This is a great sounding all FET preamp featuring switching for six-line level inputs including tape monitor. Circuit highlights include a low output impedance which acts as a buffer between the level controls and the amplifier interconnect cables, avoiding the high frequency filter effect inherent in a passive control. This preamp has a unique zero-response circuit which exploits the symmetrical performance of N and P channel field effect transistors to cancel distortion without resorting to negative response. A low impedance discrete DC regulator powers this circuit, for minimum ac impedance at all audio frequencies. FET's are used in Sonographe audio circuits because of their tube-like square law transfer functions, which exclude unmusical odd order distortions that typify bipolar transistor circuits. Unit is in excellent condition. Owners Manual available on line. Below are some specs.
Output: 10 V RMS
Phase: Phase inverting.
Response: 5 Hz to 100KHz
Signal to Noise Ratio (20Hz-20KHz): 94 dB
Distortion: less than .1% THD
Output impedance: less than 200 ohms
Dimensions: 12.25D x 17.125W x 2.5H inches
Weight: 10 lbs