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previous: Randy Jamz Oooh, I hope you isn't figgerin' on... -- 10/7/2000 1:56 AM

Re: zener diode part #

10/7/2000 3:21 AM
nuke	Re: zener diode part # The Zener diode is not a "Weber" mod. It's been around a long time, long before Weber heard of it. I've known about it for years and years. It works really well when called for. I call it the "big ass zener diode" mod. A resistor is a bad choice for a number of reasons. The biggest of which is that it increases impedance of the power supply. That makes it impossible for the for the amp to supply stable voltages when it comes under load. Too much sag. Sounds like ass. The zener on the other hand drops the voltages by a stable, predictable amount without incurring increased power supply impedance. Result is reduced power supply voltages with good regulation. The best place I've used this mod is in the later silverface twin reverbs which often show up with well over 500v on the plates. Dropping the B+ a bit is well called for in these amps, resulting in improved tone, longer tube life and retention of the clean, punchy, sparkly tone a Twin amp should have. Depending on the design of the power supply, the bias supply will probably need adjustment of values as the zener will reduce the available bias voltage if the bias is ground through the center tap. (most Fenders are). Drilling a single-hole to mount a stud-mount zener in an unseen place is not exactly hack-butchery.

10/7/2000 3:21 AM

nuke

Re: zener diode part #

The Zener diode is not a "Weber" mod.

It's been around a long time, long before Weber heard of it. I've known about it for years and years. It works really well when called for.

I call it the "big ass zener diode" mod.

A resistor is a bad choice for a number of reasons. The biggest of which is that it increases impedance of the power supply. That makes it impossible for the for the amp to supply stable voltages when it comes under load. Too much sag.

Sounds like ass.

The zener on the other hand drops the voltages by a stable, predictable amount without incurring increased power supply impedance. Result is reduced power supply voltages with good regulation.

The best place I've used this mod is in the later silverface twin reverbs which often show up with well over 500v on the plates. Dropping the B+ a bit is well called for in these amps, resulting in improved tone, longer tube life and retention of the clean, punchy, sparkly tone a Twin amp should have.

Depending on the design of the power supply, the bias supply will probably need adjustment of values as the zener will reduce the available bias voltage if the bias is ground through the center tap. (most Fenders are).

Drilling a single-hole to mount a stud-mount zener in an unseen place is not exactly hack-butchery.

Replies:

Steve A. Nuke: &n... -- 10/7/2000 3:48 AM
Randy Jamz Hmmm..... Let me go back to my 'Exp... -- 10/8/2000 4:00 PM