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Does Adcom make good Amps ?

I have two: a 555 and a 535. I've also used several 555's over the years in various systems. Currently I used my (early production run) 555 to power my 12 inch drivers (open baffle) in my 3 way (bi-amped) system. The bottom end on the 555 is exceptional. I have used my 535 to power the mids (when I was tri-amping) and it acquitted itself very well (punchy and dynamic with a natural mid-range). I tend to not use either adcom when they will be driving tweeters or speakers with tweeters as I find the high end a tad aggressive. Not "bad" just a bit more forward than I prefer. That's not to say that the adcom is bad at HF, just that I prefer the slightly softer and warmer sound of my Musical Concepts mod Hafler up top.
 
hjames said:
My friend Steve had some of the Adcom GFA-565 mono blocks - used them to run his JBL subs - but they were a funky design - original caps leaked and ruined the circuit board
(which was some weird Hard-pressed paper material) and he paid a ton to have them flushed, washed, and rebuilt. (completely different design than the original 555s)



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The boards are phenolic, paper impregnated with epoxy.
During production of some 555, 565, 585 amps, Adcom received a lot of defective capacitors that failed prematurely. They tended to leak electrolyte over a very critical part of the circuit board, the part where the voltage reference sources and some very high gain op-amps are located.
IIRC, the driver board for my 585 went through the ultrasound cleaner tank three times to get all of the crud off the board. Not a job for the faint of heart.
 
ADCOM amps when new are better than good. some might say GREAT!!!!. Are they top of the line amps, not quite. But they deliver pretty big bang for the buck. As for their life expectancy that's a good question. I had customers with no issues after 15 years and yet other couldn't tmake it through the warranty period. I don't know if it inadequate cooling because of a confined space, or speakers with a very low impedance. Bt there were about 6 or 7 in the shop every year, and we weren't an Adcom dealer. I don't remember any of them coming back once repaired. It may have been like my Crowns the signal caps and other small caps would fail eventually or as in our shop it was an occasional out put transistor . I don't remember ever having seen any other ADCOM pieces coming in to the shop.
 
twiiii said:
ADCOM amps when new are better than good. some might say GREAT!!!!. Are they top of the line amps, not quite. But they deliver pretty big bang for the buck. As for their life expectancy that's a good question. I had customers with no issues after 15 years and yet other couldn't tmake it through the warranty period. I don't know if it inadequate cooling because of a confined space, or speakers with a very low impedance. Bt there were about 6 or 7 in the shop every year, and we weren't an Adcom dealer. I don't remember any of them coming back once repaired. It may have been like my Crowns the signal caps and other small caps would fail eventually or as in our shop it was an occasional out put transistor . I don't remember ever having seen any other ADCOM pieces coming in to the shop.
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Post #22 sheds a little light on your observation.
 
tarior said:
The boards are phenolic, paper impregnated with epoxy.
During production of some 555, 565, 585 amps, Adcom received a lot of defective capacitors that failed prematurely. They tended to leak electrolyte over a very critical part of the circuit board, the part where the voltage reference sources and some very high gain op-amps are located.
IIRC, the driver board for my 585 went through the ultrasound cleaner tank three times to get all of the crud off the board. Not a job for the faint of heart.
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My info is that only the 565 and 585 had the capacitor problem ruining driver boards.
https://hoppesbrain.com/adcom-service-and-refurbishing/

https://hoppesbrain.com/pricing/

http://www.ebcelectronics.com/Adcom-GFA-565-Repair-Service.html
 
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braincramp said:
Holy Crap playit! A Dubuque Guy! Lived across the border in Stockton for most of my life. I have customers in East Dubuque so I'm over your way every 2 weeks. Thanks for the input.
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He's not the only one. I once played Euchre too - as I was raised a Dubuquer!
 
I've had 4 of them. 3 GFA 555s and 1 GFA 5500. For my pair of ML Sequel IIs I bridged the 555s and ran each of the ML's woofers with them and then ran the 5500 in stereo to both panels of the MLs.
The Sequels literally mushroom cloud-smoked one of the 555s one day and I ended up replacing it along the way with another 555 and continued on with the same configuration.
I changed out the 5500 with a Carver Sunfire and it was game over for the 5500. Sold the 5500 and it was a heavy mutha to pack correctly and ship! Holy cow! Also sold one of the 555s and the other is sitting in the closet today and I went in an entirely different direction and sold the Sunfire also.
If I wanted to go the route like above again, I'd probably go with an Adcom somewhere in it - can't afford a Krell right now.
 
I preferred the Hafler DH-220 I had to the GFA-535 I still have. Both were un-restored AFAIK, and driving difficult speakers. YMMV.
 
Adcom has made some good amps. I have a 535 and it has proven reliable and well made.

If buying brand new today, I would pick Parasound over Adcom. That's just my personal preference. Otherwise, there's nothing wrong with Adcom on a budget.
 
There's a mint Pioneer SX-1250 locally here that has been completely gone through by a very reputable shop but they want $1500 for it. I thought I'd like to try separates for a change as I've always had receivers. Plus, I really don't play my music that loud most of the time.
 
Got a couple of 555s and a few preamps. Pretty much kicked all the Carver stuff off the shelf.

I would suggest replacing the electrolytic caps on the input board. They may not leak but are known to drift.

There are also 2 resistors that get pretty warm. I would change R12 and R13 to a higher wattage. This is the first version of the board.
 
braincramp said:
Thinking about taking a chance on a 535 on ebay even though I'm always hesitant buying electronics there.
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Yes, its always a roll of the dice. I got my 535 on eBay and it came with one set of speaker terminals not working on one channel. Seller didn't know anything about that (ha, ha). Anyway, I opened it up and cleaned the a/b speaker switches and it all works fine. While I was in there I set the bias back to factory specifications and check the DC offset. Sounds pretty darn good for a $79 amp!!!
 
I've got what is probably a dumb question. If I bought a power amp and a separate pre-amp, what would I have to do to run my sub since the power amp only has jacks for 2 speakers? Do I run the wires from the power amp into the sub and then out of the sub to the main speakers?
 
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That's one way of doing it.

If the sub woofer has line level inputs you could use two Y connectors and run line level signals from the preamp to both the power amp and subwoofer.
 
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