Russian 7199s

[EWBrown]

If you decide to stick with the original 7199 driver board design (some folks will do sone strange things Yellow_Light_Colorz_PDT_05 ), and use the Russian made 7199s, try changing the 7199's screen resistor to 820k-910K, whis will make the tube fat and happy and sound a lot better.

THis may also apply to the SCA-35, though this hasn't yet been field-tested, so YMMV, etc...

/ed B in NH

[dcriner]

Ed, there are quite a few inexpensive JAN Phillips 7199s floating around - I'm using those (count me strange :o ). Do those tubes need the resistor change?

[EWBrown]

I'd leave the resistor values as original for the JAN / Philips tubes. There's something about the construction of the Russian 7199 pentode section that's just a little different, probably the internal grid spacing.

/ed B in NH

[Brinkman]

I powered up my recently-assembled ST70 for the first time. One of my Sovtek 7199s is rather noisy. Had I known Sovtek's inability to make reliable 7199s, I would have paid triple for NOS. Goes to show: do your homework before you play.

Best,
Benjamin

[guitarpsych]

If you decide to stick with the original 7199 driver board design (some folks will do sone strange things Yellow_Light_Colorz_PDT_05 ), and use the Russian made 7199s, try changing the 7199's screen resistor to 820k-910K, whis will make the tube fat and happy and sound a lot better.

THis may also apply to the SCA-35, though this hasn't yet been field-tested, so YMMV, etc...

/ed B in NH

What should the watt rating be on these? Which are the screen resistors on the board? (sorry, beginner).

[mesherm]

The screen resistor is the 1.5 meg one. A 1/4 to 1/2 watt resistor will be OK.