Audio Research SDP1 // Solid State Surround Processor

The Audio Research SDP1 is a multichannel music processor designed to expand a traditional stereo setup into a five-channel matrix, enhancing the spatial experience of two-channel recordings. Introduced in the mid to late 1990s, the SDP1 was Audio Research's foray into pseudo-surround sound, aiming to synthesize rear and center surround channels from stereo sources. ​

S/N: 25180001

• Tested all tubes (Hickok 605a)
• Cleaned control contacts
• Verified operation
• Replaced feet screws

L-R ambience extractor

Inputs: one pair, balanced or unbalanced

Input impedance: 1.5Megohms unbalanced, 3M ohms balanced

Gain: 12dB maximum (6dB balanced into unbalanced out, 10dB unbalanced into balanced out)

Frequency response: 2Hz-400kHz +0, -3dB

Distortion: <0.01% at 2V out. Noise: <30µV RMS, IHF-weighted, center channel

Maximum output: 18V balanced

Controls: two surround level, one center level, surround delay (25, 28, 32, 38, and 45 milliseconds), Mute, Power. Outputs: one pair surround, one pair pass-through L and R, one center, all balanced and unbalanced

Power consumption: 40W.
Dimensions: 19" W by 11¾" D by 3½" H

Weight: 11.5 lbs.