Other than John Broskie's TubeCAD blog, I can find no reference on the so-called Blumlein Garter circuit, where did the term come from? Did Blumlein actually invent it? Any clue or feedback will be appreciated.
I'm not surprised, because it was probably a term made up by Broskie... 🙂Never heard of it. Link?
What is the point of cross-coupled positive feedback in a bias circuit? You get slightly better pair matching, but slightly worse bias stability. Is that a good tradeoff?
Would you know where it was first used?Quick google suggests it's not a Blumlein design, but the Garter circuit is well known.
It works extremely well at keeping currents balanced. I would say its good enough to eliminate the gap in a PP transformer which can significantly improve performance overall.
Shoog
Shoog
Would you know where it was first used?
No but some tube lover called Merlin (I assume Mr Blencowe) did state he had done some research into it's history. Hopefully he will pop up.
I think Merlin mentioned that he was pretty sure it was not invented by Blumlein, but I don't know if he found where the circuit was first used...
Would you know how to get copies of the UK patents by Blumlein? He had hundreds of patents, it could be buried in one of those filings... who knows?!
http://www.diyaudio.com/forums/tubes-valves/211732-broskie-auto-bias-2.html#post3009470
Hey, let's not drag poor Blumlein's name through it. I don't know how Broskie accidentally attached Blumlein's name to the circuit, but the garter circuit was created by Jean-Victor Martens in patent FR64203E, not by Blumlein!
http://www.diyaudio.com/forums/tubes-valves/172810-ecc99-6c19n-pp-6s19p-10.html#post2534571
Oh, please stop calling it the Blumlein garter, Blumlein never used it! It was patented by Martens in 1949 (FR64203), and transformer coupled versions even earlier (US2204578). But Blumlein had nothing to do with it!
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