FS:ADCOM GFA-565 Monoblock Amplifiers

[dorokusai]

ADCOM GFA-565 Monoblock Amplifiers - SOLD - 9/10

These define manly amplifiers and would be quite possibly, the last ones you'll need for a very long time. I would keep them, but the pile of equipment here is getting ridiculous. They are very similar in specifications to my CTC BBQ, albeit in monoblock form.

I cannot include shipping for these as they are simply too much for me to eat personally, so work with me. The pictures will follow, as I have to dig them out and get them shined up for the press release. Here are some spec's:

Frequency Response: 20Hz to 20kHz, 0.005% IM Distortion (SMPTE), 1W to 300W into 8 ohms, 0.005% Distortion.

-More than 300 Watts output into an 8 ohm load.
-The ability to drive low impedence loads.
-Instantaneous Distortion Alert which indicates when distortion products are above the 1% level.

I'm going off of memory for the power figures...so they are roughly accurate if not better than my memory. The figures are per monoblock, just for clarification.

300x1@8
450x1@4
850x1@2

I think DarqueKnight owns a pair of these for his SVS subwoofers...or used to at least, so please correct me if I'm wrong Raife.

Either way, these are MONSTERS and you better have some space available as they are real estate eaters....as should any hardcore amplifier. They also generate some heat, so if you have a cold room, no worries, they will warm it up all year long.

Adcom also produced a Limited Edition GFA-585, at some point, which was a stereo version of these same two monoblocks...talk about hardcore. That's just FYI.

Stereophile reviewed these in two issues, XIV 4 & 6...but they are sold out thru SP Back Issue Online.

If anyone has these issues, it would be a neat addition to the amplifiers if you're not using them any longer. I'll pay for them in order to pass them along to the new owner, just let me know via PM.

Adcom GFA-565 Owners Manual (http://www.adcom.com/pdfs/gfa565manual.pdf)

Includes: Original boxes, original packaging and original owners manuals.

[heiney9]

Cream of the crop Adcom. Brute force and delicate all at the same time. My bro has a pristine GFA-585 and it is an excellent sounding extremely capable amp. He and I both want to own a pair of 565's, but don't have the space available. Whoever gets these will have to get naked and touch themselves....ala...Doro. They are that good!!! :p

H9

P.s. No pics please (of the touching) :D

[dorokusai]

H9 - Thanks for the extra cool info and no worries, I keep those photos private...truck stops only.

[unc2701]

Ahhhh.... the black beasts. Doro is wise to not pay for shipping 'cause those bastards are heavy. I had these driving the 25's, a 585 on the surrounds and a 555 biamping the center... still hate that I sold them when I went to the Brystons.

One thing I might add is that they've got dual binding posts, so if you're into biwiring, you can easily mix & match wires for the high's & lows.

I think I have some dirty photos of mine on the work computer. Will post if I can find 'em.

[heiney9]

I know this is Mark's thread and he probably doesn't need any help.....but I couldn't resist.

H9

EDIT: It appears these photo's are of modded/ slightly altered or repaired GFA 565's. In the spirit of keeping this thread on the up and up I removed my naked (the amp, not me) photo's. Mark's look cleaner inside than these and now I can't remember where I got these photo's from.

[DarqueKnight]

Awesome amps. I still have mine.

[venomclan]

Doro, PM sent

[dorokusai]

Here's some more data that I found in my files via an original document from "Audio" magazine.

Trivia: When did this publication, Audio magazine, cease? You old timers may know this easily, as it was one of the better magazines at that time.

Anyways, here's the extra data:

1.25-kVa Toroid Transformer
70,000uF Capacitance

Just as a side note, these figures are in the Parasound JC-1 Monoblock arena, 14 years its senior @ 1.2-kVa & 100,000uF.

Signal to Noise Ratio - >106dB
Input Impedence - 50k(Unbalanced)
Input Sensitivity - 130mV @ 1w, 2.15V @ Full Rated Power
Dynamic Headroom @ 4ohm - 1.6dB
Damping Factor @ 8ohm - >1000
Weight - 45lbs.
Dimensions - 17 x 8 1/4 x 11 1/2

Here are some comments from the article:

"Many manufacturers claim high-current capability for their amps; however, the GFA-565s deliver the goods even into 1-ohm loads. Equally important, they meet the real world test: They easily cope with even the most demanding Apogee, Infinity, Spendor and Thiel speakers."

"High powered amps like the GFA-565 can overdrive many speakers."

I'll photocopy this review and include it with the unit. There is an additional review for the matching pre-amp, GFP-565, and that will be included as well.

When you look at the internal pictures...envision 16oz. beer cans as the two Blue Caps in the pictures. They are just shy of the height, but pretty close. The toroid, for comparison, is as large as the JC1 Monoblock, just not "encapsulated", which means it has an aluminum cover. The amplifiers are taller than my CTC BBQ(7 3/4 vs 8 1/4) and combined, as deep as the same amp at 22"...that's hardcore in my book.

Another cool thought is that the Adcom + BBQ picture is 2 horsepower worth of amp @ 4ohm...as in 746 watts = 1 Horsepower.

[dorokusai]

UNC - It's funny but did you realize that you are the last person to comment on these particular amps on Audio Review? I was floating around and noticed that, kinda neat.

Heiney & DK - Thanks for the comments...and H9 for the pre-sale pics :)

[heiney9]

UNC - It's funny but did you realize that you are the last person to comment on these particular amps on Audio Review? I was floating around and noticed that, kinda neat.

Heiney & DK - Thanks for the comments...and H9 for the pre-sale pics :)

No Problem, check my edit though. I took down the photo's because those I put up looked altered compared to yours. Your's are nice and clean and uncluttered inside. Damn if I had the coin and more importantly the room, I'd be all over them. Those are nice examples, it's always nice to see original packaging and owners material.

Any chance you will or did put these up against the CTC for sh*ts and giggles?

H9

[DarqueKnight]

Doro,

Check your comcast email.

[dorokusai]

H9 - Sure, I love to play with gear, in addition to myself. The Adcoms also have bottomless power but they just don't have the magic of the CTC sonically. I've been happy with this amp since I picked it up 3+ years ago and it doesn't look like it's leaving anytime soon. I actually defined the amp in my living will for a fellow Polkie, so it will probably outlive me.

This is yet another Adcom offering that has added to my ongoing, altered perspective on the manufacturer, as I used to somewhat dislike them. I can't do anything but appreciate the build quality, topology, reliability and power of the brand....as there's not much argument to be had. I think it's a much better choice than Carver when it comes to used, affordable gear for example. This particular pair isn't exactly in the affordable category per se, but the 535, 545 and 555 are really solid amps and are always a great value.

[RuSsMaN]

Just look at em. What a statement. John Curl = No Bullshit. That's raw power.

[starchaser]

Sweet mono blocks Doro! If a good tubed pre wasn't a step ahead, i'd take very, very good care of these ladies. Gear like this, makes me regret I started at the the lower end of the spectrum... ever so slowly, getting my learn on.

[madmax]

This sale is TOTALLY unfair! Why do YOU get to keep the big one in the middle... :D

[unc2701]

UNC - It's funny but did you realize that you are the last person to comment on these particular amps on Audio Review? I was floating around and noticed that, kinda neat.


heh... wrote that when I was getting ready to ebay my pair. I think I ended up getting about $950 for 'em, but they weren't in as good a shape. I have to say that I am tempted- I do miss the monoliths.

[dorokusai]

Thanks gentlemen for the positive comments :)

These are still available....just drop me a line if you're interested.

[dkg999]

Are those real audiophile bricks holding down those Mye stands :p I had a lot of trouble finding audiophile sand to fill the struts on my Mye stands :D

[dorokusai]

DKG - :D They are Oxygen Free Concrete. The MYE gear is top notch man, glad to see another user.

[dkg999]

Oxygen Free Concrete - I am very impressed:cool: Someday I will be able to play in the high end audio equipment. You are my new hero ;)

[dorokusai]

Raife - Thanks alot for the very cool brochure....I just printed it to add to the amps.

[DarqueKnight]

You're welcome. I would have bought your 565's if they had the balanced input option. My 565's can't be converted to balanced operation because Adcom no longer makes the conversion kit, which contains a completely different input circuit board.

[unc2701]

Yeah, I tried to get mine switched over, too. No dice... but Adcom does still have rackmounts available for them.

[Strong Bad]

Raife - Thanks alot for the very cool brochure....I just printed it to add to the amps.

Printed on Oxygen Free paper? Better be you cheap F***!!! ;)

[dorokusai]

Last call....off to Ebay tomorrow. Thanks for the interest either way.

[dorokusai]

Just in case....$900? I get corporate shipping rates, so it wouldn't be as much as you think....just a last minute thought.

[dorokusai]

SOLD. Thanks James....they are going to heat up those Magnepans like you wouldn't believe.

[jdhdiggs]

NP, the mags need a little boost in the butt.

[ohskigod]

staying in the family? excellent!

[faster100]

Nice amps!! :) Good score james

[jdhdiggs]

Now someone buy the counterpoint....

[george daniel]

I'm still kicking myself for hesitating on the mono's,,damn,I'm dumb AND slow:o

[jdhdiggs]

Buy the Counterpoint... ;)

[george daniel]

Believe me I've thought about it,I want to bi-amp my Lsi's and/or the SRS 2's,I've got a Belles 350a and a Anthem amp 2 se,so I guess that I have to get one the same :confused:

[jdhdiggs]

Not neccessarily, just make sure the gains are the same or the higher gain amp has variable gain capabilities

[dorokusai]

James dropped by the other day to pick up the monoblocks, thanks much. We talked shop a little bit and I also met his wonderful wife. They may have been talked into attending Polkfest '06 but we'll see what happens :)

Enjoy the new power.

[Demiurge]

Congrats! :D

Going to Polk Fest? Scary....:p

[jdhdiggs]

James dropped by the other day to pick up the monoblocks, thanks much. We talked shop a little bit and I also met his wonderful wife. They may have been talked into attending Polkfest '06 but we'll see what happens :)

Enjoy the new power.

Still strongly doubtful on attending. It would be a royal pain in the butt and with the current schedule, I don't even know where the hell I'll be that weekend so I'm going to say no to going unless something drastically changes... And the wife, well, unless pigs sprout wings and jet engines, she won't be going.

All in all though, a decent visit, just wished we didn't have so many freaking errands that day...

Only problems so far with the amps:

1). Different gain than the Knight's
2). Passive pre-amp dial only goes to 4 o'clock, time for a new pre....

[TroyD]

Aw, c'mon, James....Polkfest will be a BLAST. Charleston is a GREAT town, the lovely Wendi can keep the better half occupied for sure, pluse she would LOVE some female representation, ahem, Cathy, Darla....

BDT

PS, if you move the adcom, let me know, I wouldn't mind having it back.

[jdhdiggs]

I'm keeping the adcom, I dig the passive pre idea. Additionally, it has built in protection for the maggies (Can't turn it up too loud if the gains are set to the 565's). If I can reduce the gain on the knights and counterpoints, I could tri-amp with not threat of blowing the speakers even with the fuses replace by wire....

I'll talk to her about it but it's doubtful....

[RuSsMaN]

The input sensitivity is lower. Have you tried a different source (with a higher output voltage)?

[George Grand]

If that's the Adcom passive pre that originated here, I wouldn't mind getting it back.

[jdhdiggs]

The input sensitivity is lower. Have you tried a different source (with a higher output voltage)?

I could do that, but at the "cranked" setting, it is plenty loud enough. If I moved to another, larger room, things might change a little.

Ideally, what I'd like to do at this point is reduce the gain on the knight's by 9dB and bi-amp.

[RuSsMaN]

James, those have 12AX7 on the front end still? Throw some 12AU7's in and cut the gain nearly in half.

George, it's the same one, you to Troy, Troy to me, me to James - all at the original $75.

Cheers,
Russ

[jdhdiggs]

Allright, that should get them close with a change the other driver tubes, that should be another dB or two and a -3dB inline filter and it should be damn close...

[RuSsMaN]

Try the 12AU without the filter, a 12AT would be about half, 12AU should be 1/5th the gain - but remember, audio isn't linear - the 12AU should be the ticket.

[jdhdiggs]

Yup, I remembered the log-linear relationship and that passive pre's are linear which is why I'm guessing 9-10 dB more gain in the knights-Double the straight line gain should be 10 dB right? I'll play around a bit.

[marker]

Hmmm, I wonder how the SRT would sound bi-amped with a 565 on each main stereo array, a third 565 on the SRT Center (which is basically identical to the main stereo array), a 555 for the main SDA arrays, and say a 545 for the surrounds.

Or even better yet, tri-amped with five 565s on each array of midwoofers (one each for the center and main stereo and SDA arrays), and a 535 for the main tweeters along with another 535 for the SRT Center tweeter. :eek:

[halo]

James, those have 12AX7 on the front end still? Throw some 12AU7's in and cut the gain nearly in half.

George, it's the same one, you to Troy, Troy to me, me to James - all at the original $75.

Cheers,
RussSo, if I replace the 12AU7's on my TAD-60 with 12AX7's it'll play louder?

[RuSsMaN]

No, and maybe.

In some circuits you can increase the gain - but it's risky. It can over-drive the main amp circuit, and damage the amp. It's best to contact the manufacturer / designer to see if you can increase the gain with a tube swap.

Some circuits that use 12AU7's can also take a 12BH7, will increase performance slightly. You can always try some mil-spec 12AU7's, such as 5814's and 6189's without worrying about damage to the circuit.

Cheers,
Russ

[halo]

Thanks! :)