What a presence knob actually does

[Frogman]

So, in my experience, the presence knobs on my amps seem to add "treble", tend to add a bit of volume, and tends to "tighten" things up.

But what I'm wondering is what it actually does/how it works, and how it interfaces with the rest of the EQ circuit.

Can any of you chime in here?

 

[Edgecrusher]

Re: What a presence knob actually does

Depends on exactly what type it is. There are some that are just an extra high EQ circuit. But the presence control most people think of associated with a tube amp isnt actually part of the tone network but instead works in the negative feed back loop. Keep in mind not all tube amps are designed with a negative feed back loop in them. The amount of negative feedback is actually one of the big differences between a tweed bassman and a JTM45. What the presence control does is when signal goes into the negative feedback loop and gets sent back to the input it grounds out some of the highs (much like the tone control on a guitar) and making the overall sound brighter or darker depending on where its set.

Clear as mud?

 

[DrNewcenstein]

Re: What a presence knob actually does

Makes perfect sense to me.

But I'm crazy.

 

[PFDarkside]

Re: What a presence knob actually does

Great explanation Edgecrusher.

 

[Soulcrusher_X]

Re: What a presence knob actually does

Depends on exactly what type it is. There are some that are just an extra high EQ circuit. But the presence control most people think of associated with a tube amp isnt actually part of the tone network but instead works in the negative feed back loop. Keep in mind not all tube amps are designed with a negative feed back loop in them. The amount of negative feedback is actually one of the big differences between a tweed bassman and a JTM45. What the presence control does is when signal goes into the negative feedback loop and gets sent back to the input it grounds out some of the highs (much like the tone control on a guitar) and making the overall sound brighter or darker depending on where its set.

Clear as mud?

To complicate things, the Mesa Mark series amps have a fixed amount of presence, like setting the knob to 5 per se, and the presence knob actually varies the amount of negative feedback. So, in this way, it doesn't change the "presence" range treble, it changes the whole attitude of the power section of the amp.

 

[Edgecrusher]

Re: What a presence knob actually does

To complicate things, the Mesa Mark series amps have a fixed amount of presence, like setting the knob to 5 per se, and the presence knob actually varies the amount of negative feedback. So, in this way, it doesn't change the "presence" range treble, it changes the whole attitude of the power section of the amp.

I know this but I went with the simple route if he didnt specify a particular amp. Complicating things just makes explaining things messy cause then you have to say... well sometimes.. this... sometimes that.. and if you do this... so I went with the K.I.S.S. method

 

[Soulcrusher_X]

Re: What a presence knob actually does

I know this but I went with the simple route if he didnt specify a particular amp. Complicating things just makes explaining things messy cause then you have to say... well sometimes.. this... sometimes that.. and if you do this... so I went with the K.I.S.S. method

I know that you know your stuff. We've had plenty of amp/tube discussions a few years ago when I was more "regular" here.

I just like to be different. Sorry. lol

 

[Stratman]

Re: What a presence knob actually does

Mine turns clockwise and counterclockwise… 0 to 10

 

[Edgecrusher]

Re: What a presence knob actually does

I know that you know your stuff. We've had plenty of amp/tube discussions a few years ago when I was more "regular" here.

I just like to be different. Sorry. lol

Roger no worries

 

[Soulcrusher_X]

Re: What a presence knob actually does

Mine turns clockwise and counterclockwise… 0 to 10

Your siggypic has some presence to it. :bigeyes:

 

[El Dunco]

Re: What a presence knob actually does

On the Mesa Boogie Dual Rectifier, if you didn't know any better because you didn't read the manual, the presence knob on the vintage/clean channel is part of the negative feedback loop and the presence on the modern channel is part of the preamp... So to get around this, I have my channel cloning set to "modern to vintage" and utilize both presence controls.

Which is probably why it's one of the most complained about amps in history, even the 2ch version has so many ways it can be set up...

 

[Aceman]

Re: What a presence knob actually does

Another much simpler form is simply a wide Q at around 2k or higher. Kind of a "global" high boost.

 

[the guy who invented fire]

Re: What a presence knob actually does

Another much simpler form is simply a wide Q at around 2k or higher. Kind of a "global" high boost.

:smack:

 

[Aceman]

Re: What a presence knob actually does

:smack:

Hey - didn't say I agree with it; But there are knobs labeled presence that do that. And it will generally brighten the overall sound of anything.

There are a lot of things in the that may not be as advertised....

 

[El Dunco]

Re: What a presence knob actually does

Hey - didn't say I agree with it; But there are knobs labeled presence that do that. And it will generally brighten the overall sound of anything.

There are a lot of things in the that may not be as advertised....

The :smack: is because it's not quite that simple. In most cases it's more to do with the power amp.

 

[Edgecrusher]

Re: What a presence knob actually does

The :smack: is because it's not quite that simple. In most cases it's more to do with the power amp.

Well now the discussion is in the "well it depends department" On this weirdo little korean made amp I have thats a no name called "rebel" the knob labeled presence is actually a active tone control and doesnt effect the poweramp at all. We could list probably a half dozen different circuits that are labeled presence. But thats not what the OP asked for really.