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Old 29th September 2009, 10:04 AM   #1
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Default SRPP+, or did JRB "borrow" from here?

What do say: MJK, Kenpeter and others? Seems like this has been around here for a long time.....

http://www.tubecad.com/2009/09/blog0171.htm
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Old 29th September 2009, 01:44 PM   #2
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Quote:
Originally Posted by revintage View Post
What do say: MJK, Kenpeter and others? Seems like this has been around here for a long time.....

http://www.tubecad.com/2009/09/blog0171.htm
Broskie did show a balanced, load splitting series push-pull circuit, based on tubes, in May 2000, which operates on the same principle as the "series" anti-triode. He gives the formula correctly for the offset on the center resistor tap based on the cathode resistance (~1/gm) of the slave device. Anyone who's thought about SRPP as much as JRB has, should come around to this eventually.

Current sensing master-slave push-pull is certainly not a new idea. The series anti-triode is toplogically like SRPP and the parallel, cathode sensing anti-triode is topologically like a differential LTP, with similar current loops. The plate sensing versions also have lots of prior art and some patents. One thing different about our work is that we are exploring the sonic aspects of high-gm slave devices as the "anti-triode".

What we have also done here is explore even more topology variations (for example fixed or servo-controlled DC output, developed different control and feedback strategies, and done a lot of practical work on real world implementations.

For anyone wanting to understand the current loop operation of this circuit, JRB gives a good detailed explanation with math:

http://www.tubecad.com/may2000/page12.html

Cheers,

Michael

PS after 30 years working in computer architecture, on "new" ideas, it clear to me that ideas are a dime a dozen. Outside of theoretical physics, the real challenge is in getting stuff to work.
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Old 29th September 2009, 01:59 PM   #3
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Exactly what I was after. Got a little irritated as JRBs presentration of his "innovation" was like it was something new. Only the name "SRPP+" is........
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Old 29th September 2009, 02:08 PM   #4
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Default That'll be the day

When JRB cites *us* in *his* column...
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Old 29th September 2009, 02:12 PM   #5
SY is offline SY  United States
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Hey, he cited me a couple years back...
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Old 29th September 2009, 02:15 PM   #6
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Hey, he cited me a couple years back...
And then you woke up
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Old 29th September 2009, 02:26 PM   #7
athos56 is offline athos56  United States
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And then you woke up
He replied to an email I sent him once .
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Old 29th September 2009, 03:03 PM   #8
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I agree with Michael, the driving idea behind "anti-triode" was preservation of the triode signature. This pointed to approaches using high gm devices, gm boosters, Op Amp loops etc, to preserve the spectra. The modified SRPP or "SRPP+" (first time I have seen that, but a nice article) and modified LTP topologies were convenient ways to implement this.

I wouldn't be surprised if some lab researcher came across the same ideas long before us, maybe even published them in some obscure journal. But long forgotten in the economic practicalities of the audio market. Hawksford Error Correction, for example, was invented and patented long ago by LLewelyn for tube circuits (Hawksford noted the origin), but ever see a tube amp with EC? The current mirror and voltage mirror circuits were invented by some Japanese researcher using tubes, but lost in the noise when neg. feedback was discovered. The Aikido first stage is the classic voltage mirror. If you really want to be impressed with lost tube technology, look thru some early analog computer texts using tubes. Simply amazing what could be done.

Don
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Last edited by smoking-amp; 29th September 2009 at 03:14 PM.
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Old 29th September 2009, 03:27 PM   #9
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Sent him a Differential White Cathode Follower design for comments a few
months back. I thought a simple twin triode circuit with near perfect CMRR
and PSRR (maybe useful for DAC?) would have been right up his alley?

Never heard anything back... Not a peep.

I never mentioned anything regarding the Anti-Triode. Didn't want him to
think I'm completely nuts. Not yet anyways...

Mind you, this sim run was undertaken with HUGE amounts of power supply
and common mode noise. If it looks a little squiggly, theres good reason.
When all the crud magically cancelled out, I immediately thought "Broskie!".
Maybe I don't understand the guy, thought cancellations was his thing???

I would never have predicted him to take interest in Anti-triode SEPP.
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Last edited by kenpeter; 29th September 2009 at 03:37 PM.
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Old 29th September 2009, 04:26 PM   #10
Gordy is offline Gordy  United Kingdom
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Quote:
Originally Posted by smoking-amp View Post

Hawksford Error Correction, for example, was invented and patented long ago by LLewelyn for tube circuits (Hawksford noted the origin),

Don
Does anyone have a copy or know where I can access the info?



Quote:
Originally Posted by smoking-amp View Post
If you really want to be impressed with lost tube technology, look thru some early analog computer texts using tubes.

Don
Yes, I would like to. However before I go lurking in second-hand book shops are there any reference sites available on the 'net?

The info on this site is very interesting (augmented cathode followers, etc.) http://www.jrossmacdonald.com/ but there must be others?
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