Adcom GFA-535II Solid State Amplifier 60W x 2

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

If you're game to try one of these very capable and highly reviewed amps, you might as well search for the II variant. That's exactly what we have here.

Tested, working properly, and sounding great.

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

Base Series Timbre Analog Interconnects (PAIR) - RCA Ultraplate

Ascent Series 8TC Speaker Cables (PAIR)

From a 1993 Stereophile review written by Corey Greenberg:
"Internally, the GFA-535 II's build quality is up to Adcom's usual high level. Low-noise, metal-film resistors and precision film caps populate the printed circuit board, while the pcb layout minimizes long wiring runs throughout. The two-transformer dual-mono power supply is quite a bit beefier than normally seen in this price range, with each transformer's 50VDC supply rails smoothed with a 6800µF/63V electrolytic cap bypassed with a 0.22µF film cap.

Okay, so Extreme Dual-Mono fetishists will bitch that the Adcom's supply isn't truly dual-mono 'cuz of the single AC power cord, but do me a favor, guys—a little deodorant now and then, hey?

Surprisingly for such a budget-minded design, the Adcom's input RCA jacks are high-quality, Tiffany-style, gold-plated types, but the output posts are a bit lower in outlook—raised plastic ridges at their bases preclude the use of spade lugs, and the round knurled plastic nuts mean that you can't use a hexdriver to tighten them down. You'll have to use bare wire stuck through the post's hole, or perhaps speaker cables terminated with either banana plugs or Deltrons.

The front panel features three LEDs: one to indicate that the thermal-protection circuit has been tripped, and two to indicate "instantaneous distortion alert"—in all my headbanging with the Adcom, I never saw any of these lights come on, and I drove this amp hard!"

Adcom GFA-535II Specifications
Two-channel solid-state amplifier

Output power:
60W into 8 ohms (17.8dBW)

Input sensitivity:
970mV RMS

Input impedance:
100k ohms

Frequency response:
10Hz – 20kHz, –0.25dB

S/N ratio:
110dB

Power consumption:
300W

Dimensions:
3" H by 17" W by 11.25" D

Weight:
19.5 lbs.

The SkyFi Testing Process for Solid State Amplifiers:

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 1KHz 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 1KHz square wave check and a 20Hz to 20KHz 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. 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.