I'm building a 5E3 Deluxe and am using the Mercury PT with the unloaded outputs of 380-380. I'm wondering what is the best method of dropping the B+ voltage down to about 350 or 330 for experimentation. I would like to even possibly wire in a switch to go from standard B+ to a lower one.
-=Karl=-
What is the best way to lower B+ voltage?
-
chris_d
- Solder Soldier
The best way is a PT that puts the right voltage out.
The easiest way might be rectifier tube swapping. Depending on what sort of rectifier you are using, and what kind of filament current the 5v tap can support, swapping in other rectifier tubes can yield lower voltages. However if you are already running say a 5Y3GT, you can pretty much only go up, not down. In addition, different rectifier tubes will have fairly different effects on the amp's response and sag.
30 to 50 volts is an awful lot to drop using the other techniques such as Zener diodes or resistors or mosfets and heatsinks, etc, so i probably wouldn't try that route myself. Rather i would aim to acquire a PT that put out close to the output i sought instead.
That is just my .02 though.
-chris
The easiest way might be rectifier tube swapping. Depending on what sort of rectifier you are using, and what kind of filament current the 5v tap can support, swapping in other rectifier tubes can yield lower voltages. However if you are already running say a 5Y3GT, you can pretty much only go up, not down. In addition, different rectifier tubes will have fairly different effects on the amp's response and sag.
30 to 50 volts is an awful lot to drop using the other techniques such as Zener diodes or resistors or mosfets and heatsinks, etc, so i probably wouldn't try that route myself. Rather i would aim to acquire a PT that put out close to the output i sought instead.
That is just my .02 though.
-chris
Hello,
you might also try a choke input power supply
http://www.tpub.com/neets/book7/27f.htm
http://www.aikenamps.com/Chokes.html
But it will alter the characteristic of the power supply.
In german we call it a "harder power supply", the voltage does not drop that fast when the current rises because of the choke.
So you will lose SAG, especially in a push-pull amp, furthermore if it's not running in class A (i don't know that concerning the 5E3).
So the best way to have a 5E3 clone that sounds like a 5E3 will be a suitable power transformer.
regards
Mathias
you might also try a choke input power supply
http://www.tpub.com/neets/book7/27f.htm
http://www.aikenamps.com/Chokes.html
But it will alter the characteristic of the power supply.
In german we call it a "harder power supply", the voltage does not drop that fast when the current rises because of the choke.
So you will lose SAG, especially in a push-pull amp, furthermore if it's not running in class A (i don't know that concerning the 5E3).
So the best way to have a 5E3 clone that sounds like a 5E3 will be a suitable power transformer.
regards
Mathias
I ran a string of 5W Zeners (12V from memory) between the PT CT and ground (band to ground) in my 5E3 for about 12 months without any problems. Worked very well and you can tune to get exactly the voltage you want. Zeners never seemed to get too hot.KHELSTROM wrote:I'm building a 5E3 Deluxe and am using the Mercury PT with the unloaded outputs of 380-380. I'm wondering what is the best method of dropping the B+ voltage down to about 350 or 330 for experimentation. I would like to even possibly wire in a switch to go from standard B+ to a lower one. -=Karl=-
I now have a VVR circuit which allows me to fully adjust the B+ right down to low levels for playing at home. See SEWATT or PPWATT for details.