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by **guitarpsych** » Sat Apr 21, 2007 7:22 am

Are there any other tubes that can be used instead of the 7199s in the st70 board? I found a coupld of 6AN8s and wondering what I can use them for, possibly in place of the 7199s?

by **TomMcNally** » Sat Apr 21, 2007 9:17 am

From what I understand, there aren't any pin for pin subs.
Sovtek makes a 7199 though.

by **erichayes** » Sat Apr 21, 2007 1:24 pm

Hi All,

The 7199 is, indeed, unique. That's because RCA designed it specifically for audio use and arranged the pinout so the plates and control grids were as far away or shielded from the heater pins as they could get. Not that that made it a good audio tube . . . it was just better than the triode-pentodes designed for video use that had been used until then.

If you want to hack on your board, the conversion that involves the simplest surgery is to a 6U8/6EA8/6GH8. I've done about a half dozen, and they worked satisfactorily. But you still have a pentode in the front end, and it just doesn't sound as good as a triode working into a long tail.

by **TerrySmith** » Sat Apr 21, 2007 4:20 pm

I've done that too, cut and jumpered for a 6GH8 etc types. At their prices you can roll many tubes for real cheap, and they still sound better than the Sovtek 7199.

by **Sal Brisindi** » Sat Apr 21, 2007 8:30 pm

From what I read, the Sovtek 7199 are not that good unless you replace a resistor in your Dynaco amp. The price of real 7199's are not so bad, why rube goldberg your Dynaco ST-70. Real 7199's are always on ebay.

Regards,
Sal Brisindi

by **Shannon Parks** » Mon Apr 23, 2007 6:02 am

I will also confirm that the 6GH8 cut-n-jumper hack is fairly straight forward and simple. Got lots of these!

by **Slartibartfast** » Mon Apr 23, 2007 6:06 am

Sal Brisindi wrote:From what I read, the Sovtek 7199 are not that good unless you replace a resistor in your Dynaco amp. The price of real 7199's are not so bad, why rube goldberg your Dynaco ST-70. Real 7199's are always on ebay.

Regards,
Sal Brisindi

Hello,

Which resistor is this and what value do you replaceit with?

Thanks,

Robert

by **Sal Brisindi** » Mon Apr 23, 2007 7:37 pm

I don't remember the value or which resistor as I have 4 spare U.S.A. 7199 tubes in my stock. Just do a search, the info is out there somewhere.

Sorry,
Sal

by **mesherm** » Mon Apr 23, 2007 10:19 pm

Adjusting the screen resistor in a 7199 was discussed here:

http://www.diytube.com/phpBB2/viewtopic.php?t=1305

by **Slartibartfast** » Tue Apr 24, 2007 5:02 am

mesherm wrote:Adjusting the screen resistor in a 7199 was discussed here:

http://www.diytube.com/phpBB2/viewtopic.php?t=1305

Thank you

Robert

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7199 tubes: Any possible substitutions?

7199 tubes: Any possible substitutions?

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