Uncle Seth Posted March 7, 2018 Share Posted March 7, 2018 (edited) 43 minutes ago, Zaphod Beeblebrox said: Peter's recent brush with cancer has pushed the release back quite significantly. Ironically, I was chatting to Peter about this about an hour ago. Stay tuned. It'd be quite rude of me NOT to stay tuned. Thanks Of course, wishing him the best of health, too! Edited March 7, 2018 by Uncle Seth Additional line of text. Link to comment Share on other sites More sharing options...
HarbethRob Posted March 29, 2018 Share Posted March 29, 2018 (edited) Late to this party. Just want to chime in and say that I am listening right now to an ME 550 (series 1) on loan to me from a generous friend with Harbeth 30.1 speakers - excellent, excellent (had to type that twice) amplifier. Does it get any better? Probably for very large sums of money. This one is in pristine condition (and the fan works!). I do not know Peter Stein but he can be very proud of his work. Edited March 29, 2018 by HarbethRob 2 Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted March 29, 2018 Share Posted March 29, 2018 11 hours ago, HarbethRob said: Late to this party. Just want to chime in and say that I am listening right now to an ME 550 (series 1) on loan to me from a generous friend with Harbeth 30.1 speakers - excellent, excellent (had to type that twice) amplifier. Does it get any better? Probably for very large sums of money. This one is in pristine condition (and the fan works!). I do not know Peter Stein but he can be very proud of his work. I have directed Peter to read your post. I am sure he is pleased that you are enjoying one of his babies. Does it get any better? Listen to an ME550-II or ME850 sometime. 1 Link to comment Share on other sites More sharing options...
marten Posted March 30, 2018 Share Posted March 30, 2018 When you go from ME550 I to ME550 II - what sort of elevation in sonic quality are we talking here - a "night and day" contrast or something like a noticeable difference only to discerning ears? Tough to get both in the same room at the same time, so just angling for a bit of an idea ... Link to comment Share on other sites More sharing options...
HarbethRob Posted March 30, 2018 Share Posted March 30, 2018 Yes, I would be interested in this too. Is it worthwhile searching out a 550 Series II? Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted March 30, 2018 Share Posted March 30, 2018 (edited) @marten @HarbethRob Well, like all things it is complicated. I will be as accurate as I can be in the description. The ME550-II was the result of a design shift for ME. I hasten to add that the fundamentals from earlier models (the ME550) remain. That is: * Zero global NFB * Critically matched semiconductors (within 1% for hFE and Vbe). * Closely matched resistors in critical areas (within 0.05%). * Oversized power transformer. * Oversized, multiple filter capacitor banks. * Gentle Voltage limiting (aka: Soft clipping). * Gentle current limiting (very few amps possess this feature, as it is impossible to implement in designs that employ global NFB). * Current limiters set for very high levels (40 Amps in the ME550). I think the ME550-II is also set for 40 Amps, though it may be higher. * Wide frequency response (DC ~ 150kHz) and zero phase shift within the audio band. * Rise time of less than 1uSec. * DC coupled throughput (though the ME550-II has an option of AC coupling for use with poor quality preamps). * High temperature operation (~55 degress C), with full temperature control via variable speed fan. OK, so the important stuff is the same in the newer model. The ME550-II differs in some important ways: * The use of double the number of modern, high(er) speed, lower distortion output devices. THD and IMD is roughly half that of the ME550. * Output impedance is roughly half that of the ME550. * DC or AC coupling available. * The ME550-II uses a modern, low noise, DC fan. This is actually a (slight) backward step from the ME550, which used an AC fan. That said, it was done to keep costs under control and the choice of fans is much broader. * The ME550-II was available with a Hi-Cap option, which doubled the amount of filter capacitance. This option cannot be fitted to the ME550 due to layout considerations. * The ME550-II lacks the full modular construction of the ME550, again due to cost constraints, but output devices and drivers can be swapped out in about 20 minutes, so it's not a nightmare to work on. * The ME550-II was supplied, standard, to possess a high input impedance, so operation with poor quality preamps is possible. When the ME550-II was released, it's sound was usually described to be like that of a small version of the formidable and legendary, ME850. So, yes, it's damned good. Edited March 30, 2018 by Zaphod Beeblebrox Link to comment Share on other sites More sharing options...
THOMO Posted March 30, 2018 Share Posted March 30, 2018 1 hour ago, marten said: When you go from ME550 I to ME550 II - what sort of elevation in sonic quality are we talking here - a "night and day" contrast or something like a noticeable difference only to discerning ears? Tough to get both in the same room at the same time, so just angling for a bit of an idea ... The ME 550 sounds a bit 2D compared to other M.E. amps I have heard. A lot of amps from that era including the Naims,Linns and the Power Envelope NADs tended to sound like that. M.E. was pretty quick to rectify that .Naim persisted with it for a long time before coming to their senses. Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted March 30, 2018 Share Posted March 30, 2018 (edited) 17 minutes ago, THOMO said: The ME 550 sounds a bit 2D compared to other M.E. amps I have heard. A lot of amps from that era including the Naims,Linns and the Power Envelope NADs tended to sound like that. M.E. was pretty quick to rectify that .Naim persisted with it for a long time before coming to their senses. I agree that early ME550 amps (steel chassis) were not as good as later ones (aluminium chassis types). The major reason was because one channel was operated in invert mode, in order to place less strain on the power supply. I've modified a number of early models to reflect the superior changes in the later ones. IMO, it is well worth doing. For me, image quality is paramount and operating both channels in non-invert mode seems to provide a superior result. That said, I've found many listeners who seem insensitive to image quality and have noted no audible difference after the change. Like all things: YMMV. BTW: Only the early ME550 and ME55 amps were built to operate with one channel inverted. All other ME amps operate in non-invert mode. Edited March 30, 2018 by Zaphod Beeblebrox Link to comment Share on other sites More sharing options...
HarbethRob Posted March 30, 2018 Share Posted March 30, 2018 Ok that is interesting and worth noting concerning the Series II. 2D - a bit closed in perhaps? Ha ha, probably would not have noticed it if you had not suggested it but I suppose it is there - listening right now to the amp. The only other MEs I have heard are the 240 high cap version (2 used as monoblocks with an ME pre) and they were pretty exciting as well. In comparing the ME550 directly to a Holton power amp (with all other components not altered), the Holton is certainly the better amp in the imaging department (and also some aspects of tonal qualities - a softer more forgiving presentation) but I have to say that the ME550 is still outstanding value and one could live with it permanently in my view . But we all know that audiophiles are restless maximisers. Link to comment Share on other sites More sharing options...
THOMO Posted March 30, 2018 Share Posted March 30, 2018 59 minutes ago, Zaphod Beeblebrox said: I agree that early ME550 amps (steel chassis) were not as good as later ones (aluminium chassis types). The major reason was because one channel was operated in invert mode, in order to place less strain on the power supply. I've modified a number of early models to reflect the superior changes in the later ones. IMO, it is well worth doing. For me, image quality is paramount and operating both channels in non-invert mode seems to provide a superior result. That said, I've found many listeners who seem insensitive to image quality and have noted no audible difference after the change. Like all things: YMMV. BTW: Only the early ME550 and ME55 amps were built to operate with one channel inverted. All other ME amps operate in non-invert mode. Try to tell a lot of Yamaha NS1000 speaker owners that they suffer from the same presentation and they refuse to believe you.In the case of the early ME 550s nice to know that it can be rectified . It seems some people do not hear imaging that way so for them I guess it does not matter. Link to comment Share on other sites More sharing options...
muzzagruzz Posted March 30, 2018 Share Posted March 30, 2018 I have the 550 mk II recently upgraded with the high cap kit and upgraded fan by Zaph. It images beautifully with my Legend Kantu’s and these speakers image with the best bookshelf types. I once had an 850, an astonishing amplifier, and can attest to the fact that Zaph is spot on when he says that the 550 MKII sounds like the 850. This ME power amp will never leave me. I’ll not make the same mistake twice! That mistake was selling the legendary 850. 4 Link to comment Share on other sites More sharing options...
vinilink Posted March 30, 2018 Share Posted March 30, 2018 2 hours ago, muzzagruzz said: I have the 550 mk II recently upgraded with the high cap kit and upgraded fan by Zaph. It images beautifully with my Legend Kantu’s and these speakers image with the best bookshelf types. I once had an 850, an astonishing amplifier, and can attest to the fact that Zaph is spot on when he says that the 550 MKII sounds like the 850. This ME power amp will never leave me. I’ll not make the same mistake twice! That mistake was selling the legendary 850. As you mentioned, I am keeping all my ME amps...3 pres with all Phono stages and 550 ii hi-cap and 850. I won't part them. 1 Link to comment Share on other sites More sharing options...
muzzagruzz Posted March 30, 2018 Share Posted March 30, 2018 One day, if I’m lucky, I’ll have another preamp, either a 15 or 25, and 550 MKII. Link to comment Share on other sites More sharing options...
Recommended Posts