The Audio Research SP-15 is a ’90s-era hybrid preamp built for detail lovers and vinyl romantics alike. It marries solid-state precision on the line stage with the glow of three 6DJ8 tubes in its phono section, delivering music that’s both clean and captivating. You get a sweet balance of surgical clarity and tube soul, with specs to match: vanishingly low distortion, ultra-wide frequency response, and a whisper-quiet noise floor. The onboard phono stage is highly regarded—dynamic, uncolored, and adjustable to suit a wide range of cartridges. With full-featured controls, balanced outputs, and that unmistakable Audio Research build, the SP-15 is as much a reference tool as it is a musical storyteller.
Production
1988
Condition
9.5/10
Serial No.
48342022 / 68343024
Orig. MSRP
$5,995
Restoration
- Replaced all tubes with Sovtek 6922 tubes
- Cleaned control contacts with contact cleaner
- Verified inputs and outputs
- Preamp and power supply come with original boxes and packing
- Umbilical connection cord is included
- Unit is equipped with a phono impedance selector for use with moving magnet and moving coil cartridges
Factory Specs
Frequency response
High level input: ±1dB 0.2Hz to 100kHz. -3dB below 0.1Hz and above 200kHz. Phono input: ±.2dB of RIAA 20Hz to 40kHz. ±1dB of RIAA 1.0Hz to 100kHz.
Distortion (THD)
Harmonic distortion: Less than .005% at 2V RMS output, 5Hz to 20kHz (Typically less than .001% at midband, phono or line input). Intermodulation distortion: Less than .003% at 2V RMS output
Noise & hum
IHF weighted, shorted input: Output (Gain down): 6µV (110dB below rated output). Input (High level): 3µV equivalent input (110dB below 1V input). Phono: 0.15µV equivalent input (76dB below 1mV input)
Gain
At 1kHz, bypass mode: Phono input to tape output: 46dB (0.2V output from 1mV input). Phono input to main output: 75dB (0.175mV input for 1V output). High level input to main output: 29dB (36mV input for 1V output).
Input impedance
Phono: Front panel selectable 47K, 100, 30, 10, 3 ohms. Phono input capacitance: 150 pF at 10kHz. High level: 20K ohms or higher, depending on switch functions.
Output impedance
200 ohms main, direct, inverted outputs. 500 ohms tape output. Recommended load 60K-100K ohms and 100pF (20Kohms minimum, 1000pF maximum)
Output polarity
Tape outputs, direct output: Non-inverting. Invert output: Inverting. Main outputs (2): Selectable non-inverting or inverting. All outputs may be used simultaneously.
Maximum inputs
Phono: 350 mV RMS at 1kHz, 1200 mV RMS at 10kHz (0.1 second maximum duration, 6dB less if continuous). High level: 25V RMS.
Rated outputs
2V RMS 1Hz to 100kHz main, direct, inverted outputs. (Maximum 80V RMS at 0.2% THD at 1kHz into 60K ohm load with 2.85V RMS high level input).
Tube complement
(3) 6DJ8/ECC88
Power requirements
95-135VAC 60Hz, 190-270VAC 50/60Hz, 130 Watts maximum
Other
Filter: 25Hz Hi-pass phono subsonic 6dB/octave rolloff (to eliminate ringing) with transition to 12dB/octave at 10Hz. Front panel switchable phono only. Controls (6): Gain, Attenuator, Balance, Mode, Input, Impedance. Switches (8): Tape monitor, Copy, Tape 1/2, Tape 1to2 / 2to1, Mute, Invert phase, Bypass, Filter.
Dimensions
(Each chassis, EIA Rack panel mounting) 19" (48 cm) W x 5 ¼" (13.4 cm) H x 10 ¼" (26 cm) D. Handles extend 1 ⅝" (4.1 cm) forward of panel. Interconnect cable extends 4" behind rear of chassis.
Weight
SP-15: 14 lbs. (6.4 kg) Net, 23 lbs. (10.5 kg) Shipping. SP-15PS: 15 lbs. (6.8 kg) Net, 23 lbs. (10.5 kg) Shipping. Total: 29 lbs. (13.2 kg) Net, 46 lbs. (21.0 kg) Shipping.
The History of Audio Research
Audio Research Corporation, affectionately known to fans as ARC, was founded by William Z. Johnson, who began designing custom audio electronics in the early 1950’s and who also operated a specialty audio retail store until the mid-1960’s. Johnson’s efforts almost single-handedly revived vacuum-tube designs at a time...
[ Read More ]
Liner Notes
From first power-up the SP15's lower noise floor is instantly apparent-silences are inherently more silent. dynamic contrasts are significantly more palpable. Consequently, a good program source has astounding verisimilitude. The frequency extremes sound with peerless rigor and focus, giving a clear sensation of wider dynamic bandwidth. And most tellingly, the SP15's staging creates a specificity of image-left/ right, back/front, up/down-that simply must be heard to be appreciated.
The SP15 achieves all this by means of several important new design features:
To begin, Audio Research engineers have obtained a considerable decrease in signal degradation by using a new, exceptionally quiet five-position attenuator switch in place of the stepped gain pot of the SP11. It provides 6dB attenuation in each of four increments, giving the user control over a wide range of input signal levels with maximum sonic purity.
New, state-of-the-art circuitboard material also allows substantially cleaner signal-handling, as does the use of just three tubes in the signal path.
In response to real-world phono cartridge preferences, the SP15 provides more useful impedance settings-47K, 800, 100, 60, and 30 ohms. And for audiophiles who prefer balanced connections, the SP15 comes equipped with high-quality XLR connectors.
Audiophiles and critics the world over will find that the SP15 combines peerless musical performance with everyday functionality and reliability. Audio simply doesn't get any better than the SP15.
Stock No.
9060652417245
