Which preamp tubes do you use in your ODS?

[hendo]

Yeah ... Rawnster you are right ... It's the JAN GE 5751 ... I assumed that it was the 12AX7WA ... my mistake.

Heisthl ... interesting thought ... thanks for the insight. I have been looking for more headroom and those big cleans so perhaps going back to the standard PI with the 12AX7 is the ticket.

[heisthl]

For max clean headroom you could go with a 12AT7, 47k/51k plates, 470R RK and a pair of 330K grid resistors (the 24k RT is still fine, as is the 4k7/2k/1uF presence), but you will lose some of the charm in the tone, mostly in the way it distorts and the degree of overtone content.

No matter what style PI you choose the PI input cap value has a big effect on perceived headroom - smaller = more headroom. To a lessor degree ditto for the output grid couplers.

[hendo]

Awesome ... thanks for the info ... I will look into making a change in there. I guess there is always a balance of finding a nice clean and not loosing the charm of the distortion.

[hendo]

Here's a pic ... just for clarification that I'm getting the info right

[heisthl]

Here's a pic ... just for clarification that I'm getting the info right

Yes that looks right for max headroom with a 12AT7 also change the PI input cap to something smaller - I like .0027 (instead of the current .02)

[hendo]

Thanks for all the valuable info Heisthl