circlotron revisted

For the three and more legged things
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Dave the bass
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#31

Post by Dave the bass »

Nick wrote:...think of it as a impedance converter instead.
Ah, just like an o/p TX then! :lol:

Re 'Transformers bad', I wonder what the original Circlotron designers were trying to achieve ("best amplifier in the world?" Dave!!) in the 1st place bearing in mind that most of the early designs used o/p TX's like you said. The Wiki page just makes mention of the fella's going after the patent and how later by //-ing o/p tubes the Circlotron evolved into OTL's.

6AS7 seems a popular choice and I read that a pair in // can easily drive high Z headphones in OTL amps...

Then I remembered thats sorta what I've got :shock: I've got an early 'Little Dot' headphone amp, it's a cheapy Chinese OTL headphone amp that runs Chinese 4P1S which are close I believe to Russian 4p1L directly heated pentodes in OTL IIRC.

Funny that.
MikeH wrote: Somewhere got an Elektor circuit, it's got a complicated driver cos it has to do the whole primary Voltage for the o/p transformer. It's got EL34's but they just work as big CF's, all the Voltage swing has got to come from the driver.
Yeah Mike, if thats from Rainer's book of Elektor ccts, yeah I saw that, It my eye too.

DTB
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Nick
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#32

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Re 'Transformers bad', I wonder what the original Circlotron designers were trying to achieve ("best amplifier in the world?" Dave!!) in the 1st place bearing in mind that most of the early designs used o/p TX's like you said. The Wiki page just makes mention of the fella's going after the patent and how later by //-ing o/p tubes the Circlotron evolved into OTL's.
I think the main advantage is it makes the transformer design simpler, doesnt need as high a ratio os it cathode coupled.
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#33

Post by Dave the bass »

Nick wrote: I think the main advantage is it makes the transformer design simpler, doesnt need as high a ratio os it cathode coupled.
Ah right, and hence cheaper? Probably. Some of that consideration has to be offset by 3 PSU's per channel I guess though.

I wonder if there are any 'lost' topology's out there waiting to be rediscovered. makes you wonder doesn't it? Well it does me :-)

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Nick
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#34

Post by Nick »

Dave the bass wrote:
Nick wrote: I wonder if there are any 'lost' topology's out there waiting to be rediscovered. makes you wonder doesn't it? Well it does me :-)
DTB
Here is one to give you a headache:

http://greygum.net/sbench/sbench101/#THE%20MATRIX

And another:

http://www.intactaudio.com/forum/viewtopic.php?t=549
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#35

Post by Dave the bass »

...of The Matrix... Mr B says "How does it sound? Absolutely marvelous. Very dynamic, clean, powerful. Clip point is almost completely inaudible. As built, this thing sounds like a pair of 845s.
-Steve"

...and the Harmonic Equaliser, I'd have to build that just 'cos it's got a cool name anyway :lol:

Meh! people have done found the 'lost wonders' before me :-)

When I'm a grown up I'm gonna be so good at all this malarky I'm gonna come up with my own super-brill sounding topology and patent it and everything and be rich and everyfink an' stuff.

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#36

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When I'm a grown up I'm gonna be so good at all this malarky I'm gonna come up with my own super-brill sounding topology and patent it and everything and be rich and everyfink an' stuff.
Why not take something old that no one has used for years, spend time marketing and hyping it until only you are the true messiah of audio and only amps touched by yourself are the true way of hearing music. Much simpler than actually inventing something new :-)
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#37

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Nick wrote:
When I'm a grown up I'm gonna be so good at all this malarky I'm gonna come up with my own super-brill sounding topology and patent it and everything and be rich and everyfink an' stuff.
Why not take something old that no one has used for years, spend time marketing and hyping it until only you are the true messiah of audio and only amps touched by yourself are the true way of hearing music. Much simpler than actually inventing something new :-)
Hmmmmm <rubs chin>.....Good lordy :idea: Of course! Hyping up audio equipment.

Thats never been done before I bet.

I'll do it! Cheers for the idea Nick, when I buy my first Yacht I'll invite you for a round the world cruise.

Now where did I leave that Dansette power amp cct?

DTB

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#38

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Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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#39

Post by Dave the bass »

...and the last missing link...?

http://cgi.ebay.co.uk/2pcs-LM3875TF-LM3 ... 2001wt_894

DTB
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#40

Post by pre65 »

Dave the bass wrote:...and the last missing link...?

http://cgi.ebay.co.uk/2pcs-LM3875TF-LM3 ... 2001wt_894

DTB
That lady e-bay seller must be a vegetarian. :wink: :lol:
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#41

Post by Mike H »

LOL ....


Dave the bass wrote:Ah, just like an o/p TX then! :lol:

Re 'Transformers bad', I wonder what the original Circlotron designers were trying to achieve ("best amplifier in the world?" Dave!!) in the 1st place bearing in mind that most of the early designs used o/p TX's like you said. The Wiki page just makes mention of the fella's going after the patent and how later by //-ing o/p tubes the Circlotron evolved into OTL's.

The way I've been given to understand it ~ and shoot me down in flames if you want nevertheless I shall press on rewardless :D

Re p-p o/p transformer, centre-tapped, a valve hanging off each end. So long as it remains working in class A, current is flowing in the entire primary winding.

Soon as it goes into class B, one half stops having any current flowing. This is BA-A-AD for several reasons like back EMF effects and one valve suddenly seeing only half the load impedance it had in class A and suchlike.

With circlotron, current is flowing in the whole primary all the time even if one valve cuts off in class B. So no nasty spikes, drastic impedance changes and like that. Image

Far as I see it current in the winding increases smoothly from zero to some maximum in one direction, and ditto in the opposite direction.


 
 
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#42

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Appendix ~ there's another issue I've just thought of / remembered. Audio transformers tend to be wound in interleaved layers, alternating primary and secondary sections. The relative number of turns per layer, and even the number of layers, can vary depending which half of the primary is being used in class B. the length of wire used can certainly different, sections on the outside of the former will be longer that those nearer the middle. Unless it's like 9 or 11 staggered sections to prevent that kind if thing which = expensive transformer, because it's an absolute pig to wind.

For a transformer for circlotron use none of that matters. You get the best of what's good about a transformer and none of the nasty bits. In theory.....


 
 
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#43

Post by ed »

I havn't fully digested this yet, but it looks interesting:

http://www.audiodesignguide.com/Hybrid2011/index.html
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#44

Post by Mike H »

Yes that is interesting, pity the pictures take so long to load




 
 
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#45

Post by pre65 »

Mike H wrote:Yes that is interesting, pity the pictures take so long to load




5 seconds ?
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