V1 on JTM45

Info for maintaining and tweaking your amp to perfection.

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stoo

V1 on JTM45

Post by stoo » Fri Jan 27, 2006 9:15 am

As I understand it the 2 cathodes on V1 share a 860 ohm resistor and a 330uf cap. If you only wanted this sound on one input would you use the same values or halve them, double them or what? I'm thinking of doing the 1.5K/0.68if thing on the other.
thanx all
stew

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Flames1950
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Post by Flames1950 » Fri Jan 27, 2006 3:54 pm

Although Marshall used an 820ohm on the normal side when they split the cathodes, this sounds kinda too gainy and flubby to me. You'd get closer to the original amount of gain using a 1.5K on the normal side with the 250-330uF cap.
The bright side can use a 1.5K/.68uF or the standard Marshall 2.7K/.68uF combination. Or the early split cathode value of 820ohm/.68uF is cool too, the cap emphasizes the highs enough to keep from being too flubby while still not having the bright slicing sound of the 2.7K.
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