audio research
SP-4

Description
Solid state stereo preamplifier.

Introduced
1976

Discontinued
?

Revisions
SP-4A (1978)

Options
Wood cabinet (WC-2) $75

MSRP (US new retail)
SP-4: $695. Later increased to $895.
SP-4A: $975. Later increased to $1,195. Later increased to $1,395

Specifications

Frequency response Head amp (optional): 5 Hz to 100 kHz (-3 dB)
Magnetic phono: +/- 0.5 dB of RIAA, 20 Hz to 20 kHz
High level: 1 Hz to 100 kHz (-3 dB)
Distortion (THD) Harmonic distortion: Less than 0.005% @ 2 V RMS output (IHF load, with optional head amp or phono input)
Intermodulation distortion: Less than 0.005% @ 2 V RMS output (IHF load, SMPTE method, with optional head amp or phono input)
THD and IMD decreases with decreasing output
Noise & hum Head amp (optional): less than 50 nV equivalent input noise with 10 ohms input (RIAA weighted)
Magnetic phono: less than 0.5 µV equivalent input noise with 1k ohms input (RIAA weighted). Typically 84 dB below 10 mV @ 1 kHz
High level: less than 2 µV equivalent input noise with shorted input and max. gain (20 Hz to 20 kHz). Typically 95 dB below rated output
Gain Head amp (optional): 26 dB
Magnetic phono: 36 dB
High level: 24 dB (IHF load)
Input impedance Head amp (optional): 10 ohms
Magnetic phono: 47k ohms (50 pF min.)
High level: 50k ohms (nominal)
Other values may be substituted. Head amp (optional) adjustable up to 100 ohms. Magnetic phono adjustable up to 100k ohms.
Output impedance Less than 50 ohms
Output polarity  
Maximum inputs Head amp (optional): 5 mV RMS @ 1 kHz
Magnetic phono: 150 mV RMS @ 1 kHz
Rated outputs Maximum 10 V RMS (all outputs, IHF load)
Power supplies  
Power requirements 120/240 VAC, 50/60 Hz, 25 watts
Other  
Dimensions 19" (48 cm) W x 8 ½" (21 cm) D x 3 ½" (8.9 cm) H (rack mount front panel)
Weight 12 lbs. (5.5 kg) Net, 15 lbs. (7 kg) Shipping

Reviews

Number 9 (SP-4: Full Review)
Vol. 4 No. 1 (SP-4)

Pictures

SP-4:

SP-4A:

SP-4/SP-4A: