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Audio Research D-115 Tube Amplifier

Sale price$0.00
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Pickup currently unavailable at SkyFi 479

Audio Research D-115 Tube Amplifier

Audio Research D-115 Tube Amplifier

SkyFi 479

Pickup currently unavailable

479 South Broad Street
Glen Rock NJ 07452
United States


Here's your chance to own a classic tube amplifier at a reasonable price.

The D-115 delivers 100W using eight KT77 tubes (it actually measured closer to 115W before clipping), while maintaining the traditional warm and precise Audio Research signature sound.

This is a well-built American made unit - not a recent Chinese attempt at HiFi -  weighing in at 68 lbs.  It's made from the highest quality components available at the time, and was hand assembled with care and attention in the Audio Research Minneapolis factory.

Condition is superb for an amplifier of this age. The paint is very clear with no noticeable scratches or dents. The faceplates are also very clean. There is no rust of signs of exposure to moisture anywhere.

The unit was bench tested carefully and it passed with flying colors. All tubes were tested and all capacitors were inspected and tested for leakage. It was driven to its full power rating while monitoring distortion without hiccups. It then was moved to our listening room where it powered our vintage B&W Matrix 801’s with authority and precision and made a really nice and pleasant combination.

Included is the amplifier with a printed owner's manual and the original box.

Click here for a PDF copy of the D-115 Owner's Manual

Technical Specifications:

Power output
100 watts per channel minimum continuous power (both channels operating) at 16 ohms from 20Hz to 20kHz with less than 1% total harmonic distortion (typically less than .005% at one watt) Approximate actual power available per channel at "clipping" (both ch. op., 1kHz): 110 Watts

Power bandwidth
(-3dB points) 12Hz to 60kHz

Input sensitivity
0.6V RMS for rated output

Input impedance
75 kOhms, nominal

Output regulation
Approximately 0.5 dB, 16 ohm load to open circuit.

Overall negative feedback
19.5 dB

Damping factor
Approximately 17

Intermodulation distortion: Less than 0.1% at 1dB below rated output (100V
p to p, 16 ohms - SMPTE method).

Slew rate
15 V/µs

Rise time
5 µs

Hum & noise
90dB below rated output - less than 2mV RMS - (Broad-bandwidth unweighted, inputs shorted)

Power supply energy storage
280 joules

Power requirements
105-125VAC 60Hz (210-250VAC 50Hz) 1000 watts maximum, 400 watts at "idle".

Tube complement
(7) 6922
(4 matched pairs) 6550
(1) 6550
(1) 12AT7

D-115 MKII:
(3) 6922
(4) 6FQ7
(4 matched pairs) 6550
(1) 6550
(1) 12AT7

19" (48 cm) W (standard rack panel) x 7" (18 cm) H x 16.5" (42 cm) D (front panel back). Handles extend 1-5/8" (4.1 cm) forward of the front panel.

68 lbs. (31 kg) Net; 84 lbs. (38 kg) Shipping

1983 -1989

The SkyFi Testing Process for Tube Amplifiers:

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 tubes are inspected for signs of stress overheating or cracking.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If it all looks clean we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier the remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will also be tested.

We also test all tubes for output gain and leakage on our calibrated B&K 747 tester against the original manufacturers specifications. If needed, the tubes will be replaced from our vast NOS (New Old Stock) vintage or modern inventory.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage Kef speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.

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



Original Box








Physical Condition


Working Condition


SKU: 100170