COMING SOON (already built and tested, but not boxed yet):
Clones: Wattkins RF DRIVE, Mr. Black OVERDRIVER, Runoffgroove 22/7, Roger Mayer STONE FUZZ, Colorsound OCTIVIDER, Devi Ever TORN'S PEAKER, Carllin COMP/FUZZ, Catalinbread FORMULA no5, Fred Briggs E11even, Divided by 13 JOYRIDE,  Lotus Pedals SNOWJOB, Sadowsky PREAMP, BJFE FOLK FUZZ 3.5%, Devi Ever STONE FUZZ, Roger Mayer OCTAVIA, 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 Silicon FUZZ FACE (modded), Mictester's BUZZAROUND-ALIKE, Xotic EP BOOSTER, D*A*M RED ROOSTER, Catalinbread  SAGRADO POBLANO PICOSO, Wolf COMPUTER FUZZ,  Death by Audio FUZZ WAR V2 (4 transistor version),, Death by Audio FUZZ WAR (7 transistor version) and many more.................

Manufactured pedals:
SOUNDCLIP COMING SOON!
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.
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.
SOUNDCLIP COMING SOON!
SOUNDCLIP COMING SOON!
SOUNDCLIP COMING SOON!
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.
SOUNDCLIP COMING SOON!
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
SOUNDCLIP COMING SOON!
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.
SOUNDCLIP COMING SOON!
Fooltone Sole Blender: A remake of a modified version of a germanium Vox Tone Bender by 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.
SOUNDCLIP COMING SOON!
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.
SOUNDCLIP COMING SOON!
Pics  of my factory built OD/Distortion/Fuzz pedals below (click on the pics for a larger image and/or a short review)
Brimstone Audio
XD-1
Source Audio
OFD
Darkglass
B3K
Creation Audio Labs
Holy Fire
Source Audio
MW Bass Dist. Pro
EBS
Multidrive
Seymour Duncan
SFX-11 Tube OD
Way Huge
Pork Loin
Digitech Hardwire CM-2
Fender
Sublime
Tech21
Red Ripper
Empress
Multidrive
Source Audio
Classic Dist Pro
Fulltone
'70
Fulltone
'69
Tech21
ParaDriver
MXR
Blowtorch
Electro Harmonix
Bass Big Muff
Real Tube
Tube Driver
Dan Electro
Cool Cat
Caroline
Wave Cannon
Dallas Arbiter
Fuzz Face (ge)
Digitech
Bad Monkey
Fulltone
Ultimate Octave
Greedtone
Overdrive
Mad Professor
Blueberry Bass OD
Ibanez
Vintage TS9
Systech
Overdrive
Joyo
Ultimate Drive
Behringer
BDI21
Made in Japan
Vintage Fuzztone
Electo Harmonix
'78 IC Big Muff
TC Electronics
Nova Drive
Boss
ODB-3
Source Audio
SB2 MW Dist.
EWS
Fuzzy Drive
Catalinbread
SFT
Tech21
VT Bass
Arion
Bass Dist. MDI-2
Digitech
Bass Driver
Full reviews of all of them will be posted as time permits.
Ashdown
James Lomenzo
Fuzzrocious
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
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.
Aguilar
Agro
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.
Fulltone
OCD V4
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
JOYO JF-14
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.
Amptweaker
Bass Tightdrive
Didn't care for it w/o the blend, but with it, it's very nice.
VFE
BassTriumverate
A 3-way crossover distortion with 3 separate OD's. NICE!
Pigtronix
Bass Fat Drive
A nice, fat & heavy CMOS overdrive running on 18V
Idiotbox
BlowerBox
Rat based, but a zillion X better! IMO, one of the best rat type pedals made.
1973 S.Hawk I
Booster/OD
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. The 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, it 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
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.
Zvex
Basstortion
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). My original Brown Dog can be viewed 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
Fuzz
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
Glove
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).
Gallien Kreuger 800RB poweramp simulator:Frank Appleton from fealabs.com makes some awesome pedals. This one was created on the talkbass forum using the actual GK 800RB schematic as a starting point, and then tweaked to turn it into a pedal. It's capable of being a high gain clean boost, an overdrive, or a heavy distortion pedal. It's dynamics are very amp-like at the lower gain settings and is very punchy. It's controls consist of an input level , master output, boost level and a 3 way hi-cut filter.(The internal pic can be viewed HERE).
Transboost: Another one of Frank Appleton's creations and I really dig it. This one uses a small output transformer just before the final output amplifier stage to yield transformer saturation as found in a tube amp. It can be used as a clean boost or a mild to moderate overdrive and I just love playing thru it. The controls consist of a 'Clip'  (for softer more compressed clipping), a 'Drive' control for more gain/distortion and a master 'Output' level.The gut shot pic can be viewed HERE).
Darkglass 'designed & inspired' B4K: Doug Castro of Darkglass Electronics makes some very well loved pedals by bassists. After buying two of his B3K's and a vintage microtubes I found that their tone just didn't suit my tonal goals at all so I found an old circuit that he posted on the DIY forums of the B3K's predecessor, called the B2K. I then revoiced it with a smoother/flatter frequency response, modified the gain stages, and added a blend control.  I call my version the B4K. I love the sound of this one now.The gut shot pic can be viewed HERE).
Acoustic 360 Germanium Fuzz: This one is the Acoustic 360 Fuzz with slight modifications by moosapotamus. It's a pretty darn cool sounding fuzz that's unlike any other. I added a relayed true bypass to it, but other than that it follows his schematic exactly. The internals of this pedal can be viewed HERE).
Lovepedal Les Lius: The Les Lius is another take on the Electra Fuzz only with quite a few modifications. It emulates a tweed Deluxe 5E3 circuit, a Tweed Twin, plus has an additonal, more distorted setting. I modified my version a bit further with a high/lo gain switch (so it can get a bit cleaner) as well as added a clean JFet boost on the output to compensate for the lower output level of the hi-distortion setting. It also has two relays for the true bypass and boost footswitches. IMO, this pedal sounds awesome with a bass.The gut shot of this build can be viewed HERE).
Dr. Scientist
The Elements
An awesome OD/Distortion Pedal for bass. I LOVE this one!
Earthquaker Devices Talons Overdrive: This is a very nice sounding overdrive with a guitar or bass with no low end loss. I built this one using the exact factory schematic and it required no modding at all. The controls are: level, presence, drive, treble, mids and bass. I added a relayed true bypass to my version but it's otherwise 100% stock  The internals of this build can be viewed HERE).
Mad Professor Amber Overdrive: Another cool design from Bjorn Juhl. After building the Amber Overdrive completely stock,  I found it to cut way too much low end for use with a bass so I modded mine to have no low end loss, calling my version the 'Dark Amber'. This is yet another variation on a Big Muff but with 2N3819 Jfets in the first clipping stage and 1N4007's in the second. The tone control is completely different too, followed by a 2N5485 Jfet recovery amp stage. After the mods, I really dig this one. The gut shot of this build can be viewed HERE).
Catalinbread Sabbra Cadabra:  Here's a cool sounding fuzz pedal with no low end loss. It's a custom tuned Rangemaster based booster, combined with the pre-amp section of a Laney Supergroup and was designed to emulate Tony Iommi's tone. The Range control varies between a treble booster to a full range boost. To tame the distortion, just roll back your bass's volume control for less dirt and more dynamics. I added a relayed true bypass to this one. The internals of this build can be viewed HERE).
MI Audio GI Fuzz:  I love this one. The GI Fuzz is a flexible high gain fuzz pedal with an ability to create anything from fat bluesy tones, to all-out sustain, to gated, synth-like bleeps. The controls: FUZZ: From nothing to all out fuzz LOAD: input impedance control, BIAS: controls the bias of the 2 transistors BODY: midrange control, TONE:Balance to control highs and lows, VOLUME: to control the output volume GAIN TRIM (INTERNAL): To tame this pedal, the internal gain trimmer is to wind things back.The gut shot pic is HERE).
Creation Audio Labs Grizzly Bass
Their 9V Holy Fire with a mid scoop control. IMO, it's a great pedal!
Electro Harmonix 'Civil War' Big Muff: With original Russian Civil Wars going for ridiculous prices these days (up to $900!) I just had to build one to see what all the fuss (or fuzz) is about. I used the same original and obsolete NOS Russian transistors (KT3102) and clipping diodes (KD521A) in mine. I actually found it to lack some mids (as almost all muffs are very scooped), so I did one mod on my version to bring them back and it's an awesome fuzz pedal for bass now. The gut shot of it can be viewed HERE.
Bugbrand Bug Crusher: This one is not really a fuzz but rather a bit crusher (signal mangler!) but the result is that it does sound really fuzzy. They are no longer made and very hard to find (extremely rare) so I built one for a very good client that searched ages for one. The rate control, controls the frequency of the 'crushing'.  I also added a clean blend to it along with all top mounted in/out/DC jacks. The gut shot of this build can be viewed HERE).
BJFE Blueberry #3: My 3rd version of the BJFE has a couple of mods. Since I find that the originals are a little low on output, I added a clean boost to mine so it has a TON of it now. I also added a relayed true bypass to this one. The gut shot pic is HERE).
Catalinbread Merkin Fuzz: Catalinbread's Merkin is loosely based on a Mosrite Fuzzrite  but it has an added transistor with 'Texture' control which is a really cool feature that takes a Fuzzrite to a whole new level.. It's a totally 60's sounding fuzz! I found that on some texture settings that it lost too much low end so I added a bass boost control to mine. Fully counterclockwise it's stock, and fully clockwise, it adds +15db at 100hz. The gut shot pic is HERE).
Elka Dizzy Tone: The originalElka Dizzy Tone was made in Italy the late 60's. Its circuit is similar to the Baldwin- Burns Buzzaroun. Using 3 germanium PNP transistors with a positve ground, the originals were only battery powered so I installed a voltage inverter in mine in order to run it on a standard 9V power supply. I also added a status led and a relayed true bypass, all in a small 1590B enclosure. There's no low end loss with this one and it's an awesome fuzz  for bass. The gut shot pic is HERE).  I am making very limited supply of this version available HERE
Shin Ei Fuzz Companion FY-2: Made in the early 70's, Japan's Shin Ei Fuzz Companions are a pretty rare find these days. They're a gnarly, buzzy sounding fuzz that reacts well with your instrument's volume control. The originals had only two controls, fuzz and volume but I added a variable scoop as well as a bass boost control since found the original circuit to lose too much low end for bass use, so I call mine the 'Bass Companion".I also installed a relayed true bypass.in this one.
Sam Ash Fuzz-Stainer MKII: A super rare fuzztone from the late 60's/early 70's, Sam Ash's Fuzz-Stainer is an Awesome sounding fuzz, especially for such a simple circuit. The originals only have 3 controls (drive, tone and volume) but I moved the internal trimmer which sets the bias of the second transistor to a pot which gates the fuzz when rotated clockwise. I also increase the output level since I found it to be a bit low. A true bypass via relay was also installed in this one. I absolultely LOVE this one! The gut shot pic is HERE).
Spaceman Gemini III fuzz: This is a really cool fuzz pedal that has both a silicon and a germanium fuzz in it with the ability to pan between either one or a mixture of both. It has a unique tone control that allows you to reverse the control on the germanium fuzz compared to the silicon one via the center top toggle switch. The originals come in a 125B enclosure but I was able to squeeze my exact clone of one into a 1590B and added a relayed true bypass (the original has a millenium bypass). The originals are built of extremely nice quality, but I'm very pleased with mine. The gut shot is HERE
Spaceman WOW Signal Fuzz: A very unique Spaceman pedal, the Wow Signal Fuzz uses an opto device to set the rate of an envelope filter sweep of the fuzz. The newest versions have more range in the rate of the LFO, a smoother fuzz and the ability to turn the LFO on or off. I modded mine to the newer specs and I like it A LOT more now, I prefer the Gemini III over it, but this one is still pretty nice and very unique. The originals come in a large 1590BB enclosure, but I built mine in the much smaller 1590B. The gut shot is HERE
Mosrite Fuzzrite no2: My second build/version of the venerable Mosrite Fuzzrite. This time I added a bass boost control as well as a relayed true bypass. IMO, this turned the standard Fuzz-rite (which I already loved) into a much more versatile fuzz, especially with a bass.  The gut shot is HERE
Ibanez OD850: An extremely rare fuzztone from Ibanez that actually precedes their infamous TS808. This one is based on a big muff but has two extra transistors, one at the input and another at the output. It also has a completely different tone circuit. It's big, fat and smoother sounding than most big muffs. The gut shot pic is HERE).
Park Fuzz Sound: A really nice germanium fuzztone based on the Solasound tonebender MKIV circuit. The originals came in a huge  enclosure and Earthquaker Devices has recently released in in a 1590B so I built mine in a 1590B as well. I added a relayed true bypass to mine and it makes a really nice vintage sounding fuzz for bass . The gut shot is HERE
LovePedal Karl Fuzz: This is a really nice and unique fuzz pedal that uses many elements of the Tim Escobedo Tripple Fuzz"Tripple Fuzz" circuit basing it's sound around that "non-selective frequency tripler" Since the PCB is so small, I used a smaller 1590G enclosure for it. IMO, it has a sound of its own. It sounds sweet at low fuzz settings, and with a higher gain there's octave and ring mod tones in it too. The gut shot is HERE
Way Huge Piercing Moose: Discontinued quite a while ago, the originals of this excellent sounding fuzz pedal are now selling for up to $650. It's based on the Foxx tone machine but I like it A LOT more. I used NOS button top 2N3565 transistors for that extra 'mojo' and I couldn't be happier with the way that it turned out. A relayed true bypass along with an octave up stomp switch allows you to switch between a standard (and nice sounding fuzz), and an octave fuzz.  The gut shot pic is HERE).
Hudson
Broadcast
Stomp Under Foot Civil Unrest
Smallsound Bigsound
Tean Awesome
Fuzz Machine
Idiotbox
Static Fuzz
Line6
Distorto
Smallsound Bigsound
Mini
Catalinbread
Super Charged
Overdrive
Boss FB-2
Feedback/Booster
TC Electronic
Dark Matter
TC Electronic
Mojo Mojo
Dr. J
Sparrow preamp
Malekko
Diabolik

Malekko
Helium
EHX
Octavix
Great overdrive / fuzz for bass or guitar
A very modifed Fuzz Face with a TON of tonal variations. No low end loss!
Fuzzy, buzzy fuzztone that woks well on bass.
A very unique fuzz & feedback sustainer but does lose some low end.
CMOS overdrive, but not very versatile and loses low end.
A pretty unique pedal that sustains your notes.
A nice sounding distortion but it is NOT transparent (i.e. it's mid heavy).
A a great Big Muff Civil War with a midrange control
A transparent and gorgeous sounding overdrive for bass.
An awesome germanium booster!
BUY ONE!
Great octave up based on the Bassmaster Fuzz!
Octavia type fuzz that sounds awesome on guitar and can sound great with a bass too.
Awesome guitar octave up fuzz, but just okay on bass
Sansamp BDDI clone but sounds A LOT better.
Keeley PSI Fuzz: Based on the opamp big muff but with quite a few changes including a germanium output stage. I really like this one! The gut shot is HERE.

D*A*M Drag'n'Fly: A great hybrid silicon/germanium fuzztone that is a derivative of the Arbiter Fuzz Face with certain combined elements of the Vox Tone Bender circuit. It's an awesome Fuzz tone for guitar or bass, period. I added a relayed true bypass to mine  The gut shot is HERE
Frantone Cream Puff: Fran always makes great sounding pedals and this one is no exception. I LOVE this pedal! It sounds frickin' HUGE.  The gut shot is HERE The soundclip below  demonstrates it better than any words that I can write.
Durham Crazy Horse: A truly unique fuzz pedal featuring first a cascaded JRC4558D into two 2N2222A transistors followed by two MPSA13's. A 'volts' control starves the opamp, but not the transistors, As its name implies,this pedal was designed to cop Neil Young's fuzzy tones but can also do a lot more. I dig it, and it has plenty of low end.  Pic of the internals is HERE
D*A*M FZ-673 Fuzz: David Main is definitely the guru of germanium tonebenders and this one proves it. He only made 10 of these, so the originals go for $700-$1000. Using PNP transistors, it's positive grounded but I installed a voltage inverter in mine in order to use a standard power supply.The FZ-673 yields all of the color and fuzz of a germanium fuzz but without the sputtery and somewhat gated decay. It took me a while to find the perfect trio of germ transistors for it but once I did, WOW! There's no low end loss with this one either. The gut shot  is HERE
Roland Double Beat Fuzz: This one is the fuzz section of an AD-50 Roland Duble Beat Fuzz-Wah pedal. I added an input level control so I could 'tame' the fuzz to have more control over it at lower fuzz settings and I think that it's a great sounding fuzz pedal for use with a bass
Prescription Electronics 'Experience': The Experience is a great sounding fuzztone in and of itself and includes a footswitchable octave up mode with it's own level control. On top of that, there's also a 'swell' mode that makes your notes fade in (kinda like a Boss Slow gear, but not as drastic). I added status leds and a rellayed true bypass in a smaller and less deep enclosure It's a GREAT sounding pedal. The gut shot  is HERE
SubDecay Flying Tomato: The Flying Tomato is a dual BJT transistor fuzz but with a few twists. First, it has a switchable input buffer that you can turn on or off. When engaged, it makes the pedal a little brighter and have more gain. It also has a bias control so you can get gated fuzztones with it too. Low and high eq controls make it even more versatile. Finally, it goes thru a JFet stage to the output. I LOVE this pedal and it has ZERO low end loss.. The gut shot  is HERE
LectricFX Mongrel Fuzz: A pretty unique circuit that uses a dual opamp driving a germanium transistor into overdrive/fuzz. I modded mine for more low end and more gain. The 'bite'  and 'focus controls both add gain and the bias sets the bias of the GE transistor. After the mods it makes a pretty nice OD/Fuzz pedal for use with a bass. Gut shot is HERE.
Devi Ever Improbability Drive: The rarest of Devi's pedals being that she only made 6 of them, it's a pretty crazy sounding fuzz pedal. I first built it stock, but then modded it for more low end. There are basically infinite tones in this one with the 1,2 & 3 controls, which add different stages of transistors, along with the two A & B switches. I made mine in a 1590B as opposed to the original's 1590BB and Infanem's 1590BB version. I also added a relayed true bypass. The internal pic is HERE.
Guild Foxey Lady: Guild's Foxey Lady Fuzz pedals are very rare these days and the originals go for big bucks. Also known as the Electro Harmonix Axis, this two silicon transistor fuzz isn't really very good for use with a bass due to its lack of low end, but once modified, it sounds awesome I also added a 'pre-gain' control to be able to tame the fuzz, or run it stock when turned fully clockwise. The gut shot of my build  is HERE.
A super good Fuzzrociuos designed RAT
Designed by Bjorn Juhl and excellent
MXR Bass
Distortion
One Control
Hooker's Green
Montarbo Sinfhoton: A super rare Italian fuzz from the '60's, this one sounds great with a bass. It features 'A' and 'B' controls which are actually treble and bass. The original has a pre-set fixed amount of fuzz but iI added a gain control to mine as well as a relayed true bypass. Gut shot is HERE.
Blackarts Toneworks Quantum Mystic: The Quantum Mystic is somewhat of a Rat circuit but with treble, mid and bass controls. It's an excellent overdrive/distortion/fuzz for bass with zero low end loss . The gut shot of my build  is HERE.
DualSil Bass Fuzz: Based on the two knob DAM GB-83 Greasebox but revoiced for bass, this pedal uses BC547B and BC337 silicon transistors for the fuzz circuit. I added an input level control (pregain) so I'd have more control over the amount of fuzz, a 100Hz bass boost at the output and a relayed true bypass. I think that it's a great sounding fuzz for bass now  The gut shot of this build  is HERE.
Germanium Bass Fuzz: Based on the two knob DAM GB-80 Greasebox but revoiced for bass, this pedal uses three germanium transistors and a germanium diode for the fuzz circuit. The first two are used in a Darlington configuration for more gain. Again, I added an input level control (pregain) so I'd have more control over the amount of fuzz, a 100Hz bass boost at the output and a relayed true bypass. IMO, it's a great sounding germanium fuzz for bass.  The gut shot can be viewed HERE.
Super Fuzz (modded): A slightly modernized version of the Univox Super Fuzz using more modern and lower noise transistors with a couple of mods, and this one is my favorite version to date. Instead of a two position tone switch, it has a variable tone control, but the real magic comes from the added 'Starve' control that starves the circuit's voltage  The gut shot of this build is HERE.
Mountainking Electronics Megalith 1590B version : My second Megalith build, but this time in a smaller 1590B enclosure with all top jcks.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. The gut shot of this build  is HERE.
Ibanez MT-10 Mostortion: A great sounding OD/distortion pedal for use with a bass that is pretty obscure. This one uses the now discontinued CA3260 mosfet chip and it's very dynamic. It features a 3 band eq section to further taylor your tone. I modded mine for a little more gain and I LOVE the sound of this one!  The gut shot can be viewed HERE.
Catalinbread Katzenkonig fuzz: Catalinbread calls this a tonebender/Rat hybrid but I found the circuit to really be neither of those two pedals. The tonebender part is a modified silcon version and the only similarity to a Rat is the reversed sweeping and modified Rat tone control. That said, it IS a really nice sounding fuzz for guitar but does cut low end for use with a bass,  I did mod mine for more low end but it still cuts the lows a little. The gut shot can be viewed HERE.
1776 / Runoffgroove Thunderbird:          Runoffgroove's excellent sounding Marshall Super Lead emulator designed to sound like a cranked Marshall.. Featuring no less than 6 opamp gain/voicing stages, it does sound great, albeit a little noisey at high gain/treble settings, it sounds great with a guitar, but it does sound really nice with a bass too. The gut shot can be viewed HERE.
Wem Pep Box: My clone of John Lennon's germanium fuzz used during the Revolver era. It uses two NOS ACY41 transistors with  "Effect" (gain) and Level controls. It's pretty dark sounding fuzz that can almost be gated at some settings. I added a voltage inverter so it can be powered with a standard 9V power supply, a relayed true bypass and a switchable input buffer to make it  brighter, or run it stock without it. The gut shot can be viewed HERE.
Crowther Prunes & Custard: My second build of one of these unique distortion pedals, only this time in a 1590B.. 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.. The gut shot can be viewed HERE.
mini-Bass Fuzz: Here's a tiny pedal with a HUGE sound. Based on the Bazz Fuss but modded with  gain & tone controls, this single Darlington transistor fuzz pedal sounds great with bass and has a really gnarly sound that cuts thru the mix withut losing any low end. I've found that often the simple circuits yield a purity to their sound that more complex designs can't achieve
I am offering a VERY limited number of these for sale HERE.
Pearl OD-05 Overdrive: This little known offering from Pearl (as in Pearl Drums) is a great sounding overdrive for bass. The cool feature about it is that instead of a tone control it has a pre-gain semi-parametric filter that allows 15dB of boost or cut to whatever frequncy you have set on the frequency control (100hz-4Khz). IMO, it's a very well designed pedal for use with a guitar or bass. The gut shot can be viewed HERE.
Fairfield Barbershop: One of my all time favorites and my 'go to' pedal for every gig. The Barbershop allows you to make it sound like you're pushing your amp to its sweet spot. It can go beyond that (more overdrive) or even be run as a clean boost but this pedal just adds magic to you tone. Easily in my top 5 of any OD pedal ever offered. I added a relayed true bypass to this one.. The gut shot can be viewed HERE.
Jack Orman Mos-Face: This is basically a siicon fuzz face but with a mosfet (BS170) used for the second transistor. It sounds really nice with no low end loss. On the lower drive settings it was a little too muffled sounding so i modded it to adress that issue. don't let its tiny 1590A enclosure fool you, this one sounds HUGE (check out the soundclip below). The gut shot can be viewed HERE.
Fairfield Barbershop #3: One more Barbershop, only this time in a tiny 1590A enclosure. It just BARELY fits in one. This particular pedal is for sale and I won't be building any more of them since to get the Jfets to have  the correrct bias for the best tone, I have to sort thru 50 of them and most do not meet the requirement. The gut shot can be viewed HERE.

little GIANT Bass Overdrive: A simple single BJT transistor overdrive, voiced for bass that sounds BIG. It features an input level control (gain), a tone control (top end rolloff and an ouput level control. It can go from almost 100% clean to a heavy overdrive with no low end loss. The gut shot can be viewed HERE.
I am offering a VERY limited number of 10 of these for sale HERE.
soundclip
soundclip
Jen Harmon Booster (aka Gretsch Playboy): A rare vintage pedal that's not really a booster, but rather a fuzz tone. With no less than 7 BC318 transistors in the signal path it makes a very nice sounding distortion/fuzz with guitar or bass.  The originals came in a larger cast enclosure with 3 slide pots, but I prefer the 1590B with a relayed true bypass. The gut shot can be viewed HERE.
Earthquaker Devices Acapulco Gold: EQD calls this fuzz pedal a Sunn Mode cranked to the max. l don't know if I'd call it that but it does sound great. The original just has a single knob (output level control) but I added a gain control to mine and I think that it's 1000X better with it. This pedal has no low end loss and can obliterate the front end of your amp with its MASSIVE amount of output.  It's powered by twin 386 poweramp opamps.The gut shot can be viewed HERE.

HBE Bajo Mos: Now discontinued, the Bajo Mos is a clean mosfet booster for bass. The originals came in a 1590B enclosure with side jacks (including the DC jack!), but I built mine in a 1590A with a relayed true bypass with a top DC jack. They are excellent sounding boosters that can overdrive the front of an amp.The gut shot can be viewed HERE.
M3 Boost (Mutron III preamp): This one is the front end of a Mutron III which makes it a really nice FAT boost for bass. This one also has a relayed true bypass in it as well asa built in 9V inverter to supply the correct bipolar 9 volts to the circuit. At unity gain, it's nearly transparent, but with the gain dimed, it cuts some highs and adds low end. The internals of this pedal can be viewed HERE.
Fat Bastard Booster: This really nice sounding booster was designed by Paul Cochrane (maker of the Timmy Overdrive). It uses 3 Jfets  and has gain, treble, bass & volume controls. It's used mainly as a clean boost but can give a little bit of overdrive with the drive control dimed. Most people use them to drive the input of an amp harder. Fulltone copied the circuit and calls his version the Fat Boost VB-3..The gut shot of this build can be viewed HERE.

AU-Drive: This is a 100% tube booster pedal that is wired point-to point (i.e. no treminal strip or circuit board). It is capable of a large amount of clean boost, but with the drive knob  dimed, it can get into low overdrive territory. It's incredibly fat and smooth, which is what one would expect from a tube preamp. I really, really like this one.

The gut shot can be viewed HERE.


AU-Drive no2: My second build of the AU-Drive. This time in a polished aluminum enclosure, with the tube completely enclosed, and with a relayed true bypass.

The gut shot of this one can be viewed HERE.

This particular pedal has been sold  HERE
AU-Drive no3: My third build of the AU-Drive. This time in a polished aluminum enclosure, with the tube completely enclosed, with a relayed true bypass and lighted controls

The gut shot of this one can be viewed HERE.



Lovetone Big Cheese: All of the Lovetone pedals have been discontinued for some time now, are highly sought after and buying a used one will cost you quite a bit of cash. Their Big Cheese is a highly modified silicon Fuzz Face. I modded mine for bass by addung a 'fat' control (bass boost). The 4 way rotary selects from: 'off' (tone control bypass), 1: scooped mids tone with tone control, 2: mid boost with tone control and "cheese" with tone control which gets gated at high 'curds' (fuzz) settings. I LOVE it!
The gut shot of this one can be viewed HERE.

1590B Klon Centaur Clone: With the original mythical Klon overdrives going for up to $1500. I made an exact clone of one only in a much smaller 1590B encosure. The gain control is actually a blend between clean and gain.
The gut shot of this one can be viewed HERE.

Earthquaker Devices Bit Commander: EQD's Bit Commander is a multi-octave fuzztone featuring base, sub (2 octaves dow)n, Down 1 and Up 1 octaves that each have their own level control. It can sound similar to an MXR Blue Box but has much more control over the octaves. I built this one in a 125B with a relayed true bypass and polished and etched enclosure. I definitely dig this one.

The gut shot of this one can be viewed HERE.

Earthquaker Devices Bit Commander #2: My Second build of the  EQD bit Commander, only this time in a 1590B with all top jacks and a relayed true bypass.

The gut shot of this one can be viewed HERE.

RAT Supreme: This one is based on the original vintage ProCo Rat (including the LM308 chip), but modded for bass (more low end), a tone and mids controls with 3 way clipping options. Mounted in a polished and etched 1590B with all top jacks and a relayed true bypass

The gut shot of this one can be viewed HERE.

Electro-Harmonix Attack Decay: This rare offering from EHX sells for up to $1200 these days so I built my own using Madbean's Rustbucket pcb. It fits in a 1590B and runs on 18V as opposd to AC like the original. It's an envelope that does volume swells that can make you sound like a backwards recording. it also a has a switchable distortion mode. I love this pedal!
The gut shot of this one can be viewed HERE.
Prescription Electronics Depth Charge: Another Depth Charge but this time completely stock and housed in an etched 1590B with a relayed true bypass.

The gut shot of this one can be viewed HERE.

Menatone Pig (custom shop): The 'Pig' Was designed to emulate a 200 watt Marshall Major amplifier and it does a very nice job of it, using 6 Jfets to replace the tube gain stages. It features treble, bass, gain and volume controls to shape your tone and amount of overdrive. The original comes in a  larger 1590BB enclosre but I chose to go with a smaller 1590B with all top jacks and relayed true bypass.

The gut shot of this one can be viewed HERE.

Creepy Fingers Doomidrive: Creepy Finger's modern version on a Univox's Uni-Drive which was actually a fuzz/wah, but this is just the fuzz section, and GREAT one it is! A faithful reproduction all the way down to the now unobtanium 'button top' matsushita 2SC859 transistors. It's an awesome fuzz for guitar or bass. The CF version comes in a larger 1590BB but I went with a smaller 1590B with a relayed true bypass on mine.
The gut shot of this one can be viewed HERE.
Wampler
Low Blow

Brian's first over- drive pedal for bass and it's a GREAT ONE!
Heathkit TA-28 Distortion Booster: Heathkit introduced this pedal in the late 60's. It sounds awesome but it's biggest problem is that even with the controls dimed it's way below unity level. I solved that by adding a clean,  transparent  Jfet booster so it can go way past unity now. The original runs on a single AA battery (1.5 volts) so I installed a voltage converter so I could have a status led, relayed true bypass and run it on a standard boss power supply. I mounted it in an etched 1590B with all top jacks.
The gut shot of this one can be viewed HERE.

Sunn Buzz: Sunn's silicon version of a Maestro FZ-1 Fuzz running on a single AA battery. The original has NO low end so I modded mine for ZERO low end loss and call my version the 'Bass Buzz'.. The originals plugged into your instrument (like the early LPB-1 and Jordan Bosstone. I added an internal 1.5 volt regulator and relayed true bypass so it now runs on a standard  Boss power supply. and mounted it in an etched 1590B with all top jacks.
The gut shot of this one can be viewed HERE.

Overdrive Pedals
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Fuzzhugger Algal Bloom: The Algal Bloom is a two transistor fuzz with gain, bloom, starve and level controls and it's a great distortion/fuzz  for guitar or bass. I mounted mine in an etched 1590B. with a relayed true bypass.

The gut shot of this one can be viewed HERE.
MXR Distortion II: The Distortion II is a fairly obscure pedal from MXR. I found it to be a bit too dark so I added a Baxandall tone stack to mine. The original also runs on 120V AC but mine runs on a 9V standard boss power supply with a  relayed true bypass, and LED clipping option, mounted in an etched 125B with all top jacks.
The gut shot of this one can be viewed HERE.

Monolith Oracle Fuzz: The oracle is a two germanium transistor fuzz with a lot of low end and sounds great with bass or guitar, The 'color' control is basically a tone control and the density knob controls the amount of fuzz.

The gut shot of this one can be viewed HERE.

Hofner Buzz Tone: The Hofner Buzztone is a 3 transistor OD/distortion/fuzz. The original uses three BC108B transistors but I modified mine to use  3 germanium ones, which had to be carefully selected to achieve the best tone. It has a huge bottom end and sounds awesome now.

The gut shot of this one can be viewed HERE.

Echoplex Preamp: Rather than just being an emulator, this one is the actual preamp circuit from an Echoplex, and it is quite the tone enhancer!  In the standard mode, it doesn't really boost much (unless you use the 3-way boost switch) but it adds a unique complexity that I find to be very appealing.

The gut shot of this one can be viewed HERE.

Sunn beta bass preamp: I took the Sunn beta bass amp schematic and created a verbatim PCB for just the preamp section. It uses CMOS technology for the distortion and it sounds awesome. In order to run it on a standard 9V power supply, I added an internal bipolar 15V power converter so it's now running on 30 volts just like the original. I LOVE this one.

The gut shot of this one can be viewed HERE.

Acoustic 370 Power amp pedal: I used the original Acoustic 370 power amp schematic to build this one. Instead of using output transistors for a speaker, I converted the output to line level. I also added an input amp so I could increase the gain going into it. It has an internal voltage converter that takes the 9VDC input and supplies +18V to the main board and +18/ -18V to the input amplifier. This is a clean boost pedal capable of very high output, but can also be used as an overdrive. One of the coolest features of the circuit is an AGC (auto-gain-control) which is  similar to the FET circuit in a URIE 1176 compressor.
The gut shot of this one can be viewed HERE.
Acoustic 370 Preamp pedal: The Acoustic 370 is by far my favorite Acoustic bass amp ever made. I used the  original Acoustic schematic to build this pedal and it runs on 32V just like the original but only requires a standard 9V power supply (double with charge pumps inside). This pedal has TONS of output!  I used vintage Acoustic 2N2484 & 2N4248 transistors and inductors in it too. It was quite a challenge but after owning 7 original 370's, I can definitely say that this pedal captures the exact tone of the original amp because it IS the exact same circuit!The gut shot of this one can be viewed HERE.
Fairfield Circuitry
4 eyes fuzz
Source Audio
Aftershock
A 3 band fuzz for bass. It's AWESOME!
IMO, the most revolutionary OD/Distortion for bass EVER offered.
PEDAL OF THE YEAR!!!!
Acoustic 370 Preamp pedal #2: My second build of the 370 preamp, only this time in a 1590DD with an XLR direct out. On this one I used a 5 gyrator chip for the graphic eq (tuned to the 370's frequencies) and a 6H inductor from a White Instruments for the midrange control. The eq's sliders have 30mm travel, as opposed to 20mm as used in the first, smaller one. The gut shot of this one can be viewed  HERE.  
More info is also HERE
Red Witch Fuzz God: This is a.really cool fuzz with no low end loss. It's basically a highly modified silicon Fuzz Face but goes WAY beyond that. The Sputter knob is actually a voltage starve control that can make the fuzz extremely gated. There's also a two way gain switch and a bright switch at the top of the panel. Te Wrath control works with the lightning bolt stomp switch that takes it into self oscillating madness as well as octave down with heavy fuzz.

The gut shot of this one can be viewed HERE.
Maxon SD9 Sonic Distortion: The SD9 is a nice sounding distortion pedal that has a circuit similar to a tube screamer. I modded this one for more low end and added a blend control & a switchable input pad to make it more suitable for bass use.
The gut shot of this one can be viewed HERE.

Acoustic 150b Preamp pedal: I always liked Acoustic 150b's too so I also made a pedal version of it. It just barely fit in a 1590B. With the internal dual charge pump it takes a 9 volt power supply and coverts it to 35 volts to enable it to run on the same voltage as the original amp so it sounds virtually identical. This pedal is not an Acoustic 150b emulator/simulator, but is actually the same circuit using NOS original transistors.

The gut shot of this one can be viewed  HERE.  

Sunn 200S Preamp: One of my favorite bass amps of all time, the Sunn 200S just has a certain flavor that I've never been able to get from another amp. With just simple volume, treble & bass controls, plus Hi and Lo Boost switches, it stands out above all other amps. I always wanted a pedal version of the preamp so by using the original schematic and Jfets instead of the dual triode preamp tube I just kept tweaking the circuit until it sounded just like one.
The gut shot of this one can be viewed  HERE
Peavey F800B Preamp (later version): This is the preamp section from a Peavey F800B ass amp. The harmonics control comes from the400 model but the preamps in both of them are basicaly identical. The second footswitch on the left turns the overdrive on and off so I can use it as a clean preamp, a distortion pedal or both. An internal dual charge pump takes the 9V input and converts it to 24V so it runs at the same voltage as the original amp on a 9 volt power supply.
The gut shot of this one can be viewed HERE.  

Peavey F800B Preamp #2 (early version): This is the earlier (and much more rare) version of the F800B. It has a different distortion circuit than the later ones. I included the slope control on this one as well as an extra volume control when the overdrive is engaged. The early version's distortion is heavier than the later version.
Way Huge Red Llama #2: My second build of the Red Llama, only this time in a 1590A. This CMOS distortion pedal's design is based on Craig Anderton's Tube Sound Fuzz which is what the Bogdan "Polish Love" (aka Helter Skelter) is based on.
Broughton
Power Stage
I had high hopes for this one and set correctly, it delivers
Peavey F800B Preamp (early version): Another vintage F800B but this time in an etched 1590B with all top jacks and a relayed true bypass. I am making only two more of this version and it can be ordered HERE

The gut shot of this one can be viewed HERE.  

Peavey F800B Preamp #3 (early version): I love this pedal so much that I built one more vintage F800B, again in a 1590B, but this time with a rotary 3-way slope control  with all top jacks and a relayed true bypass.

 

Dwaftcraft Eau Claire Thunder
Nice and CRAZY modded Big Muff with oscillation with a tone control bypass
Smallsound/Bigsound: The SS/BS Mini is an awesome OD/Fuzz for guitar or bass and I currently own an original one. Brian was kind enough to post the schematic on one of the diy forums so I etched a PCB for it and built this one in a 1590B with all top jacks and with a relayed true bypass.
The gut shot of this one can be viewed HERE.  

Darkglass B3K (clone): This is an exact clone of the well loved Darkglass B3k CMOS distortion pedal. I've owned two of the originals and this one sounds identical to them. The biggest difference is that this one is in an etched enclosure and  has all top jacks.
As much  as these are loved by many, the B3K just doesn't do it for me so I'm selling this one HERE

Traynor Monoblock II Bass preamp: I used the original Traynor factory schematic to make an exac clone of the preamp section and this one sounds awesome. The amp has 5 sliders for the graphic eq but since this one's in a 1590BB, I used rotary pots instead. It makes a nice clean tonal shaping preamp and/or a great overdrive or distortion pedal.  The gut shot is HERE.
Here's a quick soundclip of it:
Southampton Fifth Gear: Based on the vintage Electra distortion, the Fifth Gear is a slight to moderately dirty boost (although it doesn't boost all that much). It's basically the same circuit as Earthquaker Devices' 'Speaker Cranker'. It's definitely a cool little pedal.

The gut shot of this one can be viewed HERE.  

Valhalla Overdrive: This is a CMOS based overdrive that can go from an almost transparent  clean all the way into distortion territory. It covers a wide range of tones with its tone bypass switch and active baxandall tone stack  The gut shot is HERE.

Here's a quick sound clip of it:
AU-Drive HG (high gain tube overdrive): This is the same as the original AU-drive only it has an added clean mosfet boost in front of it for omore gain (overdrive) and an added active Baxandall tonestack on the output.  The gut shot is HERE.


Here's a quick soundclip of this one:
Fury: The Fury is a fixed biased mosfet booster followed by a single Big Muff distortion stage, but instead of using silicon diodes, it uses two mosfet transistors as clippers. After the distortion stage it goes into a Baxandall tonestack, and finally an amplier boost. It also has a high/low distortion switch for more heavily saturated distortion.  The gut shot is HERE.

Here's a quick soundclip of the Fury:
Ibanez PD-7
Bass Distortion
A vintage bass OD/distortion pedal from Ibanez (meh)
Roger Mayer Page 1: One of Roger Mayer's early designs built for Jimmy Page. It was created to emulate some of the tones of the early germanium Maestro FZ-1, although it is capable of much more tones than that. The tone control actually adds a TON of low end making it absolutely suitable for use with a bass. The gut shot is HERE.



Tone Factor Cream Pie: A single germanium transistor boost that can also be run as an overdrive.  It has more than enough low end to be used with a bass. Very nice! The gut shot is HERE.


Fury 'Cat' graphic: Another Fury, but this time in a custom etched and painted enclosure. The graphic design is courtesy of Jerry Friedman. There is only ONE of these and will not be any more made. This one is going to the PCHD19 Alliance charity auction on Reverb.com this November.  The gut shot of this one is HERE.


Southampton Fifth Gear V2: One of the first Southampton V2 versions of the Fifth gear that as released aout a week ago. It sounds just like the one knob version, but now has a master volume as well as a bias ('Heat') control for control of more distortion sounds. It's a great sounding pedal for bass.



Southampton Fifth Gear V1.5: I built my own V1.5 version which is the same as the original with the exception of adding a master volume.
The gut shot is HERE.



Klon Centaur clone modded for bass: I took the original Klon circuit and tweaked it for use with a bass. It now has no low end loss and more gain on tap than a stock Klon but still retains the 'Klon character'. This one also has a relayed true bypass as opposed to the Klon's buffered bypass.

The gut shot is HERE.
1590A Civil War Muff: Here's a Russian Civil War Big Muff squeezed into a tiny 1590A enclosure. I used original vintage  Russian transistors and clipping diodes in this build.
The gut shot is HERE.
Sonic Boom Bass Distortion: This one is a triple Jfet bass distortion that can go from almost 100% clean to a heavy distortion
The gut shot is HERE.



Bass Bender: Based on the Colorsound IC Tone Bender fuzz but modified for bass and has an added input gain control. It can go from clean to a very dirty distortion.
DOD Boneshaker Distortion
DOD Carcosa  Fuzz
Parametric Distortion  awesome with a bass
A VERY versatile fuzz that's great with a bass
Earthquaker Hoof Reaper: A Triple effects pedal from EQD that contains their Tone Reaper, a Hoof Fuzz and a Tentacle (octave up), that can be used one at a time in any combination or all at once! There's no no low loss with this one so it sounds awesome with a bass.

The gut shot is HERE.
Hudson Broadcast 25V: The Broadcast is a transformer coupled, discrete Class A germanium preamplifier based on the classic broadcast consoles of the 1960s. This one runs on a standard 9 volt power supply and is internally upped to 25 volts. An awesome sounding tone enhanced  boost/OD/Distortion for bass.  The gut shot is HERE.

I am making a VERY limited run of  5 of these for sale HERE
Mos-Muff: The Mos-Muff is a Big Muff with a Mosfet front end drive stage with Mosfet & germanium clippers with a vintage BC239C output stage. It's a beautiful sounding muff for bass
The gut shot is HERE.
Bearfoot Candy Apple Fuzz: This Fuzz designed by Bjorn Juhl is a germanium hybrid. It uses a regular 9V-18V input and is almost impervious to where it is in the signal chain, so it will go places and do things most other germ-based fuzzes just can’t because of their design. Vintage, crazy, ripping Germ fuzz with the convenience of unrestricted placement in your effects chain. It sounds great with a bass too.
The gut shot is HERE.
Sunn Model T Preamp: Using the original generation 1 Sunn Model T schematic, I replaced the tubes with Jfets, added more gain for more grit (Model T's are very clean) and added a booster to the output for more overall volume. This is a big sounding and fat sounding preamp for bass.
The gut shot is HERE.
Morley JD10 (JK10): I modified Morley's JD10 for a little more low end and built this one in an etched 125B enclosure with a relayed true bypass. A very nice sounding preamp/OD for bass.
The gut shot is HERE.
Interfax Harmonic Perculator #2: My second Harmonic Perculator build, this time in an etched and polished 125B with a clean Jfet output boost for more volume and a relayed true bypass.
The gut shot is HERE.
Behringer
VT999
When modded for bass, it's awesome. real TUBE OD!
Midfi Demo Tape Fuzz: Midfi designed this pedal to sound like you're clipping a cassete deck's input distortion. The early version used a TL072 chip but I found that it had a harsh distortion with a fizzy decay so I replaced the chip in mine with a MC33172 and it sounds really nice now. I've heard that the later ones also use the MC33172 now.
The gut shot is HERE.
Wren & Cuff Suppa Phat Phuk: This is a hybrid Jfet/Germanium booster that adds a little color (germanium magic) to your tone and is a really nice sounding booster for bass. The bias control allows it to be used as a clean boost, or it can be cranked up for an overdriven sound. The Phatness control cuts bass (CCW) and is full range with no low end loss fully CW. I built mine in an polished & etched 1590B with all top jacks and a relayed true bypass. The original comes in a 125B with side jacks,
The gut shot is HERE.
Durham SexDrive: The Sex Drive is a transparent booster capable of also being a mild OD, but uses diodes and LEDs to add 'compression'. You can select between which diodes or turn them off with the mini toggle.
B&M Fuzz Unit: This is a clone of the vintage, very rare British Barnes and Mullins Fuzz Unit pedal that was built by Sola Sound / Colorsound. It's very similar to a Jumbo Bender which is a 3 transistor Big Muff (no ouput summing amp) and with no diode clipping on the first gain stage. I slightly modded mine for more mids but otherwise built it stock with NOS BC184 transistors.
Death by Audio Supersonic Fuzz Gun: DBA is known for their extreme fuzztones, and this one is no exception. I really like this one for its heavy gated fuzz and it's actually pretty versatile.  The original comes in a horizontal 1590BB but I went with a polished & etched 125B with a relayed true bypass and an extra stomp switch for the oscillation mode as opposed to a toggle. I really dig this one. The gut shot is HERE.
johnk Signature Bass: After working on this circuit and experimenting with a lot of different chips and voicings, I finally came up with the Signature Bass drive/distortion. With an internal 18V charge pump for more dynamics & touch sensitivity, it can go from nearly clean to heavy distortion.  I wanted to keep it simple with only 3 knobs, but you can tame the top end with the presence (off) or use it for guitar with the lo cut switch. I'm really happy with the way that this one came out. The gut shot is HERE.
function(fx) Clusterfuzz: I built this one from a schematic posted on freestompboxes and , IMO, it sounds awesome. It features 5 clipping options and a unique '8 bit' control, making it a great sounding fuzz with a lot of versatility These go for $199 and I think that they are well worth it. You can get one here: function(fx).

The internals of this build can be viewed HERE.
Modified Octavia: I took the Roger Mayer (non transformer version) Octavia fuzz (dirty octave up), slightly modified it for bass and added an active Baxandall tonestack to it. I am in LOVE with this pedal and may be one of the most unique sounding fuzz pedals that I've built (or owned) to date. It's mounted in a powdercoated ghost black 1590B with a polished & etched face, true relay bypass with all top jacks. Soundclip coming tomorrow The gut shot is HERE.
DSM Noisemaker
Drivemaker
A VERY versatile and nice sounding OD/Disortion Pedal for guitar or bass.
Broughton
Rumblefish
Broughton's clone of a Spaceman Rumble bass fuzz
Trombetta Minibone: Paul Trombetta makes some AWESOME fuzztones. I believe that he has more experience with the Jordan Bosstone than anyone which is what a lot of his pedals are based on. By tweaking and modifiying the circuit he has created a whole new original pedal. The Minibone can go from a smooth distortion to an all out heavy fuzz. it has mood, bore, gain and volume controls, as well as two switches for hi cut and voltage sag. It can even make your guitar sound like a trumpet! The gut shot is HERE.
Maestro FZ1-A
Reissue
A very accurate RI of the FZ1-A, but massive low end loss for bass
Rosac Nu-Fuzz: The Rosac NU-Fuzz is a two silicon transistor fuzz with the fuzz always on (saturated & nasty). The tone control just sets the nature/frequency of the fuzz, from midrangy to bright. It does sound really cool, though there is quite a bit of low end loss..
The internals of this build can be viewed HERE.
johnk Anvil: I named this one the "Anvil" because it's one of the HEAVIEST sounding bass distortions that I've built to date. This one's distortion control has no clean setting ( it goes from mild distortion to massive distortion),and I think that it sounds gorgeous. It has a TON of low end and with its gyrator tone stack is capable of a zillion tones. A Jfet front end feeds two dual 4558 opamps and has 6 more transistors for the overall voicing and EQ's of the circuit.The internal pic is HERE.
Only 3 of these will be built to order HERE
VOX Flat 4
boost/overdrive
VOX V8
Distortion
A 200 volt tube boost/OD that sounds great with a bass
A  200 volt tube distortion that sounds great with a bass
A 200 volt tube overdrive that sounds great with a bass
VOX Straight 6
Overdrive
Blue Tube
Tube Overdrive
This one sounds great with the stock 12AX7.  also great with a bass
Malekko
Sloika
An interesting multi-stage  overdrive that keeps the low end
johnk B-17: This one's called the B-17 for two reasons. #1- B stands for Bass, 17 stands for 17 volts, & #2-because, IMO, this pedal is the BOMB (as in B-17 Bomber). Twin mu Jfet amps driving a Jfet into two dual Jfet opamps (TL072's) for the EQ and final output stage. the "Pre" control allows it to run clean, but it's also capable of a tons of distortion. The controls on this  one are all interactive which means that it's capable of an infinite amount of tones.I spent alot of time voicing its tone, & adjusting the gain stages. An internal charge pump supplies 17V from a 9V power supply.  The gut shot is HERE.
D*A*M Ezekiel 125B: The D*A*M Ezekiel is a very rare bass distortion and if you can even find one it'll cost you a pretty penny. I finally got around to designing a PCB for it with board mounted pots and a smaller board mounted 1P4T rotary switch so I was able to fit it in a 125B with all top jacks.It has a clean blend as well as 4 different clipping options. There's ZERO low end loss with this one(!) and is sought by many bass players as their choice of dirt.
The gut shot is HERE.
Walrus Audio Mayflower: The Mayflower is very similar to Paul Cochrane's Timmy. It has less drive than aTimmy but it does sound really good and has NO low end loss.
The gut shot is HERE.
SolidgoldFX
BETA Germanium
SolidgoldFX
BETA Mosfet
A nice sounding Bass Overdrive with XLNT Low end
More distortion than the germ version and more low end
Suncoast
B1P Bass preamp
A Pearce bass preamp in a box, complete with limiter
Ibanez Tone-lok Series FZ1 Fuzz
Ibanez BB9  Bottom Booster OD
IMO, a very cool sounding Fuzz
A GREAT sounding mild to moderate overdive for bass
Lovepedal Dragon: Lovepedal made 3 versions of the Dragon., a full germanium, a full silicon, and a silicon,germanium hybrid. This one is the hybrid. It's basically a modifed Fuzz Face circuit with a blend control ("B"). Not a clean blend, but rather a blend between input capacitors from dark to bright which also changes the nature of the fuzz. I think it's a great fuzz for bass and has no low end loss. Soundclip coming soon.
The gut shot is HERE.
Fuzzhugger Doom Bloom: Fuzzhugger's Doom Bloom is a very versatile fuzz pedal for both guitar and bass. It's a dual silicon transistor fuzz, but with a lot of controls for such a simple circuit. The head control stands for headroom, the bloom is the gain, body is low end, high is treble and the bias controls the bias of the first (drive transistor). It's capable of a LOT of tones from mild to wild.
The gut shot is HERE.
DMB Bumble
Bass Distortion
No longer made but nice, with a clean blend
DMB Bumble: An exact clone of the original and it's a very nice bass distortion, It's basically a 3 transistor Big Muff with with a clean control so you can mix in your dry signal. The original is in a 125B but I went with a 1590B with a relayed true bypass. DMB is no longer making pedals (they stopped in 2014), so you'd have to find a used one. The build quality of the original isn't all that great (there's hot glue all over the place!) but it does work well.
The gut shot is HERE.
Kustom Harmonic Clipper: This is the distortion/fuzz.circuit as found in the K200 amps from the late 60's, early 70's and is best known for John Fogerty's distortion on CCW records, The circuit is two Mosfets feeding a Jfet with germanium clippers, but can also be run as a clean or semi-clean boost/ tone enhancer IMO, it's an awesome sounding pedal for use with guitar or bass. I made the cosmetics match the faceplate of the amps that contained it.
The gut shot is HERE.
Earthquaker Devices Bellows: This is a very unique yet simple circuit and it sounds AWESOME on both guitar and bass (with no low end loss!). it can go from nearly clean, but with  really nice sounding tonal enhancement, to very distorted and ballsy. I LOVE this pedal!
The gut shot is HERE.
TC Electronic
Cinders
Supposed to be 100% transparent, but does have a tiny bit of low end loss. Still very nice though
TC Electronic
Grand Magnus
IMO, a really nice distortion for bass and only $50!!!
johnk Bass Cannon: After quite a bit of experimentation I came up with this one to be a versatile bass overdrive that also gets into heavy distortion. It can be run as a clean boost as well. The center toggle switches between silicon diodes/none/and red LEDs for the clipping

I may offer a very limited number of these for sale.
Darkglass
Alpha Omega
An awesome offering from Darkglass!
EAE
Model feT
Sunn Model T in a pedal and it sounds great!
Tech21
Oxford
An Orange amp simulator that works & sounds great on bass.
A lot of  people love them but I didn't care for it.
Not my cup of tea
VMT (Darkglass Vintage Microtubes clone-modded): After owning two originals that I found to be a bit too dark sounding for my taste, I built this clone and modded it for more top end. IMO, it's an awesome sounding bass OD now.
DOD
Gonkulator
A very nice Fuzz for Bass with a blendable ring modulator!
Way Huge 1590B Pork Loin: I really like the Pork Loin, especially after a small mod for a little more top end. It's a pretty complex circuit (the clean side is based on a Neve preamp) and it was pretty tough getting it to fit in a 1590B with top jacks and relayed true bypass, but I was able to do it with some careful measuring.

The gut Shot is HERE.
Chowny
Fuzzster
Another nice Fuzz for Bass with a separate clean control
Dunwich
Volt Thrower 125B
Dunwich
Olde Dirty Bass
A highly modified Rat circuit that is spectacular for bass.
A highly modified OCD that is awesome with a bass!
Blackarts Toneworks Revelation Superbass: This is a pretty darn cool pedal. It's basically a stripped down and highly modified Big Muff. Instead of a tone control, it has a "pre' control so you can limit the level of the signal driving the circuit. No low end loss with this one and can go from lvery light to a heavy fuzz. The original comes in a larger horizontal 1590BB enclosure with a standard 3PDT bypass, but since the circuit is fairly small, I went with a 1590B with top jacks and relayed true bypass.
Emanating Fist (D*A*M) Black Acid: This is a modified fuzz face circuit that sounds great with  bass or guitar, using two BC109 metal can transistors (I used NOS Telefunkens) with internal adjustable bias control It's unique 'drive' control determines how much low end enters the circuit's front end. It can go from clean to an all out vintage sounding fuzz. The originals come in a HUGE enclosure with a standard bypass, but I used an etched and distressed 1590B with top jacks with a relayed true bypass.
I'm offering ONE of these builds HERE.