Oops I don't mean three o'clock I mean 9 o'clock, Its three o'clock when I lean over and look at it upside down!!!

I've got my trimmer mounted externally on the rear panel and whenever I'm tweaking it I'm leaning over from in front of the amp, looking at it upside down!.

Well I figured out tonight that the presence control is doing absolutely nothing on my amp! Need to get it on the bench at the weekend and get to the bottom of this problem.

I have read every post on this forum especially the mods that Jack Zucker, ic-racer, mondoslug and others have been recommending and I especially recall, I think it was JZ saying that these tame the sharp ice-pick treble on the OD channel. Well I've not been experiencing  that much treble and where others have given details of their settings, Treble has been around 3-4 where I've had mine 7-8 and I still thought it lacked a bit of sparkle especially the high mids. I thought it was my speaker cabs, then I swapped pre-amp valves and started fiddling and found the non-operational presence control. I guess thats why I'm finding it lacking that bit of sparkle.

We'll see what it does for the tone when I nail the problem!! I just hope its something obvious like a wrong value component(which means theres another one wrong somewhere else aswell !!) or a missed connection.

Schematic...

i find that the presence control doesnt do all that much untill it gets to about 9ish. I also have my treble between 3 and 9 depending on my mood and i find the amp doesnt have lots of brightness. Mostly becuase of the characteristics of the bass. Having said that, there is a lot of super high highs at times. But then again, i am using V30s and not the standard 65 most people tend to use.