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:
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
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 This product has been superseded by a new power supply!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!
These boards feature a number of improvements over the stock arrangement with the old-style chassis-mount components:
Continue reading Introducing the Hoppe’s Brain Adcom GFA-555 soft-start power supply
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
UPDATE: a newer version of this product is available in my store here: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.
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
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!
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
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.
Here’s a custom GFA-555 I built for Mark in Michigan. This is a fully dual-mono conversion with all the tweaks. Each channel has its own, dedicated 500VA transformer, for 1000VA in total, replacing the single, 850VA stock unit.
Continue reading A custom super-high-current GFA-555 Dual-mono upgrade
