hifi engine

Manual Library / Adcom

Adcom GFA-585

Stereo Power Amplifier

add a review (2 reviews)

Adcom GFA-585


Power output: 250 watts per channel into 8Ω (stereo)

Frequency response: 10Hz to 20kHz

Total harmonic distortion: 0.02%

Damping factor: 600

Gain: 27 dB

Input sensitivity: 2V

Signal to noise ratio: 110dB

Semiconductors: 72 x transistors, 11 x zener diodes, 31 x diodes, 2 x IC, 2 x diode bridges

Dimensions: 213 x 432 x 310mm

Weight: 20.5kg



 Login or register to post reviews

Reviewed Feb 16th, 2016 by kmh3212

When I bought the amp off *bay it had a loud pop on startup and shutdown. I knew this going to do damage to my speakers. I raised the hood and suspected bad caps. That was a year ago. I cleaned up several projects and plugged it in and turned it on. The problem went from bad to a lot worse. Went ahead and ordered the caps on the input boards. Since I waited the electrolyte corrosion may have compromised a tracing or two on the boards. Now I have to repair that too. We will see. I must say after the startup pops was working fine but definitely not perfect as the seller sold it to me.

Reviewed Jul 31st, 2015 by mobay

This is a monster of an amplifier bar none. 250watts ( more like 270 + ) and a damping factor of 600...ouch! This amp will drive ANY speaker on the planet. It has one fatal flaw however.All of the capacitors should/must be replaced. This was not Adcom's fault but in the year this amp ( and for that matter many other electronic devices ) was made a group of faulty capacitors were sold, but hey ,they were less expensive, than the Japanese equivalent.. All of these would leak and fail and can result in the destruction of a speaker connect to this amp. A large THUMP on startup or shutdown tells you that you are on borrowed time. I paid $300.00 for this amp and although mine was not leaking , I replaced all the capacitors. There is a firm in NY that can do this and they charge $425 for the repair. YOU can do the repair if you are careful. Go to audikarma.org and do a search for this amp and you'll see the thread on it's repair.

OK now with that said....... did I mention that this is a monster of an amp? The torroidal transformer is rated at 100,000 uF and the unit weighs a ton ( not really but it's super heavy ) . Sound quality is great and I would characterize it as dark/neutral. The sound is effortless, and so clean that you may damage speakers with the high output because of the lack of distortion at high levels. Use fuses ( 3 amp fast blow ) to protect your speakers from excessive output that this amp can easily produce. It is that powerful.., and Oh! so very clean and undistorted=== Once fixed this amp is probably worth close to $800.00 or more and the actual cost of the replacement capacitors needed is less than $50.00. A great return on a small investment. A truly exceptional amp whose reputation was marred by a unfortunate choice of parts from a supplier who sent Adcom, and many, many other manufacturers sub-standard parts. Ask whoever is selling this amp if the capacitors were replaced and the circuit boards cleaned. ASK THEM TO SHOW YOU A BILL certifying that the work was done. If they cannot, Do Not pay more than $300.00 ( or less ).



kmh3212's picture

re: GFA-585

Well I found a GFA585 on eBay and delayed hooking it up. I finally got around to it and the first thing I noticed was the hazardous thump on startup. I was thinking uh oh that's not right. I have 4 Adcom amps now and never had an issue. I got on HIFI engine and looked up the schematics and had a place to start looking when I found the delay on startup circuit. I suspected a stuck closed delay relay. After reading the comments section I found I have some work to do. BAD CAPS!
I have never had any major issues with Adcom amps in the past. Small easily fixable stuff on one amp. Mobay comments above tell me of the bad cap problem. I went through this on computer mother boards several years ago. Manufacturers saving less than a dollar on caps caused the ruination of millions of computer motherboards. At least these amps appear easy to work on.

re: GFA-585


There is an extensive thread or threads on the cap replacement. Make sure you do photos extensively so you can trace the steps you've taken. In retrospect the replacement and cleaning of the capacitors and boards was not THAT bad, just tedious. It was certainly not expensive either. It is expensive if you have it done for you at a shop. These really are superb amps once they are fixed, and will probably outlive all of their owners once running. They are super powerful ( mine measured 282 watts ) and provide effortless power .

Good luck with yours


kmh3212's picture

re: GFA-585


This amp has been my Albatross. After pulling the caps and putting all new ones in as well as several transistors that had legs corroded off of them. I cleaned the boards of all the black fishy smelling goo, or so I thought and fired it up again. Left channel passed the smoke test right channel not so much. Luckily I had my hand on the cord when the fish smell hit and I noticed a transistor leg stating to glow. I think my recently purchased caps are leftovers from the bad years. One was already starting to swell. That black goo has migrated into the fiberglass of the board. No matter how clean it looks on the outside The goo is inside the board. I have looked for new boards but...

I am up to hear with hand stuck way over my head on my 6'1" frame. I will keep at it when the spirit moves me.. again.

BTW I got a letter from the justice department letting me know that I was a class member in the lawsuit against the companies that sent the price to low for the real manufacturers to stay in business and they dumped this crap on the whole planet. Now maybe I will get 25 cents when I am dead!



Jim Libert's picture

re: GFA-585

That was very funny post KMH3212. I had a long story written and it disappeared on me when I tried to edit. I think the "electronic Gods" were trying to punish me further. I had to start the response over (that sucks). It always funny to read about others mishaps. You saw the caps swelling and the transistor leg was glowing but you had your hand on the power cord so perhaps you could quickly unplug it. That made me laugh so hard I nearly cried. Sorry its too late. its is now a huge problem. Not laughing at you but with you. Perhaps you can use your money from the settlement and have someone repair/restore it for you. I have had my share of mishaps also. I have a Realistic STA-820 that randomly pops loud in right channel. replaced all caps still have the pops. replaced one of the drivers and I was checking voltage and shorted the legs and it smoked and also burned out the right channel outputs. I just got that repaired last night now am back to square one. Also the tuner is goofy and am trying to adjust it because the stereo fluctuates in and out. Tuners are a real hassel/chore. I have worked on a few Sanyo JCX 2100KR tuners that never seem to work correctly. I burned out a driver and 2 outputs on an Adcom GFA-535 while checking bias my meter leads slipped and sparked on something. This frustrating turn of events is what keeps me coming back for more. My first online Pioneer SX-1050 purchase ended with a loud bang and smoke from the caps the first time i turned it on. One day I will get the courage to tackle this beast/headache.I spend hours and it only takes one second to ruin all my work. I have an Adcom GFA 5500 that looks nearly impossible to recap. the outputs are soldered to the board with no bottom access and the power supply caps are custom made and screwed to another board. what a terrible design for techs. Anyway...... Back to the review. I just purchased a GFA585 I hope this is easier to access the caps or they will both go back online after I listen to them for a spell.

This website is not affiliated with or sponsored by Adcom. To purchase GFA-585 spares or accessories, please contact the company via their website or visit an authorised retailer.