Induced DC current wah inductor

[lowell]

hey all,
i tried RGs thoughts on running dc current through the secondary of a r-shack audio transformer w/ the primary in place of the inductor for the wah. i'm using a vox 847 wah. the idea was to get the inductor into an offset state i believe. I used a Boss 9v 200ma dc supply for this. I could not hear any difference. Anyone try this yet? RG?

[cjlectronics]

I have not tried inducing dc current like you mention, but I have placed magnets around the inductor and did get a noticeable difference in the wah characteristics.

It's been a while since I've read RG's article (which is awesome and I bow to El Maestro) but from what I remember one of the key features of the wah wah's inductor is the magnetic characteristics of the core or when the inductor reaches saturation. So, you want your wah wah to ride the portion of the B-H curve that is just before saturation...basically the wah pedal sweeps the inductor in and out of saturation or just before it takes on magnetic characteristics.

Anyway, by placing a magnet in and around the inductor you essentially make the inductor break over into saturation quicker. During my experiments, I didn't hear a favorable response. It was too much treble and it sounded like a siren most of the time.

You could try something similar with your Rat shack audio transformer with the induced current. Something I question is that dc through an inductor doesn't do anything...the inductor just looks like a wire. What is the physics behind this?

[dai h.]

sorry this doesn't answer your question but if you've never tried it I highly recommend trying a buffer out of the wah into a nice fuzz. A really good fuzzed wah sound is to die for. The wah really accentuates the distortion(fuzz) in a nice way. The buffer is basically to get the output to work better with the fuzz in.

[David Schwab]

Something I question is that dc through an inductor doesn't do anything...the inductor just looks like a wire. What is the physics behind this?

An inductor is a coil of wire. Run current though a coil of wire and you get an induced magnetic field... i.e., an electromagnet.

Actually run a current through any wire and you will get a magnetic field.

[lowell]

yes correct! So the magnetic field created by the secondary on the lil Radio shack xformer having DC current through it could affect the operating point of the primary which is being used as the inductor for the wah. Maybe 9V is not enough? Or maybe 200ma is not enough?