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Adcom GFA-5002

Stereo Power Amplifier

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Adcom GFA-5002


Power output: 50 watts per channel into 8Ω (stereo), 175W into 8Ω (mono)

Frequency response: 10Hz to 20kHz

Total harmonic distortion: 0.05%

Damping factor: 400

Gain: 29 dB

Signal to noise ratio: 100dB

Dimensions: 3.5 x 17 x 12.5 inches

Weight: 18lbs


schematic   English -

service manual   English -

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Reviewed Jan 30th, 2016 by misterbearbaby

Fine Amplifier Performance, Nelson Pass Design

I have used this amp in a variety of systems. It’s punchy and clean, more warm or smooth in the mids than the pre-MOS-FET designs, and always maintaining great control of the woofers. Note the amps in this series can all be mixed-and-matched since they all have 29dB gain, handy if you’re considering multi-amping. This is a great vintage amp, very sweet sound, no gimmicks, for a reasonable price. If you only need 50wpc, this is a great unit.

Another Nelson Pass design (the series was made up of the 5200 5300 5400 5500 5502 and 5800 models), this amp is a variant of his famous MOS-FET series for Adcom. These are nice amps to upgrade: Pass states on DIY Audio that “I would bias it until the sinks run 50 deg. C after an hour or two. If you don't have a thermometer, this would be the temperature that you can leave your hand on the sink for 10 seconds.” Mine currently runs cool, so less Class A operating area but very stable and it has the great, warm, tube-like MOS-FET sound.

My amp still seems perfect and I am not considering replacing the power supply caps or anything like that at this point- there may be a time, but if it sounds good, it is good. Excellent steel cab, quality binding post speaker terminals- seems indestructible



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