audio research
SP-1

Description
Tube stereo preamplifier. Generally marked 'Electronic Industries'.

Introduced
1970

Discontinued
?

Revisions
SP-1A
SP-1B
SP-1C

Options
-

MSRP (US new retail)
$750 (SP-1A)

Specifications

SP-1A:

Frequency response Aux and tuner inputs: ±1dB 20Hz to 20 kHz
  Magnetic phono input: ±1dB of RIAA curve
  Magnetic tape input: ±1dB of Ampex playback curve
Distortion (THD) Harmonic distortion: Less than .01% at 5V RMS output 1kHz on either aux or magnetic input, gain max, high impedance.
  Impulse distortion: Essentially none, 30Hz to 15kHz
Noise & hum Aux: 90dB below 1V input
  Mag: 60dB below 10mV input
Gain Aux: 20dB (voltage gain of 10X)
  Mag: 54dB (voltage gain of 500X)
Input impedance Aux: 500Kohm
  Mag: 50Kohm
Output impedance  
Output polarity  
Maximum inputs Aux: 50V RMS @ 1kHz
  Mag: 750mV RMS @ 1kHz
Rated outputs Maximum output: At least 30V RMS 1 kHz into high impedance
Output load: Up to 2000pF and down to 10Kohm for 5V RMS output
Power supplies  
Tube complement (13) 12AX7, (1) 6X4
Power requirements 117V 50/60Hz approximately 45 watts
Other Tone control range: ±15dB at 20Hz and 10kHz
Dimensions Panel: 15 5/8" W x 5" H, overall depth 14½"
Panel mounting cutout: 4½" H x 15¼" W
Depth behind panel: 14" (includes cable clearance)
Knob and panel clearance: 1¼"
Weight 30 lbs.

Reviews

Pictures

Electronic Industries SP-1:

SP-1:

SP-1A:

SP-1C: