Presence Control And Amp Response/Feel

Stratoblaster

Fractal Fanatic
Spent the evening going over my 9.02 presets tweaking only the Presence Control. It's has such an affect on how an amp plays, aside from its brightening affect. It's a very important control to really dial in properly IME. On most amps, too much will be thin/crispy and play kind of weird. Set to "0" the amp is really lifeless, stiff, and not responsive...it feels...bla.

So there is a sweet spot zone where the amp comes to life, fattens up, with just enough sizzle and will feel amazing. To fine tune the high end I use the AMP block GEQ (passive 5 band).

I made adjustments to my presets using only the Presence Control which made them feel and sound just that much better. In general, I only need to use the range from about 1.5 -> 4; depends on the amp, etc.

I should note I adjusted all of this with a CLR that was fairly cranked (gig/jam level); the small adjustments with the Presence Control won't be as apparent or as 'dramatic' with headphones/low volumes.

Anyway, was an interesting and revealing evening concentrating on only the Presence Control....was worth it...:speakerthree:
 
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Presence is typically a high pass filter on the negative feedback loop of the power section. More presence means more highs from the feedback loop are diverted to ground and those frequencies are dampened less giving a brighter, more open sound.

Depth also works much like presence, but in the opposite direction with a low pass filter. It gives more low end response by diverting low frequencies from the feedback loop to ground.

You can also achieve some of the same effect on the feel by adjusting the overall amount of Negative Feedback in the amp's advanced parameters. More negative feedback gives a stiffer, cleaner, more dampened response (more headroom - think Blackface). Less negative feedback is more open, looser, and will break up a bit sooner (less headroom - think Tweed).
 
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Presence is typically a high pass filter on the negative feedback loop of the power section.

I've often thought of the Presence control as a 'frequency dependent gain control' for the highs since it doesn't work in the same way as conventional tone controls do. As you say, it affects the negative feedback loop which, when you make adjustments to that circuit, affects the response and feel in a major way.

You can also achieve some of the same effect on the feel by adjusting the overall amount of Negative Feedback in the amp's advanced parameters.

When AFX owners start to look into fiddling with the Advanced Parameters I've suggested first starting simply with the Negative Feedback setting; tweaks to that will very much change the character and feel of an amp big time, especially since the function of the NF loop affects the entire amp dramatically. I've always played with that parameter a lot....
 
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