SKU: VTBP-M-800D Category:


What’s Old is New Again

In 1982 James Demeter built the first of his series of VTBP-201 pre-amps. His idea was to build a Tube Audiophile Pre-amp with Classic Bass Amp style tone section. There were other Pre-amps at the time but they were just guitar amp circuits that had major design flaws. His first customer was Leland Sklar. Lee took our proto-type to try it out and kept it. Lee used the pre-amp and it’s backup for another 25 years until he downsized his rig. In 2012 He decided to donate the #1 Pre-amp back to its creator. We were very happy to see it back and of course we had to listen to it. We were amazed how warm and clear it was. It sounded very similar to the current VTBP-201 but it was rounder and a bit slower than the newest model due it unregulated power supply and old school parts. Around the same time we found 150 of the original PCB’s that were used in that model. We decided to clone Lee’s pre-amp but, put it in the smallest box possible with our 800D power-amp. The result is the VTBP-M-800D. At 10.5 lbs. It is one 800 Watt tube tone monster.


All tube pre-amp circuitry Hand wired in the USA using High quality components, DC filament, full 280V high voltage supply. Classic passive tube tone controls Treble, Middle, Bass with frequency selector and presence with frequency selection. We replaced the original bright switch with our new Mode switch that lets you control the overall tone: Dark, Normal and Bright. The unit has a pre-amp output if you need to run more amplifiers. A select Jensen transformer drives our 800 watt class D Amplifier. There are two Speakon combo jacks on the back to hook up your speakers. We offer upgrades for Jensen transformer Direct outputs and a line level effects loop. The amp weighs 10.5 lbs and messures 13”wide x 5.5”high x 9”deep. Built right here in the USA in our Barn in Templeton CA.

Tone section:

  • Treble Control: The treble control gives 6 dB of boost or cut at 4 kHz (6dB per octave, shelving type).
  • Middle Control: The middle give 6dB of boost or cut at 500Hz (wide Q, peaking type).Bass Control: The bass control gives 9dB of boost or cut at a selectable frequency of 60Hz or 120Hz (6dB per octave, shelving type).
  • Presence Control: The presence control gives up to 12dB of boost at a selectable frequency of 2kHz or 4kHz (active type, 6dB per octave).
  • Mode switch: Dark, is a high frequency cut fatting up your fundmental. Normal, flat opertion showing off more overtones. Bright, brings out the overtones on the dullest basses or speakers.
  • Internal Volume Trimmer: This control is designed to match the output volume of the VTBP-M-800D with the sensitivity of any Bass.
  • Optional, Studio Output: The VTBP-M-800Dm- features a mic level Jensen DB-E output transformer for a balanced studio output.
  • Effects Loop: in/out line level
  • Power Amp Outputs: Operating at 4 (800w),8 (500w) or 16 ohm (250w). 1/4” & Speakon

Preamp Specifications

  • Inputs: one instrument level 1/4” jack.
  • Output impedance (line): > 1 kohm, (unbalanced)
  • Minimum load impedance: 10K
  • Input impedance: > 1megohm
  • Maximum output: + 24dBV
  • EQ gain : + or – 12 dB
  • Signal to noise ratio: – 80dB
  • THD : .5%
  • Outputs (preamp): 1/4” unbalanced , Optional 3 pin XLR Direct out
  • Frequency response : 10Hz to 40kHz
  • Tube: 1-12AX7a selected 1-12AT7
  • Operating voltage: 115V or 230V AC
  • Power supply: 280V DC
  • Filament: 6.3 V DC

Power Amp Specifications

  • Outputs (power amp): 1/4” Speaker & Speakon
  • Output impedance (power amp): 4 ohm, 8 ohm, 16 ohm
  • Output Power (power amp): 800 watt RMS @ 4 ohms, 400 watt RMS @ 8 ohms

Additional information

Weight 10.5 lbs
Dimensions 13 × 9 × 5.5 in
Transformer Type

Stock Transformer, Jensen Transformer (+$250)


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