Bassist Magazine (December 1996)
By Mike Collins
Every so often a “must have” unit comes along; Mike Collins tries out the latest studio accessory.
Considering a rackmount pre-amp for your bass? Prefer the sound of valves to that of transistors? Maybe you are working on recording sessions and want a compact rackmount unit to take into the studio rather than lugging a combo amp around? You could do worse than opt for the latest Stateside “must-have”; Demeter’s Tube Bass Pre-Amp, keeping you in company with the likes of Sting, Darryl Jones, Stanley Clarke, Abe L., Marcus, Adam Clayton and Lee Sklar. Well, I was impressed, with some of my favorite players of all time listed there.
Jim Demeter has been designing, building, repairing and modifying valve-based products since 1980, and his Demeter amplification products are hand-built in Santa Monica, California. The catchily-named VTBP-201 uses modern valve technology which utilises features found on only the most expensive valve equipment, giving the warmth and dynamic range that only valves can produce, yet with much lower noise specs than most solid state devices, thus making this unit ideal for studio work.
Construction and Controls
The pre-amp comes in a distinctive-looking sturdy 19″ metal rackmountable unit painted black with white lettering, very capable-looking thanks to classically understated visuals. On the front panel sit the customary High and Low inputs, with Volume, Bright switch, Treble, Mid, Bass EQ switch, Bass, Presence, Presence EQ switch, and a power switch with an associated LED indicator. As this is a point which creates confusion, the High input is for normal musical instruments while Low allows the use of high level input signals up to 5 volts peak to peak–when both jacks are used, the inputs are mixed equally. It’s also worth knowing the specs of the EQ controls for comparison with the competition, so here goes: Treble and Mid offer +/- 6dB boost/cut, working at 4kHz and 500Hz respectively. Bass gives an even greater +/-9dB of boost/cut, operating at either 60 or 120Hz, while Presence provides a substantial +12dB boost at either 2 or 4 kHz. Finally, the Bright switch gives a 6dB per octave boost from 2kHz upwards.
One the back panel; a 1-amp fuse holder, 1/4″ jack output socket, a pair of jack sockets as FX send and return, XLR balanced studio output socket on the 201-DBL model, EQ Enable switch, and ground lift switch. The balanced output provides a much cleaner feed for recording direct from the pre-amp, an important feature for studio players, while the ground (earth) lift switch disables the earthing connection to the mains, which you may need to do to avoid earth loops when the pre-amp is earthing via the jack connections to other equipment.
If you use the pre-amp to feed a power amplifier for live playing, rather than connecting directly to a recording mixer, you may need to adjust the internal volume trim to match the output volume of the Demeter to the input sensitivity of the power amp. This is easy to access by removing five small screws for top panel removal. Looking inside the casing, power supply and circuitry are cleanly assembled, featuring two 12AX7A valves with associated high-quality resistors and capacitors, where a Jensen output transformer feeds the balanced line XLR output, a mains transformer feeds the solid-state rectifier with associated smoothing condensers, with plenty of room around the components to facilitate servicing or valve changes.
For studio work, I normally use an Ampeg B15 (valve) combo with normal and bright channels, the usual Volume, Treble and Bass rotary controls, an ultra-low EQ switch for bass and corresponding ultra-high EQ switch for treble. These switches roughly relate to the bass and presence EQ switches on the Demeter, whilst the bright switch on the Demeter is like plugging into the bright channel on the Ampeg. The Demeter also has a middle EQ control which facilitates subtle adjustment of these frequencies for even more tonal variety. Comparing the Demeter with the Ampeg, I felt that the Ampeg was a little ballsier, while the Demeter was much more sophisticated. The EQ controls work at different frequencies and I quickly found myself preferring the significantly wider range of tones I could get from the Demeter, playing along to some favourite album tracks for comparison, seeing if I could match the sound of my original ’59 Precision Bass to these. Sure enough, I managed to get very close to Larry Klein’s sound on Aaron Neville’s Everybody Plays The Fool and Bob Glaub’s sound on Angola Bound from the same album… then I noticed that these guys are both listed as VTBP-201 users. Consistency, too! Encouragingly, I also got pretty close to Larry Kimpel’s sound on George Duke’s ‘illusions’ album, the final clincher for me.
The words ‘dog’s’ and ‘bollocks’ seem to be appropriate in this case. For studio work, the VTBP-201 would be hard to beat if you like valve sound. I will put my money where my mouth is and am actually buying one of these units (gulp–accumulated Bassist staff) confident in the knowledge that I will be able to get most of what I am getting out of my Ampeg, while considerably extending the range of sounds I can create. Every studio player should have one!
If anyone is encountering difficulties with rare valve types, Mike Cooper of Groove Tubes UK explained that they specialise in sourcing hard-to-find replacement valves for a wide range of popular amplifiers and pre-amplifiers. They offer several alternatives to the 12AX7 ranging from very clean to extremely ‘hot’, and a couple of 12AX7s from Groove Tubes cost about £30, not unreasonable given the cost of the pre-amp itself. Mike Cooper offers an ‘appointment only’ service where you can bring in your instrument and amplifier and he will swap your valves for the different models while you play through the amp to see which suits you best. Incidentally, Terry Finn from Demeter’s UK distributors, The European Office, states that the 12AX7A valves supplied with the Demeter are sourced from the same factory as Groove Tubes valves, but gave a thumbs-up to pukka Groove Tubes alternatives and confirmed that he will supply customers with these if desired as replacements.
- Signal To Noise Ratio: Greater than 98 dB
- Total Harmonic Distortion: Less than 0.1%
- Frequency Response: 10 Hz to 40 kHz
- Maximum Output 20 Volts RMSs into a 100 kHz load
- Height: 2.6″
- Weight: 19″
- Depth: 9″