VTBP-201-800D Bass Pre/Power Amp (800 watts RMS @ 4 ohms)


100 in stock

SKU: VTBP-201-800D Category:


1 Rack Space, 11 Pounds, Tube Warmth = All the bass amp you’ll ever need.

Now you can truly have it all. By integrating a Class D power amplifier with Demeter’s classic tube bass preamp, we have created a product that can drastically simplify your bass amplification setup without compromising your tone. Although the Class D power amplifier is solid state, our transformer coupled circuit design preserves the tube warmth from the preamp section and offers a clean 800 watt RMS (4 ohm) output in a lightweight (11 pound) single rack space unit.

Our pre/power amp circuit is unlike any other. Using Jensen transformers, we have achieved complete isolation between our pre & power amp section. This allows for noiseless operation, whether you use the preamp on it’s own, or in tandem with the power amp output. Our transformer based design also has the unique advantage of ‘warming’ up the power amp output.

After almost 30 years of production the Demeter Amplification Tube Bass Preamplifier is still the only musical instrument preamplifier to incorporate truly modern tube design technology with circuit features found on only the most expensive and esoteric hi-fi tube equipment. The VTBP-201-800D has the warmth and dynamic range that only tubes can produce, yet has lower noise specifications than most solid state devices. Using the integrated power amplifier, you can achieve an incomparable punch and clarity that represents the best of old and new technology, together in a package that will save your back!

The VTBP-201-800D Tube Bass Pre/Power amplifier uses a regulated B+ power supply which provides quick transient response with extremely low noise. Regulated DC is supplied to the tube filament which gives the unit extremely low noise. We use only the finest 1/2 watt, 1% metal film resistors, polypropylene capacitors, high quality, computer grade switches, and a 7025A vacuum tube, factory selected for lowest possible noise and distortion. The VTBP-201-800D also has a low output impedance which lowers distortion and insures proper power amplifier input matching. Custom toriodal power transformer. New single space rack mount steel chassis.

Each amplifier is carefully hand-wired using only the highest quality parts and tested at our factory in Templeton, California. You can see as well as hear the quality and attention to detail on both the inside and out.


Inputs: Two inputs are provided: Passive, for normal musical instrument inputs. Active, for high level active instruments. When both jacks are used the inputs are mixed equally.

Treble Control: The treble control gives 6dB of boost or cut at 4kHz (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).

Bright Switch: The bright switch gives up to 6dB per octave of boost from 2kHz.

Internal Volume Trimmer: This control is designed to match the output volume of the VTBP-201S with the input sensitivity of any power amplifier.

Studio Output: The VTBP-201S features a mic level Jensen DB-E output transformer for a balanced studio output.

Power Amp Outputs: Operating at 4 (800w),8 (500w) or 16 ohm (250w). 1/4” & Speakon

Tuner Output: This output is unaffected by controls.

Mute Switch: Mutes the audio out.

Effects Loop: Has in/out switch and level controls.


Preamp Specifications

  • Input impedance: > 1megohm

  • Output impedance (line): > 2kohm, (unbalanced)

  • Output impedance (mic): > 50ohms (balanced)      HBP1J : 150ohm, (balanced),

  • Minimum load impedance: 600ohms

  • Maximum output: + 24dBV @ 600ohms

  • Gain: Adjustable to + 10dB Mid 440Hz to 4KHz

  • EQ gain : + or – 15dB

  • Signal to noise ratio: – 80dB

  • THD : .5%

  • Frequency response : 10Hz to 40kHz

  • Tube: 1-12AX7a selected 1-12AT7

  • Inputs: 1/4″ (passive and active)

  • Outputs (preamp): 3-pin balanced mic/line, TT, XLR & ¼”

  • Chassis: Single space rack

  • Operating voltage: 115V/230V AC switchable

  • Power supply: 250V fully regulated

  • Filament: 12.6V fully regulated

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


Download user manual


Additional information

Weight 11 lbs
Dimensions 24 × 16 × 10 in


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