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12ax7

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kilgore trout
Posted on Wednesday, December 18, 2002 - 04:40 pm:   

is it possible to put a 12ax7 phase inverter in one of the "transitional" HD 130's, if so how would i go about doing it?
michael kaus
Posted on Friday, December 20, 2002 - 01:46 pm:   

Speaking from experience, I DID retro fit a 12ax7 BACK into a 130 watt head that had been converted to solid state driver. IT WAS A NIGHTMARE! I had the original directions from MM to remove the tube and replace it with a SS driver so I figured I would reverse engineer it and put it back. Worked great-right up to the point where I dropped the needle nose pliars on the bias board while it was hot! 700 volts doesn't bounce around very long before it eats some stuff. Haven't had time to see what all I fried, so I don't know how bad it is. If you are interested, I could probably scan the directions sometime and you could see them for yourself. Email me if you are interested. Mike.