GM70 Justification

If they glow, this is the place to be
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Paul Barker
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#61

Post by Paul Barker »

don't think the uTracer will tell us much about them.

Well cheap though.
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pre65
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#62

Post by pre65 »

Found this on the interweb-

" ground g3 and the anode and run the tubes as triodes with g2 as the anode. You'll still have a 120W dissipation element to use as the plate in that implementation. Should make a nice PP Class A triode amp. In this case it should not take too expensive an OPT to deliver a very nice amp indeed. You'll get a plate resistance( and mu ) like a 2A3's so 5k a-a will do quite well...so will 6k6 kOhm plate-to-plate.."

:lol:
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Paul Barker
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#63

Post by Paul Barker »

Not many valves with G2 120 watt.

Probably Worth the waste of heater power.

Anyway I ordered two, £72.43 delivered for a 120 watt dissipation valve with mu and rp of 2a3!

No bwainer :D

So that is my Owsten project decided.
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pre65
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#64

Post by pre65 »

Well done Paul, I look forward to the results. :)
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Paul Barker
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#65

Post by Paul Barker »

right up Thomas' street
Last edited by Paul Barker on Sat Jun 22, 2013 4:46 pm, edited 1 time in total.
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andrew Ivimey
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#66

Post by andrew Ivimey »

Ha! GU 81m. I've just ordered a pair because spec wise they look stupid. And they were very cheap.... wonder why! Some time ago someone used one of the grids as anode. There are possibilities but ultimately crazy.

I might just slip back to 2a3 for an attempt at quality.
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#67

Post by IslandPink »

Sounds like it's time for a seperate GU-81 thread ?
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Paul Barker
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#68

Post by Paul Barker »

Might have to build it into the van and run long speaker cables to the room!
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slowmotion
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#69

Post by slowmotion »

Big amp ... !
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andrew Ivimey
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#70

Post by andrew Ivimey »

Maybe not.....
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simon
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#71

Post by simon »

I'd looked at GU-81s too and wondered... I've looked at the coppers just today and also wondered, but a bit more seriously. But I've sent Rod Coleman some dosh for the filament modules. Just need some chokes now and I'm about ready.

The news that Bud's packing up in three years is serious though.
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thomas
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#72

Post by thomas »

right up Thomas' street
Looks good to me.....
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IslandPink
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#73

Post by IslandPink »

More justification -
http://www.jacmusic.com/nos/GM70/

Amusing, though to note that in his price list, Jac says only offers the graphite ones , "Copper plate is extremely rare and sold out"
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Cressy Snr
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#74

Post by Cressy Snr »

What's going on with this thread?

Since that picture was posted I can't read a word of it unless I magnify the pages and scroll across each line to read. Annoying :?
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Paul Barker
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#75

Post by Paul Barker »

I'll delete the picture. I am not hosting it so it is mahoosive. Sorry. :shock:
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