PAB smoothing mod

[tubenit]

Occasionally, I have had a PAB (preamp boost) not sound quite as smooth as I'd want.  On this recent Tweed BluezMeister & active FX build, the PAB tone was significantly different then when the tone stack was fully engaged. It seemed to add some high end hash that I didn't care for.

So, I tried adding a cap to smooth out the highs.  I tried numerous values from 120p to 390p. I had a ceramic 250p that sounded really good and a 300p silver mica that I liked also. 120p didn't do much.  390p sounded OK but perhaps lowered the harmonics somewhat.

Note that this cap is only engaged when the PAB is engaged.

Using the 300p (or 250p),  the tone ratio between treble, mid & bass using the PAB was somewhat more similar to having the tone stack engaged. (it's somewhat brighter but very subtle)  I like that.  What it does then is allow a boost in volume and overdrive without too much of a tonal change.  Sustain and harmonics and blooming remain intact just fine to my ears using the 300p.

The preamp boost has a smoother tone now.  

With respect, Tubenit

[Geezer]

Hmm, never would have thought of putting a cap in that position! The PAB does dramatically alter the tone in a way I never liked, so this is a great addition for better, more tweakable performance.

THANKS T!

G