DESCRIPTION

The SP-3A-1 is a vacuum tube preamplifier that was introduced in 1975 and discontinued in 1978. It is the most common of all the SP-3 model variations.

Frequency response ±1dB 10Hz-30kHz, IHF load
±1dB of RIAA 30Hz-30kHz
Distortion (THD) Harmonic distortion: Less than 0.005% at 5V RMS output, IHF load
IM distortion: Less than 0.005% at 5V RMS output, IHF load, SMPTE method
Noise & hum High level inputs (unweighted wide-band): more than 90dB below rated output
Magnetic phono inputs (below 10mV input) 20Hz to 20kHz: more than 70dB below rated outputs. Power line components (hum): more than 66dB
Gain 57dB, magnetic phono input, main outputs, IHF load
34dB, magnetic phono input, tape outputs, IHF load
23dB, high level inputs, main outputs, IHF load
0dB, high level input, tape outputs, IHF load
Input impedance Magnetic Phono: 50K ohms typical (150 pf shunt)
High Level: 100K ohms typical
Output impedance Less than 600 ohms @ 1kHz (all outputs). Recommended load: 20K or greater
Output polarity
Maximum inputs 300mV RMS @ 1kHz (magnetic phono input). High level inputs overload proof.
Rated outputs Maximum output: 25V RMS @ 1kHz, all outputs
Power supplies
Tube complement (2) 12AX7 LN, (6) 12AX7
Power requirements 120/240V, 50/60Hz, 60 Watts
Other Tone controls: Bass and treble variable ±18dB at 10Hz and 15kHz respectively
Dimensions 15 5/8" W x 5½" H x 12½ D
Weight 14 lbs. Net. 20 lbs. Shipping