Fender Super Reverb Presence Control

[admin]

Greg: I have never full appreciated the function of the presence control in the Fender Super Reverb. My ear tells me it is acting like a mid control. Can you enlighten me?

[soundmasterg]

Hi Peter,

I'm not sure what you're asking because the stock Fender Super Reverb doesn't have a Presence control.

Most amps that have a Presence control are sampling some of the output going to the speakers, and then redirecting it to the phase inverter as negative feedback. A pot and/or a cap is placed in this line to send more or less of it into the amp. There are usually two resistors in the NFB loop, but you can also introduce a cap closer in parallel with the resistor closest to the speaker and this will roll off the highs more than if it is not there. This setup would normally be used in an amp intended for bass. Using NFB in an amp evens out and widens the frequency response, yet too much can make an amp sound cold and lifeless. The Vox AC30, and many Fender Tweed amps do not have any NFB. Most Fender Blackface and Silverface amps, most Marshalls, Hiwatts, etc., have NFB, and quite a few of those use a Presence control too. The Fender Bassman 5F6A does have a NFB loop and a Presence control for example. The frequency ranges that these controls work at can be modified by the resistor, cap, and pot choices used in the NFB circuit.

Greg

[paologregorio]

Egads, I hate that control! I think it should be abolished. It's a complete mystery to me, other than I know if it's up all the way, the amps a bit too bright, and maybe distorts sooner than it otherwise would, while if I turn it all the way off, the amp sounds a bit too muddy, if that's the appropriately descriptive term.

My Brown Face Fender Twin has a presence control...I never use that amp, except in photo shoots. I've had the amp gone through twice, and ensured that it's been equipped with all spec correct components (caps, etc), and I'm still not happy with it. If it weren't encased in blonde tolex, and an antique vintage amp, I would have tossed the thing years ago! Nope, it's not for sale... it looks cool, and I'm able to get exactly one cool sound out of it, which comes in handy once in a blue moon.

I think Greg's explained the control's function as simply as it can be, because I've asked a few amp techs the same question as you Peter, and that's as short an answer as I've ever been able to get. It's pretty much the same exact answer I've heard. It's an illuminating explanation, but if I ever try to repeat it to anyone, I end up reducing it to gibberish in translation. Thanks for the patient explanation as to the control's function Greg.

Is your amp one of those modern type Super reverb amps that's not a reissue Peter? Or perhaps a pre-CBS Brown Face "Super" amp?

[scott_s]

Ah, the Presence control -- when I built my 5E7, I had to double-check my wiring because as far as my ears could tell, it wasn't doing a damn thing. Okay, maybe I can hear a tiny tiny bit more hiss when it's turned all the way up, but that's it. Is it supposed to have a really noticeable effect??

- Scott

[soundmasterg]

It can be setup to be quite noticeable, but usually its more of a subtle effect....kind of icing on the cake in a way.

Greg

[rick_ovic]

Lol! I didn't think my '66 Super Reverb had a presence control.

I started reading this thread and thought how I must have overlooked this feature on my amp.

Now I've checked and it doesn't have one. Life is back to normal again.