Gibson Scout Tone

[rifflicks]

Hello ....Can I replace a fixed tone control (for lack of a better term) in an old Gibson Scout with a variable Band pass filter....this Scout is way too bright (ear piercing)....I was hoping to use a trim pot....adjust it and leave it.
I've attached the section of the Scout Schematic I want to replace with a picture of the type of Band pass filter I want to use.

[HotBluePlates]

... Can I replace a fixed tone control (for lack of a better term) in an old Gibson Scout with a variable Band pass filter....this Scout is way too bright (ear piercing) ....

You could, but that bridged-T filter probably isn't what's making your amp too bright.

T-filters like that one create a mid-range dip, like what you're used to hearing in a blackface Fender amp or maybe a Marshall amp. The one in the Scout seems to be centered on about 500Hz.

There are a few components in your amp brightening the sound. C2 (0.001uF) just ahead of the T-filter shaves bass tremendously. C5, the cathode bypass cap of V2B is a 0.1uF, and also boosts that stage's gain only for highs. I'd recommend first making those two caps bigger (maybe 0.02uF for C2 and 5-25uF for C5).

Do you have a link for where you were looking at info for the bandpass filter? It looks interesting, but I suspect "bandpass" means it will be all midrange with no treble or bass and you simply move the center of that midrange hump up/down with the control. We're conditioned to hear maximally-flat amps (like some tweed models) as midrangey, while amps with deep mid notches (like blackface amps) sound more balanced and hi-fi.

[rifflicks]

 Here is the link.... http://electronicdesign.com/analog/rediscover-truly-tunable-hall-network
I was hoping to tune the low end of the filter to  around 50hz, and use a trim pot to adjust the high end of the filter to lower the ceiling of the high frequencies (chop off the ear piercing treble).

[rifflicks]

After a doing little more research, I have learned that by the time I set the high frequency end of the band high enough to hear all of the harmonics produced by a guitar I'm right back where I started with to much treble passing thru it.
  Thank You HotBluePlates..... I will try your suggestions on the caps.

[HotBluePlates]

After a doing little more research ...

...Can I replace a fixed tone control ... with a variable Band pass filter...

Thank you for the link you provided!

It turns out this circuit is a notch-filter, much like the existing bridged-T filter in your Scout. It only becomes a bandpass filter if it is sitting inside a feedback loop (which then inverts the response).

So in its native form, it is the same as what you have, but allows you to move the notch (now center on ~500Hz) higher and lower. As it happens, I have an amp right now that does this exact same thing. I based my circuit on the bridged-T, and I'll admit while the swept notch works as intended it is not a useful tone circuit for everyone. It's handier if you like the overall sound of the guitar and amp already with almost no coloration, or if you're going for some major tone changes.

That said, this circuit may be cheaper and easier to implement than the way I did mine. Mine required a dual-gang pot. I'll have to play with this one some and see if reasonable component values land on a decent-sounding circuit.

[rifflicks]

Thank You again  HotBluePlates..... I went with a .022 for C2....tried a 5uf and the went up to 8uf and stopped there...it sounds great...starts breaking up about 5 and sounds like my Tweed Princeton when it's dimed....the reverb and tremolo are icing on the cake.... Finding and replacing those caps in Gibson's rat's nest wiring was a chore.....I really appreciate the help.