The first function of the High-Q Driver (model QV1) is to match the impedance of the guitar pickup to the impedance of the instrument cable. Typical electric guitar pickups have very high impedance, especially at high frequency; they are not able to drive long instrument cables without losing the high harmonics. The sound turns to mud. The QV1 has a high input impedance of 10,000,000 ohms and a low output impedance of 330 ohms, allowing all of the sound to pass through the instrument cable with virtually no loss of tone.

The second function of the QV1 is to open up the pickup bandwidth. This can be viewed as an extreme example of audio equalization. A complex pole-pair near the jw axis gives a sharp gain boost of over 20dB (Decibels) where the pickup needs it most - just where the output starts to fall off.

A rotary dial switch inside the QV1 box is used to adjust the high-Q filter to match different pickups. There are 16 dial settings from 0 (for bright pickups with high treble) through F (for mellow pickups with low treble). The first plot below shows the gain of the QV1 by itself, for three different dial settings. The next two plots show the output spectrums of two different pickups, with and without the QV1. The bandwidth in Hz (Hertz) is indicated for each case, showing that the QV1 High-Q Driver expands the bandwidth by more than one octave.

The table at the end gives QV1 gain values for each of the 16 rotary dial switch settings.