Adcom GFA-555 (original?)

My limited knowledge of the 555 is that it's a pretty good sounding (I can attest that it indeed is) amp for the $, and is rock solid dependability-wise (so far, so good). Judging from what they bring on Agon, ebay, and the FM here they seem to hold their value pretty well, and IIRC they're a tad more highly regarded than the II. I've only had mine for a few months but I'm quite pleased with it.

Ben knows his Adcoms better than I. I will add that I am also the owner of an original GFA-555...the gift that keeps on giving. Get yourself a good pre-amp and you'll be surprised just how clean this piece can sound.

I've been rocking to mine for a couple of years now and am really only thinking of upgrading my pre to the GPA-750.

And enjoy!

cnh

I have one. It is a solid amp!! for the $ cant beat it.

ben62670 wrote: »

The 555 is a solid amp. It is 2ohm stable stereo, and 4 ohm bridged:eek:

and a Nelson Pass design which i don't think the 555 II is

nguyendot wrote: »

Just traded my CC-300 + klipsch sound dock for this amp in minty condition.

Thoughts on this model? It's not the II, and I have no idea what the difference is.

Speaking of which, I need to take that CC-300 off the for sale list

It's in the archive, I've posted it atleast 1/2 dozen times in the past 2 years. Do a search and you will find all the info and more about Adcom 555's.

I am not posting it again, I thinks 6 times is enough.

H9

nguyendot wrote: »

Ah. Thanks for the clarification. I had no idea what it meant. Yeah I'm not powering any magnepans so no problem....

Doesn't matter the 555 will power Maggies just fine. The torture test were the Apogee Scintilla speakers, the 555 had a few problems driving those (they reach down to 1/2 to 1 ohm) so the 555II with the Darlington output stage had much less issue driving those insane speakers.

http://www.apogeespeakers.com/reviews/scintilla_stereophile.htm

H9

I used to own one. It's definitely a solidly built workhorse and is a decent amp for the price. Replace the caps on it if it hasn't already been done and it should give you many more years of dependable service. I found the sound a little on the bright side for my tastes with the set-up I had then. YMMV.

nguyendot wrote: »

So I read that this amp has no output relays... is that why the amp still has sound after it is turned off until the capacitors are drained?

Yep, well designed amps don't need current limiters or any type of soft start, muting, or output relays. I'll add that this is true for SS amps, tube amps may need a soft start or muting.

H9

FTGV wrote: »

Actually many a "good" SS amp use mute relays and soft start circuits.Because of high in-rush currents involved with charging large amounts filter capacitance and some toroidal type transformers soft start are all most a necessity.Also if a mute relay is used to remove bias current at turn off it will be sonically benign.

Ok, I guess I'll be more specific, inexpensive and poorly designed mute relays, soft starts and the like are more detrimental than good. I've read many higher end designers state they would prefer not to use such devices unless absolutely necessary and yes, they can be integrated to be transparent but you don't find that on your everyday mass market piece.

H9

nguyendot wrote: »

Let me go read over it again, I swear they said the II model went to triple outputs.

Yes the output stage is a triple darlington config,while having superior drive capability into lower impedances it is not considered to be the best approach for pure sound quality.