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previous: Major Pain Hey MoB,The rating for the fila... -- 11/19/2003 3:13 AM View Thread

Re: Filament rating

11/19/2003 3:15 PM
Man o'BluesRe: Filament rating
Your heater winding rated @5A is overrated for your amp, which draws 2.7A heater current (2x6L6 + 3x12AX7 = 0.9Ax2 + 0.3Ax3=2.7A). I have found that when using Hammond trannies with 115V primaries AND overrated filament windings, the heaters can easily get overvoltaged. For kicks, try subbing in EL34's which draw 1.5A each and you should see the voltage drop to within the +/-10% margin.  
 
Also, I have found that the back-to-back parallel diode trick works, but it can inject noise into the circuit. The resistors are IMO, a better solution. BTW, you only need the resistors on one leg of the secondaries, I believe. Or just stay with the EL34's ;)

 
Replies:
Major Pain Thanks for the great info fellas. <... -- 11/19/2003 5:22 PM