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Old 14th November 2002, 12:52 AM   #11
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Default TOO BAD

Hello,

Too bad.You would have loved the sound of these huge graphite plates!

In case you may need more data on the 6C33C:

DATA 6C33C

Ciao,
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Old 14th November 2002, 02:06 AM   #12
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Default Re: PRETTY COOL TUBE

Quote:
Originally posted by fdegrove
Click the image to open in full size.Does anyone know Rp of this tube?
At first glance you're going to need iron along the lines of the 845.
Frank,

I did a bit of extrapolating, and came up with an Rp of 1100 - 1500 ohms which tallies pretty well with the 845. Of course the final Rp is dependant upon the bias point, and may in fact be higher.

Thanks for the curves too. Best I've seen for the tube.

I've thought about getting a quad of the GM70's and buildidng a PP amp from them, along very similar lines to the SE schematic posted before (the bias supply implementation stinks though - blech). However long term supply of the tubes has me a little concerned. If they're like all the other thoriated tungsten transmitter tubes, they should last for many many years. But.......
Maybe I should just buy 8.

Oh, and that heaters a killer - 60W per tube! I thought the 813 was greedy.

WRT sockets for the GM70. Why not solder to the pins?

Cheers
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Old 14th November 2002, 02:50 AM   #13
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Default GM70

Hi Brett,

Quote:
and came up with an Rp of 1100 - 1500 ohms which tallies pretty well with the 845. Of course the final Rp is dependant upon the bias point, and may in fact be higher
Thx for the info,Rp must be in that area.

Quote:
(the bias supply implementation stinks though - blech).
Silly how people look for a dream amp and then neglect details like that.
And there are other things there I don't like.

Quote:
Maybe I should just buy 8.
Just for starters,you mean?
These would solve your 845 problem though.
(Unless you are looking yo help out someone else with those.)

Quote:
WRT sockets for the GM70. Why not solder to the pins?
You could do that.

Ciao,
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Old 14th November 2002, 06:47 AM   #14
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Quote:
Originally posted by Colt45
Maybe I'll have to quit smoking so i can afford more tubes..
What are cigarettes these days $7-8/pack. A pack a day habit is a couple hundred dollars a month -- $2500 a year. Now those are loone bucks so about $1600 USD. Buys a few tubes -- some iron too.

Sounds to me like you should quit -- your food will taste better too (or so i am told).

dave
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Old 14th November 2002, 07:51 AM   #15
dhaen is offline dhaen  Europe
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Quote:
Too bad.You would have loved the sound of these huge graphite plates!
Be aware that there are 2 kinds of GM-70;
one had the nice graphite plates that Frank mentions, the other has pressed metal.
Ask the supplier specifically, as the number is the same.

The iron need not be so expensive. IMO it's worth saving a little for.

BTW heater hum is an issue. The heaters are 20v.... that old chesnut....
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Old 20th November 2002, 12:47 PM   #16
miguel2 is offline miguel2  Portugal
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Hi

Some time ago I though of making a power amp with the 6C33C. But the prices of the iron really scared me. For single ended operation these xformers are a bit odd (under 600 ohms on primary). I was playing with a double 6SN7 driving a single 6C33C in single ended mode. Erno Boberly has a design on that too.

The main advantadge of these tubes is the use of *only* around 200V. But current is quite high. I believe the GM-70 needs much higher voltages.

For lowest prices I believe Russia is the place to go.
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Old 20th November 2002, 07:26 PM   #17
dhaen is offline dhaen  Europe
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The 6c33 also has the advantage of being indirectly heated.
Do check out the caveats regarding bias stability.

IMO The best places for samll quantity orders are:



http://tonywelch.com

and

www.kwtubes.com

Cheers,
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Old 20th November 2002, 10:33 PM   #18
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Default DEAR JOHN...

Hi,

Allow me to correct the link to Tony Welshs' site:

http://www.tonywelsh.com

Cheers,
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Old 20th November 2002, 10:59 PM   #19
dhaen is offline dhaen  Europe
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Oops!

Thanks,
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Old 20th November 2002, 11:04 PM   #20
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Default 6C33C

Hi,

Do any of you have personal experience with this particular tube?

I'm looking for info on stablity and drive requirements.

Do you know of a tube tester that can accurately test it or a bench setup to do this and burn in ?

Cheers,
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