Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Dive on May 03, 2014, 10:17:45 pm
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I'm brushing the dust off a long sitting amp build. I built a plexi 50 with EL34's a few years ago, love the amp. Wanted to experiment with KT88's, in as I recall a plexi 50 board but may need to make a few mods to boost the power up to a pair of 88's. Would like a little cleaner range before overdrive begins. But that may be more in the preamp?? So, what resistors and choke and such and capacitor value's for the power supply would be good here? Then what other components on the board may need changed in value, from the plexi 50 design to go to this? I am having to try to recall what I knew about this project back then and get it back on the workbench. :icon_biggrin:
Thanks
Dive.
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The '88s will drop right in with minimal bias change and make essentially the same power as the '34s, perhaps a bit more abrupt when they top-out.
The "higher" power *possible* with KT88 is probably not going to turn disappointment to joy. It also means new PT and OT and significant cost and weight.
Finding the higher power in '88 probably starts with the data-sheet and a collection of known-good commercial plans.
A perhaps better plan is to double-up the EL34s with "100W" PT and OT.