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Ampeg V4B with KT88's: screen R's 470 or 1K?

1/5/2005 12:21 AM
Ampeg V4B with KT88's: screen R's 470 or 1K?
Recently recapped an early 70's V4B and got it running again. When I bought it, it had been modded for EL34's, complete with 1K screen resistors. I'm thinking about putting 470 ohm screen R's back in. Here's the thought process: the plate voltage is about 540V which is not so rugged for KT88's; there's a 470 ohm "choke" resistor which will limit screen current quite a bit; and back in the day Ampeg had an "upgrade kit" which was a quartet of 6550's, the KT88's cousin; and Dr. KT88 has opined in the past that KT88's sound better with screen R's at or below 470.  
Any thoughts one way or the other on that? Ever run a V or VT Ampeg with 470 ohm screen R's and 6550's or KT88's, with good or bad results?  
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