[Bemopti123]

No, it’s not class D, but I bet it’s a far more sensible option to putting $1300 into a vintage amp.

The thing about this modding inquiry is the amp that he is attempting to mod...It has a typical Class A/B design with large power supplies and what it seems to me, large wattage available, thus lower powered Class D option or Chip Amp option might not be what he is looking for. 

Nevertheless, the H2O that I am partial to, provides plenty of watts as well as current, besides being sonically refined.  Being that the original poster is not answering or reacting to our little side tracked Class D devices, I think his mind might be made up. 

I have not done major modifications to any older equipment asides from a Nait 3 integrated and a HK 1979 vintage receiver.  None of the modification was worth more than $500-  Was it worth it?  Who knows?  Sometimes, we attempt to hear or see that our $ was well spent but it might all have been sonic placebo. 

I always say, the most important aspect of the electrical design is that the circuit was well laid out and components had a justifiable positive sonic attribute. 

I believe that very few designers become as fanatical in terms of sonic impact as the designer for Lejonklou audio...read what he says about the sonic improvement or detriment of even solder types, length of wires and other seemingly mundane components....http://www.lejonklou.com/the-reason-behind/

No modification will make a major positive sonic difference if the original circuit was not well designed.

[Rusty Jefferson]

I'm having a little trouble with folks calling these vintage amplifiers.  They aren't from the 1940s-50s.    Also, they've been substantially upgraded/modded (except for the power supplys apparently) by a knowledgeable equipment designer/builder.

I appreciate that class D (or chip amps) is the new flavor of the day in amplification, but I don't think class A and A/B amplifiers are dinosaurs.  In 20 years when the current class D amps become "vintage" will they be maintainable/repairable, or will they just be thrown in the recycling bin? 

[Bemopti123]

I'm having a little trouble with folks calling these vintage amplifiers.  They aren't from the 1940s-50s.    Also, they've been substantially upgraded/modded (except for the power supplys apparently) by a knowledgeable equipment designer/builder.

I appreciate that class D (or chip amps) is the new flavor of the day in amplification, but I don't think class A and A/B amplifiers are dinosaurs.  In 20 years when the current class D amps become "vintage" will they be maintainable/repairable, or will they just be thrown in the recycling bin?

Vintage or legacy products in terms of audio, I think people remember the times when Adcom was being reviewed everywhere but then, they sort of disappeared in the past decade and half. 

The heyday for Adcom, for me was when they had Nelson Pass as designer for some of their amps. 

I don't know why, perhaps audio snobbery, I never got to purchase an Adcom, never called my attention.  For what I understand, they were originally based in NJ now they have been reintroduced and moved HQ to Arizona?

I wouldn't want to call class D a new flavor, like soup du jour or the like, I think Class D is the new equivalent to Class A/B, because it is easier to produce or mass produce and the majority of audio devices that need to be made in large quantities...In terms of reliability, even the dirt cheap Crown amps, I call them the king of Class A/B per $ spend, use Class D technology and for what I can tell, they are rock solid.  Sure they will not be able to be repaired if they go South in a decade or more.

Nevertheless, when they do go South, you would always be able get what new device they will have on sale then. 

BTW, I also do not like the idea of throwing a perfectly fine piece of audio gear but I have several pieces that are not necessarily repairable unless you get a new board, meaning, they are not "repairable" in the traditional sense I guess. 

[Charles Calkins]

 Hi Guys:

   I've had several mods done to gear I've owned in the past and to tell the truth I found it hard to tell the difference between stock and mode.

                                                                     Cheers
                                         
                                                                Charlie

[Photon46]

Hi Guys:

   I've had several mods done to gear I've owned in the past and to tell the truth I found it hard to tell the difference between stock and mode.

                                                                     Cheers
                                         
                                                                Charlie

Hard to tell when mods will make much improvement or not I suppose. FWIW, I had Reference Audio Mods West do a major rebuild/mod of a PS Audio HCA-2 amp many years ago. It was a night and day difference it sounded so much better and I don't use such language lightly. Of course it wasn't all upside though. Now, years later, the amp has developed a hum and RAM is long out of business and PS Audio wouldn't touch it as it bears little resemblance to the amp that left the factory now.

[Bemopti123]

To me mods are fine as long as you are willing to sacrifice the Washingtons and also the original piece...perhaps you will find your ticket to audio nirvana or perhaps you will have squandered all those Washingtons for a bunch of very expensive parts.  Who knows unless you take the plunge?  Being that I am like most people into what is already well crafted, I would not go towards a mod unless it passes the muster of the factory technicians.  But then...this piece in question is not some ultra esoteric Swiss made amp.   

[WireNut]

Just for fun, here's my two early 555's, 1986 models, still in perfect working condition.

After 32 years it's time to replace, at the very least, the lytic caps before they leak like my turntable.

Waiting on the part Fairy to get here.


ADCOM 555's:






JVC QL-7 Turntable leaking caps.





 

[Rusty Jefferson]

Just for fun, here's my two early 555's, 1986 models, still in perfect working condition.

After 32 years it's time to replace, at the very least, the lytic caps before they leak like my turntable......

Sometimes we just need a little prodding!  Order parts from John?

[Pstores]

  I compared my Adcoms with two others unmodded. And 6 out of 6 in a blind taste test picked the modded ones each time. There was a significant difference in them. I even tried to fool them. They still picked the modded 565’s.  Just not sure if the next mods will be worth the gain.  Anyone know of a solid 300 watt per channel into 8 ohms or 850 watt at 2 ohms per channel class D amp that can drive manepans without breaking a sweat? I haven’t seen to many amps that can drive the Maggie’s as well. The Krell KSA 250 even fell short compared to these 565’s. I am going to demo an AVA Fet or Set amp. I think Franks Amps are built with as much drive as these have. I’ll fine out soon I think. I have demoed a ton of amps. None have been able to drive hard 4 and 2 ohm loads like the 565’s. This is were these amps shine.  Here is an article from Stereophile
On a review of the 565’s. These are just stock ones. Adcom had a great circuit with good parts in some places. And cheap in others. When you replace the cheap ones. These amps really come alive and loose the harshness and grain people complained about. They are tight, fast, very hard hitting,  clear, with awesome 3d imaging. With little to no coloration.  And they are dead quite. Which is great for a high current amp. These are unlike any other Adcoms ever made.

https://www.stereophile.com/solidpoweramps/adcom_gfa-565_monoblock_power_amplifier/index.html

[Pstores]

Another thought process is this concerning class D. I remember when CD’s first came out. They sounded different. It was this different sound people gravitated to. But people slowly went back to vinyl and now streaming. I just don’t think ill ever be sold on class D.

[Bemopti123]

  I compared my Adcoms with two others unmodded. And 6 out of 6 in a blind taste test picked the modded ones each time. There was a significant difference in them. I even tried to fool them. They still picked the modded 565’s.  Just not sure if the next mods will be worth the gain.  Anyone know of a solid 300 watt per channel into 8 ohms or 850 watt at 2 ohms per channel class D amp that can drive manepans without breaking a sweat? I haven’t seen to many amps that can drive the Maggie’s as well. The Krell KSA 250 even fell short compared to these 565’s. I am going to demo an AVA Fet or Set amp. I think Franks Amps are built with as much drive as these have. I’ll fine out soon I think. I have demoed a ton of amps. None have been able to drive hard 4 and 2 ohm loads like the 565’s. This is were these amps shine.  Here is an article from Stereophile
On a review of the 565’s. These are just stock ones. Adcom had a great circuit with good parts in some places. And cheap in others. When you replace the cheap ones. These amps really come alive and loose the harshness and grain people complained about. They are tight, fast, very hard hitting,  clear, with awesome 3d imaging. With little to no coloration.  And they are dead quite. Which is great for a high current amp. These are unlike any other Adcoms ever made.

https://www.stereophile.com/solidpoweramps/adcom_gfa-565_monoblock_power_amplifier/index.html

Have you tried SS amps by McCormick, the DNA Virginia series, or the SimAudio Moons?  the Henry Ho's H2o 250 Signatures have driven my mom's Kappa 9s to ear bleeding levels and they are known to keep Apogees until clear control.  They will produce momentary peaks of 2KWs when driven to 1 ohms.   

My experience with earlier class D amps vs newer Class D designs is simply execution.   

In terms of CD vs Vinyl, it will be a never ending debate but many still collect CDs as well as well as vinyl....the issue with both formats, specially as of now is the quality of the original master...current vinyl reissues of popular artist are simply digital recordings, remastered and reissued. 

[Emil]

H2o 250 Signatures have driven my mom's Kappa 9s

Your Mom?

How cool is that?

[Bemopti123]

H2o 250 Signatures have driven my mom's Kappa 9s

Your Mom?

How cool is that?

She has got the most pumping stereo in her neighborhood.  jajajajaja. 

[rollo]

  I compared my Adcoms with two others unmodded. And 6 out of 6 in a blind taste test picked the modded ones each time. There was a significant difference in them. I even tried to fool them. They still picked the modded 565’s.  Just not sure if the next mods will be worth the gain.  Anyone know of a solid 300 watt per channel into 8 ohms or 850 watt at 2 ohms per channel class D amp that can drive manepans without breaking a sweat? I haven’t seen to many amps that can drive the Maggie’s as well. The Krell KSA 250 even fell short compared to these 565’s. I am going to demo an AVA Fet or Set amp. I think Franks Amps are built with as much drive as these have. I’ll fine out soon I think. I have demoed a ton of amps. None have been able to drive hard 4 and 2 ohm loads like the 565’s. This is were these amps shine.  Here is an article from Stereophile
On a review of the 565’s. These are just stock ones. Adcom had a great circuit with good parts in some places. And cheap in others. When you replace the cheap ones. These amps really come alive and loose the harshness and grain people complained about. They are tight, fast, very hard hitting,  clear, with awesome 3d imaging. With little to no coloration.  And they are dead quite. Which is great for a high current amp. These are unlike any other Adcoms ever made.

https://www.stereophile.com/solidpoweramps/adcom_gfa-565_monoblock_power_amplifier/index.html

   Actually yes the Arion HS500 hybrid mono blocks. 1000W into 4OHm with a peak current of 40A. I have used them on Maggies, Soundlabs Appogee and GT audio Works with great success. A 6H30 input tube and Duelund copper CAST output coupling caps.
If you are in NY area you can borrow mine to check out.
Back to Adcom, if mod cost is reasonable just do it.


charles