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previous: Kent Thanks Bruce,On the wierd o... -- 3/11/2002 3:48 PM View Thread

Re: Harp Mods

3/11/2002 4:38 PM
Bruce /Mission Amps
Re: Harp Mods
Hmm... I can't see how a 12DW7 would unbalance anything.  
The tube is like a 12AX7 and a 12AU7 in the same envelope.  
In the 5E3, the phase inverter is just a single triode, wired as a cathodyne driver (zero gain) so any triode in that spot would still do the same thing, albeit with different amounts of attenuation but it would still should be balanced.  
The AC mismatching of the power tubes does a mildly interesting tone thing though and it can be done with using different grid load values on the 6V6s.  
With all things, a singular mod is never the magic or silver bullet!!  
I read that G. Weber thing a few months ago and it is a bit confusing, in terms of what the pot does, other then upset the AC balance of the PI.  
You don't have to rebuild the PI of the 5E3, just  
strap another 180K to 220k reistor over one of the 220K grid load resistors and you'll get a slight mismatch of the AC signal going into the power tubes.  
IMHO, the darker grind comes from lowering the voltages to the preamp tubes and some of the harp tone comes from using less gain in the front end and subseqently turning the volume up louder.  

Kent Oops, sorry for my poor interpretat... -- 3/12/2002 1:41 AM
Steve A. Bruce:3/12/2002 7:08 PM