Adcom GFA-535 MK1 Power Supply Kit


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.

13 in stock (can be backordered)

SKU: Adcom GFA-535 MK1 Power Supply Kit


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! Kit assumes you will be removing the crappy OEM twist-lock speaker connectors, and replacing with binding posts of your own choice. The holes in the chassis are large, so most binding posts will require some creative solution to mount them. I use large washers and a little epoxy. Alternately, you can drill new holes and mount the binding posts elsewhere on the back of the chassis. Kit comes with hole plugs to fill in the “B” speaker positions.

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.

Here are some excellent instructions that were kindly provided by a customer. The amp shown is a MK2, but the procedure is essentially the same.



Additional information

Weight 16 oz
Dimensions 8 × 8 × 3 in

2 thoughts on “Adcom GFA-535 MK1 Power Supply Kit

  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.

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