Increasing plate voltage on power section

[greiswig]

On my 2-tube build, I settled on KT-88s as my preferred tube. They just pack a lot more oomph than a pair of 6L6s.

The plate voltage on them is only about 430V, though. From what I understand, KT-88s prefer to be run higher, at around 500V or a bit more. If I were going to bump that up, would it be as simple as getting a higher voltage PT and adjusting the dropping string to keep the preamp tubes where they are? Do I have to make corresponding changes to the bias voltage section as well? Also, what is the 'right' target voltage to try to run these at? And am I right in thinking they'd be happier at the higher voltage?

Thanks and Happy Holidays!

[ToneMerc]

Greiswig, I have spec'd out a Twin style PT just for such a project. A #40, silver chassis KT88 project. My thoughts are if one is to use these tubes, run them at least 480-500V. So I settled on target voltage of 485v-sub 500V range and about a 90v rectified bias supply.

HT tap- 365/370V
Bias tap - 65V

100K grid bias resistors

TM

[greiswig]

Thanks, TM. Why did you settle on the low end of the voltage range...485 instead of 500? And were you able to find a stock transformer that was suitable? I guess I need one in a Twin-style package for the D'Lite chassis, though, so I probably would have to get a custom wind anyway.

[ToneMerc]

No reason other than it's the low end that I wanted to start with.

Here's the 500V one that I spec'd on the BN D'lite PT (022723) frame. It's the greatest amount of wire/current capability (HT & Fil) that Alden said they could make work on that frame. This should get you 500V.


Primary: 120 Volts
Secondary: 375 - 0 - 65 - 375 Volts @ 300mA
6.3 Volts @ 650mA
6.3 Volts CT @ 7 Amps (3.15V-0-3.15V)
TM