=========================================================================== FAQ and Digest for wah wah pedals =========================================================================== From META@UNB.CA Tue Mar 2 00:01:55 1993 Subject: Re: Wah-Wah Schematic Wanted Organization: The University of New Brunswick Date: Sun, 28 Feb 1993 21:00:21 GMT In article <1mpi1pINNqhc@geraldo.cc.utexas.edu> hughes@ccwf.cc.utexas.edu (paul) writes: >In article <1mlvmfINNifo@west.West.Sun.COM> flloyd@l1-a.West.Sun.COM (Fred Lloyd [Phoenix SE]) writes: >> >>I've got one of the old, original VOX Wah-Wah pedals and it makes >>so much noise (both hiss and pot scratches) as to render it unusable. >>I'm considering rebuilding all of it and am looking for schematics >>for good Wah circuits. Doesn't have to be VOX schematics, only has >>to be good sounding. >> >>Can anyone help out with the above? Advice? > > >I have an OLD Guild wah-wah/volume pedal that has a pitifully shallow effect on >my guitar signal. Also, it has a very small range on the pedal's arc that has >the greatest effect on the sound, but it's a painfully difficult place to have >it. In other words, unless someone wants to buy this off me I would be quite >interested in other schematics for wah pedals. At least I can reuse the >chassis. I don't know much about it except that it's a Guild, has been sitting >in a closet for about 17 years prior to my recovering it, and it's at least 22 >years old and in excellent physical condition. I'm thinking I'd be better off >building a new one than trying to buy one used, or selling it and putting that >money toward a used one. > >Any offers? > >The Panther! >-- >[)----> "What proof can they exhibit that may show it's not too late? >[)----> It's time to feed the dragon, but our lives' are on the plate." >hughes@ccwf.cc.utexas.edu [-=-] Not subject to laws, physical or otherwise. >. >. Hold everything!!! Both of these can be made more playable by doing a few things that are relatively easy and cheap to do. 1) Scratchy? Get a better pot ($5 max), squirt it with some contact lubricant (usually available at electronics or high end audio places). The scratch won't be eliminated entirely forever, but you should notice a definite decline. If you're desparate, you can also take some needle-nose pliers and pry the lugs for the cover of the pot off (those parts that are folded down over the fron panel of the pot itself). This will expose the actual conductive element and the "wiper". Chances are that the wiper is corroded and has rubbed off a large amount of itself on the conductive element. Clean up the element well with contact cleaner, if you have something to get the corrosion off the wiper, do that, or swap it with a wiper from another pot of similar dimensions. You may want to give the wiper a little tweak to make sure that there is enough pressure to make a decent contact with the element, then put the whole thing back together, and away you go. 2) Hiss. A few things. A) replace all resistors in the circuit path with equivalent value METAL-FILM types; these are lower noise, and don't cost much. B) Make sure you feed the wah-wah with the highest level signal it can tolerate before distorting to keep the S/N ratio decent. C) Stick a small value capacitor between the output and ground to shunt off part of the hiss, while keeping most of the guitar high-end. Start with about .001uf and experiment from there. This also works for vintage fuzz boxes too. (Oops, remember to stick that cap between the wah-circuit output and ground, not the jack output lug and ground. Wah's tend to lose high end anyways by their very nature, so trimming off content over 3khz or so is unlikely to be noticeable with the wah engaged. Once you disengage the wah, though, such high-end loss likely WILL be noticeable which is why you want the muting capacitor for the wah circuit only.) 3) Unmangeable range. Most wah-wah's I've ever seen use the pot as a simple variable resistor; i.e.using only two of the 3 terminals. Also most gear-driven wah-wah's I've ever seen DON'T employ the entire rangeof the pot. On many of them, you can pop the back cover off, move the vertical gear-thing aside, and turn the pot one or two gear teeth over so that the gear arrangement now covers a somewhat different part of the pot's range. If that is insufficient to solve the problem, check the pot's resistance and see whether the centre frequency increases as the resistance of the pot gets smaller or larger. Then see what range of resistance values you get when the wah is in the "sweet spot" (at least the one sweetest for you). Armed with this information you can now do the following: - solder a carefully chosen resistor value in parallel with the two pot terminals so that the same foot movement results in a smaller (hence more usable) range. - solder another pot in parallel with the original pot like so: >from board------PA1--------PA2---------PA3 PB1---------PB2----------to board where PA1, PA2, PA3 represent the 3 terminal of the add-on pot, and PB1, PB2 represent the two terminals in use in the original pot. Now, by varying Pot-A you can add a fixed resistance to the whole thing (the R-value between PA1 and PA2), and reduce the overall range of the foot-controlled pot by having the parallel resistance of PA2-PA3 and PB1-PB2. Alternatively, it might be useful to have pot A replaced by one side mounted pot (assuming you have a nice cast aluminum, easy- to-drill chassis) that sets some constant add-on resistance (use only two terminals to replace the PA1-PA2 resistance) and another side-mounted pot that sets the "range width" (the parallel PA2-PA3 resistance). You should be able to tweak these enough to get the desired range of sounds in the desired range of foot movement. Pot values? Hard to say, other than that they should probably be LINEAR taper, and the add-on resistance should be about half the original pot value (e.g., if original is 100k, add-on shouldbe 50k), and the parallel should be about double the original or as close as you can get in standard values (e.g., a 250k in parallel with the original 100k). If you have linear taper ones, it should matter which terminals you use (as long asone is the centre lug). If you have audio taper ones, you may find that wiring them for "anti-log" taper (i.e., backwards) may provide better control in some cases. --------------------------------------------------------------------------- From fhartery@kean.ucs.mun.ca Fri Dec 2 18:56:40 1994 From: fhartery@kean.ucs.mun.ca Newsgroups: alt.guitar Subject: Re: My wah wah isn't working Date: 30 Nov 94 23:52:43 -0330 Organization: Memorial University. St.John's Nfld, Canada NNTP-Posting-Host: leif.ucs.mun.ca In article , coll0046@gold.tc.umn.edu (George E Coller) writes: > TC10005@hermes.cam.ac.uk (T CUTTING) writes: > >>I have a Cry Baby wah wah pedal, and obviously it sounds bloody good...until >>recently. It now crackles horribly when I go from bass to treble (and vice >>versa). I think the problem is the rotary resistor that the foot pedal >>moves... >>So. Anyone got any bright ideas on how to fix an ailing wah wah pedal? >>Reply to here or >>tc10005@hermes.cam.ac.uk > > Mine did the same thing and I fixed it for now by opening it up. You can > get to the potentiometer by removing the two nuts on the switch and the > part near the gear. Then I sprayed it with good old WD-40 but you can use > electrical parts cleaner from Radio Shack. Try to spray it where it will > seep into the actual part. Then I just kept turning it back and forth to > clean up the contacts. (Dirty contacts are the reason for the noise). > > One cool note. After putting it all back together I noticed I had > forgotten to set the gear attached to the potentiometer correctly so that > the foot action would work. You can reset it easily by loosening the tab > that holds the pedal gear next to the drum gear and then sliding it away > to release the pedal gear. The cool part is that to a degree you can set > how much wah there is because there is a little slack in the placement of > the gear. (I know this sounds kind of confusing on line but it should > make sense when you have your Cry Baby in front of you. The construction > is pretty elementary (This is not an insult but a compliment to the good > folks at Cry Baby mfg.) I set mine so it wouldn't go into an insane > treble when the pedal was at maximum. This way at maximum with the wah on > I had a pretty good cutting sound that didn't rip the ears. > > Anyone else have suggestions on how to care for the Cry Baby? > > G. Coller > Mpls. Hi folks, This is a pretty common post on this news group, but I thought my two cents would still be valuable. The common answer people have correctly used to noisy/scratchy/intermittent wah-wah pots is to use contact cleaner. What is not really stated is the type of cleaner to use. WD-40, though it works, is really not appropriate for electrical work. I know some will repost to this saying they had no problem here. Really, the best cleaner to use is one that also has a silicon lubricant included. Why ? Well, if you ever cleaned a slider pot, you would understand. Cleaners can strip off the lubricant on the pot leaving you with a dry contact. With repeated turnings of the pot you are actually wearing down the carbon that creates the pots resistance. The ultimate fix for the problem is to replace the defective pot with one that is physically sealed to keep out dust. Right now I cannot state a pot (or source for one) that easily fits into the chassis of a wah. This is because the threaded shaft for the locking nut is often too short to secure the pot physically in place. It would be a nice idea if someone could recommend a pot they used similar to one I have just described. I am rebuilding my Cry Baby and if I find such a pot, I will try to answer my own repost here too. Fabian Hartery Research Engineer/Remote Sensing Centre for Cold Ocean Resources Engineering Memorial University of Newfoundland St. John's, Newfoundland Canada --------------------------------------------------------------------------- From: dhobart@luc.edu (Dean Hobart) Newsgroups: alt.guitar Subject: Re: My wah wah isn't working Date: Fri, 2 Dec 1994 11:26:18 +1000 Organization: Loyola University Chicago In article <1994Nov30.235243.1@leif> fhartery@kean.ucs.mun.ca writes: [I cut a bit here...] > The ultimate fix for the problem is to replace the >defective pot with one that is physically sealed to keep out dust. Right >now I cannot state a pot (or source for one) that easily fits into the >chassis of a wah. This is because the threaded shaft for the locking nut >is often too short to secure the pot physically in place. It would be a >nice idea if someone could recommend a pot they used similar to one I have >just described. I am rebuilding my Cry Baby and if I find such a pot, >I will try to answer my own repost here too. >Fabian Hartery >Research Engineer/Remote Sensing >Centre for Cold Ocean Resources Engineering >Memorial University of Newfoundland >St. John's, Newfoundland >Canada If this is a dunlop pedal, you can get a replacement pot directly from them for $10 US or something like that. I don't know the order info, but there was a card included in the box when I bought this thing (years ago) that had part ordering info. I would call the manufacurer and enquire about replacement parts. Since, as you've pointed out, this is a very common problem, I would hope they offer the parts. This was a sealed pot, by the way (in the dunlop), so it was difficult to clean/lubricate it without opening it up! I don't have this pedal anymore, or I'd just post the info off the card... sorry. Since then, I've built my own wah pedal because I wasn't happy with the sound of the dunlop ;-) Hope this helps. Dean Hobart Loyola University Chicago DHobart@luc.edu --------------------------------------------------------------------------- To: "John Slaney" Cc: n9343176@gonzo.cc.wwu.edu, aldridgeD@ccc.govt.nz, rg@futserv.austin.ibm.com, tjs@eecs.umich.edu, @relay.nswc.navy.mil:tspradl@rainman, keen@eden.com Subject: Re: Goldmine WAH In-Reply-To: (Your message of Thu, 09 Feb 95 15:39:21 GMT.) <199502092040.PAA14739@dialup.oar.net> Date: Thu, 09 Feb 95 15:11:50 -0600 From: "R.G. Keen" John, the Vox wahs used inductors of 0.66 Henry. I measured one in the lab. The transistors were different types at different times. put in whatever you have and make it so you can trade them out and experiment. Where did you find the DPDT Carling stomp switches? I need several, fairly quickly. R.G. --------------------------------------------------------------------------- From: masons@cadvision.com (Steve Mason) Newsgroups: rec.music.makers.guitar Subject: Re: ***Noisy Pots Update*** Date: 28 Feb 1995 04:19:49 GMT Organization: CADVision In article , dam@dcs.gla.ac.uk says... >Unfortunately you can't, unless someone comes out with a plastic conductive >version of the pot or an adapter to let a plastic conductive pot fit. I'm >afraid you're going to have to live with rapid wear cheapo carbon pots >Problem with the cry baby is the specialist pot spindle it uses to fit > the gear. I don't have a crybaby, so I can't look at it, but surely there must be a way to adapt a good quality WIREWOUND pot into it? I'm sure electrically it would work, so it must be just a matter of getting the physical linkage to work. Wirewound pots make a HUGE difference, and if they do get noisy, you can clean them easily, and repeatedly. Though I'd never reccommend WD-40, use a good cleaner like Nu-Trol, or Blue Shower. Also, seems to me you can get SEALED pots that don't get dust and dirt in them. Although I bet these are hard to find in Audio Taper versions. Steve From billdonnelly@usa.net Mon Jul 21 11:40:57 1997 Newsgroups: rec.music.makers.guitar From: BJD Subject: Re: Crybaby Wah Static Date: Mon, 21 Jul 1997 10:30:13 -0500 David J. MacKenzie wrote: > > Mugwump <_mugwump_@geocities.com> writes: > > > > Does anyone know how to get rid of the static in a Crybaby? First, it > > > was so noisy that I couldn't record with it...now, it's so bad that I > > > can't perform with it either. Let me know what you can. Thanks. > > > Replace the pot. > > Or perform the mods in one of those guitar repair books (Craig Anderton's?) > to convert it to optical, so you'll never have to replace the pot. > (I haven't done it myself... maybe someday I'll get ambitious enough.) Before replacing the potentiometer, I suggest spraying in some contact cleaner. Usually this solves the problem and saves you the hassle of desoldering and resoldering in a new pot. If the crackling continues, check the circuit board and feel around for any disengaged components. I had a bunch of noise in my Crybaby at one time. I discovered a capacitor had worked loose in its seating. I added a touch of solder, and the unit worked like new after that. So before replacing anything, look and feel for anything loose. It's not always the potentiometer. BJD From kludge@netcom.com Wed Nov 12 00:25:26 1997 Newsgroups: rec.audio.tech Organization: Institute for Boatanchor Studies From: kludge@netcom.com (Scott Dorsey) Subject: Re: Best stuff to clean pots ??????? Date: Wed, 12 Nov 1997 01:50:11 GMT In article <01bcef04$50245fc0$6b4c93cd@roger> "Roger Mielke" writes: > >I need to clean all the pots on my bd. Any reccomendations on what material >to use ? Try CaiLube by Caig. I used Cramolin and DeOxit for years, but this really is an improvement. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." From kludge@netcom.com Thu Nov 13 22:51:03 1997 Newsgroups: rec.audio.tech Organization: Institute for Boatanchor Studies From: kludge@netcom.com (Scott Dorsey) Subject: Re: Best stuff to clean pots ??????? Date: Fri, 14 Nov 1997 00:34:13 GMT In article <64g256$8nt$1@sanews.uswc.uswest.com> LOGIN@uswest.com writes: >In article <01bcef6e$aa125360$80507910@walt.shr.dec.com>, "Walter Clark" writes: >> I had GREAT success restoring carbon and plastic pots with Cramolin Red. I >> have a r-r that developed some noisy controls about 3 years after purchase. >> I cleaned the pots with Cramolin and they are still fine 15 years later. > >Yeah, but *WHERE* do you get this stuff?!?! I've never heard of or seen it. Cramolin is a Caig Labs product, and it has been replaced with DeOxit and Cailube. I know that MCM electronics carries their line, as well as a lot of industrial electronice suppliers, and that they have a web page. Good stuff. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." ------------------------------------------------------------------------------ More wah information: http://users.aol.com/AnalogMike/kraft.htm ------------------------------------------------------------------------------ There is an article by Craig Anderton in the July 1985 Guitar Player on modifying a vintage Thomas Organ wah pedal to use an opto-isolator to permanently cure scratchy pot syndrome. The April 1984 issue has an analogous circuit for volume pedals; it is also in Craig's book "Projects For Guitarists". Those circuits used a CLM6000 opto-isolator, which (or a substitute, the NSL32) is sold by PAIA, http://www.paia.com/. ------------------------------------------------------------------------------