wah fine tune knob and sweep taper

[vincediamond]

The Dunlop DB01 Dimebag Darrell Crybaby From Hell Wah Pedal has a "fine tune knob" that sets the lower and upper limits for the wha's sweep pot. Is this the bandwidth?

This "fine tune knob" must be a trim pot across the wha's sweep pot wiper terminal and one of the side terminals it seems

Fine Tune:
Rotating this knob clockwise extends the high end of the sweep range, making the toe down position brighter as opposed to a darker sound when rotated counterclockwise.

I wonder how they did this fine tune parameter

A wah is a bandpass filter with variable center frequency

The Q knob/parameter seems to me it sets the resonance peak
but how would u change the "upper" and "lower" cutoff frequency points?

The wah wah has a upper and lower cutoff frequency points but how do u change them? (this is true bandwidth)

The Dunlop DB01 Dimebag Darrell Crybaby also has a Booster circuit, i'm guessing its a pre-boost to give more gain to the first transistor so it clip's or overloads the inductor.

I found a problem with that, is it boosts some frequencys but cuts and makes other frequencys very thin, why is that boosters do this? T

he booster changes the sweep/range making some frequencys boosted and others very thin why? (it makes the sweep/range worse in some ways)

New DJ mixers have a variable slope/contour control connect to the crossfader to change the slope/sweep of the tapper

How can this variable slope/contour parameter be connected to a wahs sweep pot to change the slope and contour/curve of the tapper?

[vincediamond]

Q variable control-
1.) controls the SHAPE of the filter peak
2.) adjust the frequency WIDTH

Fine tune-
1.) extends the HIGH end of the sweep range
2.) adjusts the Toe-down Frequency

Sweep cap. selector switch
1.) determines the Frequency CENTER


Frequency RANGE chart

Range Switch Heel Down Fine Tune MAX Fine tune MIN.

1 400hz 2.2Khz 1.5Khz
2 400hz 1.9Khz 1.3Khz
3 375hz 1.8Khz 1.2Khz
4 345hz 1.6Khz 1.0Khz
5 295hz 1.4Khz .75Khz
6 250hz 1.2Khz 1.2Khz

[Mark Hammer]

To prevent users from pushing the pot past its natural rotation and breaking it, the gear mechanism that rotates wah pots only covers maybe 75% of the full possible rotation of the pot, leaving a bit of the rotation at each end unused. Long ago (but not far away), we used to "adjust the sweep" of our wah pedals by loosening the bracket a bit, moving the pot over a gear tooth or two or three, and tightening up the bracket again.

The fine tune control essentially duplicates what we used to do physically in an easier-to-do electronic fashion.

[vincediamond]

The fine tune control essentially duplicates what we used to do physically in an easier-to-do electronic fashion.

Do u know how they did it electronically?

What are some thoughts you think they might have done to get a fine tune adjustment?

[R.G.]

Oh, dear.

vincediamond is our old friend walters/markphaser.

The style is distinctive.

[Steve Conner]

I built a wah-wah with an analog synth filter and expo converter to make the pedal travel "linear" in octaves. It takes some getting used to but can cover a very wide range. There are two pots inside that set the upper and lower extremes of the range, and since it was a synth filter, it was easy to adjust the Q/bandwidth with another pot. (Q and bandwidth are the same parameter for a 2-pole filter.) You really don't want to be around when it's cranked up into self-oscillation.

It's just a modded version of the old "Psychedelic Wah-Wah" DIY kit that Maplin used to sell, so if you want to know more, dig up the schematic for that. The original has the range and Q pots too.

I've also designed DJ crossfaders and taper circuits, but I can't really be bothered writing about it.

[vincediamond]

1.) i thought Q and bandwidth are different parameters how are they the same?

2.) two pots inside that set the upper and lower extremes of the range

how can u do this with a wah wah pedal to add 2 pots to set the upper and lower limits for the range?

[Steve Conner]

It's easy, just OMGRTWTFBBQM!

Q and bandwidth are the same because a second-order filter only has three parameters: cutoff frequency, Q, and midband gain.

Bandwidth is just cutoff frequency divided by Q, and likewise, Q is cutoff frequency divided by bandwidth.

They can be independent for filter orders higher than two: one example would be a fourth-order bandpass made of cascaded second-order highpass and lowpass sections. If you wanted, you could give each section a very high Q, but space the two cutoff frequencies far apart to give a very wide bandwidth.

[Regis]

I think R. G. is correct, Walters is back to spread madness and chaos.

[vincediamond]

I thought bandwidth was the low pass cut off frequency and the high pass cut off frequency = a bandpass filter

Q is the resonance peak not the bandwidth


1.) Where is the cut off frequencys upper and lower points in a wah wah pedal?

2.) The wah's pot adjusts the Frequency of the bandpass filter, the bandpass filter has to have 2 "cut off points" the upper and lower. How do you set or adjust the cut off points which is the bandwidth not the resonance

3.) On DJ mixers they have TAPER parameters for the crossfader and volume controls now to get different taper curves/slopes. How can i apply this to a wah's taper pot?

[R.G.]

walters/markphaser

[vincediamond]

I predict that "RG" will go to great lengths not to answer the questions
in this thread

[R.G.]

I predict that "RG" will go to great lengths not to answer the questions in this thread

Actually, I will not go to any lengths at all to not answer. It's much easier than that.

No.

I just won't. I spent a great deal of time with you first as walters and then markphaser trying to help you understand anything at all. I watched others with more patience than I have try to help you. I watched people try to figure out whether you were a bother-bot, troll, or something else. The only conclusion to that is that whatever you are, it's not helpful to try to help you understand.

But you do get mad beautifully.

You have my sympathy and best wishes. I hope someone can help you out.