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Old 24th Feb 2014, 5:58 pm   #1113
mole42uk
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Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by crackle View Post
With regard to EL34 valves and matching a set of 4 for use in say a 100 watt guitar amp, is it best to match the anode current or the GM value when pairing them up.
I match sets using both Ia and gm - in other words, for a given grid bias, both anode current and the gm number match. A 'set' of four matched valves will have the same Ia and gm on each one.

I have tested some matched sets from Groove Tubes and AFAIK they do the same.

Richard
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