Audio Components

Bass Guitar Pre-Amplifier

A solid state bass guitar pre-amplifier designed to have a flexible effects path and high gain tone control. The input is a buffered high impedance fixed load design to allow long cable runs and minimal passive pickup loading.  The input gain is adjustable to accommodate a wide variety of bass guitars.  There are two effects loops separately mixable with individual high cut tone controls.  Each effects loop has 2  TRS insert points, one for the front panel for pedals followed by another on the rear for an outboard compressor.  Effects loop one contains a simple adjustable fuzz circuit, a front panel on / off switch and an additional TRS jack for a remote bypass switch.  Effects loop two is intended for clean only operation and has no additional features.  After the effects loops are mixed with their own level adjustments, the signal enters a high gain three band shelving tone control.  The master output volume is next followed by a third order active crossover.  There are two full range outputs, on both the front and rear panel, and a high and low pass output on the rear panel.


  • Frequency Response: <10Hz to 100kHz -1dB (tone controls flat)
  • Input impedance: >500k ohm
  • Maximum Gain: 40dB, all gain controls set fully CW
  • Maximum input level: 18V peak
  • Maximum output level: 15V peak
  • Bass tone control: +-20dB at 20Hz
  • Midrange tone control:  +-20dB at 2kHz
  • Treble tone control:  +-30dB at 20kHz
  • 2 Way Crossover fixed at 200Hz with 18dB / Octave slopes

Portable Practice Amplifier PPA-100

A solid state combo amplifier designed for compact portable use without sacrificing sound quality. Clean reproduction can be utilized for any input source.  The design combines a simple input gain system and a three band shelving tone control with a 100WRMS power amplifier and two way speaker system.

Details on the design and re-build of this amp are published here.


  • Dimensions: 15″ x 13″ x 11″
  • Frequency Response: Pre-Amp <10Hz to 100kHz -1dB (tone controls flat)
  • Speaker Frequency Responce: 50Hz – 15kHz +-5dB
  • Speaker Sensitivity: 92dB at 1W / 1M
  • Input impedance: >500k ohm
  • Minimum input level: 110mV peak for maximum output
  • Maximum output level: 1.5V peak at pre-output
  • Power output: 100WRMS into 8 ohms
  • Bass tone control: +-15dB at 20Hz
  • Midrange tone control:  +-15dB at 2kHz
  • Treble tone control:  +-20dB at 20kHz
  • Switchable 18dB / Octave crossover at 200Hz for use with external woofer