Dingwall Passive 2 directions Tone Circuit

[davidchampoux]

I'm wondering what's the electronic to achieve the double direction of the new Dingwall Super P passive tone?

For those who don't know what I'm talking about : simply put, the tone is 100% at middle course of the pot. Roll off the pot, it acts like a regular tone control, cutting the highs. But turn more than the center point, it'll cut in the mid range (I suppose around 800 hz?). Brilliant!

I understand I can do that with a balance pot (2 pots together) with a center detent. one side will be the usuall capacitor to roll off the highs, but the other side ?? Is it only a cap? Or is there some inductance as well? Serie or parallel? Is it a resistor in series with the cap? What value?

Any help greatly appreciated!

[line6man]

Capacitor in series with an inductor, to form a bandstop filter.

[davidchampoux]

any idea of the values?

[iiipopes]

Bill Lawrence has a similar add-on for mid-cut only he calls a "Q-filter." Same principle: coil w/ capacitor to provide a band-pass to ground. I like it on guitar, but I don't like it on bass.

For bass, instead, an EMG EXB does much better, so that the lows and highs are boosted to keep the same signal level.

[davidchampoux]

Hmmm losing level in the passive world might be an issue... I didn't hear any lost from the youtube demo of the Dingwall though :

http://www.youtube.com/watch?v=cIiN7LRCA2Q

[line6man]

The volume drop is the biggest issue in the real world. Which is one reason people don't do it often.

As far as values, it's going to be very difficult to figure out what will center the cut at 800Hz, when the pickups are an unknown complex impedance in the circuit.