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Old 18th February 2011, 08:26 PM   #21
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Quote:
just what Hammond is similar to TO-300?
If you mean the anode impedance, 5k to 6,6k is fine and gives some 35 W with 450 V supply voltage. (UL-version)
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Old 18th February 2011, 11:19 PM   #22
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Simulation of post #15 based upon 100W Edcor CXPP 5K.
Though I have cheated slightly, fudgin' UL taps at 50%.

20WRMS clean sinewave before it ventures out of AB1.
28W AB2 in short bursts, but you eventually build up a
blocking distortion. 350V was perhaps too conservative?
450V could certainly raise those power figures.

Last edited by kenpeter; 18th February 2011 at 11:25 PM.
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Old 19th February 2011, 03:41 AM   #23
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http://www.diyaudio.com/forums/attac...-pwilsoup1.gif

Q1 is our direct coupled phase splitter (no Voltage gain of its own, but
a big gain in drive current) with freebie constant current source across
VBE to load the plate of V1b.

V1b enhances Q1 with all the functionality of a long tail pair of Triodes.
Both -Mu/2 and +Mu/2 Voltage gains of astonishingly equal impedance.
V1b input is cap coupled, as the LTP would have been. +Mu/2 actually
Schade, just scaled to match Mu. Same things if completely different.

One transistor has replaced 2 triodes, a coupling cap, and quite a few
supporting resistors... And this driving stage can abuse a much higher
mu Triode than LTP without plate resistance becoming a limiting factor.
So, open loop gain might be slightly higher than usual for a Williamson.

Note the phases of the PNP splitter outputs are reversed of "normal".
Pretty much had to be P so Schade would be the correct phase for
splitting w. impedances equal. If modding an existing amp, gotta swap
lines at OPT or somewhere else before closing the big loop.

Difference from Williamson? Concertina comes after a virtual LTP of Mu
and Schade. Rather than before a real LTP of Mu and Mu.

Last edited by kenpeter; 19th February 2011 at 04:09 AM.
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Old 19th February 2011, 04:16 AM   #24
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Based upon simulation, plate of V1b sees that 180 ohm freebie current source as a resistance slope of 290K.
Temped to try something similar for V1a, but keepin' parts count low is nice too.

Last edited by kenpeter; 19th February 2011 at 04:21 AM.
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Old 20th February 2011, 08:30 PM   #25
Helmuth is offline Helmuth  Netherlands
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I try to see what is exactly the idea of williamson.

As far I understand it is the overall feedback and a big bandwidth output transformer.

So what is there that I do not see. Or can some one sum the design key features.

Regards,Helmuth
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Old 20th February 2011, 09:02 PM   #26
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Three stages of open loop gain, and equal impedances driving each output pentode.

Concertina by itself is low component count way to split,
but cathode impedance drives with different damping than plate impedance.

Long tail pair fed from one side only, would also not be a perfectly even split.
Teaming up concertina with the long tail pair was the genius of the Williamson.

Last edited by kenpeter; 20th February 2011 at 09:06 PM.
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Old 20th February 2011, 09:11 PM   #27
Helmuth is offline Helmuth  Netherlands
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Quote:
Originally Posted by kenpeter View Post
Three stages of open loop gain, and equal impedances driving each output pentode.

Concertina by itself is low component count way to split,
but cathode impedance drives with different damping than plate impedance.

Long tail pair fed from one side only, would also not be a perfectly even split.
Teaming up concertina with the long tail pair was the genius of the Williamson.
Hi Kenpeter,

I have problems understanding the words youre using I am Dutch.

What do you mean by long tail pair. And teaming up concertina?
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Old 20th February 2011, 09:14 PM   #28
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Quote:
Originally Posted by kenpeter View Post
Three stages of open loop gain, and equal impedances driving each output pentode.

Concertina by itself is low component count way to split,
but cathode impedance drives with different damping than plate impedance.

Long tail pair fed from one side only, would also not be a perfectly even split.
Teaming up concertina with the long tail pair was the genius of the Williamson.

...at the time. You would do it differently these days, probably with sand as your earlier posts show and with far lower parts count.
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Old 20th February 2011, 09:17 PM   #29
Helmuth is offline Helmuth  Netherlands
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Quote:
Originally Posted by kenpeter View Post
Three stages of open loop gain, and equal impedances driving each output pentode.

Concertina by itself is low component count way to split,
but cathode impedance drives with different damping than plate impedance.

Long tail pair fed from one side only, would also not be a perfectly even split.
Teaming up concertina with the long tail pair was the genius of the Williamson.
Hi Kenpeter,

I have problems understanding the words youre using I am Dutch.

What do you mean by long tail pair. And teaming up concertina?
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Old 20th February 2011, 09:18 PM   #30
SY is offline SY  United States
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A Williamson is, at its essence, a grounded cathode voltage amp direct coupled to a cathodyne (split load). The split load drives a differential voltage amp, which then drives the output stage. Leave any of these stages out and it's not a Williamson.
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