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banaca 20th January 2013 08:19 PM

12FQ7 Why and will it be shortage?
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Good day,

Can you tell me why engineer are using them and I notice they are hard to find... will it be a shortage of them? Can we replace them?

kevinkr 21st January 2013 01:49 AM

Good linearity, and probably cheaper at the time the amp was designed than the 6FQ7.. Tubes with 6.3V filaments almost always cost more than equivalents with now nonstandard filament voltages, as no one in the commercial realm generally wants anything else, the QS 4 is obviously an exception.. FWIW I would look for replacement tubes while you can find them.

banaca 21st January 2013 02:09 AM

Thanks Kevinkr , can I use the 12cg7 ????

cogsncogs 21st January 2013 03:40 AM


Originally Posted by banaca (
Thanks Kevinkr , can I use the 12cg7 ????


Eli Duttman 21st January 2013 03:59 AM

THE tube that's in production to try is the 12BH7. A check as to what the OEM did with pin 9 should be made. Odds are pin 9 is unconnected and that's exactly what is needed, as the 12BH7 can be used in both "6" and "12" VAC regimes.

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