What values for a Resonance Control?

[leadfootdriver]

I'll put one on the Express. I like how the amp gets into rippin' power distortion, but I'm used to bigger lows. I think a Resonance control would do the trick. I'll use an output jack spot to mount it.

What say you?

[Colossal]

I've used the 1M-A/0.0047uF version with great success in a number of amps (mostly modded Marshalls). I have it in my modified Liverpool. The effect is subtle but you can feel the effect it has on the cab. If you are using a PPIMV, be aware that at lower levels, the contribution from anything in the negative feedback loop such as Resonance and Presence is also reduced. So the amp needs to be wide open for the resonance to have the most noticeable effect. It does add the beef though.

I use this scheme:
Impedance tap -> 0.22uF -> Resonance circuit -> NFB resistor -> Presence circuit

The 0.22uF cap on the impedance tap lets everything at audio and below through but keeps DC off the resonance pot.

[martin manning]

Leadfoot, are you up for an experiment? Try this idea I'm calling a "presonance" control. All you need is a 5k resistor and a 10kA pot to replace your presence pot; should go from bass boost to treble boost.

[leadfootdriver]

I've used the 1M-A/0.0047uF version with great success in a number of amps (mostly modded Marshalls). I have it in my modified Liverpool. The effect is subtle but you can feel the effect it has on the cab. If you are using a PPIMV, be aware that at lower levels, the contribution from anything in the negative feedback loop such as Resonance and Presence is also reduced. So the amp needs to be wide open for the resonance to have the most noticeable effect. It does add the beef though.

I use this scheme:
Impedance tap -> 0.22uF -> Resonance circuit -> NFB resistor -> Presence circuit

The 0.22uF cap on the impedance tap lets everything at audio and below through but keeps DC off the resonance pot.

Thanks for helping out.

I have seen those values posted before, but I figure like anything, people might tweek them out. I wanted to get a feel of what was the most common values.

This guy has 2 ways to wire it up with the difference being lugs 1-2 are connected or not connected.

Which one would you suggest?

[img:497:465]http://home.comcast.net/~jbjdav26/Resonance1.jpg[/img]

[img:497:465]http://home.comcast.net/~jbjdav26/Resonance2.JPG[/img]

[Structo]

I believe those are both electrically the same.

The pot is being used as a variable resistor.

[leadfootdriver]

Sheeit... Any objections to just hard wiring the cap in line with the feedback lead? I tested it out with a 1M pot, and full blast seems just right!

[martin manning]

No reason not to hard-wire it if that's the way you like it. By full-blast do you mean full CW or CCW? I was kind of hoping you'd give the presonance control a try- that could be a very interesting thing to have on one knob.

[leadfootdriver]

It's done. I like it much better. The Express has plenty of high end to spare. With the Resonance mod; the extra low end allows you to get Voxy.

To be honest, I thought the stock form was to thin and narrow. This is what it needed for me; it helps to make single coils sound like single coils.

[IMG768]http://i258.photobucket.com/albums/hh26 ... G_1214.jpg[/img]

[Colossal]

I was kind of hoping you'd give the presonance control a try- that could be a very interesting thing to have on one knob.

Martin,

I'm installing it right now...stand by.

[Colossal]

Hey Martin!

Killer mod man, works great! It's a little unstable in my Liver-mule (very ugly PTP Liverpool test build) but it does work well. The low end is huge but the clarity is not affected. Well done (we need a thumbs-up icon).

+10

[Bob S]

Gotta try this.
I'm building a Liverpool-ish amp that's already way off the reservation as far as layouts go.
More to follow...
Thanks Martin.

[sliberty]

Sorry, I realize that I am being a bit dense, but I am not understanding the presonance schematic. COuld someone please post a diagram showing this in the Express circuit (or at least part of the Express circuit showing the PI and the rest of the NFB loop coming from the OT.

Thanks,
Steve

[ChrisM]

I don't understand where R3 is going.

What's the feedback ratio?

[martin manning]

Maybe this will help clear things up. I added C2 here, effectively replacing the original presence cap, which might make an improvement in the range of tones available. R4 lowers max FB a little at all frequencies and will reduce the apparent bass boost a little.

Dave, is this this the way you implemented the original, but without C2 and R4?

[Colossal]

Dave, is this this the way you implemented the original, but without C2 and R4?

I did it this way (so yes, without C2 and R4).

[EDIT: I have since updated to version 3]