I have a Peavy JSX 212 combo (it's tubed) and I was wondering what the resonance and presence knobs do to your tone.
Ibanez RG350DX - ESP LTD EC-500

Peavey JSX 212 Combo - Digitech RP 250
On my 5150, the Resonance boosts the bass and Presence boosts treble frequencies quite a bit.
Resonance is power amp bass and presence is power amp treble. It changes how the amp interacts with the speakers.
... really?

i thought it was the opposite: presence is the power amp's bass.
Quote by lespaul#1
Indie stands for Industrial I think, like Marilyn Manson.

Ibanez RG2EX2 (Dimarzio Breed in bridge)
Epiphone Les Paul 100
Laney LV300T
Line 6 Toneport GX

The Falling Object Model
Presence allows you to fine tune the high end frequencies, while resonance allows you to fine tune your low end frequencies. Both presence and resonance knobs are passive, so they're not adding any frequencies, they simply attenuate your low (resonance) and high (presence) end.