Look what i just got. Adcom GFA 565's
- Thread starter bob06
- Start date
Schmidlapper
Super Member
That is some very impressive workmanship, I popped over and checked his website and you are getting some special Adcoms built for sure. Pretty much what Adcom would have done if they weren't trying to be more cost friendly and wanted to go more high tier.
Those cool amp stands are Cool !!!
No pun intended
well maybe ! I love all my Adcom Amps. I have 5503 for my front stage in my Theater I had since new, maybe close to 20 years. I need open them up and take a peek
that nothing nefarious is going on in there
Athanasios
Big fan of Adcom here. I even considered carrying their products when I had my brick and mortar shop. I've had all of the classic line...535, 545(II), 555(II), 585 plus a few of the preamps. Still have a GFP 565 and the GFA 585SE. It took three trips through the ultrasonic cleaner to finally get the 585 flying right.
I predict that you will very much like the 565s. I do have to disagree with Hoppe on one thing; I don't think the GTP line are all that terrible to listen with or work on. His workmanship does look to be quite exemplary.
I predict that you will very much like the 565s. I do have to disagree with Hoppe on one thing; I don't think the GTP line are all that terrible to listen with or work on. His workmanship does look to be quite exemplary.
bob06
Addicted Member
He told me he's considering making new boards for the 585's.
bob06
Addicted Member
Had a thread in DIY. Search COOL Amp Stands.More info on these please... hey, that rhymes!
Congrats to you on getting them finished That's some serious power as well! I'm thinking that's for each amp? Bridged is roughly 4 times those numbers if I remember correctly?
That's some serious power as well! I'm thinking that's for each amp? Bridged is roughly 4 times those numbers if I remember correctly?
bob06
Addicted Member
Yes that's correct those numbers are per amp. Bridged I could raise my roof.Congrats to you on getting them finished
Man, bravo all the way. Those are sweet as hell. Wish I had just one for my Vandersteens.
And just for my 2 cents, I'll sleep much better, and gladly give up that nth degree of sonic clarity, for a protection circuit.
And just for my 2 cents, I'll sleep much better, and gladly give up that nth degree of sonic clarity, for a protection circuit.
bob06
Addicted Member
He explained to me how he runs these Amps thru his torture test. I was shocked. I would never dream of running them as hard as he did. He put them thru hell. He even runs them at 1/2 power at 1ohms.
I think if they survived after all that then I'm good to go.
damacman
Resident Psycho
Do elaborate.He explained to me how he runs these Amps thru his torture test. I was shocked. I would never dream of running them as hard as he did. He put them thru hell. He even runs them at 1/2 power at 1ohms.
Phloodpants
Member
Actually, I'm happy to sell the boards to DIY'ers for $35/ea! I can't fix them all myself! I was being low-key about selling them—a little worried about copyright, being that they are straight-up copies of the artwork from the original boards. But after talking to a lawyer friend, he doesn't think there's anything to worry about. The current holders of the Adcom brand name would have no right to prevent me making after-market parts for old products. And they are distinct products from the originals, in that they are nicer quality, with the plated through-holes and newer fabrication technology.
I have already sold a handful of boards, and three of those people have reported back with success! It is a rather huge undertaking, more than one might expect. (Thus the fairly high price for my service on this.) But I provide a parts list so you can order a complete set of Dale and TE 0.1% resistors and the like, along with part numbers for known equivalents for all the semiconductors, if you should have blown components. There are also some parts upgrade suggestions, like good MKP caps and non-inductive resistors on the zobel, and better electrolytic caps to use. (Panasonic FC, ED and Nichi FG.)
I don't know where this rumor about Adcom having used paper or phenolic boards comes from. Every Adcom amp I've seen has used a decent quality FR4 fiberglass board, even the very early rack-mount version of the GFA-555. There were some earlier models than that, but I haven't seen them, but I did fix a GFA-1A that was fiberglass. (Neat amp.)
It's not paper, but the electrolyte does soak into the fiberglass. No surprise, fiberglass is basically BPA plastic; easy to dissolve, and eager to absorb chemicals. The electrolyte continues to seep out, even after it's been cleaned perfectly off the surface. I've seen 565's come to me that were once repaired, but went DC again. There was corrosion on the new solder joints.
I don't want to worry that a customer's amp is going to go DC, thus, the new boards. Some people have crazy expensive and irreplaceable speakers.
I have restored a GFA-585 with a pair of these 565 boards! There are some minor mods to the circuitry, but it can be made 100% identical. There are two boards in the 585, and they're mounted vertically instead of horizontally in the 565. There are some minor physical modifications, but it comes out neatly. It becomes a slightly harder to work on because the board layout isn't optimal sideways, but these amps are very reliable once properly fixed.
I don't have a board for the GFA-555 or 555II. They don't suffer from the same capacitor issue as the 565/585. I've seen a few very slightly leaky capacitors on 555's, but it's not due to a bad batch like the Elna's the 565/585 had. And failure modes not nearly as dramatic. The Elna's literally spray all over the inside of the amp. Adcom used many different types here, and none seem more prone to failure than the others.
In the 565, the bad caps just happen to be adjacent to highly sensitive areas like the DC servo. The slightest leakage causes issues.
Phloodpants
Member
This is a personal choice, and entirely dependent on your equipment, budget, and tolerance for risk. If your speakers are still made, parts are available, and you can afford to replace a woofer, then run without relays. If you have something rare and expensive, well maybe the relay's a good idea. They are prone to corrosion, and it's the weakest connection point.
I'm not perfect, and can't guarantee that an amp I built won't blow out. It can blow up for reasons beyond my control as well, power surges, lightning, abuse, bad wiring, spilled beer, and manufacturing defects. But I have done around 200 amps in the last two years, and AFAIK, only one has blown out in the field. (I'll dig into it this week.)
