Balance, dynamics, bass, power

Could be more transparent and airy, highs could have more extension

I have the stereo version of these mono blocks, the GFA-585 Limited Edition. Since there is no such section, I review it here, under GFA-565.

When searching for an amp for my new Inifinity Kappa 90 speakers, I first settled for the Rotel RB-991 (2X200W into 8 ohms). I hadn't auditioned it with my speakers, but both of the local HiFi stores, who carry both Inifinity and Rotel, thought the RB-991 would be a good choice for the Kappa 90's (in its price range, $1000). At first I was very happy with it and thought the system sounded great. After about six months, however, I began to feel that the bass wasn't quite fast or distinct enough. I found the treble a bit annoying as well, it was simply fatiguing to listen to the Rotel for long periods of time. The Rotel has razor-sharp resolution of the highs, but it's not very forgiving. Cymbals can cut like knives into your poor ears, if your speakers are on the bright side. The highs of my Kappa 90's are definitely on the bright side. Perhaps it's the Emit-B ribbon tweeters. The Kappas are also notoriously difficult to drive, with its double 10" woofers. I thought the RB-991 would do the trick, but I felt that something was missing in the lower end.

While I was quite happy with the system, the lack of distinct bass and the harsh treble bothered me quite a bit. I found an ad for a ADCOM GF-585 and searched the web for information about it. This is where I found the GFA-565, which is pretty much the same as the GFA-585. As you have noticed, there are several rave reviews. Anyway, I bought it for $700 (good deal?) and hooked it up to the rest of my system.

The sound of the GFA-585 is completely different from the RB-991. First of all, the GFA-585 has much better control in the low end. It is probably partly thanks to its higher power (2X300W into 8 ohms), but also to its dual mono design and massive capacitor banks. I'm no amp design engineer, so I won't go into the details. The GFA-585 has a very nice midrange, with beautiful depth and imaging. Voices are great and one can clearly distingush different vocal tracks, keyboards etc. that one would "normally" only hear as "part of the picture but not quite distinguishable". The highs are, to use the words of another reviewer, "subdued". This term describes the treble very well. I'd say that the highs are smooth and never harsh, but they lack the top end extension and detail. That's right, subdued. They are not grainy. Perhaps this is typical of bipolar designs, as opposed to MOSFETs. The subdued treble is a double-edged sword: On the one hand, it is never harsh, never fatiguing and it is forgiving with harsh recordings. On the other hand, it lacks the razor-sharp resolution and airy feeling that you can get from for example the Rotel (MOSFET). I guess it is down to personal taste, but I prefer the GFA-585. I listen to a lot of blues and rock music, where there is lots of crashing cymbals and such "harsh" sounds. The ADCOM delivers them in a subdued yet natural way. The cymbal sound of the Rotel cut like knives, not very pleasant. Classical pieces, with viloin, could be harsh with the Rotel, but never with the ADCOM. However, when listening to good quality recordings the Rotel could create a very nice and open treble.
Finally, the ADCOM handles dynamics extremely well. That is, fast passages between quite and loud pieces are reproduced the way they should. The GFA-585 stops and accelerates admirably. The RB-991 did an OK job, but it couldn't compare to the GFA-585 when it came to dynamics.
Finally, I'd say the overall sound of the GFA-585 is "dark". If you like it bright, go elsewhere.

All in all, the GFA-585 is a great amp and a bargain on the used market. If you want deep and tight bass, full and dynamic midrange but subdued highs, this amp is for you. If you have difficult to drive and/or bright speakers, it's a great choice. This is definitely a rock'n'roll amp. Great bass and forgiving highs. You can play it loud without titing your ears. However, if you want that open airy feeling around flutes and pianos, if you want that top end bright treble, the GFA-585 is not for you. I have come to really like this amp and I think it will stay with me for a long time. If and when I upgrade it, it will have to be a real high end amp.

My system:
Arcam DIVA CD72 CD player
Linn Kolektor pre-amp
ADCOM GFA-585 power amp
Infinity Kappa 90 speakers
Supra Ply 3.4 speaker cables (bi-wired)
Cambridge Pacific interconnects

Similar Products Used:

Rotel RB-991

Unlimited power, transparent, beautiful mids and subdued highs - not bright at all.

They don't make them anymore

If you have a chance of getting these amps go for it. They are better than amps twice their price and I got both for $500 and the 565 preamp for $300 and a pair of Dahlquist DQ20s to go with them for $1100. If you can find a better system for under $2000, you are the MAN. If your on a budget and music is a priority in your life then you would do well to look at Adcom.

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I wish

ADCOM doesn't make these big beauties any longer, but they crop up on the resale market on a regular basis. Powerful and reliable--possibly the best buy in mono amps in the last decade. Yes pookie, you will need two, but once you have them you will never again fear that YOUR amps will lack the guts to drive that new pair of speakers you are contemplating. I run the big Magneplaner three-panel monsters 6'x4' each and the 565s don't ever breath hard. The only weakness these and any other ADCOM I have ever owned have had was that their switches wear out. I rank them at a 4.0

Non-removeable power cord

I bought these brand new 10 years ago and sold them about 1 1/2 years ago for about half price.I ran a set of Kappa 8's like Mike did (see 4th review down)and never had any trouble with either component.When I bought the Kappa 8's I had the 555.It worked, but the speakers needed more juice to perform the way they were meant to.The 565's hadn't been out that long & I got a great deal trading my 555 in on them.My system was set up for classic rock & I played them loud & hard whenever I could.I started out with a SS Adcom pre-amp which lasted about a month.It was a piece of junk.I traded it for a Luxman tube pre & got ahold of a Cary pre a few years later.What a great combination.The power of the Adcom with the warmth of the Cary was very nice.It had a decent soundstage & detail, not to mention the tremendous bass punch.Not as refined a sound as some would prefer, say as compared to a class A operation with electrostatics set up for jazz/classical, but this amp was made for high power/current applications.I've changed all my audio gear since selling the 565's & expanded my listening parameters.I replaced the 565/Cary setup with a Bryston/Pass labs combination, so quite a change.Looking back on my time spent with the 565's, the only complaint is that they are just a bit noisy, but that had a lot to do with the Cary and the stock power cords in addition to the problems associated with household electrical noise.There was a slight bit of hiss at idle, but you had to get right next to the speaker to hear it.Once the music started, you only heard music,even at low volume.I have to add that sometimes when I wanted to create a concert in my living room I wore ear plugs to keep from damaging my hearing.Yep, they can play at deafening levels for those that wish to do so.A 5 star rating could be given based just on price vs.watts, but these amps go a bit further than brute power.Adcom tried to make them both affordable and musical, and it's really too bad they didn't keep the 565's in the lineup and refine it.A very good deal when new, a tremendous bargain on the used market.

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Adcom 555

Power, ability to blend, trouble free, sounds like more expensive amps

kinda heavy

I like these cause they sound mint. If you can find em, buy em. A real find. My friend had them and sold them. I knew how awesome they were, I replace a Nac PA7 for these...they blow them away. Huge detail and unbelivable soundtage.
Buy em if you find em...

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ARC

Extremely high current capability. Will produce 1 kilowatt into 1 ohm. Very smooth and detailed sonics.

Monoblock design takes up a good amount of system real estate.

I've had these amps for some time. They replaced an AudioPrism tube amp in my system that was sonically excellent. The Adcom 565's have 20 output transistors per amp!, 40 for the pair. These amps have an extremely even, smooth sound and possess incredible dynamic range. The sound is different than the 555 type 2 (rounder and more foregiving on the top end). I still believe this is the best product ever made by Adcom.

P.S. The Conrad Johnson PV-5 is a great match for these large amps. Front ending these amps with tubes provides a very lush sound.

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Conrad Johnson Pre-amp with Martin Logan speakers. I've had McIntosh tube and transistor, Dynaco, and B&K.

Incredible power - Detailed soundstage - Excellent bass - Heavy construction - Dual Binding posts for bi-wiring

I don't have the balanced input option

I bought these for a pair of Acoustat Model 3 Electrostatic full range speakers that I bought on the web. The guy I bought the speakers from had a 400 W amp. I have theoriginal Carver 500 (pre-cube) that he built in his garage. It clips at about 320W per side and it really wouldn't open up the Acoustats. I bought these and they really changed my views. With these, the Acoustats became transparent. The system is a Sunfire tube pre, Cal Audio CD , with transparent interconnects. I had to sell the Acoustats because of a new room that had mucho glass (My wife wouldn't let me blocj the view, but I have kept the Adcoms and have driven a number of other speakers with them. These include Infinity Overtures, Silverline Sonatas, and my old pair of Klipsh cornerhorns. In all cases they have an open soundstage and plenty of power. I would highly recomend these. As I understand, these were built in very limited quantutues by Adcom to "position" the company more to the high end. they were primarily used to get into higher end audiophile stores. All I can say is they are built like a tank (and are fairly ugly as well). As to the switch, I bought an Adcom pwer conditioner and use it's switch, it also provides turn on staging. While the best looking amp I have had was a early Harmon Kardon tube amp, I believe these are the best.

If you se a pair for this kind of price, pick them up, you will not regret it.

Similar Products Used:

Carver, Audio Research, TOA, Harmon Kardon (tube)

More power than an arc welder

16 1/2" of rack space for one pair - which is a lot for an ugly component

I turned down buying these when I bought a pair of Infinity Kappa 8's under the impression that my 245 watt carver amp was just the bomb. Uh, yuh. I couldn't turn the power up to "2" before the Carver shut off. Fine, I will buy the Adcoms for $500 each. I felt ripped off for all of about the time it took me to get home and hook them up.

I used these amps for speaker wars in college, Fraternity parties and movie marathons. Using 4 to drive a pair of Infinity Kappa 8's and a pair of Kappa 9's, I have actually broken lights, tripped breakers, caused brownouts when turning on all amps at once, etc. Still, the Adcoms have never showed any signs of strain. I have been merciless on these things for 6-7 years (and the first ones I got were used, too) and they still perform like they were brand new.

While the carver sounded nice on less demanding speakers, they didn't have the power reserve these monoblocks have. I had even destroyed amps by trying to use them on my Kappa 8's as rear channels before I got the second set of monoblocks. Amazing that some amps can't survive a week under limited use, while these can survive 7 years of abuse and not even show signs of age.

Although I could have gotten away with some smaller amps, the overkill system has guaranteed that my amps will not strain even under severe conditions. My system has stunned people who thought their car stereos were loud and impressed those who know what high end systems can sound like.

These amps are not for everyone. They are big, heavy and ugly. If you can get past that and buy them, you won't regret it. I paid $1000 for my first pair and was reluctant to get them. I paid $1750 for my second pair and was happy to get them. What a difference a year of personal experience can make in determining the worth of a component.

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Adcom GFA-5800, Adcom GFA-2535, Carver TFM-45

PURE CLEAR POWER! AWESOME SOUND STAGE. VOCALS ARE ESPECIALLY EXCELLENT... WOMENS VOICE EXCEED EXPECTATIONS.

ADCOM DOESN' MAKE THEM ANY MORE. THEY COST ALOT TO PURDUCE--THEY OVER ENGINEERED THEM AND WAS COST PROHIBITIVE. BETTER FOR ANY ONE WHO OWNS THEM!

Simply put, these amps got great reviews when they first came out. They will sound great with just aboout any gear. They have pleanty of power and noooo harshness. They rival the sound of many exotic amps such as krell and arc, but who has the money for those anyway. They sound awesome, have excellent binding posts in the rear, you can bi wire them easily... The RCA conections are top tffny' Style. They're heavy brutes, with staying power. Excellent heat sinks and no problems for over 5 years. Today is 7-01-00. If you can find them buy em. You will not be sorry ever!!!
Make sure you have the room for these mono-blocks. For any new comers mono blocks mean you need one for the left and one for the right. Don't ask the wife-she will say they are too big, just buy em and when she says why are they so big, say bigger is better....

Similar Products Used:

NAKAMICHI PA7 STASIS(200Wx2)
ADCOM GFA 585 LTD
ADCOM GFA 555
ARC