DB - Vacuum Tube Microphone Preamplifier

An entire year of research and design led to the product you see here.

It would have been selfish to build just one for myself, so I am offering a limited run of this two-channel tube preamp. It is available to anyone who wants a classic transformer balanced tube preamp, with high quality components and useful features, at an affordable price.

Download Pro Tools 12 session file: Drivin' Nails in My Coffin. 

QUALITY COMPONENTS

The preamp’s key components are not easily found in modern production models. I tested numerous combinations of transformers, tubes, and coupling capacitors before deciding on the final tonal characteristics that sounded best to me. 

Matched pairs of 1960s new-old-stock General Electric tubes meet or exceed published specifications of transconductance. The GE 5-Star 6072a is legendary for its larger-than-life 3D quality, while the choice of either a NOS RCA or GE 12AU7 contributes its hi-fi soundstage, tight bass, and neutral highs. 

Jensen has led in transformer research for decades. Their JT115k input transformer is designed for the highest practical 1:10 step-up ratio within their company’s design tolerances. Paired with Jensen's JT-10K61-1M output, these are perfect transformers for a tube preamp. 

Glass-sealed Russian paper-in-oil and Teflon bypass capacitors are used for coupling following tube gain stages. Polypropylene film and electrolytic caps are used elsewhere in the audio and PSU circuits.  

High quality stepped-gain rotary switches are used instead of potentiometers for repeatable gain selection and to help maintain signal integrity. 

Features 

  • 63 dB Gain
  • XLR Inputs/Outputs
  • 1/4" Instrument Input
  • -20 dB PAD 
  • +48V Phantom Power 
  • Ø Polarity Switch 
  • Low Shelving Filters
  • Rear Panel Grounding Lug
  • 120 VAC IEC Fused Power

 
Carefully-Selected Components  

  • Jensen Transformers
  • NOS General Electric 6072a
  • NOS General Electric 12AU7
  • Paper-in-Oil Coupling Capacitors  
  • Teflon Bypass Capacitors  
  • Stepped Attenuators
  • DC Heater Supply
  • Toroidal Power Transformer
  • Turret Board Construction

  
Specifications  

  • 20Hz-20kHz (+/- 0.2 dB)
  • Noise EIN: -125dB (max)
  • Input Impedance 2.4k ohms
  • Output Balanced 600 ohms
  • Low Shelf POS 1: Flat
  • Low Shelf POS 2: -3dB at 75Hz
  • Low Shelf POS 3: -3dB at 275Hz
  • Dim (3U): 19" W x 5.25" H x 11" D
  • Weight: 19.0 lb

 

    ONE PAYMENT of $1,999.99

    DB VACUUM TUBE MICROPHONE PREAMPLIFIER

    DB VACUUM TUBE MICROPHONE PREAMPLIFIER

    In cart Not available Out of stock

    The DB Vacuum Tube Microphone Preamplifier is a classic transformer balanced tube microphone preamp with instrument DI. Features 63 dB of selectable gain, +48V Phantom Power, -20 dB PAD, phase reverse, and two custom switchable low shelf filters. The circuit includes special components such as Jensen transformers, paper-in-oil coupling capacitors, stepped gain attenuators, and NOS General Electric tubes from the 1960s. Allow 4-6 weeks for build and delivery.

    $999.99 2ND PAYMENT (DUE BEFORE SHIPPING]

    $999.99 2ND PAYMENT (DUE BEFORE SHIPPING]

    In cart Not available Out of stock

    Item will ship after receiving 2nd final payment of $999.99 + shipping.

    OR MAKE TWO PAYMENTS

    $1,000 DOWN PAYMENT (non-refundable)

    $1,000 DOWN PAYMENT (non-refundable)

    In cart Not available Out of stock

    A non-refundable down payment ensures your position in line for a DB Vacuum Tube Microphone Preamplifier. I provide this option as a way to help you manage your budget by splitting up the payments into two installments.