ADCOM GFA 555 vs 555 ii which is more desirable..in your prof. opinions?

[RandyWilliamson]

GFA 555 vs 555 mk.ii which is more desirable? to match with my monitor 10s upgraded XO's RDO198s to follow.

Im leaning on adcom cuz im a basshead....thats right I said it.
But no seriously i love my monitor 10's and am excited...pleez help with your much valued experience....

Throw in your preffered pre-amp with this combo as well...tube even if this is a wise entry level opportunity to introduce myself to it.

Thanks again to all.

This is my first tru blue hi-fi system and I just want to make some wise choices avoiding financial pitfalls.
So I need all the help I can get.

[cnh]

Although OLDER and perhaps needing new caps, etc. The original Adcom GFA-555 is the best in that series.

Either unit has more than enough power for those 10s.

cnh

[comfortablycurt]

http://www.polkaudio.com/forums/show...ight=adcom+555

Check out this thread, it describes all of the differences between them.

The consensus seems to be that the original 555 is better.

[cnh]

Randy,

Here's heiney9s discussion of what's a good Adcom pre-amp! I hope he doesn't mind but this is GREAT INFO!

The best pre amp Adcom made was the GFP-750. It was a Nelson Pass design based very closely on his $4000 Aleph P, which is considered among the best sounding SS pre-amps. The 750 is a dead neutral preamp in both passive and active mode. If you don't like dead neutral sounding components I'd steer clear of it.

I have one I'm borrowing from my brother...........it's dead neutral and when paired with my warm, open Aleph 30 amp it certainly sounds much different then what I'm used too. For me the jury is still out as to whether or not it has the correct synergy I'm looking for. That said, it's a fantastic sounding pre-amp.

The GFP-750 retailed for between $1250-1500 depending on when it was purchased. Typically mint units sell in the $800-950 range used with lesser units (many missing the remote) selling for $650-800. I believe you can still get the remote from Adcom, but if you find a unit w/o it I'd call Adcom to make sure.

The GFP-710 and GFP-715 are also among their better designs. Anything with a tuner in it is not the greatest and leaves a lot to be desired. The GFP-555 is also one people commonly see.......not the greatest unit either.

This would be my only recommendation for Adcom pre-amps

GFP-750
GFP-715
GFP-710.......in that order. Anything else short of free; I'd look else where.

Hope this helps

Linky to a review from Stereophile http://www.stereophile.com/solidpreamps/133/

H9

P.s. we were using the GFP-750 to run Ted's currently acquired (by my brother) BAT VK-120's since the Adcom is a true balanced pre and they sounded absolutely fantastic, dynamic, balanced, very open and detailed, not a hint of harshness. If it's good enough for those; it's good enough for anything

[RandyWilliamson]

Comftorble Curt I saw that one but it wasnt very clear...and to be honest I was think the ii's might be more probable to have good caps functioning...vs...the older......altho I may not be too far from being able to replace the caps..but would rather not.

So I just want to hear for sure if the original is truly more desirable becuz that thread and the review posted there by H9 in my eyes shows a fair to good/healthy upgrade but you guys know better than me...i guess it would boil down to opinions so lets hear them.

thnks CNH and thanks for the order it gives me the opportunity to build around my budget...much appreciated.

[RandyWilliamson]

anymore opinions out there?

[engtaz]

I have heard that the 555II fixed somethings that were no done right on the 555 and that's about it.

[Face]

i have heard that the 555ii fixed somethings that were no done right on the 555 and that's about it.

what?

[Serendipity]

555, I believe it has more power.

[comfortablycurt]

I have heard that the 555II fixed somethings that were no done right on the 555 and that's about it.

I've always heard the opposite.

The original 555 was a Nelson Pass design, and was very simple in it's design. That's part of what gave it the sound that it has. Nelson Pass wasn't involved with the re-engineering of the 555II though, and from what I've gathered, the Adcom engineers took it and tried to improve on it, but in doing so, they made it's design more complex, but not necessarily better.

This detracted from the SQ from what I've heard. Out of all the reviews I've read, the consensus seems to be that most people prefer the original version.

[ben62670]

I llike emu

[RandyWilliamson]

Ben what is Emu?

[engtaz]

I believe what I wrote was paraphrasing a comment buy Nelson Pass. I did not say which was better.

[george daniel]

Ben what is Emu?

Emu is the name for a modded 555 adcom,,jk,,, get the 555 and make sure the caps are not leaking/ get Ben or someone ,yourself if you can weild a soldering iron,,and do the cap mod,, use the search function, as someone here just recently did it,,pretty simple..Good luck.

[RandyWilliamson]

You speak of thiiissss:

http://www.polkaudio.com/forums/show...ight=adcom+555

565 mod applies to 555?....I can do it but I'd have to get around to it I guess..im just a lazy bastard sometimes...plus rigging my home theater and this is some work as is.

[heiney9]

Comftorble Curt I saw that one but it wasnt very clear...and to be honest I was think the ii's might be more probable to have good caps functioning...vs...the older......altho I may not be too far from being able to replace the caps..but would rather not.

So I just want to hear for sure if the original is truly more desirable becuz that thread and the review posted there by H9 in my eyes shows a fair to good/healthy upgrade but you guys know better than me...i guess it would boil down to opinions so lets hear them.

thnks CNH and thanks for the order it gives me the opportunity to build around my budget...much appreciated.

Well there is really only a few years difference between the two models so caps and longevity will be about the same.

I like the older versions for a couple reasons

1) I like direct coupled amps......caps influence sound
2) The orignal is much simpler and closer to Nelson Pass's original design. The MKII is unecessarily complicated.
3) Not a huge fan of the Darlington output stage (again think simplicity).

Either would be fine but I'd replace the coupling caps right away if you get the MKII. That's where the weakness is in any amp that is capacitor coupled of that age.

Hope this helps

H9

[heiney9]

I believe what I wrote was paraphrasing a comment buy Nelson Pass. I did not say which was better.

Here is the exact quote: from 2002

I designed the 555. I believe the Mk II added a couple
of what were considered improvements, and it seemed
to me that it included triple darlington outputs instead
of 2 follower. I might have the schematic around, but
all told it was a simple bipolar design with a current
sourced input diff pair followed by a common-emitter
gain device that was also current sourced. This drove
the followers.

It was typical of all the 5XXX amps that I did the first one
and then they improved it until it had too many parts,
and then I would design the next in the series

Americo Borza sent me an old 555 in the hopes that I
would update it, and it still sits here, a perfect candidate
since so many of them were built.

Personally, I would score a few of these and run them till
they die and then update them. If you wait long enough,
an update will be issued.

H9

P.s. I love the 2nd line in paragraph 2 :D. Also the highlighted part is sort of tongue in cheek (meaning it probably didn't improve anything)

[GV#27]

Either would be fine but I'd replace the coupling caps right away if you get the MKII. That's where the weakness is in any amp that is capacitor coupled of that age.

Hope this helps

H9

The MK2 is direct coupled.I believe they are using a servo instead of a coupling cap.

[heiney9]

The MK2 is direct coupled.I believe they are using a servo instead of a coupling cap.

I think you're correct. I'm confusing it with the 545 MKII. I've had that model on the brain since I owned one for so long. They do use a servo for d/c offset in the 555 MKII. Sorry for the mis-information.

[engtaz]

Thanks H9 That's the statement I read.

[lakesailor]

I have had both in the past and really you cannot go wrong with either amp; both are great buys for the money they sell for these days. If I ever got another I would likely hunt for one of the later Mark II versions that had a removeable power cord.

As I recall Stereophile reviewed both (likely find online) I believe they felt that the Mark II was an "improoved" version of the original 555 for whatever that is worth. Either way you can do no wrong. Go funky and buy one of the all white albino versions...they were very cool.....

[Poee7R]

Ive owned both.

If I were to buy another one, it would be the MKII. Smoother on top than the original, and better at dealing with tougher loads. Not to mention they have a better resale value, not much but still a bit.


Dave

[RandyWilliamson]

I want to thank everyone who helped make my selection in my first entry level hi-fi stereo rig.....I am the proud owner of a GFA-555 picked up locally.....completely immaculate in it's original box....tested and played right in front of me.
Absolutely no hums...4 big ones later she went home with me....and I cannot complain...this was no ebay buy without me viewing the hardware!....
I have a GFA-710 on it's way w/remote.....315$ after shipping....
Tommorrow I will pick a cd player.

Still contemplating that marantz 5 cd carousel...or maybe the 400's with a dac.....or a bluray player that does it all.....

[comfortablycurt]

Very nice, congrats on the new toys.

I take it you snagged the 710 that was just up on ebay? Congrats.

I'm likely going to be getting either a 710 or a 715 pretty soon. I'm getting a GFA-545 this weekend, so a pre-amp is next on the list.

I'm looking forward to hearing your thoughts on the new setup once you get it all together.:)

[RandyWilliamson]

Oppo BDP-83 wins....just pulled the trigger...I think I'll be happy with 1 cd playing at a time if it doubles for a Blueray player!...if not either way a carousel will have to wait.
Hoping it can serve the level of dac the marantz does.....not that my ears are anywhere near experts yet.

[Face]

If not, you can always pick up an external DAC down the road.

[Tony M]

Does anybody have experience using the gfa555 with POLks' big SDA SRS's? The speakers with 8 mbs and 4 tws. in each.

He also has a ADCOM 5802 amp. My friend who just bought the charlotte sda's has both kinds of amps and wants to know.

He's going to join the club soon:D

He has 2 555mk2's and would love to bridge the power in each BUT he also has seen the warning not to use bridged amps:(. Is there any way he can get around it so he can have astronomical power for his new man toys?

[heiney9]

Don't use bridged amps with SDA's..............well actually you can't because of the common ground issue.

The 555 is great with the big SDA's. The 5802 would be even better as it's a bit more refined than the 555 and has more reserves and is all around better amp. The 5802 is NOT common ground so you'll need to get some beefy speaker cable and tie the negative speaker terminals together to make it common ground and compatible with any SDA speaker.

[heiney9]

Don't use bridged amps with SDA's..............well actually you can't because of the common ground issue.

The 555 is great with the big SDA's. The 5802 would be even better as it's a bit more refined than the 555 and has more reserves and is all around better amp. The 5802 is NOT common ground so you'll need to get some beefy speaker cable and tie the negative speaker terminals together to make it common ground and compatible with any SDA speaker.

H9

P.s. DO NOT attempt to tie the terminals together on bridged amps. It will not create a common ground and the amps will go POOF with authority as well as probably damaging drivers and crossover in the SDA's

[lakesailor]

Does anybody have experience using the gfa555 with POLks' big SDA SRS's? The speakers with 8 mbs and 4 tws. in each.

He also has a ADCOM 5802 amp. My friend who just bought the charlotte sda's has both kinds of amps and wants to know.

He's going to join the club soon:D

He has 2 555mk2's and would love to bridge the power in each BUT he also has seen the warning not to use bridged amps:(. Is there any way he can get around it so he can have astronomical power for his new man toys?

I used a single GFA 555 Mark II with a pair of SDA-SRS and was very happy with the results at the time. The GFA 555 series is a great amp and can comfortably drive just about anything.

I still think they are a great buy used. Good luck.