audio research

Two-chassis hybrid tube/FET stereo preamplifier.



SP-11 Revised
SP-11 MKII (1987)
SP-11 MKII Special Edition (1990): Limited to 50 sets in gold/champagne faceplates to celebrate ARC's 20th anniversary.


MSRP (US new retail)
$4,995/$5,995 (SP-11 MKII)


Frequency response High level input: ±1dB 0.2Hz to 100kHz. -3dB below 0.1Hz and above 100kHz.
  Phono input: ±.2dB of RIAA 10Hz 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: 20Kohms or higher, depending on switch functions
Output impedance 250 ohms main, direct, inverted outputs. 500 ohms tape output. Recommended load 60Kohms 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 60kOhm load with 2.85V RMS high level input).
Power supplies  
Tube complement (6) 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.
Dimensions 19" (48 cm) W x 5.25" (13.4 cm) H x 10.25" (26 cm) D (each unit). Handles extend 1 5/8" (4.1 cm) forward of panel. Interconnect cable extends 4" behind rear of chassis.
Weight SP-11: Net 14 lbs. (6.4 kg); Shipping 23 lbs. (10.5 kg)
  SP-11PS: Net 15 lbs. (6.8 kg); Shipping 23 lbs. (10.5 kg)
Total: Net 29 lbs. (13.2 kg); Shipping 46 lbs. (21.0 kg)


Issue 40&45 (SP-11: Full Review), Issue 41 (SP-11: Update), Issue 43 (SP-11: Special Report), Issue 47 (SP-11 Revised: Editor's Choice), Issue 50 (SP-11: Capsule, SP-11 MKII: Special Report)
Vol. 9 No. 4 (SP-11), Vol. 9 No. 7 (SP-11)




SP-11 MKII Special Edition: