Keep your modded 555! A great N.Pass design! You will just be wasting money on that ARC amp (and having future reliability issues with it)! Even the stock 555 is a formidable contender!
Audio Research D240 mkll vs Adcom GFA-555
Hey Folks, I currently have a modified Adcom GFA-555 but have the opportunity to purchase an Audio Research D240mkll. Will there be a significant increase in sound quality? Speakers are Sonus faber Chameleon B's and source is Tidal through a Project Pre Box S2 Digital (as preamp).
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Nelson’s design of the 555 was just fine. In production, how that was handled, in order to make for ’over the top reliability’, ease of build, ease of servicing, etc... and how all that was executed --- that is what resulted in a grainy amplifier. Nelson’s job was the circuit design. The rest (AFAIK) was handled by whomever Adcom had do the rest. And that includes layout, fusing, chassis, etc. All of that had a major impact on Nelson’s supplied circuit. Modding the 555 or the 5500 or any of the other adcoms... in a way that is centered around removing the built in obstacles to positive gains...generally has a very positive effect on the sound of the given Adcom. The individual modded amplifier will be fine, but as a production item (fully maxed out in all ways), as percentages of failures go...reliability would (and does) generally take a huge step backwards. So much of a step that it could easily make a company insolvent. And at times, it has happened. Extremism has its costs. ’Best sound quality’ and reliability in the long or sometimes even short term, do not normally fit together. Their demands for existing --are in opposite directions, in high end audio. I state it as an incontrovertible fact, in an imperial manner but there are a few exceptions. The problem is that, if exception is given for that 2-3% of the best of the best, that actually DO exist... 110% of the companies out there will refer to themselves as the exception that is in that small few percent range. Which is impossible, so +95% have to be full of it or ignorant of their own products limitations. Marketing, in all sensible guises and attempts, must never touch this, at any price. Eg, ’CTC builders’, for Parasound, etc, each of the three people did a part of the final issued design, with aspects of all that controlled/directed by Parasound. CTC wanted performance, and Parasound wanted utter reliability, and reasonable projected price points being met. Which is why John Curl, afterward, supplied a huge amount of data to the DIY folks on turning the HCA-3500 into what CTC really wanted it to be. My guess is with Richard’s OK beforehand. So --much respect to Richard for allowing that. In the end, it is the psychological positioning of the buyers that is at the heart of this scenario and how it has had to play out in the consumer marketplace for high end audio. The inability to understand the complexities that lie behind the curtain, and how they (the buyers and users) react to the given shadows on the wall... |
I bought a D240 MKI and it had noise problems in all units! ARC gave a free update to D240 MKII that eliminated the noise issue, however the amp sounded bad for the first hour of warmup. Dumped the amp at a big loss. The ARC tube and tube/FET products of that era were very good IMO. Newer ARC is too solid state sounding for me. |
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I have a modded 555 as my back-up amp. When I sent my McCormack DNA-1 to SMc Audio for a rebuilt I pulled out the Adcom. I allowed it several days of burn-in since it had been boxed for several years. Upon listening, I tried to like what I was hearing as it would be over a month till I received my 1st string amp. back. Unfortunately its performance was so inferior to what I was used to that I shut down the system and listened through my Shure 535 in ear phones to music on my computer via Spotify. The music came to life more through this mid-fi set-up than through using the Adcom with my system. I take no pleasure in expressing my disappointment with the Adcom. Many years ago, with a much less resolved system its performance was satisfying. This experience is testimony to how much better modern gear designs are. Just taking into account the advancement in resistors, capacitors, transistors etc. etc. |
How about a re-capped Krell about 20 years younger? from Eric Post. That's exactly what I did. Have a KSA-80B and had it gone thru by the factory--recapped etc. Using it to drive Apogee Scintillas at One Ohm. Been a year after recapping and sounds very nice. This amp was made to drive this speaker by Dan. Did a modern streaming front end. Sounds very real. |
That ARC is a great ampI would grab it asap as I can tell nobody above here has ever heard the potential of this unit. It is well more sophisticated and dimensional in my experience which I can promise I have actually heard the unit. It also has a friendly input impedance for a tube preamp. Match it up with any decent Tube unit like ARC, Quicksilver, Audible Illusions etc and you will have a great system to play with your speakers or any great speakers full-range like Vandersteens or Magnepans. Best JohnnyR |
I happen to think the ARC is just fine myself, having owned and happily used 2 different SS ARC amps in the past. I was not specifically promoting the Adcom amps, re mods or whatnot, I was just covering the fact that not all amps are as they could be, or can be, due to the constraints of reality. If I was to start with an unknown base amplifier, and then modify from there (all being equal), I would start with the ARC amp, not the Adcom. But I would happily tinker with either brand of amplifier. It is possible to make one sound better than the other and then keep working on each... and make each leapfrog the other in sound quality. Back and forth, back and forth... As this is the main thing about most all amplifiers. Having seen the insides of almost any amp known to exist in the high end (nudie amplifier images abound all across the net), I will say that I have not yet seen an amplifier that could not benefit from a little intelligently applied TLC, be it a $2k amp or a $100k one. Point being, is that it is really..near impossible to say that one has a modded out Adcom, vs an ARC that is stock, and then get an opinion. As the modification level or what was done to the Adcom, is an unknown except to that of the owner, but that the ARC is a known quality for at least some, as it is a known model with a known stock condition and sound quality. That the modded Adcom is an X that no one here outside of the owner of it can quantity and weigh against. It is a good question, but it is lopsided for all but the OP... and we cannot help solve it. |
I bought an Adcom 555 MKII, along with a GFP-565 preamp, brand new back in the 1980s and used them with Magnepans for about 5 years. I never had it modified and what teo_audio stated in his post about graininess makes a lot of sense to me. I subsequently used McCormack and Aragon high current amps over the next 10 years and, in my opinion, they both sounded very similar to each other and both were significant upgrades over the unmodified Adcom. Over the past 5+ years I’ve used class D amps, stereo Class D Audio and Emerald Physics units and currently a pair of D-Sonic monoblock amps. All of these newer class D amps outperform all of the large, heavy class AB amps I’ve previously used by a wide margin. They're better in every area I care about: low distortion, high power, high signal to noise ratio, powerful and realistic dynamics, solid and stable imaging, highly detailed and possessing an overall accuracy, smoothness and naturalness. If you’re looking for a significant upgrade, I’d suggest trying out at least one high quality class D amp. Tim |
noble100"All of these newer class D amps outperform all of the large, heavy class AB amps I’ve previously used" You must have employed the use of some really mid-fi or mass market class AB amplifiers in your Music Reproduction System if that was the result and consequence you experienced when substituting Class D amplifiers for them in you're system but the important thing is that you made some real, genuine, audible improvements and I can only suggest, recommend, and encourage you to audition some superior amplifiers within the same Music Reproduction System such as properly designed, specified, manufactured and installed Class A amplifiers. Good luck to you there is more out there don't stop now! |
clearthink:" You must have employed the use of some really mid-fi or mass market class AB amplifiers in your Music Reproduction System if that was the result and consequence you experienced when substituting Class D amplifiers for them in you're system..." Hello clearthink, As I stated, I've used 3 high current class AB amps in my system thus far, an Adcom, McCormack and an Aragon. I believe most members would consider all 3 of theses as at least good quality class AB amps with the possible exception of the unmodified Adcom being considered mid-fi and mass market. I think a very large and expensive Pass Labs AB amp would be required for a class AB amp to outperform my current D-Sonic monoblocks. I've auditioned Parasound and Bryston high current amps already and discovered those will not. Sure, an even larger, hotter and much more expensive class A amp may sound marginally better. But my D-Sonic monos are smaller, run cooler, were $2,100/pair, are paid for, consume orders of magnitude less electricity to operate and I perceive their sound quality performance as exceptionally good. Thank you but I don't consider your suggestion of switching to class A amplification as clearly thought through. However, I suggest you consider auditioning a good quality class D amp in your system to broaden your audio knowledge and experience. Tim |
noble100" I've used 3 high current class AB amps in my system thus far, an Adcom, McCormack and an Aragon. I believe most members would consider all 3 of theses as at least good quality class AB amps with the possible exception of the unmodified Adcom being considered mid-fi and mass market." Those are not only mass market midfi amplifiers they are so old as to be nearly laughable they would likely need substantial service and parts replacements because of the age of the components contained there in. |
Having owned multiple models of ARC solid state and Adcom amps through the years, I am certain the ARC would sound superior to the Adcom. I would advise calling ARC, however, and verifying if the D240 is still serviceable (if it ever broke down). I like ARC gear, but some of the older solid state stuff has components they have obsoleted and cannot be serviced. I would advise making sure the D240 isn't one of them. |
Thank you all for your thoughtful input. Everyone had great points and all were taken into consideration. The conclusion was I decided to take a much larger leap and purchase a Pass Labs XA-30.5 from someone here on AG (much to Erik_Squires chagrin I think). But I've enjoyed the modded Adcom and have been wanting to hear Nelson Pass's recent work and this was an opportunity to make that move. It's probably the only Pass amp I could ever afford but the reviews have been nothing but stellar. So thank you all again. |
The D400 MKII which is a similar, higher power amp, can not be fixed by ARC if the PS caps need to be replaced due to age. The D240 MKII does sound good after about 30 minutes of play. But sounds poor during the first 3o minutes, even if left on continuously. I think it is due to the odd ball, multiple emitter power transistors used. Why buy an amp made in 1992? There are better buys with more current power amps. |
