Presence control mod

[msclford]

Anyone know of any good resources on adding a presence control? I have a Peavey Valveking 112, and unfortunately the 212 got the presence control, not the 112. I just don't need that loud of an amp.

[msclford]

The amp that I want to add presence control to is a Peavey Valveking 112. Here is a portion of the schematic with my thoughts on where I might be able to put the control. Let me know your thoughts on this.

[Chris / CMW amps]

Hi

I can't see the "texture"-circuit on the attached schematic.

Putting a presence-circuit on that 1st cathode will have no impact at all because off the 22u cap in series with a 470 ohms resistor.

EDIT: try getting that 2x12" schematic.

[msclford]

schematics

Here are the schematics of the output sections of both the Valveking 112 and 212 amps. VR13 is the resonance control and VR12 is the presence control on the 212. Have to decide what to do now.

[Steve Conner]

You can see that the presence and resonance controls are basically just a feedback network that feeds back from the speaker output to the cathode of the first tube. It's hard to say without the full schematic of the 212, but I'd imagine you can just copy the feedback circuit shown on the 212 schematic (R9 plus the little clump of stuff on the end of the shielded cable) and put it in place of the network on the 112 schematic (R164, R165, C146 and S103) to get the same controls that the 212 has.

[Enzo]

And ignore the texture control, it is not involved with the presence circuit. The texture control is essentially a volume control for ONE of the power tubes, so you can set the amount of mis-balance.

Look at the 112, there is a feedback tap at the output transformer, and that gpes to the feedback/resonance/presence components, then a line goes back to the circuit to complete the NFB loop. Now look at the 212. A tap off the OT, the components, the line back to the amp circuits. Wire the 112 up like the 212.