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previous: Paul C Hey Randy - are you going for the f... -- 8/22/1999 3:57 AM View Thread

Re: AC30 with 2 el84's?

8/22/1999 7:21 AM
Steve A.
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Re: AC30 with 2 el84's?
Paul:  
 
 
 
    Yes, the Hoffman kit is just the basic preamp and power amp without the reverb and tremelo (which makes it a good project for a DIY amp). I'm glad you brought up that point about the cathode bias resistor: you would replace the single 50R resistor for all 4 tubes with a single 100R resistor for just two- right? And if you wanted to be able to select between 2 and 4 tubes you could wire up each pair to a 100R resistor, and then switch off the cathodes to one of the pairs for a 2 tube output section. As for the cathode resistor bypass capacitor I have an annotated AC-30 schematic that indicates that a 250uF cap was used in the 60's (not the 25uF value indicated on many of the drawings). So you'd probably want to use something like 100uF bypassing the 100R cathode resistor of each pair- right?  
 
 
 
Thanks!  
 
 
 
Steve Ahola

 
Replies:
Carlo I settled on a 130 ohm cathode resi... -- 8/23/1999 5:20 AM