Using a zener to drop plate+screen voltages

[tmh]

I'm receiving a Marshall Major next week that I'm looking forward to getting up and running.

One thing I'm concerned with is the amp's historical predisposition to blowing up in a fiery fashion. Apparently the 600-650V on the plate are more than some KT88's really wanna see. One quality of the Major that's fairly rare in musical instrument amps is that it runs in ultralinear mode.

I know just enough about electronics to get crazy ideas and not enough to know whether they're good or bad. So... something I'm wondering about is the possibility of using a zener to drop the voltage down a tad. 75V maybe. Is a zener a good way to do it? Or a mammoth series resistor?

One thing I'm going to do right away, something that I haven't really found any info about folks doing, is to put a nice, quiet CPU fan in there, getting some air circulating around at least the output tubes and possibly a second fan to try and cover the output tubes and the transformers. I think that might help things a bit, at least for the tubes.

Anyway, please share any technical savvy regarding the idea of using a zener or series resistor to drop the plate voltage down a bit, to keep from blowing up the tubes. And if the fact that the amp runs in ultralinear mode changes anything, please bear that in mind.

Thanks!

Scott

[jackinnj]

Lotsa articles on that beast -- http://www.timeelect.com/hackmarshall.htm