BEST VOLTAGE FOR D-LATOR TUBE

[sergio]

What are the voltage values most appropriate for a D-lator?

CF plate voltage about 300V and recovery plate voltage about 180V ?

Thanks Sergio

[heisthl]

I've read that before and followed it - but these days I have the plates at around 310/280 (shared supply node) and never looked back. Here's an example of a built in loop (the 3 10k resistors are optional but make it "smoother").

[sergio]

Thanks Heisthl ,

Sergio

[briane]

I think recall the accepted standard is to feed the dlator 320-340 volts. sounds best at about 335 IMO.

[Structo]

Isn't that a bit high for a 12AX7?

[Bob-I]

Isn't that a bit high for a 12AX7?

That's the B+ so the actual anode voltage will be somewhat lower. In any case they seem to be ok at this voltage.

[markusw]

Accidentally, I ran a 12ax7 in a reverb driver (Gary's single tube reverb) at 420V plate voltage for a while until I changed the dropping string. Maybe a couple of 100 h in total. I didn't burn.

[dogears]

Real Dlators can have in the 255V range on the pin 1 of the cathode driver section. Around 28-31V on pin 3 if using the 27K/1.8K combo.

The recovery amp has 230-235V on pin 6.

This is the ballpark for the real ones.

The B+ is indeed in the 335V range.

[Smitty]

I've read that before and followed it - but these days I have the plates at around 310/280 (shared supply node) and never looked back. Here's an example of a built in loop (the 3 10k resistors are optional but make it "smoother").

I noticed you have a 100K plate load resistor on your cathode follower. What does that do?

[dogears]

That is not a plate load but a dropping resistor to decouple the cathode from the plate resistor of the recovery amp. If it were me, I would add a cap there. Cheap and easy.....

I've read that before and followed it - but these days I have the plates at around 310/280 (shared supply node) and never looked back. Here's an example of a built in loop (the 3 10k resistors are optional but make it "smoother").

I noticed you have a 100K plate load resistor on your cathode follower. What does that do?

[Smitty]

Without a decoupling cap it's definitely loading the stage. As the stage draws current there will be a voltage drop at the plate. Sort of an unbalanced split load. Wonder how it sounds compared to decoupled? My guess is it's a little more compressed. I'll have to remember to try it...