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previous: Ken Gilbert Re: Asymetrical long-tail PI questions... -- 1/20/2000 8:20 PM	View Thread

Williamson vs Mullard

1/20/2000 10:46 PM
Mike D.	Williamson vs Mullard Ken, I agree, the Williamson design is a masterpiece. However, my personal experience building this circuit was not so good. My implementation suffered from instability both HF and LF. I changed to more of a "Mullard" style front end, actually see the Leak Stereo 20 at http://home.mira.net/~kiewavly/Leak/Circuits/Stereo20.gif Anyway, this was much more stable and also sounded better for some reason. Williamson's design is fussy about the output transformer and I was using a scavenged tube PA amp transformer. Also, I believe my layout was not so good with the Williamson, whereas the Leak circuit is remarkably similar to the standard Fender/Marshall/Vox and the layout was a breeze, due to familiarity! To sum up, do not try building a Williamson out of junkbox parts with a half-assed layout! I think the Mullard designs were so very popular with hobbyists because they were more forgiving, even though the THD figure of a proper Williamson is superior. Regarding the concertina splitter (split-load, cathodyne, whatever). My Dynaco and Eico power amps use a concertina directly driving the output tubes and I think both amps sound fantastic. It is interesting that the most highly regarded hi-fi designs of all time use different phase splitters. Williamson - Concertina (Dynaco also) Quad - paraphase Mullard - long-tail Regards, Mike D

1/20/2000 10:46 PM

Mike D.

Williamson vs Mullard

Ken,
I agree, the Williamson design is a masterpiece.

However, my personal experience building this circuit was not so good. My implementation suffered from instability both HF and LF. I changed to more of a "Mullard" style front end, actually see the Leak Stereo 20 at http://home.mira.net/~kiewavly/Leak/Circuits/Stereo20.gif

Anyway, this was much more stable and also sounded better for some reason. Williamson's design is fussy about the output transformer and I was using a scavenged tube PA amp transformer. Also, I believe my layout was not so good with the Williamson, whereas the Leak circuit is remarkably similar to the standard Fender/Marshall/Vox and the layout was a breeze, due to familiarity!
To sum up, do not try building a Williamson out of junkbox parts with a half-assed layout! I think the Mullard designs were so very popular with hobbyists because they were more forgiving, even though the THD figure of a proper Williamson is superior.

Regarding the concertina splitter (split-load, cathodyne, whatever). My Dynaco and Eico power amps use a concertina directly driving the output tubes and I think both amps sound fantastic.

It is interesting that the most highly regarded hi-fi designs of all time use different phase splitters.

Williamson - Concertina (Dynaco also)
Quad - paraphase
Mullard - long-tail

Regards,
Mike D

Replies:

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