|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
82.35.157.35
In Reply to: Re: Is there a good set of plans for a good tube OTL amp posted by Dr. Philosophy on January 22, 2005 at 14:02:19:
Hi,> Thorsten, have you heard a Bruce Rozenblit OTL?
I heard a DIY one from his designs. It used EL509's.
> I would surprised if they did not sound different
> from other OTLs.I would be surprised if they did. They are a rather traditional implementation of an SEPP OTL output Stage with large amounts of overall feedback and many stages. The "novel" part is the way BR attemps to impbalance the drive signal to the output valves in order to compensate the different gain between the common cathode and common anode part of the output stage. An extensive discussion of the merits (or lack thereoff) of his solution can be found in the Tubecad Journal. Ignoring the different approaches to the Drive Signal Imbalance, the average Croft OTL and one designed by BR have more in common than they differ.
However, I reapeat, if you like what you got, good on you. Enjoy.
> He's also got a true single-ended one now.
That one I have not heard, if I find myself with too much time I'll probably build something similar (the basic design goes back to a 1950's Japanese design BTW).
Follow Ups:
Hi Thorsten,A few years ago you helped me by email with some issues in an SE 300 B amp using your C3M driver circuit. I have been interested for some time in the idea of an SET OTL, and am interested the Transcendent Sound produced one. Never heard it though. If you do get around to experimenting with such a circuit, I for one would be very interested in learning about it.
I built one of the first, if not the first, pair of M60 kits that Atma-Sphere sold quite a few years ago. (It used 12AT7's and 12AU7's in the driver circuit.) I modified them quite a bit with Ralph Karsten's help. Later I traded them for another component. While I personally like SET's better, I do think--from a subjective experience viewpoint--that each has their advantages. The OTL's can have amazing speed and transparency. The Atma-Spheres did sound good when I briefly tried them with some warm-sounding Tannoy Stirlings I used to have.
So I think an SET OTL with at least about 5 watts per channel is a very intriguing idea.
I just can't imagine how one would get the output impedance of an SET OTL amplifier down into the range where it could drive any real world (8-ohm) speaker, using a realistic number of any real world triodes of which I am aware. For 500-ohm headphones, maybe. (Obviously, since Transcendent has apparently done it, it can be done, but I want to see the schematic. If it requires tons of NFB, it's a Pyrrhic victory.)
I suppose you know that according to BR, the author of the Tubecad article completely misunderstood his circuit. btw, I don't go for the 'If you like it, then good on you' school (and I doubt you really do either!). That is is just a way of avoiding disagreements. It is not true that if a person thinks something sounds good, then it it really does sound good to them!.
Hi,> I suppose you know that according to BR, the author of
> the Tubecad article completely misunderstood his circuit.I suppose you know that the Tubecad Article author analysed the circuit according to how it ACTUALLY works. IF BR's understanding as to how it works differs, well that BR's problem. I cited the article simply because it saved me repeating the main points.
I would prefer to not get into exhaustive discussions of any of BR's Circuits. He has been off base so many times (including Discussions I had directly with him) and is way too constantly puffing himself up on him being an EE (That don't impress me much - so, BR got an EE degree, well so do I, but I don't keep banging on about it and tub-thumping about it all the time) for me to take him overly serious.
> btw, I don't go for the 'If you like it, then good on you'
> school (and I doubt you really do either!).Actually, I do. With the implied limitation that just it sounds good to you it by no means has to sound good to anyone else. Personal truth is just that and unarguable. However personal truth is rarely universal.
> It is not true that if a person thinks something
> sounds good, then it it really does sound good to them!.Why not? If I feel I enjoy a good Redwine because it tastes good and I don't enjoy good White Wines as they don't taste good, who is to argue that in reality I'm imagining redwine tastes good and in reality white wine is what tastes good TO ME?
This post is made possible by the generous support of people like you and our sponsors: