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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 outletsThis 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 visibleExtras & 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
This is a seller’s market for the model at this ask: US$2,900 sits above the US$2,000 median but below the US$4,094 75th percentile, so it reads as upper-mid market, not a bargain. It is still inside the normal used spread, but I’d call it a fairly ambitious price unless the unit is exceptionally clean, recently serviced, or comes with strong provenance.
That said, this is a respected vintage Audio Research line, and the SP-8 has the sort of full-bodied, detailed tube preamp sound that keeps it on many shortlists. If it’s quiet, stable, and truly original or properly serviced, the appeal is real; just verify tube condition, service history, and whether the controls are noise-free, since age-related maintenance matters more here than cosmetics alone.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Audio Research Corporation, founded in 1970 in Minneapolis, Minnesota, by William Z. Johnson, traces its roots to his pioneering work in custom audio electronics during the 1950s and his operation of a specialty retail store through the mid-1960s. After a brief stint selling his designs to a larger firm, Johnson regained independence to establish ARC with a singular mission: advancing the state-of-the-art in music reproduction. From modest beginnings in the back of his shop, the company evolved into one of America's oldest continuously operating high-end audio manufacturers, now housed in a state-of-the-art 48,000-square-foot facility in Maple Grove, Minnesota.
ARC specializes in performance-driven electronics, renowned for vacuum-tube amplifiers, preamplifiers, and electronic crossovers that emphasize sonic purity over flashy features or aesthetics. Drawing on circuit designs rooted in the 1950s, the brand integrates tubes into modern contexts, delivering what it calls "high definition" sound through genuine technological advances. While not venturing into speakers, turntables, DACs, headphones, or cables, ARC's focused lineup prioritizes amplifiers and preamps that set benchmarks for musical realism.
Positioned at the pinnacle of high-end audio, Audio Research is hailed as a true originator of the genre, commanding respect among audiophiles for its unwavering commitment to excellence and innovation. Enduring the 1970s tube revival against solid-state dominance, ARC thrives via elite specialist retailers worldwide, standing alongside peers like Conrad-Johnson as a vintage-inspired yet forward-thinking force in the niche boutique market.
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