hoppesbrain

Hoppe’s Brain is full! Declaring a hiatus on new repairs and refurbishings.

Posted on February 14, 2018February 27, 2021 by hoppesbrain

Hi Everyone,

Hoppe’s Brain is thriving, but demand for my services has been overwhelming! My waiting list has grown to more than a year, so I’m sorry, but I must declare a temporary hiatus on accepting new clients for repairs and refurbishings.

I need concentrate on my existing customers. Thanks for understanding.

I still sell circuit boards and kits, and this area of Hoppe’s Brain will continue to expand. Look for my store to go online in the next few weeks. In the meantime, contact me with the form below and let me know what you want. (Power supply boards for GFA-535, 545 and GFA-555 amplifiers, GFA-565 input boards, etc.)

If you’ve emailed me and not heard back, I will get back to you within the next few weeks.

Thanks to my awesome customers for making Hoppe’s Brain a success!

Chris

Boards, boards, boards!

Posted on December 27, 2017December 28, 2017 by hoppesbrain

Hey there people! Here’s a sneak preview of some new circuit boards that just arrived, in preparation for my web store grand opening. All but two of the boards shown will be available for purchase by DIY’ers. (Along with existing boards like the GFA-555 soft-start power supply and GFA-565 input boards.)

They are:

Continue reading Boards, boards, boards!

A tour of a Hoppe’s Brain GFA-555 restoration

Posted on November 7, 2017June 16, 2023 by hoppesbrain

UPDATE 2022.12.19 This is how I was doing GFA-555’s 5 years ago, and I have a new article describing how I do them now…
https://hoppesbrain.com/2022/09/26/another-tour-of-a-hoppes-brain-adcom-gfa-555-restoration-5-years-later-with-better-technology/

Hi everyone! One of my customers sent me a particularly nice GFA-555 MKI to be refurbished. It’s never been tampered with, and has very few scratches on the case… just beautiful. So I thought I would take lots of pictures along the way as I refurbish it, and show you the latest iteration of my GFA-555 rebuild process. This is the full monty upgrade package including the Hoppe’s Brain soft-start power supply board, with all sound quality and reliability improvements. $1025 in total.

Continue reading A tour of a Hoppe’s Brain GFA-555 restoration

Introducing the Hoppe’s Brain Adcom GFA-555 soft-start power supply

Posted on August 1, 2017August 5, 2020 by hoppesbrain

Update! This product has been superseded by a new power supply!
BFA-555 Smart Soft-Start Power Supply

Exciting news! Hoppe’s Brain power supply boards for the GFA-555 are here!

20171102_210531

These boards feature a number of improvements over the stock arrangement with the old-style chassis-mount components:

Soft-start circuit reduces stress on components like switches and capacitors.
Capacitance upgrade from 4×15,000uF to 4×27,000uF. Nearly double!
Earth-loop breaker with diode clamp safety shunt.
Amp is converted to a 3-wire, earth-grounded chassis appliance, for safety and better noise rejection.
Surge protection MOV
Snubber capacitors across AC side of bridge rectifiers
Compact layout. Overall wiring lengths reduced, fewer mechanical connections, and a much cleaner internal layout.

Continue reading Introducing the Hoppe’s Brain Adcom GFA-555 soft-start power supply

How I clean Adcom GFP-555 and GFP-565 record and playback selector switches

Posted on June 1, 2017September 23, 2017 by hoppesbrain

Hey folks, I hope this will be useful to anyone attempting to clean an ALPS sliding listen/record selector switch like those used in the Adcom GFP-555 and GFP-565. These are common in many brands of preamps and receivers.

Continue reading How I clean Adcom GFP-555 and GFP-565 record and playback selector switches

Earth loop-breaker boards

Posted on May 26, 2017January 15, 2023 by hoppesbrain

UPDATE: a newer version of this product is available in my store here:
https://hoppesbrain.com/product/earth-loop-breaker-board/

OK, this tiny circuit board is just too cute!

It’s an “Earth loop breaker”; A common method of providing some isolation between star ground and chassis, lowering noise in an amplifier. I designed it for the GFA-555, but it will also work in many amps.

Continue reading Earth loop-breaker boards

Improving turn-around time: Narrowing focus, new lab

Posted on May 20, 2017May 27, 2017 by hoppesbrain

Hello everyone,

My sincerest apologies; My communications have been terribly slow, and my turn-around time for refurbished equipment is getting out of hand. I have customers waiting up to four months for their equipment, and that’s no good. I wouldn’t want to wait that long!

I never anticipated such a level of interest! Many thanks to all of my customers; it’s a pleasure to help you build your music systems, and I love hearing people’s comments after they get their gear back.

I like to say “YES!” to everyone’s projects, but I have taken on more work than I can possibly keep up with. I am buried in emails, and it’s getting hard to find time to work at the bench. Things are snow-balling on me.

It’s a good problem to have. It means I’m succeeding, but I won’t be for long if I don’t limit the scope of what I do.

Continue reading Improving turn-around time: Narrowing focus, new lab

Killing the buzz in the Adcom GFA-535. New power supply boards!

Posted on May 5, 2017January 2, 2026 by hoppesbrain

Adcom GFA-535 owners; Has it always bugged you, how the right channel of your amp buzzes through your speakers more than the left channel? Yeah, me too. The buzz is a buzz-kill… so I killed the buzz! With this thing I made.

Now, the GFA-535 is a legendary little amplifier, deserving plenty of buzz, but it’s too bad so much of it comes out the speakers. Oddly, the GFA-535’s bigger sibling—the GFA-545—using the exact same amplifier boards as the 535, is nearly silent as a stone. What’s going on?

Continue reading Killing the buzz in the Adcom GFA-535. New power supply boards!

Nifty power supply circuit boards for Adcom GFA-535 and GFA-545

Posted on March 16, 2017April 2, 2017 by hoppesbrain

Improved power supply boards for Adcom GFA-535 and GFA-545!

Continue reading Nifty power supply circuit boards for Adcom GFA-535 and GFA-545

ADCOM GFP-750 upgrade

Posted on March 11, 2017December 17, 2025 by hoppesbrain

The Adcom GFP-750 preamp was designed as a companion piece to the GFA-5802, with matching aesthetics. It’s a MOSFET based, single-ended Class-A preamp designed by Nelson Pass. Conceptually, it’s similar to the Pass Aleph P and the ‘Bride of Son of Zen’ DIY project.