AMZ FX ANALOG ALCHEMY GEOFX MEF ROG MEF DIY WIKI

making a "q" wah pedal?

Started by jimbob, July 02, 2005, 11:10:56 AM

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jimbob

July 02, 2005, 11:10:56 AM
Im building a wah without the rocker part in a mxr size box. Instead of a standard wah pot- what king of pot would be used in this? 100ka? I was looking online for the one Dunlop made- I guess they dont make it anymore? It was small black with 1 pot for controlling the Q.
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

cd

#1
July 02, 2005, 12:15:00 PM
Quote from: jimbobIm building a wah without the rocker part in a mxr size box. Instead of a standard wah pot- what king of pot would be used in this? 100ka? I was looking online for the one Dunlop made- I guess they dont make it anymore? It was small black with 1 pot for controlling the Q.

Use the same value pot as a regular wah.

markr04

#2
July 02, 2005, 12:57:34 PM
Are wah pots typically log or linear taper?
Pardon my poor English. I'm American.

jimbob

#3
July 02, 2005, 01:33:13 PM
I swore it used to be sold as a black, 1 pot, Dunlop? MXR? i cant seem to find it anywhere. At one time they were also on sale at muysiciansfriend for 49.99$
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

KarbonHed

#4
July 02, 2005, 02:05:40 PM
Quote from: jimbobIm building a wah without the rocker part in a mxr size box. Instead of a standard wah pot- what king of pot would be used in this? 100ka? I was looking online for the one Dunlop made- I guess they dont make it anymore? It was small black with 1 pot for controlling the Q.

The Dunlop QZ-1 Q-Zone?

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=29609&highlight=qz1

jimbob

#5
July 02, 2005, 02:21:14 PM
Very good! i new it existed! i wish i had a schem to that just to see main differences
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

cd

#6
July 02, 2005, 02:36:29 PM
Quote from: jimbobI swore it used to be sold as a black, 1 pot, Dunlop? MXR? i cant seem to find it anywhere. At one time they were also on sale at muysiciansfriend for 49.99$

Yeah, you don't need to use that pot.  That pot is a special heavy duty one with a gear on it that is supposed to be used inside wah pedals.  If you're just going to make a fixed frequency filter (AKA wah without the rocker) you can just use a regular $2 Alpha pot.  In terms of taper, linear or log will work.

jimbob

#7
July 02, 2005, 02:50:54 PM
thanks cd. Thats eggzachary what i was wanting to do. I read somewhere that Zakk Wylde usedes his wah in a fixed position for his leads-..not that thats my sound, but i like that fixed position sound and hate adjusting my wah to the perfect position. Im thinking about adding a 5p1t cap switch and buffer ect.. everything just like my wah..
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

jimbob

#8
July 02, 2005, 05:46:50 PM
KarbonHed- thanks! i didnt realize that was the schematic! i feel like a real dum arse after posting " i wish i had the schematic"  :oops:


http://forum.musikding.de/attachements/Q-Zone.jpg

its uses an ic?
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

KarbonHed

#9
July 02, 2005, 06:27:17 PM
Quote from: jimbobKarbonHed- thanks! i didnt realize that was the schematic! i feel like a real dum arse after posting " i wish i had the schematic"  :oops:


http://forum.musikding.de/attachements/Q-Zone.jpg

its uses an ic?

More info and a link to the manual -

http://filters.muziq.be/model/dunlop/crybaby/qz1

I have a better schem of that here, marked as being from www.anubics.com, which seems to be broken with lots of 404 errors. Can't find a weblink for it on there, but I could mail it to you if you want.

Edit:

just uploaded it to - http://www.ruinbird.com/lektrik/dunlop_qz-1.gif - it'll be there for a few days...

jimbob

#10
July 03, 2005, 01:05:03 PM
Just got it. thanks!
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

Mark Hammer

#11
July 03, 2005, 03:45:17 PM
If you're just going to use it like a resonant booster/filter, there is little need for a fancy pot, or indeed any particular taper.  Keep in mind that the pot for foot treadle purposes has to:
a) stand up to defensive tackles in workboots who like to play heavy metal in their spare time to help lose weight and get them down to a trim 350lbs.,
b) complement the particular arc of foot movement where the most articulation exists (it will all be concentrated in the "forward" movements), and merge it with the resonant frequency range where centre frequency changes "mean" the most, and
c) provide the articulation range needed without requiring the full rotation of the pot (the rack and pinion systems really only rotate the wiper about 3/4 of its entire range, so as to prevent pot damage when our football player accidentally pushes the pot all the way to the end).

Since a pot being twiddled to a set position by human hands (rather than feet) does not require any of these considerations, just about any 100k pot  ought to do, although I suppose some tapers may be closer to some players' tastes.

If it were me, I'd do the following:
1) use a 50k linear-taper pot
2) solder a 47k or 51k fixed resistor to each end (outside lug) of the pot, and connect those resistors to the points where the pot is normally connected (wiper is the same as always)
3) wire up a DPDT toggle or slide switch such that in position A it shunts one of the resistors and leaves the other in circuit, and in position B it shunts the opposite resistor and lifts the first shunt.

Why do I suggest this?  Because you have no idea in advance which taper will allow you to dial in the tones you want most.  In theory, and in practice, one uses a given taper in a wah so that the critical frequency changes you want are distributed around enough of a rotation arc that you can easily select the centre frequency you want with your foot.  In the scheme I propose, the full range of our virtual 100k pot is distributed over twice as much pot rotation (actually, about 2-1/2 times as much, when you consider the typical unused rotation in a foot-operated wah).  If you can't find the centre frequency you want under THOSE conditions, I'd be very surprised.
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