fazer

Re: Advice for gain stage and Master output with tube preamp
« Reply #20 on: March 11, 2020, 10:13:03 PM »
Quote
Would moving the 1M resistor to ground (R1) before the 68k change anything? If it's ok I could mount it on the input jack t save space...



Shouldn’t hurt anything and that’s how Marshall and Fenders  are set up


sonolink

Re: Advice for gain stage and Master output with tube preamp
« Reply #21 on: March 12, 2020, 04:22:55 AM »
Just as I thought but wanted to be sure :)

Thanks!
Cheers
Sono
Why sleep when you can mix?
M.P.Stavrou

PRR

Re: Advice for gain stage and Master output with tube preamp
« Reply #22 on: March 13, 2020, 01:59:54 PM »
This is all basic audio level control. Why so many questions??

This preamp can make output over 40V peak; "must" go there to get "the tone".

You can't possibly need more than 2V-3V for any next stage (except the guts of a Fender).

So you want roughly 20:1 loss.

You mention frequency response from a too-high value pot feeding a line. So don't use the 1Meg pot, that's just wrong. Even when driving just a foot of wire a 1Meg at half-gain will roll-off the top of the audio band.

The 12AX7 stage is taken from a handbook and actually aimed for a 220k load. When you figure a lot of Fenders you see that Leo knew that and often got pretty near.

220k and 10k pot is 20:1 loss and <10K line impedance for all practical purpose.

sonolink

Re: Advice for gain stage and Master output with tube preamp
« Reply #23 on: March 13, 2020, 03:43:51 PM »
Thanks a lot for the explanation PRR ;)
Why sleep when you can mix?
M.P.Stavrou


 

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