grounding a weber v dump

[mac0611]

Hi guys,

I am installing a weber v dump zener in a scratch build/4x6L6 amp with express preamp. The plate voltage (twin reverb trannies) is about 430VDC, and I want to get it down to around 390VDC+/- The issue is grounding the zener properly with respect to the first filter cap without getting a hum problem. The zener mounts to the chassis, which means the center tap won't be tied into a tight loop with the first filter cap. Can anyone give me a tip or diagram to implement this without inducing hum into the circuit? thanks!

[Structo]

When I used a Zener to drop voltage I installed it on the center tap of the HV.
Don't forget to solder a .01uF ceramic cap across the Zener to help with noise.

[rooster]

Hey, FWIW, KF used to take the Twin Reverbs with that PT and load it with 6V6s for a pretty cool sound. If I remember right the plate voltage was around 405-410VDC stock, with all the tubes running. A great combo actually. (This was a SF version amp, BTW.) Are you sure you need that Zener?

In other words, have you completed the amp and now find that you have 430 on the plates, or are you predicting it?

[mac0611]

thanks for the replies! Yeah roost, I hve anywhere from 425 to 440 depending on my line voltage. I have a 40V zener.

I'm wondering if I should tie th PS grounds together and hook them t
o the ground side of the zener?