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previous: bd Best hammond PT for push/pull EL84 ... -- 8/10/2004 2:07 AM View Thread

Re: Best hammond PT for push/pull EL84 amp

8/10/2004 5:38 PM
SheaRe: Best hammond PT for push/pull EL84 amp
272FX, if you're using an EZ81 rectifier.  
 
The heater voltage might run a little high. If it gets up to 7 volts, then use a 6.3v pilot lamp that burns the most current of any you can find. I think 250ma is about as high as they go.  
 
If you're not going to use an EZ81 rectifier, then you'll probably want a lower HT voltage. The EZ81 drops a lot of voltage, but it still comes out a bit on the high side with the 272FX. So if you're going to use a rectifier with a lower voltage drop, you'll need a lower HT voltage. In that case, look into the 270FX. The 270EX would probably work too.  
 
If you're going to use solid-state rectification or a GZ34, you might want to start out even lower, say with the 270DAX or 270DAZ.  
 
One thing I know from experience is that the 272FX / EZ81 combination works, keeping in mind what I said about the heater voltage.  
 
Or just get one of those Heyboer 18-watt Marshall power trannies from Graydon Stuckey. Then you don't really have to worry about the heater voltage, and you'll have 2 separate 6.3v windings, which apparently has some technical advantage over running the EZ81 off the same winding as the rest of the amp (although I've done that with no apparent problems).  
 
Shea

 
Replies:
bd Thanks Shea -- 8/10/2004 6:18 PM
Tonestack Re: Best hammond PT for push/pull EL84 amp -- 8/30/2004 1:26 PM