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61.41.229.22
Not trying to 'diss' either format.Respect,
Guy
Follow Ups:
hate to say better than the OTLs I have owned or tried in my system.But to be fair I use Hieff Loudspeakers.Currently using trans t16 OTL to drive bass horns with 300b SET on top .OTL do have wide frequincy responce and good bass drive but the magic of SET is just not there, at least for me and local audiophiles who have done the same, many of my friends have gone back to SET after OTL, as always YMMV
I was afraid someone would post something like that. I've seen this ascribed to the idea that the multiple pairs of OTL output devices have a negative effect on the overall transparency relative to a top notch SE amplifier, although I haven't gone out of my way to make this particular listening comparison because I can rationalize that both topologies, properly implemented, are so far ahead in quality compared to most commercial recordings.
Good question. Actually OTLs make extremely inefficient pure class-A SE amps like SETs are, but PP types should be plenty of. OTLs do not require expencive OPTs (I know you know this, but...) and when diy'ing and generally playing around with circuit ideas, that's a good thing not having to spend time and money hooking up the output iron. So I would think it should have a little more threads than it does simply because OTLs can be cheaper to make.
I think a lot of people are turned off because relatively few tube types are usable in practical OTL amps. Also there seems to be a certain amount of hush-hush in the circuits used in most of the OTL amps. There doesn't seem to be any Nelson Pass types among the OTL designer clan, unfortunately. So many patents, and so little time...
I dunno, perhaps I'm lost, but I seldom bother to check in here anymore, even tho I'm a OTL fan myself. It just seems like this is a place for Atmasphere amp users and techs. Dont get me wrong, Atmasphere are great amps, but I'd love a little more diy talk.
I agree with your basic sentiments, but I would point out that Ralph Karsten is extremely cooperative with DIY types and has made his schematics readily available in the past. The same could be said about Bruce Rozenblitt. On the old ASOG website, there was a lot of talk about innovative modifications to the basic Atma-sphere design, including ideas about modifying the input voltage amplifier, doing away with driver tubes, etc. These themes are absent from this forum perhaps because those who were more technically knowledgable have abandoned us, e.g., Paul Speltz, Jennifer White-Wolff Clark, Al Sekala, Mark Gilmore, Kevin Covi. Those guys used to post on a daily basis. Most of them are now involved in the commercial aspects of audio and/or otherwise estranged. Then again, the fact remains that there are only two really viable methods for designing an OTL output circuit, the Futterman and the circlotron, which seem to have proven superior to the other variations on the theme. Finally, a lot of knowledgable DIYers just don't seem to give a hoot about OTLs, I think because most of them have no experience with the approach, and many actually like to deal with the design problems posed by the output transformer. I recommend Kevin Covi's website for anyone who wants to read good stuff about OTL design theory, and if you can find it, the archives of the ASOG would also be a good source, esp the Tweaks section.
My topology for a DC coupled OTL differs substantially from both the Futterman's and Circlotron's and it seems plenty viable to me, having given trouble free day-to-day use for seventeen years now. However, it wouldn't be wise for me to go into much detail about its specifics since I don't have the requisite intellectual property protection.
There you go. I guess we will have to imagine your circuit. I certainly did not mean to imply that there are no viable alternatives to the Futterman and circlotron. Do you plan to market amplifiers using your novel topology?While we are at it, can anyone exposit on the Joule and Graaf circuit topologies? I really know very little about either of those two. I have been guessing that Joule uses a mu-follower to drive a circlotron, but it's just a guess.
You are basically correct about the Joule OTL's topology. The details in the exceution of the design are of course a more complex and what makes the Joule amps what they are. Having had a tutorial by Jud Barber on the design of his amps, while not rocket science, I certainly understand that he preferes to keep certain implimentation/excecution details of his OTLs to himself.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
Ah, sweet mystery of life....I really don't think that a general verbal description of the circuit would compromise the market for Joule, but it certainly is his (Jud Barber's) decision to make.
Maybe I'm too close and familiar with the Joule OTL's, but I would think that just looking at the tube compliment and knowing its single eneded input, circletron amp would tell a fair amount about the basic circuit, would it not????Jud is not much of a internet guy, being the old skool gentleman that he is :-) , so you will not be seeing him posting on internet forums to discuss things such as this but I have seen him talk with interested folks at shows about various design aspects of his amps.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
And his affection for the mu-follower is not a secret either. I wonder whether the amps use NFB at the output and if so how it is implemented.
There is variable feedback at the output... [ knob on top of the amp - upper right corner of the picture shown in this post :-) ]. Feedback is local I believe.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
And I suppose the power transformer(s) are toroidal; the flat disc shape would be hide-able inside that massive chassis, under the circuitry.
Yes, multiple transformers per monoblock... at least (big) one is torridial... plus there is the variac, then I think one other smaller transfromer (which I can't recall if its torridial or not) plus another little transformer for the digital meter power supply.Compared to what you find in most (tranformer output) tube amplifiers, the power supply design is a good deal more complex! :-)
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
I suppose I ought to make a try at marketing this OTL topology, but I somehow have never got around to it - too many competing projects and things to do, I suppose, and I've been more of a lab rat being an all purpose circuit board and system level analog & digital designer & programmer by day.Graaf had come out with at least one 'DC coupled' OTL, but from the schematic I saw it would have a very high DC potential at its output, requiring a return at the same elevated potential or a DC blocking output capacitor the latter of which would disqualify it from really being fully 'dc coupled' in my book.
The OTL guys are busy listening to music,while the SET guys are busy futzing with their amps...:-)OTL amps are a very,very small minority compared to all the OPT amps...
GOOD ONE Don. ?!?Goofy question?!? - GREAT response!Me for one (perhaps SO many others).
I spend SO MUCH more time (enjoying) listening to music . . .
NOT fiddling with gear and bumbling with endless tweeks.
(like chips on CD players) LOL! I put mine in a bowl . . .
NOT (much) post to forums either - too much music to play!
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