Audio Research SP9 MKII Tube / Solid State Hybrid Preamp with Phono Input

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These ARC preamps are our best sellers.

The SP series, as opposed to the LS series, features a built-in phono preamp section for convenient connection to your turntable.

Legendary warm tones, mostly due to tube harmonics, is the signature for these preamps.

In perfect working and overall cosmetic condition. We've only rated this an 8 for "Physical Condition" due to its age and the fact that we're super conservative.

Yes its priced like the day it left the factory in the late 1980's - but well worth it as you're not likely to find a better sounding preamp in this price range.

Important Phono Stage Notes:

This preamp does offer end-user adjustment of the phono cartridge loading. However this involves soldering a pair of precision resistors to a specific set of terminals on the underside of the main preamplifier board.

This specific example was adjusted with 100 Ohm resistors to work with typical low to medium output MC (Moving-Coil) phono cartridges.

If you need this this converted back to the stock 47K Ohm resistors, or a different value to match your specific setup, please let us know during your purchase for proper adjustment.

Manual is a printed copy, not original.

Tube Notes: (2) Sovtek 6922 (More rugged substitute vs the stock 6DJ8)

Audio Research SP9 MKII Owner's Manual

Details and Specifications:

INTRODUCED
1987

OPTIONS
Remote control $500 (1994)

MSRP
SP9 MKII: $1,795. Later increased to $1,875.

FREQUENCY RESPONSE
High Level Section: ±.5dB, 5 Hz to 50 kHz, - 3dB points below 1 Hz and above 200kHz. Phono: ±.3dB of RIAA, 30Hz to 40kHz.

DISTORTION (THD)
Less than 0.1% at 2V RMS output. (Typically less than 0.005% in midband)

NOISE & HUM
High Level: (1) 70 µV RMS maximum residual unweighted wideband noise at main output with gain control minimum (98 dB below 5V RMS output). (2) More than 100dB below 1V RMS input (less than 7µV equivalent input noise). Phono: 0.12 µV equivalent input noise, IHF weighted, shorted input (78dB below 1 mV input).

GAIN
Phono input to tape output: 46dB. Phono input to main output: 66dB. High level inputs to tape output: 0dB. High level inputs to main output: 20dB.

INPUT IMPEDANCE
50K ohms line inputs. 40K phono (Phono provisions for any value below 47K ohms or added input capacitance for matching certain magnetic cartridges).

OUTPUT IMPEDANCE
500 ohms main output. 850 ohms recorder output. Recommended load 60K ohms and 100pF. (20K ohms minimum and 1000pF maximum).

OUTPUT POLARITY
-

MAXIMUM INPUTS
Phono, 200mV at 1kHz (1000 mV RMS, 10kHz). High level inputs essentially overload proof.

RATED OUTPUTS
2V RMS 5Hz to 50kHz, all outputs; 60K ohm load (main output capability is 50 V RMS output at 1/2% THD at 1kHz into a 100K ohm load with 5V RMS high level input)

POWER SUPPLIES
Electronically–regulated low and high voltage supplies and electronic decoupling. Shielded toroid transformer. Line Regulation better than .01%.

TUBE COMPLEMENT
(2) 6DJ8/ECC88.

POWER REQUIREMENTS
100-135 VAC 60 Hz (200-270 VAC 50/60Hz) 50 watts max.

DIMENSIONS
19” (48 cm) W x 5 1/4” (13.4 cm) H (standard rack panel) x 10 1/4” (26 cm) D. Handles extend 1 5/8” (4.1 cm) forward of the front panel. Rear chassis fittings extend 7/8” (2.3 cm).

WEIGHT
13 lbs. (5.9 kg) Net; 22 lbs. (10 kg) Shipping.

Audio Research SP9 Owner's Manual

The SkyFi Testing Process for Preamplifiers:

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.

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