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Old 24th July 2012, 04:57 PM   #141
DougL is offline DougL  United States
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Looking at the Schematic, the output stage appears to be a classic White Cathode follower.
I looked it up in "Valve Amplifiers" Third Addition by Morgan Jones. Page 113,114.

Basically, the output stage has no gain. It also requires that the input signals are inverted and equal phase applied to the grids.

Like the M2, Voltage gain is from the transformer.
The real trick is the bias. Can't wait to see how Nelson did it.
Like the Futterman amp, they require (some)feedback to lower the output Z.

I love it.

Thanks Nelson.
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Old 24th July 2012, 05:09 PM   #142
labjr is offline labjr  United States
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Quote:
Originally Posted by Zen Mod View Post
it's extremely hard to find 4x600R xformers anywhere .......

Cinemag has one but not sure it will fit this application.
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Old 24th July 2012, 05:20 PM   #143
Zen Mod is offline Zen Mod  Serbia
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to quote Mighty ZM :

Quote:
Originally Posted by Zen Mod View Post
.........

Papa is often having redish eyes ........

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Old 24th July 2012, 05:33 PM   #144
flg is offline flg  United States
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Quote:
Originally Posted by generg View Post
Thanks flg! It is a pleasure to follow the discussion, unfortunately beyond my horizon.....
Not necessarily. It is somewhat beyond our imagination also. We'll probably figure it out. Maybe after a few beers? I would think if the shematic has errors, N.P. would have realized it by now. That basically means, there is something non-semetrical here in order for it to be whatever he said, like a circlotron?
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Old 24th July 2012, 05:34 PM   #145
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Quote:
Originally Posted by Nelson Pass View Post
One of the charms about the transformer vs JLH/PLH phase splitter - go to
http://imageshack.us/photo/my-images/153/plhp.jpg/
is that it delivers pure symmetry in the same way a circlotron does - each like
polarity part is subjected to the same conditions, although in opposite
phase.

It is possible to do this with a phase splitter ala JLH/PLH, but if you look
carefully
you will see that the bottom output device is run Common-Source
mode
and the top device is Common-Drain. It is a rare circuit that will
deliver real symmetry under these conditions.

At first glance I would agree with that, but after read this papers from the follow URLs I am a bit confused and I'm not sure anymore.
The Tube CAD Journal: symmetrical solid-state output stages
Tube CAD Journal: No Gain Output Stages
Tube CAD Jounal: No Gain Output Stages
Tube CAD Jounal: OTL Gain Output Stages
Tube CAD Jounal: OTL Gain Output Stages

Last edited by tiefbassuebertr; 24th July 2012 at 05:39 PM.
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Old 24th July 2012, 05:35 PM   #146
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Old 24th July 2012, 06:44 PM   #147
lhquam is offline lhquam  United States
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Quote:
Originally Posted by Zen Mod View Post
lalala

possible variations

all with different amount of Zen

some having Mu , some uM , some MuuM



edit : added original Pa's (with title ) sch , redrawn slightly , for easier comprehension
I understand how the first (leftmost) circuit would work, and was assuming that Nelson's F6 schematic (rightmost) had an error in the position of the phase dot in the bottom secondary. Did Nelson REALLY intend that the phases be the same into the output MOSFET gates? Not according to this post F6 Amplifier. I suspect an error in the original schematic.
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Old 24th July 2012, 06:53 PM   #148
flg is offline flg  United States
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Yes, I agree. A few posts later I responded with F6 Amplifier but I don't believe I got a reply.
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Old 24th July 2012, 06:57 PM   #149
lhquam is offline lhquam  United States
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Quote:
Originally Posted by Zen Mod View Post
lalala

possible variations

all with different amount of Zen

some having Mu , some uM , some MuuM



edit : added original Pa's (with title ) sch , redrawn slightly , for easier comprehension
I understand how the first (leftmost) circuit would work, and was assuming that Nelson's F6 schematic (rightmost) had an error in the position of the phase dot in the bottom secondary. Did Nelson REALLY intend that the phases be the same into the output MOSFET gates? Not according to this post F6 Amplifier. I suspect an error in the original schematic.
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Old 24th July 2012, 07:42 PM   #150
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Could it be that he is more clever than us?
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