I just grabbed a Plexi based amp with the plates running at 485v. I would like to run it with 6V6's to hit it's sweet spot earlier. How can this be accomplished.
I have, in the past, done component value swaps in amps but I AM NOT a builder or expert. Please try to speak in layman's terms if possible!
Thanks,
Ron Damato
Best method for dropping B= voltage to use 6V6's
Moderators: pompeiisneaks, Colossal
Re: Best method for dropping B= voltage to use 6V6's
Use a different power transformer.
Use a tube rectifier or a tube rectifier that increases the voltage less. If you're using a SS rectifier, then it increases the VAC X1.4 (300VAC becomes 420 VDC - sort of). A GZ34 is 1.3, a 5V4 is 1.2 and a 5Y3GT is 1.1.
OR use the zener diode method to lower B+ ...... (do a search)
OR use a VVR to dial down the voltage to the power tubes and LTPI tubes.
With respect, 10thtx
Use a tube rectifier or a tube rectifier that increases the voltage less. If you're using a SS rectifier, then it increases the VAC X1.4 (300VAC becomes 420 VDC - sort of). A GZ34 is 1.3, a 5V4 is 1.2 and a 5Y3GT is 1.1.
OR use the zener diode method to lower B+ ...... (do a search)
OR use a VVR to dial down the voltage to the power tubes and LTPI tubes.
With respect, 10thtx
Re: Best method for dropping B= voltage to use 6V6's
Ron,
Since you are not an experienced builder or tech, let me start by saying that you will probably need a tech to do this work for you.
There are several alternatives, and I am sure that the others here will offer more choices. But the first thing that comes to my mind is a VVR. A VVR (variable voltage regulator) is normally used to lower the voltage going to the tubes of an amp for the purpose of lower ing the volume without losing the character of the cranked tone. You could use a VVR here in one of two ways.
1. Leave the larger tubes in the amp, and use the VVR to reduce the output of the amp to where you want it to be. If you chose this approach, I'd recommend connecting the VVR so that it reduces voltage to all tubes in the amp (preamp and power amp tubes).
2. SWitch to 6V6's, and use a customized VVR to reduce the voltages to where you need them to be (350V perhaps) at it's maximum setting. Lower settings would still offer lower output as well. If you chose this approach, I'd recommend connecting the VVR so that it reduces voltage to only the power tubes.
I like #1 because it will most easily allow you to achieve breakup at lower output levels, while still allowing you to crank it up full tilt when you want to.
Other choices include using different values of dropping resistors in the power supply, using zener diodes, changing your power transformer, etc.
As I mentioned, none of these mods is for an inexperienced tech, so find a good amp tech nearby, and get his thoughts as well.
Good luck.
Steve
Since you are not an experienced builder or tech, let me start by saying that you will probably need a tech to do this work for you.
There are several alternatives, and I am sure that the others here will offer more choices. But the first thing that comes to my mind is a VVR. A VVR (variable voltage regulator) is normally used to lower the voltage going to the tubes of an amp for the purpose of lower ing the volume without losing the character of the cranked tone. You could use a VVR here in one of two ways.
1. Leave the larger tubes in the amp, and use the VVR to reduce the output of the amp to where you want it to be. If you chose this approach, I'd recommend connecting the VVR so that it reduces voltage to all tubes in the amp (preamp and power amp tubes).
2. SWitch to 6V6's, and use a customized VVR to reduce the voltages to where you need them to be (350V perhaps) at it's maximum setting. Lower settings would still offer lower output as well. If you chose this approach, I'd recommend connecting the VVR so that it reduces voltage to only the power tubes.
I like #1 because it will most easily allow you to achieve breakup at lower output levels, while still allowing you to crank it up full tilt when you want to.
Other choices include using different values of dropping resistors in the power supply, using zener diodes, changing your power transformer, etc.
As I mentioned, none of these mods is for an inexperienced tech, so find a good amp tech nearby, and get his thoughts as well.
Good luck.
Steve