VVR For cathode biased amps under 50 watts

[hackworth1]

Lower red wire = B+ in from rectifier. Upper red wire = B+ out to first filter cap.







Braided wires go to 1 Megaohm Potentiometer. Drill a 3/8 inch hole above your power cord hole on a 5E3 chassis. Center of this hole Should be about 7/8 of inch from the lip on the chassis.

yellow goes to wiper (center lug on pot).

[guitjopicka]

Are you selling these Hack?

[hackworth1]

I made this one for a guy who wanted one with his 5E3 kit. I can make you one, too. PM for details.

[andyfromdenver]

Thank you for posting this!!!!

[charisjapan]

Originally Posted by hackworth1

Lower red wire = B+ in from rectifier. Upper red wire = B+ out to first filter cap. Braided wires go to 1 Megaohm Potentiometer. Drill a 3/8 inch hole above your power cord hole on a 5E3 chassis. Center of this hole Should be about 7/8 of inch from the lip on the chassis. Yellow goes to wiper (center lug on pot).

Where do the Green and Orange connect?

I distance to the 1M ohm pot critical? I was thinking that it would be hard to reach (and potentially hot!) up in there, and maybe a bracket to the back opening would be nice.

Does this need an on/off switch, or is it off when the pot is at "0" or "10" position?

I like the idea of a VVR for about a 50% cut to be nice to neighbors, but want to have those 10-12W available now and again.

[hackworth1]

Green to the the ground tab on your pot and orange to the hot side on your pot. Instructions are included. You must drill two holes in your chassis to mount it. Drilling template is included. Both the MOSFET and the terminal strip ground tab need be tight to the chassis. Fits easily in a 5E3 chassis in the space between the PT and the board.

It's not a long run from the pot to the unit. There is no switch. The pot controls the voltage. Full on is full on.

These work well - up to - about half a sweep on the pot.

You can't get any good sound out of them beyond that. Sounds like a child's electronic guitar toy when cranked down very low.

When building your 5E3, you can use the available ground lug tab on the VVR as a PT side Chassis ground.

[hackworth1]

Drill a hole in terminal strip for the MOSFET Center lug (Drain) to pass thru.


Use heat sink as a security measure to prevent damage to MOSFET.


Attaching resistor to ground here permits ease of access for the machine screw and nut on the other side. Leaves ground lug open for other use.