Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Woodsmoke on January 27, 2016, 12:27:18 pm
-
Hey Doug/Whomever,
I have one of your turret boards and layout instructions for this amp (non-trem version) and have a question- I've omitted the 5U4G tube in favor of a couple diodes (each on the 325 reds, then running to the standby switch). Do I need to connect the yellow 5V rectifier leads from the PT to this circuit or can I seal and tie them off (leaving them out of everything)?
Bonus question, what value resistor should I put in series with the diodes to create the same voltage drop (or thereabouts) as the missing rectifier tube?
Thank you!
-
5U4 drops 45-50 volts.
A resistor does not really do quite the same thing as the internal voltage drop of a 5U4, but I would start my calcs as follows:
Typical amp current figure 60 ma. (.06 amps)
45 volts / .06 = 750 ohms.
Power: I*I*R = .06 * .06 * 750 = 2.7 watts
That R can and will get hot, I'd get a 10 watt.
Yes, you can tape up the 5V windings.
-
Awesome. This is everything I needed to know. Thank you.