Hugsley HG01 Tone Controller

Features: 

   High-Gain Tube Emulation JFET Amplifier 
   Single Potentiometer Multi-Pole Tone Control 
   Compact Dimension (approximately 1.0 inch sq.) 
   Single 9.0 Volt Battery Power Source 
   Approximately 1500 Hours on Single Battery

Application: 
   
   On-Board Guitar Preamplifier 
   External "Stomp Box" 
   Active Pick-up

Specifications: 

   Gain of +20 dB at Mid-Boost 
   Input Impedance greater than 500 kOhm 
   Output Impedance less than 1.0 kOhm (at minimum control set) 
   Current Draw Approximately 350 micro-Amps

Circuit Description:

The Hugsley HG01 Tone Controller may be analyzed by dividing it into three functional circuits. The first being a Low-Noise, Class-A, JFET amplifier with a unique biasing scheme that emulates the transfer and distortion characteristics of a vacuum tube triode amplifier. The second function is that of a filter/attenuator circuit that emulates the loading characteristics of a classic vacuum tube amplifier tone-stack. The third circuit is embedded into the filter/attenuator and provides a Class-A, Mid-Boost amplification function that is centered at approximately 1 kHz.

By controlling the tone with a single potentiometer, the overall effect is a smooth sweep across a broad spectra of audible variations ranging from the "bell-chime" tone of a vintage single-coil pickup, through the "thin-body" tone of a light-wood guitar and finishing with a rich and high-volume overdrive tone.

The circuit is intended for guitar "in-board" installation but the applications are only limited by the imagination of the user.