New Adcom 555ms with SDA-2B
rhythm
Posts: 60
Hello, I see a lot of positive comments here for the classic Adcom 555 with vintage SDA speakers. I think most of the posts I've seen have been about the classic 555, and I'm wondering about the latest Adcom offerings.
I'm wondering specifically if the Adcom GFA-555ms would work well with my 2B's. It's rated at 125W/200W for 8/4 ohms, and is labeled as a high current amplifier. Any experience with this amp with vintage Polks? Would this model do the 2B's the justice they deserve?
Thank you,
Greg
I'm wondering specifically if the Adcom GFA-555ms would work well with my 2B's. It's rated at 125W/200W for 8/4 ohms, and is labeled as a high current amplifier. Any experience with this amp with vintage Polks? Would this model do the 2B's the justice they deserve?
Thank you,
Greg
Comments
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I didn't even know Adcom was still business. 😁
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To me, a name for a brand doesn't mean much.
They are owned by a Taiwan based company now... As to performance is hard to know without hearing them- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
A couple of reviews I've read refer to this as "the Nelson Pass-designed GFA-555ms amplifier", so it sounds like it's quite related to the classic 555, but I'm figuring this must be a newer 'version' in one way or another. And being that it's new (as of late 2023 I believe), I was hoping perhaps someone on this forum had tried one of these and could share their experience with it, and whether or not it's got the power that these speakers like to have. Specs are one thing, but real experience is another, so if anyone has tried it...
Thanks,
Greg -
Possibly could be similar...
original series II
new version
- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
Definitely a more modernized implementation at the least...
Main thing of course is: how does it sound and perform? Hopefully someone here has checked the new model(s) out (GFA-555se or GFA-555ms) and can report what they think. -
Just in my brief online searching, I noticed the new version goes for about the same as the old version used, fwiw- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Only the original Adcom 555 was a Nelson Pass design IIRC. The 2 and later versions used a Darlington configuration, which strayed away from Nelson's design.
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Only the original Adcom 555 was a Nelson Pass design IIRC. The 2 and later versions used a Darlington configuration, which strayed away from Nelson's design.
I thought both versions used a Darlington configuration, but the mk2 used a triple Darlington and the 555 used a Darlington pair. -
Interesting, I was not aware. Back in the day the discussion was the difference between the two was that the mk2 had it and the original didn't.
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Only the original Adcom 555 was a Nelson Pass design IIRC. The 2 and later versions used a Darlington configuration, which strayed away from Nelson's design.
5802 -
Yes but the 5802 and others in that 4 digit series were not common ground.
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Yes but the 5802 and others in that 4 digit series were not common ground.
Was the 555 Common Ground?
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Where's the large capacitors in the new version?SDA SRS 2.3TL's
Silk Audio MS-90-BT integrated tube amp
Yaqin MS-20L integrated tube amp
SDA 2B TL's -
Yes. I'm pretty sure all the 3 digit Adcoms are. When I started here (2009) the big 3 for SDA was Adcom, Parasound and Carver TFM. -
They went to not so large capacitors if I had to guess 😁- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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I have reworked a 555se for a friend and have been into a few original 555’s and 555ii’s. Not familiar with the “ms” version. As I understand it, the original 555 is the only “true” Pass design. But the later versions still use the same (essentially) physical layout, transformer, rails, final stages and main caps. Rectifiers moved up on top the caps in ii and later. To answer the question above, the big caps are still there, the newer versions just have pcb’s that mount on top of them vs the “free air” configuration of the original 555. Worthy of note, up to se, there are no speaker protection relays. Chris Hoppe offers a really nice kit to add protection and a 12v trigger as well. I plan on building a couple of those this winter…
The units I’ve had (and still have) are absolute tanks. The driver board is a completely different schematic when going from 555 to ii and se is the exact same schematic as the ii. The se has nicer heat sinks (less sharp edges, beefier) and felt a little more “mass market” than previous revisions. Original 555’s definitely have more of a homebrew feel when it comes to build quality, if that makes sense. Every one of them has had heat issues in the early stages. I’ve rebuilt several using Chris Hoppe’s replacement kits which beef up the board, all of the components and adds heat sinks to most of the semiconductors in the gain stages.
I have found that I prefer the ii’s with Chris’s kit installed. The top end is better, imaging is better, and the background is quieter. I also like how robust the kit is. I sold my original pair of 555’s. I never disliked them, I just didn’t need six of them… 😎
Chris offers a lot of good info and is quite responsive to questions. An odd, mad genius kind of individual, but super nice. Chris knows lots of lore about the 555. Definitely a guru. Here’s the website: https://hoppesbrain.com/
And yes, the 555, ii, and se are all common ground.
You can’t go wrong, just get some good healthy feed circuits, speakers that love the juice, and enjoy! 🤘🏻🤘🏻
Current Collection: Monitor 4a (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
...SDA SRS 2.3TL's
Silk Audio MS-90-BT integrated tube amp
Yaqin MS-20L integrated tube amp
SDA 2B TL's -
Original 555:
555ii with Hoppes board installed:
Current Collection: Monitor 4a (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
@JayMX
You're correct Chris Hoppes is a very generous guy with information. I reached out to him to go through my 5802, he told me NO AMOUNT of money would get him to touch another, EVER!! I was so bummed after seeing what he had done to a couple.
😂😂 Mad genius is correct.
His basic statement was Adcom had a premium product but put zoo monkeys in charge of the build with hammers. The things he found and had to overcome to rebuild them was basically insanity for such a premium amplifier. He plainly stated "it's not if it will break down, it's WHEN will it, because it is going fail badly when it dies.
It was the most powerful amp Adcom ever built.
I never did find anyone worth their salt to touch it.
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Doesn't Hoppe have a soft start board for the adcom 555? My 555 went though power switches pretty regularly, but it hasn't in several years due to the fact it let out the magic white smoke. I don't think it's worth putting money into.
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I’m pretty sure I had to tie the Negs on my 585 I had many moons ago.
I never got the opportunity to try it with a A1 or Dreadnought.
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I’m pretty sure I had to tie the Negs on my 585 I had many moons ago.
I never got the opportunity to try it with a A1 or Dreadnought.
Wow, I forgot all about that beast. I guess the 5802 was the second most powerful amp Adcom built.😜
Adcom didn't make too many amps above 250wpc.
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Lots of good and interesting information on this thread about the Adcoms. I was looking for a good amp for my SDA-2B's under 2K, and I got curious about these newer Adcoms. They have a few in the current lineup: GFA-555se, GFA-555ms, and GFA-565se which are at 2K or less, but there doesn't seem to be much info on them, other then the specs that Adcom shows. On the fence about taking a shot with one of them.
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Stick around for a while. Get up to 100 posts and advertise in our wanted section. There's probably some really good used stuff here members would part with. Where do you hail?
Welcome to Club Polk.Gustard X26 Pro DAC
Belles 21A Pre modded with Mundorf Supreme caps
B&K M200 Sonata monoblocks refreshed and upgraded
Polk SDA 1C's modded / 1000Va Dreadnaught
Wireworld Silver Eclipse IC's and speaker cables
Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)
There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus -
Southern CaliforniaWhere do you hail?
Thank you!Welcome to Club Polk. -
FYI, saw this on FBM this morning:
ADCOM Pro PowerAmp $800 $1,100
Listed 2 weeks ago in Stone Mountain, GA
https://www.facebook.com/share/1FkU2LpJro/"Sometimes you have to look to the past to understand where you are going in the future"Harry / Marietta GA -
IIRC the 5802 is not common groundRandy-Maine
2ch-RTA15tl crossover upgrade
by David WMG
Yamaha cr1000 cr2040
HT-Yamaha Parasound Acurus
MIT BJC Cs1000p Polk Rotation -
boston1450 wrote: »IIRC the 5802 is not common ground
No, not at all. Nice amp but at this stage in it's life a ticking time bomb. -
Have you put any thoughts on other brands ? I use a Parasound 2250 (bought here CP) & I've used Acurus 200/3 (now my CC & rears) . I was using Adcom 555 w/565pre & to me it was a upgrade. Mind you I didn't upgrade the 555 as you can improve it... On my 2b's I used a Yamaha CR2040 & they stayed together for 2 years before I gifted the 2b's to my oldest & she still rocks them today. Don't hesitate to research other optionsRandy-Maine
2ch-RTA15tl crossover upgrade
by David WMG
Yamaha cr1000 cr2040
HT-Yamaha Parasound Acurus
MIT BJC Cs1000p Polk Rotation -
No good for SDA speakers but, that seems like a very nice price for a 300w amp?
