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Old 10th March 2004, 12:44 PM   #1
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Default quad 6bm8 per channel

Hello everyone,

I am playing with the idea of building a cross coupled input stage and phase splitter using the four triodes, and utilize the four pentodes in each channel for quad push pull. Please tell me what do you think about it and if you can refer me to a design you know about that uses this concept I will be very grateful.


Thanks

Glass_painter.
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Old 11th March 2004, 09:31 PM   #2
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Hi there...it looks you are after a good AC balanced front end and phase inversion....so you put on piles of feedback....as DC coupling is used throughout the stages, tube drift has to be linearised to avoid wild operating conditions........and there lies a problem.......this theory is difficult to satisfy in practice.......I believe QUAD (uk) got pretty close..........I ain't got any details.

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Old 11th March 2004, 09:39 PM   #3
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Hi,

hey rich,

Quote:
I believe QUAD (uk) got pretty close..........I ain't got any details.
Quad? As in the Quad II using EF86s and a PP of KT66s?

That amp wasn't DC coupled but that's not what Glass-painter wants to do anyway.

I think he want to use 4 ECL82s in PP of which the triode sections will serve as input and splitter/drivers.


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Old 11th March 2004, 10:12 PM   #4
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Hey Frank.....good to hear......yes your'e right....the prev comment/config rang a bell..but I couldn't quite put my finger on it...

Our chap is after ECL82's ? they are going fast in the trade........I'm having difficulty getting hold of them in EU....I find the triode section (med mu) is excellent in virtually any building block. A good tube to start off with as a screen is fitted between P/T sections. Not with the 83...



rich
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Old 11th March 2004, 10:29 PM   #5
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Hi,

Quote:
Our chap is after ECL82's ?
I think he has a stock of them already, mostly PCLs or UCLs, not sure which.

Retail in Western-Europe the ECL82 is fetching Euro 14+ already...
Five to ten years ago nobody even dreamt about using that one.

I'm pretty sure there are still tons of them around though....It's just that it's a little too popular at the moment.

I was thinking of using it as a series reg but at those prices it's just not worth it, too many other good alternatives are available.

You OTOH, may have to stock up fast as you're using it professionally, aren't you?

BTW, I haven't really checked but is the triode section close to 1/2 of a ECC85?

Cheers,
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Old 12th March 2004, 04:03 PM   #6
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Hi there....I remember these tubes were used en masse in late 1950's HiFi autochangers and TV time bases. Millions must have been made..........
I'll have to research suppliers as the UK is fast drying up.....unless someone mutters from continents....
As for ECC85 triode subs.........umm...I want to avoid heart transpl surgury.

I have some CV9167QDA...bomb proof equiv's.....used conservatively my last lot just got through 15 years at 15mA a piece; at 35-40hrs /wk running. Can't grumble......but for what to use for new HP designs ??? ....is everyones dilemma. I'm not an ECC82/83 fan; although their future appears more guaranteed than any others.....the future in conservatively running tubes holds more promises ......


rich
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Old 12th March 2004, 10:18 PM   #7
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Default Quad 6bm8 push pull

Hello everyone,

The ECL8x family of tubes has been my favorite for years and I have started collecting them back in the days when Buggle boys ware costing 2 -3 bucks a piece.

What I am thinking of building is a cross coupled input stage and phase splitter similar to STAX topology in their tube headphones amps capacitor coupled to an output stage with the four pentodes. What do you think would be the performance of this setup???

By the way you can use the ECL85 or the 6F5P for pre amp power supply they are still very cheap.

Again, any comments and/or schematics will be very welcom.

Thanks.

Glass_painter
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Old 12th March 2004, 10:37 PM   #8
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I have several UCL82 valves if anyone is interested, Im open to offers?--I think its only the heater volts thats different, so for a new-build this isnt so important.

Drop me an Email!
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