Sold: ADCOM GFA-535 II fully modded

Posted on by hoppesbrain

Hi Folks, I have another ADCOM GFA-535 II for sale! As with all the amps I sell, this unit has been completely torn down, rebuilt, refurbished, and obsessed over. This amp not only sounds better than new, but I intend it to last another 30 years or more! I go way beyond  a simple re-cap. Any and all parts that may potentially deteriorate have been replaced, and I’ve paid a lot more attention to detail than the factory with things like wiring and matching components.

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And this one has a little special something. A powder coated top cover! (I got a deal on getting a bunch of covers done.)

Isn’t it beautiful? And pretty much scratch-proof.

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Features:

  • All electrolytic caps replaced: Power supply filters upgraded to 4x 10,000uF Cornell Dubilier 380LX. Nichicon Fine-Gold audio-grade capacitors used in signal paths, and Panasonic FC in parallel with WIMA MKP (foil) for output stage local supply bypass.
  • Input capacitors changed to WIMA MKS4
  • Transistors in the critical input stage are replaced with a carefully matched pairs of Fairchild KSC1845. This step is important to assure low DC offset at the output, and low distortion. The stock transistors are rarely well-matched, especially on later models.
  • Emitter resistors changed from 5% tolerance sand-cast types to DALE RS 1%. These are more reliable, and frankly, prettier.
  • Sealed Bournes trim-pot installed for precise bias adjustment and better reliability.
  • High-current bridge rectifiers are installed and heat-sinks attached. This helps prevents power supply droop while the amp is being run hard.
  • New power switch and spark-supression capacitor.
  • New surge-protection MOV
  • Circuit boards are cleaned and solder joints inspected and touched-up wherever needed.
  • Wire-wrap transformer connections removed and soldered permanently.
  • All wiring meticulously and obsessively neatened.
  • New 30A binding posts (Pomona 6883)
  • New power cable with strain relief and heavy-duty plug

The final steps are to torture-test, set bias and do listening tests. The amp is run into a dummy load, and power output readings near clipping are recorded. (Approximately 80WPC into 8 ohms.) The amp is driven hard for 30 minutes, allowing it to heat up, and it should show no signs of distress. It should cool itself down in a reasonable time, and the bias should remain steady throughout the temperature range.

I’ve been listening to this amp through my JBL 4208 near-field monitors for a couple of days now, and it sounds excellent as expected.

Cosmetics: The faceplate is nearly perfect, with just a few nicks on the edges, which have been touched up, and are barely noticible. The cover is absolutely perfect, as it has been freshly powder-coated. I would say it looks like new unless you really scrutinize it up close. Please click on the pictures to see it in hi-rez, and judge for yourself.

I stand behind what I sell, and my intention is that you have a great sounding amp that lasts a long, long time.

Contact me here if you’re interested!

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