UL for EL84. 22-24% is better than the dogma....40% is lowest distortion....

[smoking-amp]

"looked to me like he connected the UL tap to the catode and cross referenced the PP plates
ahead of his time ?"

Hey,that's my Elliptron design! Extremely advanced. What was the title and source of that article?

Maybe: "Amplifiers and Superlatives" by D.T.N. Williamson and P.J. Walker (Wireless World)? I don't see Elliptron in that article, just ordinary CFB.
There is also JAES April 1954 Vol2, No2 by Williamson and Walker, I don't have a copy of it unfortunately.

 

[tinitus]

getting closer
http://www.next-tube.com/articles/williamson/Williamson.pdf

appears that Williamson and Walker designed the Quad amps together

 

[tinitus]

and the original
http://www.mif.pg.gda.pl/homepages/jasiu/eka/wil/AandS.pdf

cant find that genuine paper with original Williamson
but it was definately very similar to Quad schematic
and their answer to ultra linear
not sure what its called
super linear
trafo coupled catode feedback
or ?

 

[smoking-amp]

I don't see anything about "cross coupled" in the "Amplifiers and Superlatives" article. Is that where you meant? I just see CFB coupled, like for the Quad ampl.

 

[tinitus]

Hey,that's my Elliptron design! Extremely advanced. What was the title and source of that article?

I found it on google, somewhere
that is yours ?
hey, thats fun, I hope

yeah, I know its not the original drawing from Williamson and Walker
couldn't find it again
but it was similar to yours
and very close to Quad schematic

hey, your Elliptron looks interesting, using UL tap to drive the catode in crossreferenced circlotron style
bloddy hell, was it really 2003

 

[gingertube]

EL84 (6BQ5) are great in Ultralinear, better than triode or pentode mode with respect to THD and IM - See this for comparisons.
http://www.retrovox.com.au/STC6BQ5.pdf

Some "light" reding for those with UL Interest.
A definitive Ultralinear study by F. (Fritz) Langford-Smith and A.R. Chesterman (Yes - that is F. Langford-Smith of Radiotron Designers Handbook fame.) Investigates tapping percentages for the 6V6 in particular.
http://greygum.net/files/radiotronics/UL.pdf

By the way, Greygum (2nd link) has quite a few articles from Radiotronics. Radiotronics was the "industry" magazine from the AWV tube factory in Sydney, Australia where F. Langford-Smith worked.
Go here for the list of articles.
AWV Radiotronics - Miscellanea

As for the other Ozzie link that appeared earlier in the thread - well my mum always said "If you don't have anything good to say.... then don't say anything at all" - enough said.

Cheers,
Ian

 

[tinitus]

I don't see anything about "cross coupled" in the "Amplifiers and Superlatives" article. Is that where you meant?

no, but that's what I saw in a schematic looking very old

 

[smoking-amp]

"but that's what I saw in a schematic looking very old "

Could be, a fairly obvious scheme, just never seen it before. Sure would like to see that schematic and what they had to say.

 

[tinitus]

Could be, a fairly obvious scheme, just never seen it before. Sure would like to see that schematic and what they had to say.

hey, I'm sure I saved it, somewhere
but I have so many links its become hard to find anything

but it was a really complicated scheme
you know how messy those older schematics look

gave up on google
will look further, to see if I have it saved
you know, sometimes stuff is hidden in a link to some other site
but I usually also save it as picture document, if important
too many of those too

 

[smoking-amp]

I know what you mean. I tried to find a schematic I had seen on the forum here this summer, only months before searching. Never could find it, spent a whole day trying. I even posted a new thread asking if anyone remembered it. One person did, but they couldn't remember anymore about it! Then a month ago, I ran across it in the RDH4! Was an amplifier with global feedback to the preamp tube screen grid.

There were some posts here a few years back that had a superficial resemblance to Elliptron mode. Was about a patent for a P-P OT used for SE mode. The two winding halves were used in a way to cancel the DC. It gave 3 versions, only one of which actually worked. Required an inductor though.

 

[tinitus]

Could be, a fairly obvious scheme........

might be when you think of Blumlein
invented the cross ferenced bias, mentioned previously
and didn't he also invent ultra linear
just didn't yet have the trafo UL tap
and I didn't know that Williamson's amp was 'adapted' to be used for most of the UL tapped amp
and another surprice that the Quad scheme may have been way ahead of them all
but as usual, it's also a matter of marketing
and that was obviously very strong on the side of UL tap
and lots of other good stuff was put in the shaddow

it's kind of interesting that all this seems to come alive now
UL tapped trafos are still the industrial standard
but may not last so long
for what I know, Amplimo only has the rights to the name Super-triode
I dont think they can ever have a patent on the trafos
so, if there will be a demand, others may follow
that is if there are available curcuits
like with the hen and the egg
but the Amplimo is certainly a good start

well, from what I found on other fora, many have failed with the super triode
found a debate between Le'Cleach and some others debating with Japanese enthusiasts
even the good man AllenWright was around saying that it wouldn't work
or was the other Wright
problems with increased distortion
but maybe it's easier with trafo coupling
for which I guess it was originally invented

 

[tinitus]

just found something called Ultra Para Linear

found here
http://locofonic.alphalink.com.au/valves.htm

 

[gingertube]

Parafeed + Ultra Linear - what else would you call it ???
Cheers,
Ian

 

[tinitus]

Parafeed + Ultra Linear - what else would you call it ???
Cheers,
Ian

hey, this got me thinking of UL Circlotron

funny, I always thought PPP meant paralel PP
and just now I find it means parafeed PP
leading to UL PPP
and Circlotron

I hope its still 'on topic'

 

[smoking-amp]

Since parafeed is not normally needed for P-P, I would think that PPP would usually refer to parallel P-P.

It's hard NOT to get UL with Circlotron, since just using a fixed screen voltage from ground reference gives UL, due to the cathode moving around.

 

[Yvesm]

That's why each screen is tied to the opposite anode !
And to obtain a fixed screen voltage from the two full floating PSU you just have to sum them with two resistors and a by pass cap !
You may even stabilize'em if you wish

Yves.