KiT34 + GZ34 + KT77

[Richard]

Hi Mark

6ca7 will need the same as el34. All KT series need similar. So you should only need provide 2 settings.

Assuming you're using 470R for el34 and 560R for KT77 then I would keep the 560Rs in place and provide a parallel 3k3 resistor path via a switch for each 560R. 560R//3k3=478R.

There will only be a small current through that path c.15mA so you could use a 4 pole rotary switch to switch all at the same time for neatness (such as RS 320-742 make before break and can be limited to 2 or 3 positions).

If you are presently using 2 different values to 470R and 560R then choose the value of the extra switched R to suit what you're using.

All this said, I doubt you will hear much difference between those settings and the change was only done to make sure the KT77s didn't over-run. I'd expect the el34s to sound similar on 470R or 560R and have run both values in my own 5-20 monoblocs.