Adcom GFA-535 Vintage Solid State Amplifier - Dual Mono Design

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General:
Adcom amplifiers are workhorses that sound fantastic. They are known to perform and sound better than amplifiers many more times expensive. The GFA-535 is no exception. 

The GFA-535 is rated from the factory at 60WPC into 8 ohms, but on our test bench it actually performed better than this measurement at 90WPC !

Features include distortion protection, A + B speaker output,  and a super solid design with good heat dissipation. 

This amplifier also comes with its original manual. It will be shipped with our specialized packing for safe transport.

SkyFi Cosmetic Notes:
Some scratches at the top of the unit, faceplate is super clean. Overall very good shape.

Brand Background:
ADCOM started in the 1970's. Our first offering wasn’t amplifiers but phono cartridges. They were no ordinary cartridges; however, they were extraordinarily musical "moving coil" designs that extracted a lot of information from a record groove. These products were so successful that other companies asked us to begin making cartridges for them, too! And so, we became a manufacturer!

Early Electronics... ADCOM's first electronic product, the groundbreaking GFA-1 power amplifier, appeared in December 1979. It was substantially more powerful than most of its competition at 200 watts per channel and was one of the first "high current" designs available. . Again, it was an affordable and standout performer. Critical response was phenomenal and the GFA-1 became the "hot ticket" amplifier of its day, as did the successor GFA-1A.

Ownership:
Second Owner

Connections:
RCA inpuit, Two sets of Speaker outputs.

General Sound:
Smooth, uncolored, undistorted natural and clean

Working Condition:
Working perfectly and tested in our lab and listening room.

Included:
Unit and Manual

Packing:
Will be packed using our highly developed in-house process and custom packing materials.Specs:
Power output: 60 watts per channel into 8Ω (stereo)
Frequency response: 10 Hz to 20 kHz
Total harmonic distortion: 0.04%
Damping factor: 180
Gain: 27 dB
Input sensitivity: 0.97V
Signal to noise ratio: 110 dB

Dimensions:
3.39 x 17.01 x 12.48 in

Weight:
20 lbs.

Approximate Age:
1990

Link to Manual:
Click Here

Recommended Cables:
Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Speaker Cables - Better

Testing Process:
We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

If the amplifier passes visual inspection, we move on to a controlled power on sequence using a Sencore safety analyzer to monitor current draw in real time. Once the amplifier is determined to be safe to operate, we connect it to full AC mains for function and power testing. We connect the speaker outputs of the amplifier to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1 KHz test signal at the amplifier's input and slowly increase its amplitude while monitoring the output on an oscilloscope for signs of noise, clipping, distortion, or improper channel balance. We continue increasing the signal level until the amplifier reaches clipping.

At this point we take an output power measurement and compare it to the spec sheet of the amplifier to verify proper performance. If the device under test has both balanced and single ended inputs they are both tested at this time.

We finish off the bench evaluation with a 1 KHz square wave check and a 20 Hz to 20 KHz sine sweep to assess the amplifier's frequency response characteristics.

This battery of tests will usually reveal if the amplifier has any issues that need further attention.

Before the device leaves the bench, we perform a listening test with actual music using a variety of preferred test tracks. Our benches are outfitted with familiar monitor speakers which help us identify inconsistencies that will not always show up on our test gear. The main things that we are listening for are hum or noise with no signal present, proper center image, clicks, pops, or any other obvious undesirable audio characteristics.

If the unit passes all of these tests it is moved to our long term testing rig where we simulate real word operating conditions for 6-8 hours minimum. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when the unit has fully come up to temperature.