AMZ Mosfet Boost, Presence Tweaks????

[bigstomper]

Just built the Jack Orman mosfet booster because I was looking for a fairly neutral pure clean boost.  I love the presency shimmer this boost gives....HOWEVER...with my Teles and some of my "chimer" sounding amps it is almost too much. I do use my guitars tone knob to fix it...but it would be nice to be able to tweak it on the pedal. Is there a good spot in the circuit to tweak the presence? Or would a guitar type tone control tacked on at the end be a good solution? Any help would be appreciated. Thanks!

[Caferacernoc]

"Or would a guitar type tone control tacked on at the end be a good solution?"

Yes. That will work fine.

[bigstomper]

Thinking about using a .047 cap....but not sure what value pot would be best?  How would you figure that out?

[Caferacernoc]

Messing around with this:

http://www.muzique.com/schem/filter.htm

Says 5k or 10k would give a decent range.

[bigstomper]

Most appreciated.  Question....so the frequency that is generated using a .047 cap and a 5k pot would be about 667 hz.  Is this a measurement of how dark the control can get?  I've use the RC calc for determining rolloff freq in such apps like a TS feeback loop....but am a little fuzzy on how it works in a tone (cut) control application.  Thanks....hopefully I didn't sound confusing.

[Caferacernoc]

Right, that would be the cutoff at the most extreme setting. And as you back it off the the cutoff would go up. Once it gets to 4000hz or so it would have little effect.

[shredgd]

Just built the Jack Orman mosfet booster because I was looking for a fairly neutral pure clean boost.  I love the presency shimmer this boost gives....HOWEVER...with my Teles and some of my "chimer" sounding amps it is almost too much.

That's exactly the reason why I built an EH LPB booster, which I'm now extremely happy with, and has replaced the mosfet booster in my pedalboard!

[PaulC]

Another way you could do it is to add an inductor/gyrator in series with the source cap.  This would limit the gain in the high freqs. 

If you get a little slick with the inductor/cap values you could have a switch or pot making the unit act like a flat booster/treble booster/mid booster etc...  and there wouldn't be anything added to the output of the circuit.

Later, PaulC

[nelson]

Why not just change the input impedence to say, 1M?