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Old 30th June 2007, 06:55 PM   #1
Jeb-D. is offline Jeb-D.  United States
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Default Does such a tube exist?

Looking for an octal dual triode with High Mu but with a higher Gm than a 6SL7/6SU7. Pretty much an octal equivalent to 12AT7 would be ideal.

Does such a tube exist
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Old 30th June 2007, 08:12 PM   #2
gianis is offline gianis  Greece
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I think that does not exist...try parallel 6SL7..
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Old 30th June 2007, 08:39 PM   #3
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Quote:
Does such a tube exist
AFAIK, no.

What are you trying to accomplish, Jeb? If you have an existing chassis with an Octal socket, buy a "hole shrinker" from Bottlehead and put a 'T7 in. If you are looking to do something Octal only, you are SOL. High gm/low Rp triodes are (AFAIK) a post WW2 phenomenon found only in 7 and 9 pin mini "bottles".
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Old 30th June 2007, 09:55 PM   #4
Jeb-D. is offline Jeb-D.  United States
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Quote:
I think that does not exist...try parallel 6SL7..
That would have worked unfortuneatly the amp is already build and I'm just trying to improve it without total redesign. I was shooting for a minimalist design and it turned out a little too minimalist if you get my drift. The following stage loads it down a little too much to get the gain I was looking for out of half a 6SL7 per channel.

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What are you trying to accomplish, Jeb? If you have an existing chassis with an Octal socket
Yes, existing chassis.

Quote:
buy a "hole shrinker"
I'm using a similar adapter now and it does the job. But it would look better with an octal and no adapter.

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High gm/low Rp triodes are (AFAIK) a post WW2 phenomenon found only in 7 and 9 pin mini "bottles".
That's some good tube history.


I found a tube 2C52 that has a higher Mu and higher Gm than a 6SL7. It's not ideal, but it may work well. Was unable to find a data sheet for it though. Anyone know where I can find one?
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Old 30th June 2007, 09:58 PM   #5
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Jeb-D,

You may look at the ECC32 (mu=57, gm=3500 umho) or the ECC33 (mu=68, gm=7700 umho). They appear to be still obtainable according to advertisers on the internet. Be aware of the fact that these figures are quite operating point (Ia) dependant; these are according to my scource at fairly high current.

Edit: I do not know whether the pin connections are the same as the 6SL7, should that be of consequence.
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Old 30th June 2007, 10:14 PM   #6
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by Jeb-D.


That would have worked unfortuneatly the amp is already build and I'm just trying to improve it without total redesign. I was shooting for a minimalist design and it turned out a little too minimalist if you get my drift. The following stage loads it down a little too much to get the gain I was looking for out of half a 6SL7 per channel.



Yes, existing chassis.



I'm using a similar adapter now and it does the job. But it would look better with an octal and no adapter.



That's some good tube history.


I found a tube 2C52 that has a higher Mu and higher Gm than a 6SL7. It's not ideal, but it may work well. Was unable to find a data sheet for it though. Anyone know where I can find one?
mebbe this , I didn't check :

http://tdsl.duncanamps.com/pdf/vm345.pdf
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Old 30th June 2007, 11:40 PM   #7
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Maybe this is helpful. Some data on the 2C52.

http://wps.com/archives/tube-datashe...-56-40M/12.JPG
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Old 1st July 2007, 12:48 AM   #8
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According to my information, ECC32 has mu of 32 and Gm of 2300 umho. ECC33 is not much different, with mu of 35 and Gm of 3600 umho. Their pinout is the same as 6SL7 but they may not be suitable for what you want, because mu is only ~ 1/2 of 12AT7's mu. Linearity is another thing to watch out for with the ECC33, which was designed as a computer tube!
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Old 1st July 2007, 02:02 AM   #9
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Dear me!

Where did my datasheet get their information? I never actually used them as far as I can recall. The original Leak TL12 did use the ECC32 I think, but all was a little long ago.

Thanks Ray, this needs checking then, in which case I also cannot recall a different solution. As was said, when the demand for v.h.f. tubes (higher gm) came, the miniatures were already going; that format then became the natural choice.

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Old 1st July 2007, 02:06 AM   #10
Jeb-D. is offline Jeb-D.  United States
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Thanks for the input guys. I think the 2C52 will probably be worth a try. While the links you guys found had some helpful data, It seems like there are no curves for this tube anywhere on the net. Guess I'll have to buy one and tweak with it.
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