Audio Research D240 Solid State Amplifier

Free Shipping on *ALL* Electronics (Excluding Speakers, Contiguous 48 US States Only)

Refined yet powerful solid state amp from Audio Research made right here in America.

This amp is circa 1992, so 29 years as of today.

In overall beautiful cosmetic condition with no significant signs of use.

**Please note that RCA shorting plugs are required to enable Single Ended Operation. If you ask we'll be happy to provide a set with your purchase. 

Your purchase also includes the original box.

Audio Research D240 Amplifier - Owner's Manual

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

Kimber Kable - RCA Interconnects

Kimber Kable - XLR Interconnects

Kimber Kable - Speaker Cables

Kimber Kable - Power Cords

Technical Specifications:
Solid-state stereo amplifier

INTRODUCED
1991

MSRP (US NEW RETAIL)
$2,995 ($6k in 2021).

POWER OUTPUT
120 watts per channel into 8 ohms, 240 watts per channel into 4 ohms

POWER BANDWIDTH
(-3dB points) 8Hz to 60kHz

INPUT SENSITIVITY
1.6V RMS for rated putput (25.8dB gain) unbalanced or balanced

INPUT IMPEDANCE
150k ohms normal or invert, 300k ohms balanced differential

OUTPUT REGULATION
0.05dB 8 ohm load to open circuit

OVERALL NEGATIVE FEEDBACK
7.7dB

DAMPING FACTOR
170

SLEW RATE
50V/µs

RISE TIME

1.5 µs

HUM & NOISE
Less than 150 µs RMS (106dB below rated output IHF A-weighted)

POWER SUPPLY ENERGY STORAGE
144,000 µF

POWER REQUIREMENTS
105-125VAC 60Hz (210-250VAC 50 Hz) 480 watts at rated output (120WPC 8 ohms).
800 watts maximum (240WPC 4 ohms), 140 watts idle

OTHER
Input Polarity: Non-inverting at normal inputs. Balanced pin 2+.

DIMENSIONS
19" (48 cm) W (standard rack panel) x 5¼" (13.3 cm) H x 11 ⅝" (29.5 cm) D (front panel back). Handles extend 1 and ⅝" (4.1 cm) forward of the front panel. Output connectors extend 1" behind rear panel.

WEIGHT
38 lbs. (17.3 kg) Net
49 lbs (22.3 kg) Shipping

The SkyFi Testing Process for Solid State 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 transistors are checked for signs of stress or damage.

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 everything reads 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 then 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 be also be tested.

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.