Carver C-9 Sonic Holography Generator

For sale is a Carver C-9 Sonic Holography Generator pre amp. In good condition with a few scratches. Orginal box and manual. This a cool little piece to own. 
The goal of sonic holography is to remove distortions in pitch caused by the doppler effect while recording and playing back audio on a sound system. While an audio source is recorded by a microphone, the membrane that picks up sound vibrations moves towards and away from the source. This results in a doppler shift that is preserved in the recording. When that recording is played through a speaker, the cone vibrates back and forth in order to move air particles and create sound. This introduces a second doppler shift, especially when the same cone is producing multiple frequencies at the same time. Both instances of doppler distortion degrade the overall quality of the output. Sonic holography attempts to remove these distortions using a proprietary filter designed by Bob Carver.