Audio Research SP-8 SP8 Vintage Tube Preamplifier

Audio Research SP-8 MKII tube preamplifier in Mint minus condition. I say mint minus as the additional silver faceplate as some scratch/distortion on the upper left corner.

I am the original owner and I have cared for this piece very well, recently fully restored with upgraded capacitors plus all switches and controls fully cleaned and lubricated, plus new tubes. LED's are original and work well.

included are both the Silver and Black faceplates and knobs that were purchased when the unit was new. Currently the unit has the black faceplate installed and the silver knobs as shown. Tubes are all NOS Russian Electro Harmonic, roughly 40 hours of use since the tubes were installed. I would remove the tubes and package separately for safe shipping. Owners of these preamps often Roll tubes to get their own version of perfect sound, these tubes are certainly a good starting point.

Audio Research SP-8 MKII Tube Preamplifier – NOS Russian Tubes, Black & Silver Faceplates and Knobs. Original owner sale, all documentation. (Instruction manual, schematics, factory inspection checklist)

Condition: Mint minus, fully serviced by professional tube audio technician, collector-level condition.
Included:
• Both black and silver faceplates
• Both black and silver original knobs
• Russian Electro Harmonix NOS tubes installed in all sockets. Low use, 40 hours.
• All electrolytic caps replaced with high-quality upgrades.
• Original box included, and will be double boxed for shipping.
• Manual and schematics.
Details:
This is the Audio Research SP-8 MKII, one of the most sought-after vintage tube preamplifiers. The MKII revision features refined circuitry and a 12AT7 tube in the V8 position, providing improved gain structure, stability, and sonic clarity over earlier MKI units.
Phono input Performance:
The SP-8’s built-in moving-magnet phono stage has solid performance, especially for its era:
• RIAA accuracy: ±0.25 dB over 30 Hz–40 kHz ,very tight response for an analog stage.
• Frequency response: extends well below 1 Hz and beyond 100 kHz (–3 dB points).
• Low noise: equivalent input noise around 5 µV for magnetic cartridges.
• High gain: ~60 dB overall from magnetic phono to main output-plenty for most MovMag cartridges.
• Four high-level inputs plus tape monitor circuit.
• Two switched, two unswitched grounded AC outlets
This unit has been professionally serviced:
• All capacitors upgraded for improved voltage regulation
• Russian NOS tubes installed, delivering warm, detailed, and dynamic sound
• Internal switch contacts and tube sockets fully cleaned and inspected
• All toggle switches, function switches and potentiometers cleaned and lubricated.
Cosmetic Condition:
• Mint- condition – chassis, faceplates, and knobs
• Black knobs and faceplates are pristine
• Silver knobs pristine, faceplate has one corner with minimal damage
• Chassis has no marks or damage, no corrosion
• Rear panel serial number clearly visible
Extras & Value:
• Additional faceplate and knobs
• MKII revision is highly sought after for its performance and reliability
• Pre -amplifier will be professional packaged and tubes will be removed for shipment.
Tube Complement :
• V1 12AX7EH Russian Electro Harmonix
• V2 12AX7EH Russian Electro Harmonix
• V3 6922EH Russian Electro Harmonix
• V4 12AX7EH Russian Electro Harmonix
• V5 12AX7EH Russian Electro Harmonix
• V6 6922EH Russian Electro Harmonix
• V7 12BH7AEH Russian Electro Harmonix
• V8 12AT7EH Russian Electro Harmonix