: I really love this one and they aren't very expensive. It's a very natural sounding overdrive and can go from clean to mean! No low end loss and a super nice sounding grind to the overdrive which can go from clean, to mild to a very heavy distortion.
Earthquaker Devices White Light: Based on a DOD 250/MXR Distortion + circuit but with some major improvements.Instead of the old LM741 chip, it uses  half of an LM833N, it also has a unique 'Weight' control which adds a ton of low end before the overdrive (there's NO low end loss with this one!). Along with the standard asymmetrical standard clipping, it also has a 'comp' switch which clicks in four more germanium diodes for more dirt and compression. An awesome sounding pedal for bass that can go from clean to heavy distortion.
Atlantis (V2) BOD: Another overdrive that I  came up with after alot of experimentation. This one is based on the OCD (V4) but was modified for no low end loss, made some mods to the voice and gain of the drive circuit and used a different opamp. It has mosfet & germanium asymmetrical clipping and a baxandall tonestack. I'm really pleased with how it turned out.
Atlantis V3 BOD: While I really like the way that the Atlantis V2 came out, I wanted to try a tilt control instead of the baxandall treble and bass tonestack, and I actually like this one even more. The V2 is a bit more 'hard' and nasty, whereas the V3 is smoother and more sophisticated sounding. the tilt control is centered at 900Hz and goes from adding lows and reducing highs CCW, to flat in the center, to cutting lows and adding highs clockwise. Along with the OCD's tone control, it makes it a much more versatile pedal capable of a lot more tones.
Demeter Fuzzulator FUZ-1: This often overlooked offering from Demeter is a great sounding pedal for use with a bass. It can go from a clean boost to a mild overdrive to a heavy fuzz. It also features a loose/tight switch which changes the tone and amount of the clipping using a combination of led, silicon and  germanium diodes. It's very smooth & touch repsonsive with excellent note definition.
TODD: TODD stands for Transparent OverDrive Deluxe. It's based on the Runoffgroove Peppermill but I modded it for bass and added a three way clipping switch with options for twin red leds, none and four germanium diodes. It uses a mosfet for the input stage, driving a Jfet  to get its tube-like and touch responsive tone.
Shin's Music Dumbloid 'Special': The original pedals sell for $600 from Japan and were designed to sound like a Dumble Amp. While I personally don't think that they do, it does still sound really good. I mounted mine in a smaller enclosure. It has a very nice and ballsy feel to it and the note harmonics have a nice bloom when they sustain. The original uses a Burr-Brown OPA2134 op amp, and while they usually are a big improvement over standard dual op amps, I hated it in mine so after testing it with 40 others, the MC33172 sounded the best by far.
Acoustic 360 Fuzz: After drawing up a circuit layout for this pedal from the vintage Acoustic 360 preamp's fuzz section, I then modded it to run on 9V. Using all of the same NOS transistors and components, it sounded pretty good but felt that it still could use an eq and a clean blend. I added a 'tilt' tone control and a clean blend, as well as a Jfet output booster to give it even a little more output. This one's a very unique sounding germanium fuzz that can add slight upper octaves.
Bass Tightdrive
Didn't care for it w/o the blend, but with it, it's very nice.
A 3-way crossover distortion with 3 separate OD's.
Bass Fat Drive
A nice, fat & heavy CMOS overdrive running on 18V
Rat based, but a zillion X better! IMO, one of the best rat type pedals made.
1973 S.Hawk I
A very nice, vintage transparent OD/Booster
JHS Superbolt: JHS pedals are famous for 'borrowing' other circuits, then renaming them and taking credit for the design. The Superbolt is actually a slightly modified Runoffgroove Supreaux V1 which is a Supro amp emulator. This one includes and internal 18V charge pump and a 'fat' switch for more low end. I actually modded mine for use with a bass for no end loss and it's a great sounding pedal now.
Bixonic Expandora: This discontinued pedal is probably best known for Billy Gibbons using it. It's kind of a Dual Rat (two LM308N's) with a very unique opto expander drive circuit (using a Sharp PC419). The two toggle switches select different amounts of crunch/drive. I found it to cut too much low end and highs so I modded it for no low end loss and added back the top end, so it's a  cool sounding overdrive fuzz now. T^he originals came in a round enclosure but I built mine in a smaller polished aluminum 1590BB.
SOBOD (Sparkling Orange Bass OD/Dist): Starting with a few different BJFE & Bearfoot pedals as the basic circuit, I modified this one to my own specs (gain structure, overall tone, and filtering). It can go from clean, to a mild overdrive, all the way up to a heavily saturated distortion. It's designed for a bass but it also sounds great with a guitar. The controls are: mid, treble, distortion and volume  and it's very amp-like in its dynamic response.
Earthquaker Devices Monarch: The EQD Monarch Overdrive was designed to emulate the sound of a Orange amplifier. It's a very nice sounding light to medium OD for guitar or bass with a teeny bit of low end loss, but I decided to mod mine for a full low end.
Bearfoot (BJFE) Emerald Green Distortion Machine: Yet another a great sounding and very dynamic Vox amp emulator/overdrive from BJFE/Bearfoot Surprisingly, it didn't require any mods for more low end. The Controls are "voice' which boosts or cuts bass, Treble for adding or reducing the top end, Distortion and Volume. It uses two Jfets with a germanium 2N1308 transistor in between them.
FETF2B: Another FET version of the Alembic F2B but this time, without the extra overdrive, mounted in a smaller 1590B enclosure. This is NOT an overdrive but can be used to push your amp's front end into clipping since it has a TON of output. This pedal can be run as a clean/transparent boost or be used to enhance and thicken up your tone. A very limited production of only 10 is available HERE.
Goosoniqueworx SEVENTHEAVEN: This one emulates a Bogner Ecstasy amp. It sounded great with a guitar but needed to be modded for bass use. Running on 18V with its internal charge pump, t features Volume,Presence, Treble, Mids, bass and Gain controls, along with a 'Structure' switch that increases the gain and an extra boost footswitch for even MORE gain. After the mods, it sounds great with a bass now.
Ramble FX Marvel Drive: A great sounding Marshall emulator. This one has no tone controls but rather the dual inputs of a Marshall amp jumpered together. It surprisingly makes a great bass overdrive/distortion pedal. Volume I is the bright channel, and Volume II the 'Normal" (full range channel). it can go from nearly 100% clean to an extremely dirty Marshall amp running at full tilt.
Way Huge Pork Loin: I had an original one of these but sold it since I found it to be too muddy/dark sounding. I later decided to build a clone of one so I could mod it to be more of what I wanted. so I bought another original to analyze it. By changing just one capacitor in the summing amp, I was able to open up the top end and now I really dig this pedal. By the way, the clean side is basically the identical circuit found in the coveted Neve 1073 module.
slo100: A very high gain distortion pedal that emulates a Soldano SLO100 amp (using Jfets). It can almost get perfectly clean and is capable of very light overdriven tones too. It cuts a tiny bit of low end but it does sound awesome.
Way Huge Fat Sandwich: I built this one following the schematic exactly but I moved the internal 'curve' trimpot to be an external control. I also mounted it in a smaller 1590B enclosure. Although it is a very nice sounding distortion pedal, this one does cut quite a bit of low end so I really can't recommend it for use with a bass. I later modded it for more low end, but it still has some low end loss.
ProTone Body Rot II: This great sounding distortion pedal is based on a 386 amplifier chip, however this one DOES NOT exhibit the fizzy decay that 99% of the others that use that chip have. I modded it for more low end so it has zero low end loss now, and I really dig this one
TC Electronic Spark Booster: The Spark Booster is actually a clean booster but it is capable of light to moderate overdive sounds too. Along with the gain, treble and bass controls, it also has a 3-way switch with fat, clean, and mid boost settings. It has a lot of output so it can also be used to overdrive the front end of your amp and there's no low end loss with this one. I found it to be a little dark so I modded mine for more top end and also moddded the fat and mid settings for more gain.
Green/Matamp Amp Simulator: This one is very similar to the Orange amp emulator with a slightly different tone stack that is post gain stage (the Orange's tone stack is pre-gain stage). Four Jfets (two J201's and two 2N5457's) are used to simulate the tubes and it has a TON of low end if you want it. It's and excellent sounding preamp/OD for bass use.
Blackarts Toneworks Quantum Mystic: An overdrive/distortion pedal that can go from clean to pretty heavy.distortion. It features a Treble, Middle and Bass tonestack and has a TON of low end. Two TL072 opamps driving a pair germanium clipping diodes yield a smooth and rich harmonic distortion.
Ibanez TS808 Bass: Another TS808 Tube Screamer, only this time with seperate Treble and Bass controls, plus a 3-way clipping option switch. If you like Tubescreamers for guitar but don't care for them on bass, this one just might change your mind about that.
Maxon Distortion Master DS-830:  The Maxon Distortion Master is an often overlooked distrotion pedal. It's not just a distortion pedal since it can go from perfectly clean, to a mild overdrive, and all the way to a heavy distortion. It sounds really nice with a guitar but I found it to be a bit too boxy for bass, cutting some low end. By replacing a single capacitor to lower the bass control's frequency, it's an awesome sounding pedal for bass use now.
Darglass Vintage
Micro Tubes
Click on pic above for review
Himmelstrutz Gramps+ Fuzztortion: Using three Jfets (2SK170-GR's), this distortion./ Fuzz pedal has no low end loss. Along with the treble, tone, cream (gain) and volume controls, it also has a 3-way 'Temp' switch (temperment) that slightly changes the nature of the drive as well as a gain switch that adds more gain. It's a very unique sounding distortion pedal that yields more of a 'vintage' type of tone.
Frantone Bassweet: Fran Blanche used to work for and design pedals for Electro Harmonix so it's no surprise that this fuzz is based on a Big Muff but with quite a few changes made to it, inlcuding a pair of germaniun transistos in the dual distortion circuit. I has a TON of low end. I modded mine with a bypassable mid control so I can run it 100% stock, or boost the midrange. I would consider it a heavy & thick fuzztone. They are no longer available are are pretty hard to come by these days so I just had to build one for myself.
Skreddy Mayonaise MKIII: And yet another Big Muff variant, but this is one of my favorites. It uses four vintage NOS SE4021 transistors, all carbon comp resistors and ceramic capacitors. It has a ton of low end and sounds like a vintage (triangle) Big Muff. Marc really did his homework on this one (view the gut shot HERE).
Zvex Distortron #2 (modified): This is my second build of Zvex's Distortron, and I like it even better than my first one. This time, I not only modded it for bass use (lowered its 'voice'), but I also removed the 'crackle okay' from the drive control so when the gain is adjusted, there's NO noise. This one has the 2-1-3 subs switch and the LO/HI gain switch and it sounds awesome on bass. The internal pic can be seen HERE.
Very nice Mosfet OD/Distortion. Basically a modified Distortron.
T-Rex Mudhoney: The Mudhoney is actually mostly based on a Rat but it sounds completely different. It uses an OP07CP chip (like some later Rat versions) but also has two BJT transistors (BC546B's) used as buffers on the input and output stages along with a Jfet (2N5457) on the output of the OP07CP after the tone control. I modded mine for no low end loss and IMO, it's a great and smooth sounding OD/distortion pedal now. The gut shot of this build can be viewed HERE.
Basic Audio Scarab Deluxe: Basic Audio has created a 'modern' tonebender type of fuzz with this one, only it';s capable of a lot more tones than a Vox Tonebender. Along with the usual volume, tone and fuzz controls, the Scarab Deluxe also has a bias control that enables it to go from a smooth, a gritty fuzz to a gated fuzz and the the fat control yields anywhere from a slower fatter distortion to a tighter snappier one. It's a pretty darn cool vintage sounding fuzztone without the hassle of using PNP germanium transistors or a negative voltage power supply.
idiotbox BlowerBox: Based on a ProCo Rat but with active treble and bass controls so it really doesn't sound like a rat anymore. I built this one after buying the original, larger 1590BB one. The new ones are in a smaller 1590B just like mine with all of the controls on top. This pedal can get really sizzly if you run the treble up and can have a ridiculous amount of low end running the bass control up. So far, it's one of my favorite Rat incarnations to date. ( the gut shot pic can be viewed HERE).
Runoffgroove Britannia: This one is a very well designed Vox AC30 Top Boost emulator so it's not really suitable for bass and it sounds so good on guitar that I didn't want to mod it for bass use. The DIY build info is HERE. I etched a PCB for this one which IMO, made it a lot easier to build since all of the pot wiring is done on the PCB. The gut shot pic can be viewed HERE).
Chunk Systems Brown Dog:  From Australia, the Chunk System's Brown Dog is a gated fuzz specifically made for use with the bass guitar. With the gate control, you can vary the amount of gating, from none to very heavily gated. It features separate level controls for the clean and fuzz which can go from mild to wild. It also features an envelope output to sync with their A00Funk pedal for even more synthy sounds.
(gut shot shown HERE)
Dead Astronaut Space Patrol Fuzz:  The Space Patrol Fuzz is basically a Big Muff, but with some really cool mods. Besides the hi/lo tone switch for more low end, it also has a 4 way rotary that switches between: Fuzz, Synth (octave) Fuzz I, Duck and Swell, and Synth (octave) Fuzz II which opens up a whole new range of sounds. The original comes in a 1590BB but I squeezed mine into a 1590B. (the gut shot shown HERE)
MXR El Grande Bass Fuzz: The El Grande is based on the Biff Muff but with A LOT of changes to the circuit. First, it uses dual-paralleled transistors for the first four gain stages. Its tone control circuit doesn't have the huge mid scoop, and then is followed with a selectable frequency and variable Sub boost/cut stage I brought all of the internal switches and boost/cut control to the outside of the pedal, which IMO, makes it a lot more versatile. IMO, it's a very nice fuzz pedal for bass. The gut shot pic can be viewed HERE).
Human Gear Animato:  The elusive Animato circuit has finally been analyzed and a schematic drawn out by Adam Crowell. Much of it's circuit is similar to a modified Big Muff, but the input stage is a germanium Sziklai  pair going into a dual drive pot. I built one stock and another with an added tilt control for more tonal options and it sounds great with a guitar or bass.  (the gut shot is shown HERE). I am making only 10 of these pedals for sale. More info on them is: HERE
Bearfoot Blueberry Bass Overdrive: The BJFE Blueberry is highly coveted and very hard to find these days since they've been discontinued, and even if you do find one, they command very high prices. Fortunately Bearfoot recently introduced their version which sounds very close to the original so I built one of my own using a friend's to clone the circuit. It's a low gain OD but it does sound really good. The gut shot pic can be viewed HERE).
Vox Trike
A heavy and unique Octave fuzz with -2, -1 and +1 octave settings!.
Boss DS-1 (Keeley modded):  The stock DS-1 isn't all that thrilling with its vanilla sounding distortion so I performed the Keeley mod on mine, and then gave it a little more low end. After the mods, it turned an inexpensive, mediocre distortion pedal into and excellent one both for guitar and bass.
Way Huge
Green Rhino
The GR is a modded tube screamer with much more tone control & is nice with a bass!.
Electro Harmonix
Behringer SF300
Super Fuzz
EHX's clone of a Fulltone OCD only better!
Behringer's Super Fuzz sounds great and is way more flexible than the originals
Rockett Pedals WTF Fuzz: Designed for Rockett by Paul Trombetta, the WTF (i.e. What The Fuzz?) is a really cool fuzztone. The gain and volume are self explanitory but the real charm of this pedal is the "WTF" control which basically 'starves' the circuit. It can get pretty wild gated tones when you turn it up and with the 'G@!N turned down its does some sub-octave stuff too.I can't believe how many tones that you can get out of this tiny circuit. Kudos to Paul Trombetta for this one!  The gut shot can be viewed HERE).