Presence vs Middle

[Jack Sparrow]

Is there a reason why some amps have Presence and others have Middle, but none seem to have both? I've never owned an amp with Presence so I'm not sure how it compares to Middle but I think they both effect the mid-range tone. Weber has a version of the 5E7 circuit that replaces Presence with Middle. That uses the same chassis and the same number of pots in different order but other chassis would have room for both controls. Are they mutually exclusive? Are they redundant? Obviously, some people prefer Middle over Presence or Weber wouldn't offer the option, so there must be some difference.

[diagrammatiks]

plenty of amps have both.

they are both frequency filters just in different places in the circuit.

[Chuck H]

And affecting different frequencies. Just to address the OP... They are not equivalent in many ways. Perhaps the designs you've seen where one is subbed for the other are simply poetic license by the builder who though that the mid control wasn't all that useful but a presence control would be. But to reitterate... Not the same. One affects only mids in the preamp and the other affect high mids and up by deleating them from the power amps negative feedback circuit. Both controls have very different effects. Especially when the amp is clipping the power tubes.

[Bruce / Mission Amps]

Weber was just looking for a spot to put a middle pot and eliminated the presence pot. Why? To sell more stuff regardless of how it works and most of the time, every player sets the presence control pot in those tweed amps in about the exact same position... so, like Fender did... drop it and just use a resistor.
Not that it matters to the actual question but that so called Weber "middle control" in the 5E7, (or equivalent) is almost worthless as far as a real mid frequency control.

[Jack Sparrow]

Sorry I haven't been able to get back to this for a few days. I appreciate your comments. I see how the addition of the middle control in the Weber circuit is just another 100K pot between the treble and bass controls. I figured if it was that simple to add a middle control, why not? Unless it interferes with the real presence control. I'm planning to make my own face plate and omit the ground switch so making room for another knob shouldn't be a problem. OTOH, if it does almost nothing, I suppose it's best to leave it out and carry on with the original circuit.

[Enzo]

And when you say they "replace" a mod control with a presence, you are assuming an equivalence that is not there. If they only have room on the panel for so many controls, or they are using pre-drilled chassis with only so many holes, they can decide which controls to include and which not to, but that doesn't make them equivalent. They might find a presence control more useful than a mid or vice versa on a particular model, so if they don;t have room for both, they pick the one they want more.

They are different controls, the mids is part of hte EQ circuit, while presence is a feedback control for the powr amp.

[wyatt]

Sorry I haven't been able to get back to this for a few days. I appreciate your comments. I see how the addition of the middle control in the Weber circuit is just another 100K pot between the treble and bass controls. I figured if it was that simple to add a middle control, why not? Unless it interferes with the real presence control. I'm planning to make my own face plate and omit the ground switch so making room for another knob shouldn't be a problem. OTOH, if it does almost nothing, I suppose it's best to leave it out and carry on with the original circuit.

Partly because passive Mid controls all always a bit of a compromise, they tend be be too broad in the range they cut. They are probably the least effective control in the tone stack.