Inductor's Role in Tone?

[markphaser]

What would change the permeability of the core ?

What would change the permeablitly of the inductor?

[Paul Marossy]

You'll want a wah inductor's internal resistance well under 100 ohms to get things to come out right. If it's too high a Q (i.e. too low a resistance) you can further damp it with the 33K to 100K damping resistor across it. If the internal resistance is too high, you can't make the external resistance high enough to un-damp it, as there are no negative resistors.

Interesting. So, what exactly determines the DC resistance of an inductor? What's the difference between a 500mH inductor with a DC resistance of 220 ohms, vs. one with less than 100 ohms? I assume it wouldn't sound as resonant?

[formerMember1]

Paul, if you read this, there is some info about it, maybe it will help, but i know you read it before, seems so much work, no wonder they are expensive and vary from fulltone to arielfx to castledine in sound etc,... 

http://www.arielfx.com/inductor_guide/guide.htm

[markphaser]

halo inductors: These were introduced to the world in 1967 inside Vox wah boxes. They had two types: small hole core and large hole core. The halos had the "magical" 500mH - 520mH inductance
more neat the coil is (= less wires crossing) the higher inductance value it has. You might think that if you won't wind a nice coil you'll end up with an inductor with a too low value. Don't worry too much as the cores have a high value and we will actually have to adjust them in one of the next few steps to lower the inductance to fit into our desired
Checking The Resistance
For our needs the resistance range is 29 - 33 Ohms. How many turns do you actually need to have on the bobbin? I don't know!
You should start with 550 turns and check for resistance by sanding down the insulation on the edges of the wires and use a DMM to determine the correct value. 550 turns is probably a little too high, so remove about 10 turns of wire and check again.
Do this until you are within the range I stated above. Don't get too caught up upon numbers, If you get 28.92 Ohm don't throw away the coil and start over.
take a DMM and measure the inductance. You will notice it is higher than 520mH, don't worry this is fine!
Take the inductor apart and using the small square of sanding paper, sand down very very little of the middle of one of the cores. I can't warn you enough times - Take very very little off one ferrite core's middle, just enough so it will show on the sanding paper. Now, reassemble the core and measure it again for inductance. You will notice the value dropped down quite a bit. If you need to lower the inductance a little more, repeat this step until you are happy with the results. Be very careful - it's easy to take off too much ferrite and than you'll have to make a new coil with more wire on it to reach 500 - 520mH (so you'll have the right inductance value but not the right resistance value, although the inductor will probably sound very good anyway).
In case you took a little too much off the core and when checking for inductance you get 480 - 490mH don't worry because that value will raise a little bit in the next 24hours,

[Paul Marossy]

Paul, if you read this, there is some info about it, maybe it will help, but i know you read it before, seems so much work, no wonder they are expensive and vary from fulltone to arielfx to castledine in sound etc,... 

http://www.arielfx.com/inductor_guide/guide.htm

Thanks, I haven't seen that page before. Very interesting.

[formerMember1]

Cool!! Glad to know i could help you, instead of you always helping me, 

I see you are over 5,000posts !!

[Paul Marossy]

Cool!! Glad to know i could help you, instead of you always helping me, 

I see you are over 5,000posts !!

Yeah, I surpassed 5000 posts now. I'm no Hammer, but I try to be helpful. 

[markphaser]

The wah pot changes the oscillators or feedback frequency, the parallel resistor coupled inductor changes the Q point or limits the Q point of the inductor. The feedback cap changes the current reactance of the feedback path create the oscillation. The inductor and the resistors around the inductor is a tone network that sets the oscillators frequency.

The Wah pot is like a second feedback path its the output of the inductors/tone network/feedback cap and its a output for dry signal
plus the wah pot has a 2 caps network so its like a tone control feeback output.