what is the idea behind the presence knob

Re: what is the idea behind the presence knob

Depends on which amp you are talking about. On some amps the presence control is just a higher than the treble additional treble control in the preamp section.

The conventional power amp presence control reduces the amount of high frequency feedback through the power amp. This increases the gain and distortion characteristics of the power amp at higher frequencies.
 
Re: what is the idea behind the presence knob

There are gurus here that can better express the function, but the prescence knob controls a wider spectrum of treble tones than a typical treble control.

To me, the presence control does not affect the tone as a treble control would. It seems to replicate the difference in tone that one would experience walking around the room while listening to the tone of the speaker, from front-and-center as well as off-center angles.

The presence control can be a powerful control. It is the most powerful knob on my model T, besides the volumes. I find it easier to get into an amp with a presence control. The presnce control also seems to make a larger variety of speaker/cab combos work with an amp. Just like any other knob on the amp, the amp might need to be cranked up a bit for the presence control to "come to life".
 
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Re: what is the idea behind the presence knob

The presence control is actually connected to the negative feedback circuit of the amp. When you turn up the presence, what actually happens is the treble frequencies are not "Damped" by the negative feedback circuit and the treble sounds brighter. Lew
 
Re: what is the idea behind the presence knob

what lew said. In a general sound kinda way I think of "presence" as a wide boost centered around 2k. Try this on a stereo with a graphic. See how the overall clarity/crispness of the whole thing changes...
 
Re: what is the idea behind the presence knob

yup. i prefer amps without em
 
Re: what is the idea behind the presence knob

I see the presence control as the high frequency "equivalent" of the subwoofer.

When the frequencies aren't there, you notice. But you can't pinpoint the exact freqs.

(grossly oversimplified explanation)
 
Re: what is the idea behind the presence knob

yes i have noticed that when im playing at low volumes it makes the tone sound a bit hifi but when the amp is cranked it makes the tone stand out more, such as in a band situation. The amp is a jcm2000, i have heard they do better on older marshalls, any opinions?
 
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