Audio Research SP-3A-1 Tube Preamplifier - Restored

Free Shipping on *ALL* Electronics (Excluding Speakers, Contiguous 48 US States Only)

Many consider the SP3 as the finest preamp ARC ever produced.

Its classic looks and reliable operation have made this piece a favorite among classic collectors.

This particular sample came from a collector that didn’t use it very much. It mostly sat on a shelf looking pretty.

Cosmetic condition is very good for an SP3. The top cover is free from rust, the knobs and faceplate are near perfect, and the silk screening is intact.

All SP-3's have a very capable phono section which sounds amazing and will handle most cartridges. 

We rebuilt the voltage regulation and power supply, and it's good to go for another 50 years. 

Click here for a PDF copy of the SP-3A-1 Owner's Manual

Our Testing Process for Preamplifiers at SkyFi:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage. Special attention is paid to the power supply which is the most common source of failure for preamps. We then power up the unit and run a simple 1k sine wave while monitoring the low voltage output on an oscilloscope for signs of distortion or noise to get a baseline.

At this point we will lubricate and clean all switches and potentiometers (that are not sealed) with a high quality contact cleaner, and then re-test all functions for any signs of noise or scratching.

Final testing involves putting actual music through the preamplifier We have learned over time that some issues are only noticeable to a trained ear while listening to a familiar source material. Our test bench has reference vintage Kef speakers that we are super familiar with which will quickly reveal any discrepancies. Some preamps will then move into the listening room where they will be tested with our in-house reference system.

Technical Specifications:

Frequency response:
15Hz-30kHz, ±1dB

Distortion (THD):
0.005% at 5V out

Maximum output:
25V at 1kHz

S/N Ratio:
90dB (Aux input, no ref. level given)

Dimensions:
15 5/8" W by 5" H x 12½ D

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.