Choosing plate voltage

[SamiBami]

I'm newbie to tube circuits and interested in building tube distortion/overdrive
based on 12AX7 (due to the high amplification factor)
it is easier to choose low voltage (9,12,18v filament will get 6.3/12.6v)

what are the criteria for plate voltage that I should consider?

Thanx,
Sami

 

[DF96]

To a first approximation, the lower the voltage the more distortion you will get.

 

[SamiBami]

The lower voltage the more distortion, is that due to clipping of lower voltage?
But also the higher voltage the more amplification

 

[DF96]

Both clipping and non-linearity. The 12AX7 is very linear when driven into a high impedance load with adequate anode voltage.

Two options: study the data sheet, or try it and see.

 

[SamiBami]

What plate voltage would you suggest for this application?

 

[DF96]

Sorry, I design for low distortion so I haven't a clue. I'm sure someone will be able to help.

 

[mario13]

it depends on the circuit. I built a similar OD with a 12ax7 in cascode. My plate voltage was about 125v. It was a litle clean for my liking so i addaed some clipping doides as well. Experiment with low voltages first and see how it sounds.
Best of luck!
Mario.

 

[mastodon]

Try running the first half of the ax7 on a high plate voltage (150V or more) for lots of gain, then couple the signal into the second half which you run at a low voltage (50V or less) to drive it deep into distortion.

 

[SamiBami]

Thanx guys for your answers 🙂
if any body has something to add..

 

[Merlinb]

You may like to look at one of the many DIY valve overdrive pedals:
The Real McTube Article: How It Works

http://www.diystompboxes.com/pedals/schems/shakatube.gif

Beavis Audio Research