Star Grounding for a Line Stage Tube Preamp

[Uunderhill]

Correction Cin ~ 20pF

 

[DF96]

Here is the shunt volume control I decided to go with.

You will get a little thermal noise from the 24k, which is why people don't often use shunt volume controls. Max volume is still some attenuation but that won't matter too much if you already have too much signal. The source will see a varying load so this may mean the LF cutoff will vary with control position - another reason why people don't use shunt controls.

There was quite an audible difference when switching the shielded side of this cap around.

Unlikely, unless there was something wrong. What you should get is a minor difference, or no audible difference at all.