How does the Hendrix wah compare to the mod-able wah at GGG

[markphaser]

Thanks for the information

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What Components or Values change the current Reactance in a Wah?

The "sweep capacitor" first and foremost. Then the inductor.

It their another way to change the current Reactance ?

What do u mean by current Reactance?  What is Current Reactance

Do u mean that the feedback cap and the inductor create a Vector or current reactance but what does that do?

[Paul Marossy]

Thanks for the information

Quote
What Components or Values change the current Reactance in a Wah?

The "sweep capacitor" first and foremost. Then the inductor.

It their another way to change the current Reactance ?

What do u mean by current Reactance?  What is Current Reactance

Do u mean that the feedback cap and the inductor create a Vector or current reactance but what does that do?

Read the patent: http://www.diyguitarist.com/Misc/Patent_3530244.pdf

The amount of current thru the sweep cap determines the amount of apparent capacitance and the amount of reactance, which is what changes the tone. That sweep cap lies at the heart of the circuit, so it has the most influence on the sound. The inductor has some part to do with it as well.

I see it like this - the wah circuit is resonant circuit that causes an apparent capacitance using reactance and by varying the amount of current thru the sweep cap. This also manipulates the input impedance of the transistor on the input which also messes with the frequencies that get accentuated/attenuated. I'm not sure if that is totally correct, but that is my interpretation of how it works.

EDIT: Also, check out this thread - http://www.diystompboxes.com/smfforum/index.php?topic=39546.msg283002#msg283002

[markphaser]

Thanks for the information

"varying the amount of current thru the sweep cap"

To vary the amount of current would need a resistor or trim pot in the feeback path is that what u mean?

The feedback cap varys the amount of current also but it changes the rate of change of the current. Reactance is a Vector
so the network is a feeback cap with a inductor creating reactance or a vector

[Paul Marossy]

To vary the amount of current would need a resistor or trim pot in the feeback path is that what u mean?

The feedback cap varys the amount of current also but it changes the rate of change of the current. Reactance is a Vector
so the network is a feeback cap with a inductor creating reactance or a vector

The 100K pot is what varies the current thru the feedback cap. That is why when the 4.7uF cap goes bad, it acts like a volume pedal - it's just dumping that current directly to ground. I suppose you could look at the pot as though it's changing the rate of change of the current - or in other words, the frequency! Right?

[markphaser]

Thanks for the information

I thought the 100K pot did two things vary the rate of change/frequency and the Dry signal so its like a mixer/blend parameter
because it is a variable feedback and output pot all in one if the output is tapped off the wiper of the wah pot.

[Paul Marossy]

I thought the 100K pot did two things vary the rate of change/frequency and the Dry signal so its like a mixer/blend parameter
because it is a variable feedback and output pot all in one if the output is tapped off the wiper of the wah pot.

In the patent document, if you read from the bottom of column 3 to about line 15 of column 4, it talks about the aggragate Q of the circuit. That resistor between the sweep cap and the base of the input transistor is what allows all of the frequencies to be developed somewhat. If you were to take that resistor out, the patent document claims that because the aggregate Q of the circuit is so high that virtually only the frequency selected would appear at the output. So, in other words, there isn't a dry signal being mixed with the effected one, it's all going thru a sonic blender! The inductor is what creates the resonant peak.

[markphaser]

Thanks for the information

Where do u get patent documents for guitar pedals?

how do u find the patent documents for them?