Bass Preamp Reviews

Now that I’ve had a chance to spend some time with all of my preamp/channel strips, I thought that I’d write a short review as to my take on all of the ones that I currently own.
Some of them are quite expensive, others are in the ‘mid-price’ category, and a few can be found used for very little money and are true bargains.

I have paired all of my preamps with a compressor if the preamp doesn’t already have one built in, but these reviews are just for the preamp only. I’ll review the compressors seperately.

Ampeg SVP-Pro:
Introduced in 1994, discontinued 2007. $699 MSRP. No longer made, but can be found on the used market quite easily since they made quite a few of them. Expect to pay anywhere from $350-$550 for a very clean one. This is an all tube preamp (four 12AX7’s and one 12AU7) and it is very nice, full, and punchy sounding. It has the ability to simulate an Ampeg SVT (it should, since it’s basically the front end of an SVT-II Pro amplifier). It has a completely tube path from input to output with the exception of the graphic EQ, which is solid state, and can be bypassed completely with a switch on the front panel. It has plenty of output to drive any power amp. Big, strong and fat sounding, this is a nice preamp for those that want to capture the “Ampeg sound’. My only complaint is that these can be somewhat noisy preamps, and are a little touchy as to the quality of the tubes that you install in them. used a NOS RCA 7025 for its final gain stage, at it made a huge difference in reducing its noise. It is a really nice preamp to have on hand if you're looking to get the  "SVT" sound at any volume level. Tip: to keep its noise as low as possible, don’t be afraid to have the “peak” LED flashing frequently, it won’t be distorting, and keep the master level turned up to 12:00 o'clock or higher on the output.Keep in mind that the solid state graphic EQ section can distort somewhat easily, so be sure the lower it's level matching fader if you’re going to use it to boost alot of frequencies.

Front panel: (L to R): 1. ¼” Input jack , (3) -15db pad switch, (2) Mute switch, (4)Gain control,(5) peak/mute LED, (7)Ultra Lo and (6) Bright switches, (8)Drive Control, (9) Bass, (10) Midrange, (11) Mid select frequency, (12) Treble, (14)Ultra Hi, (13) Eq in/out, 9 band graphic EQ with additional (16)Gain matching slider,(17) active/peak LED, (18) Master Volume, (19) Power LED and (20)Power switch.

Rear Panel: (21) AC input, (22)115/230V switch, (23) foot switch jack, (24)two ¼” TS preamp out jacks,(25) effects send/(26)receive jacks, (27) tuner out, (28) pre/post eq switch for the (29) direct XLR out, and XLR output. Mine also has an adjustable pot for the XLR (not shown) but some of these do not have this feature, depending on the year. The XLR’s output is before the master output and is transformer isolated.

Ampeg SVP-CL:
Another 100% tube preamp from Ampeg. Introduced in 2004, discontinued 2009. $699.00 MSRP. This one is basically the front end of an SVT Classic or an SVT-AV. Once again, a great way to achieve the “SVT sound”, and its more of a pure SVT since it doesn’t have the drive control, or graphic equalizer found on the SVP-Pro. Four tubes consisting of two 12AX7’s and two 12AU7’s. In my opinion, this is a little better sounding preamp than the above mentioned SVP-Pro and has a bit more clarity, and detail with A LOT less noise. My particular one is a very early model, that were known to have a very low output signal. There was a factory Technical Information Bulletin (#TIB 00015) for this and I have since performed the update on mine. It did yield more output, but not all that much more (approx 3dB). I run mine into an Aphex 661 and then into a power amp, so it’s not really an issue for me to increase its output. The front end is not very sensitive with a passive Jazz bass, so don’t be afraid to use the input gain control liberally. If you’re not going to run a compressor in the signal chain after it, I would recommend that you use a power amp that has a .775V input sensitivity to get its full power.

Front Panel: (1) ¼” Input, (2) 10dB Pad, (3) Mute switch, (4) Gain, (5) Peak LED, (6) 5 position Ultra Low Selector, (7) Ultra High Sw.(8) Bright Sw. (9) Bass, (10) Mid (11) Mid select (12) Master volume (14) Power Sw.

Rear Panel: (15) AC input,  (16) Footswitch, (17) Preamp Outputs (x2),  (18) Pre/Post sw. (19) Ground lift, (21) Tuner Output.

Art Pro Channel:
This relatively inexpensive two 12AX7A (OEM Sovtek) tube preamp from ART has ALOT of features for the money, and I have found it to be a fantastic bargain. With a retail price of only $390, and a street price of about $319.00,. in my opinion, this mic channel/preamp is the best you can buy for the money. Everything from tube driven gain (for a little grit, but not really for all out distortion), a low cut filter, your choice of either a very adjustable tube or optical compressor,  two frequency selectable low and high tone controls, with two band parametric. and plenty of metering so you can actually see what you’re doing. This is a very nice, full and smooth sounding bass preamp that is also surprisingly quiet. I was able to dial in a tone anywhere from clean and bright, to ‘old school’ and wooly, and everything in between. It has plenty of output to drive any power amp. It is very lightweight and occupies two rack units (2U). The controls are laid out in a straightforward  manner.
Its basic sound reminds me of Ampeg’s SVP CL but with a bit more clarity and definition. If I had only one complaint,. It would be that the input jack is located on the rear panel instead of the front.

Tech 21 Sansamp RPM:
MSRP $435.00/$329.00 (street). Here’s a very nice offering from Tech 21. RPM is 100% solid state, but in my opinion, Tech 21 is one of the few companies that has mastered the art of tube sounding preamps. I chose this model over their RBI (also a very nice pre) because of its adjustable mid shift control that allows you to cut or boost any frequency between 170 Hz to 3KHz. It is capable of a lot of different tones and can emulate an Ampeg SVT with a few twists of the dials. It has very low noise and plenty of output to drive any power amp. The blend control allows you to mix the ‘drive’ signal with the clean signal for endless variations of slightly to heavily overdriven ‘grind’.

RPM front panel:

RPM Rear Panel:

Tech 21 Sansamp PSA-1:
MSRP $875.00/ $659 (street) This has always been one of my favorites in the studio and is equally at home stage as a bass preamp. With no less than 5 gain stages, you can dial in just about any amplifier’s gain structure, all the way from Fender or Ampeg clean to Marshall or Vox distortion. The equalization is somewhat limited, but the ‘buzz’, ‘punch’ and ‘crunch’ controls actually effect the signal’s frequency response and tonal shaping. I’ve paired mine with an Ashly DPX200, which allows me to add compression if I want to, as well as having a parametric to allow this preamp to get any tone that I could ever need. It has 49 factory presets and allows you to store up to 77 more of your own, accessible from either the front panel up/down switches or via midi.

PSA-1 front panel:

PSA-1 rear panel:

Ashly BP41:
Bass Preamp: 1985-1995. These can be somewhat difficult to find, but they are out there at reasonable prices. A very nice and smooth sounding preamp, with great sounding equalization. Two separate inputs (selectable), bass, mid, treble and a single parametric with a range from 31.5Hz – 3150KHz, allows just about every tone imaginable. A built-in crossover for bi-amped rigs, stage level control, output mute switch and headphone out with its own volume control.

Yamaha PB-1:
1982-1996. These are definitely one of my favorite bass preamps that have ever been produced. Very clean, fast and clear, yet smooth and warm at the same time. Extremely flexible in its ability to shape your bass’ tone, and it’s almost impossible to get a bad sound out of it. This unit’s chassis is very deep and heavy, and exudes a high-end feel of impeccable Yamaha quality. Controls include: Volume, Treble, Bass (Fender tone stack), a fully parametric mid band, high and low pass crossover frequencies and level controls and a headphone output with level control. If you’re looking for a bass preamplifier and you come across one of these, my advice is “buy it”.

Demeter HBP-1J:
MSRP $999 / $849 street. This is a very nice, clean, clear and smooth tube preamp for bass. Although it is somewhat 'colored',  in my opinion, it's still  very transparent and open sounding. The main tone controls are passive and very 'Fender-ish'. The two band parametric is very flexible for tone shaping and sounds absolutely gorgeous. This preamp has a very full and 'round' sound to it. I use an Empirical Labs EL-8 Distressor in the effects loop to get a really nice fat tone without squishing it. To me, this preamp sounds like a vintage tube amp, yet very 'Hi-Fi' at the same time. Mine is the Jensen transformer (HBP-1J) version that uses a transformer on the direct output.

Alembic F-1X:
MSRP $1250 /  $999 street. If you aren't familiar with Alembic's tube preamps, you must have been hiding under a rock for the last 35 years. These are absolutely great sounding preamps, based on a Fender AB763 black-face circuit. Big, warm, fat, punchy & clear are the first things that come to mind when describing how they sound. Their F2B is a two channel version, whereas the F-1X, is a single channel, but also includes and added 'deep' switch, a direct out on the front panel as well as an active crossover for two=way rigs. In my opinion, the deep switch is uneccessary (and basically unuseable) since it cuts so much 'meat' (midrange) out of the single, but other than that, I think it is a 'world class preamp.The torodial power supply runs the preamp tube at 300 volts.

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