Building a single "Presence" control circut??

[Duke of Metal]

hey guys,
anybody have instructions on how to build a single control presence knob??  somthing kinda like you find in amps, but without the bass, mid, and treble controls.

Any info is appriciated it.


thanks,
Duke

[travissk]

Well, depends on what definition of presence you're going for . A presence control usually involves one of the following:
-A simple high-end boost past the range of the treble control. This would be an active boost and would occur after your tone stack, otherwise the passive EQ controls will kill off most of the extra high end, since the treble control is usually shelving.
-Tube amps will bleed some of the ouput back into the input, in effect producing feedback. This is mostly high-frequency signals, and will be negative feedback since the signals will be out of phase. Therefore, it will act to stabilize the input signal, rather than producing that noise you usually think of as feedback. More negative feedback reduces the amount of "presence" you have, so the presence control limits the feedback. i.e. setting it to 10 (or 12 on my Classic 50 ) will just about cut off all feedback and you'll be left with all the high frequency stuff.

Unless you're modding or building a tube amp, I'd say build some sort of treble booster and go from there, or alternatively find a parametric/graphic EQ that will let you clean boost treble frequencies and leave the rest of the curve flat.

[Lonestarjohnny]

I don't fully understand what you want but maybe I can help you til someone else can reply, first the presence knob on all amp's I've had the pleasure to know, the Bassman, Plexie, these have a presence knob that add's more treble to the circuit, and they all work off the Negitive feedback loop from your amps speaker,
Maybe what you want is an early Tweed Fender tone control, it adds bass or treble with just one knob, if that's what your lookin for just go to the Schematic Heaven and look at a tweed Champ tone circuit.
JD

[Torchy]

Go here
http://www.muzique.com/lab/tone3.htm

[Duke of Metal]

hey guys,
well.. see, my original plan was to mod my tube poweramp for a presence control. But after looking at a schematic with a tech friend of mine, we found out that it doesnt have a Negetive Feedback Loop. and Due to that, I cant install a presence control inside the amp.

So, what I am thinking of doing is build some sort of a single knob presence control and put it in a small compact MXR style box and mount it in my rack case with the other gear and use it after my preamp or just before the poweramp.

Hope that explains it better.


thanks,
Duke

[Duke of Metal]

Go here
http://www.muzique.com/lab/tone3.htm

Thanks for the link Torchy... which one of those 3 would I use??

The BMP Tone Control?
The New AMZ Tone Control?
Version 2 of the AMZ Control


thanks,
Duke

[Torchy]

I used the Version 2 AMZ Control with the Fetzer from runoffgroove ... I liked the Fetzer and the V2 so I put them together, with the V2 just before the volume pot. Probably not technically right but gave me a subtle mid-boosty kinda circuit ...