|
Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
|
|
|
Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
|
In Reply to: More context... posted by Al Sekela on December 22, 2006 at 14:05:48:
"It is unlikely your OTL amps contain the proprietary technology I've experienced, so I doubt your OTL amps could resolve all the details present in the source."Well Al I don't have the OTLs anymore because they were simply too hot for my apartment (at 500 watts idling per monoblock I think you can understand). As to them being more or less microphonic I would say that:
1) They used FAR fewer tubes in the output stage than your MA-1 clones (they had 4 6C33Cs per monoblock as opposed to what? 12 in your MA-1). This alone probably accounts for a big difference in microphonic behavior as you have 3x more output tubes.
2) I think tube matching will limit the low level resolution. Getting all those tubes to play well together is simply not possible. I could watch the DC offset shifting around subtly during soft passages and not so subtly (still less than 20 microamps though) during loud passages. What this indirectly showed is how well the tubes STAYED matched during dynamic passages and this was with only 2 push pull pairs per monoblock. I can imagine 12 tubes will further smear the low level resolution, same BTW for big transistor amps.
This lack of matching is a big issue with PP amps and why Allen Wright's Vacuumstate amp is interesting because he has found a way to keep them DYNAMICALLY balanced so this low level smearing doesn't occur or at least is greatly minimized.3) The output tubes in my OTLs were the heavily ruggedized 6C33C-B that was built to withstand high G forces for long periods and still function properly. This means internals had to be very solidly built and you can see this if you look at the internal construction of one of these bad boys. Does this make it less microphonic? Maybe but I am sure this heavy construction doesn't hurt in that regard.
In the end I am now getting great sound from KR audio hybrid SET amps. So now I have only 1 output tube per channel to worry about contributing to microphonics and it is the best built tube in the business. I get superb low level details because there is no problems with tubes handing off to each other, which you can readily hear with most PP amps, whether tube or transistor.
"Skinny silver wire sounds, well, skinny. Sorry to disagree so firmly with you on this point,"
No worries, I have heard what you are mentioning but I think it has more to do with construction than the wire itself. I am now using some Goertz flat silver ribbon (total of 18 gauge but only about 0.15 mm thick per conductor) that seems to combine the resolution I hear with silver wire with more body. I have plenty of copper designs with thicker wire and they simply lose information and in some cases lots of it. For me 12 gauge solid core will lose substantial information.
"If you haven't heard the Gilmore Raptors, then your judgement of 'class D' amps is a prejudice based upon insufficient data."
Well Al I owned a pair of Class D amps with very good conventional power supplies, same sound. I have heard the H2O signatures based on conventional power supplies, same sound. I have heard the Jeff Rowland's with both switching and conventional supplies, same sound. I have heard UcD with big conventional supplies, same sound. Bel Canto, same sound, PS audio, same sound etc. etc. If the Raptors are really different then they are completely unique among all Class D amps I have heard (and its in excess of 10 now that I have heard at length now with all different Class D technologies). Couldn't live with any of them.
The ONLY one that I heard that was acceptable was the Sharp SM SX100 but as you may know, at $20K it was hardly an inexpensive option and it was basically a power SACD DAC with a very expensive volume control.
Now as you are a former tube guy with good taste in amps and speakers I give you credit that maybe you are right about this one Class D amp but my experience is weighing heavily in the negative. Maybe I will get the chance to try them someday. In the meantime you should try to hear a KR audio amp so you now what I am enjoying.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Re: More context... - morricab 12/23/0616:13:48 12/23/06 (1)
- Thanks for a thorough discussion. - Al Sekela 13:00:00 12/25/06 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
