BFA-535 Power Supply for Adcom GFA-535 MK1


Improved power supply kit for Adcom GFA-535 MK1. Fixes the hum and buzz issue with the 535 MK1, as described in my original blog post.

6 in stock (can be backordered)

SKU: Adcom GFA-535 MK1 Power Supply Kit Categories: ,


Installation documentation here.

Improved power supply kit for the original Adcom GFA-535 MK1. This kit fixes the hum and buzz issue with the 535 MK1, as described in my original blog post.

  • Dramatically reduced hum, buzz and noise from amplifier output. (GFA-535 MK1 had a ground topology design issue.)
  • Capacitance increase from 4×6,800uF to 4×10,000uF.
  • Ground loop breaker circuit prevents hum and noise from ground loops, while providing superior shielding compared to OEM. (Assuming you install an earth ground wire directly to the chassis as recommended.)
  • WAGO cage-clamp terminal blocks make gas-tight, firm connections that will never come loose.
  • Bridge rectifiers are mounted to the chassis for heat-sinking. (Some GFA-535s die from overheated bridges.)
  • Two-layer circuit board with double-thick 2oz. copper traces.

Note: The Hoppe’s Brain GFA-535 Power Supply Kit assumes you will be removing the “B Speaker” binding posts, speaker switches and associated tangle of wires, and installing a single set of hard-wired binding posts. The Hoppe’s Brain Adcom GFA-535 Binding Post Adapter Kit covers the “B Speaker” mounting holes, but if you should wish to retain the the B speaker functionality, it is possible to drill additional holes and install a bottom row of binding posts, though it’s a tight fit with other components on the power supply board.

Also note: For safety and best noise performance; Please install a 3-wire power cord, or power inlet. Ground the chassis straight to earth ground. Refer to Rod Elliot’s excellent article on earthing your Hi-Fi.


This is an advanced electronics project. You should have some experience repairing audio amplifiers. Please read through the documentation before ordering.

30 minutes free tech support is included with every purchase. Time beyond 30 minutes is billed at $75/hour. This includes time spent researching your issue, writing emails and talking on the phone.

I am happy to provide technical support, but please anticipate paying for for my time as part of the cost of your project. Tech support time is always billed, whether the issue is yours, mine or one of my suppliers.

Alternately, consider asking your question on a forum such as DIYAUDIO.COM. Send me a link and I may comment on the thread.


Additional information

Weight 16 oz
Dimensions 8 × 8 × 3 in

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3 thoughts on “BFA-535 Power Supply for Adcom GFA-535 MK1

  1. Is it absolutely necessary to eliminate the B speaker terminals? I drive another pair of speakers in a separate room on my B channel and would like to continue without adding another piece of equipment.

    1. Yes, the new board uses the real-estate vacated by the B speaker jacks to locate the bypass capacitors and drain resistors, and additional space is taken by the cage-clamp terminals.
      You could mount the B speaker binding posts to the left and right of the A speaker posts.

  2. I’ve been enjoying this upgrade along with the binding post kit for about 6 months now. Despite little electronic repair experience, the instructions referenced made the project most manageable. And my amp has never sounded better. Highly recommended!

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