Audio Research SP 12RM (Rack Mount) tube stereo preamplifier.
Frequency response High level section: ±.5dB, 4Hz to 30kHz. -3dB points below 1Hz and above 70kHz
Magnetic phono: ±.25dB of RIAA, 30Hz to 20kHz
Distortion (THD)Harmonic distortion: Less than .02% at 2V RMS output, 20Hz to 20kHz
Intermodulation distortion: Less than .07% at 2V RMS outputNoise & humHigh level: (1) 250µV RMS maximum residual unweighted wide band noise at main output with gain control minimum (86dB below 5V RMS output) (2) More than 90dB below 1V RMS inout (less than 20µV equivalent input noise)
Magnetic phono: 5µV maximum equivalent input noise, wideband RMS (-66dB reference 10mV input) (Less than 1µV above 200Hz or -80dB reference 10mV input)
Gain Magnetic phono input to tape output: 34dB
Gain Magnetic phono input to main output: 60dB
Gain High level inputs to tape output: 0dB
High level inputs to main output: 26dB
Input impedance50K ohms phono; 100K ohms high level
Output impedanceLess than 4000 ohms main output and tape output from phono.
Recommended minimum load for maximum audio quality 60K ohms and 300 pF maximum capacitance.
Output polarity Maximum inputs
Magnetic phono, 600mV at 1kHz. (3V RMS at 10kHz)
High level inputs essentially overload-proof.
Rated outputs 2V RMS all outputs into 60K ohm loads (Main output capability is 50V RMS output at ½% THD at 1kHz into a 500K ohm load.)
Power supplies Electronically-regulated solid-state supplies. Frequency-compensated high-voltage supplies have a total equivalent low-frequency stability of 1 farad of capacitance. Line regulation .05%.
Tube complement (5) ECC88/6DJ8 dual triodes
Power requirements 100-135VAC 60Hz (200-260VAC 50Hz) 30 watts max.
Dimensions 15.6" (40 cm) W x 4.5" (11.4 cm) H x 8.9" (22.6 cm) D. Knobs extend .7" (1.8 cm) forward of front panel. Rear chassis fittings extend .9" (2.3 cm).
Weight 9 lbs. (4.1 kg) Net;
All used products are fully tested, repaired as needed, and in 100% correct working order.