Adcom GFA-545 Solid State Amplifier - Upgraded by Musical Concepts

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General:
The Adcom GFA-545 is legendary among audiophiles for its outstanding performance and exceptional value. Designed by renowned audio engineer Nelson Pass, the GFA-545 was built around a simple, high-fidelity circuit with a short signal path to deliver the purest, most transparent sound possible.

Rated at 100 watts per channel into an 8-ohm load, the GFA-545 has more than enough power to drive the vast majority of speakers with ease.

This isn't just any GFA-545, either. This particular amplifier has been professionally upgraded by Musical Concepts, a well-known company specializing in high-performance audio modifications. The amplifier features higher-quality internal components for improved performance, and Musical Concepts' logo is displayed above the power button.

This amplifier has been thoroughly tested and inspected in house and is operating exactly as it should. It will be carefully packed with the same attention to detail that we give all of the equipment leaving our shop.

SkyFi Cosmetic Notes:
Very light wear on the units top cover, It great shape overall.

SkyFi Technical Notes:
This amplifier has been upgraded by musical concepts. From a visual observation it looks like they replaced the RCA jacks, speaker terminals, and power transformer, and made select modifications to the amplifier circuits.

Brand Background:
ADCOM started in the 70s. 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:
Single Owner

Connections:
RCA inputs, Speaker output terminals, Captive Power Cord

General Sound:
Smooth, uncolored, undistorted natural and clean

Cosmetic Condition:
7/10 = Good. One or two minor scratches. Well Maintained. See our detailed rating description here.

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

Included:
Just the unit and power cord.

Packing:
Will be packed using our highly developed in-house process and custom packing materials.Specs:
- Power Output: 100 watts per channel continuously into 8 Ω (20Hz - 20kHz); capable of 150+ watts per channel into 4 Ω.
- Total Harmonic Distortion (THD): < 0.04% at rated power.
- Frequency Response: 10Hz to 20kHz ± 0.25dB.
- Damping Factor: 400 (20Hz - 20kHz).
- Signal-to-Noise Ratio (SNR): 110dB (A-weighted).
- Input Sensitivity: 1.25V for rated output.

Dimensions:
17" W × 5.5" H × 12.25" D (approx. 432mm × 140mm × 311mm)

Weight:
24 lbs.

Approximate Age:
1986

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.