Dunlop - Cry Baby GCB-95: how to improve it for cheap

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.

Dunlop - Cry Baby GCB-95: how to improve it for cheap

Postby bajaman » 30 Jul 2007, 06:24

Forget about Teese wahs and all the bullshit about specially manufactured parts etc., here is how to make any standard cry baby wah sound much better. :wink:
First - replace all those shitty little blue capacitors with some better quality ones - I used those little grey MKT film types, but you could use xicon film for still better results. (They are 10n x 2, and 220n x 2).
Second - find the 4.7uf electrolytic capacitor and it's 82k ohm bypass resistor - replace them with a 3.3uf BP paralleled with a 680n film type (for close to 4uf) and a 100k metal film resistor (or metal oxide).
Third - replace the 390 ohm resistor with a 510 ohm ( or parallel 2 x 1k ohm)
That is it :wink: - just plug in your guitar and enjoy wah wah sounds ( not woh woh as in the stock GCB95)

No need for special taper pots, fasel inductors or any of the other bullshit stuff - just good quality capacitors and the correct value resistors is all you need
Cheers
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Postby grolschie » 30 Jul 2007, 11:06

Nice! Thanks. :D
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Postby jt » 30 Jul 2007, 22:22

Another cheep thing to play with is the transistors.In my gcb95 replacing them
with two BC109B made an audible difference.
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Postby madbean » 25 Aug 2007, 16:51

I picked this up from AMZ, I think-- use the input buffer stage off a TS to reduce loading on those old, cheap Crybabys (well, I converted mine into a Crash Sync, but that's besides the point).
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Postby Aharon » 25 Aug 2007, 17:06

I just rebuilt my wah and it sounds much much better than the stock Jimi Hendrix Dunlop it was.

Did the following:

5115 transistors (Q1 hfe 400,Q2 hfe380)
Tropical fish 0.22 caps for mojo.
Improved 0.01 caps.
Variable Q.
Rewired for true bypass,effect to ground when in bypass,zero click switching.
Resistor values as per Axis Wah at Fuzz Central.


I also read that you can mimic the ICAR pot taper (not 100% but close enough for R&R)by using a 0.33 cap going to the pot.

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Postby RLBJR65 » 12 Sep 2007, 00:01

jakehop wrote:Alright guys, I'm very interested in hearing how you guys tune your wah effects. I've spent a lot of time recently at studying that wonderful effect, and I'd really like to hear your guides at how to tune such a circuitry, as I kinda feel like I'm stuck (i.e. sometimes my wah's sound fantastic and I'll sell them, and sometimes they sound dull and I'll keep them, as I have certain standards towards my musician friends).

Bajaman mentioned having a good DMM to measure the values and tune it from there - how is that done? R.G. Keens excellent article, but I'm still looking for a more "hands on" approach as to how to connect theory with practice. English is my second language, and even though I feel I'm pretty good at it, I still need that "hands on" to completely get it.

I hope to get at great talk about that cool effect! :twisted:

mfg Jake


Not sure if this is what your looking for but there are some tips from bajaman and others in subforum Pimp-My-Cheap-Pedal.
http://www.phpbbserver.com/freestompbox ... stompboxes
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Postby DougH » 12 Sep 2007, 17:44

I used R.G.'s article and just played around until I found some ideas I liked. It didn't take much experimenting, from what I remember. It's amazing what an improvement a couple resistor changes will make.
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Postby jakehop » 13 Sep 2007, 00:00

Thanks to both of you for your answers.

Doug, where do you find the "hot spots" of the circuit?

mfg, Jake
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Postby modman » 13 Sep 2007, 00:22

have a look at these for directer practical info:

http://homepage.ntlworld.com/s.castledi ... z/wah.html
A guideline to go about modding you Dunlop Wah pedal
http://www.stinkfoot.se/andreas/diy/mods/dunlop.htm
Another guideline, different focus
http://www.diyguitarist.com/DIYStompboxes/WahMod1.htm
"The whole point of diy is diy. It's not dsoiyathodtr - do some of it yourself and then have others do the rest" (paulc)
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Postby estragon » 13 Sep 2007, 14:50

I took this quote from bajaman from another thread because it's the most down-to-earth wah tuning description I've seen so far:

bajaman wrote:Many wahs today go - wow wow or even woe woe, because they are using a combination of components with no regard to fine tuning the resonance or the inductor capacitor combination.

I have taken many anaemic sounding woe woe pedals and transformed them into very usable wah wah pedals, simply by changing all the capacitors to higher quality film types - especially the two 220n capacitors.

Recently, i purchased some red and yellow fasel dunlop reissue inductors , and noticed a wide spread of inductances from 300mH up to 650mH. Of course, these are going to resonate in a completely different range of frequencies when used with the standard 10n feedback capacitor.

A good wah wah sweeps through two octaves - I try to get mine to sweep from 440Hz to 1760Hz (A to A two octaves higher). After replacing all the stock capacitors with some MKT film types, quite often a very small capacitor in parallel with the 10n can achieve this tuning. Other times, I have had to reduce the 10n very slightly to again achieve this tuning.
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Postby DougH » 13 Sep 2007, 19:53

jakehop wrote:Thanks to both of you for your answers.

Doug, where do you find the "hot spots" of the circuit?

mfg, Jake


I don't remember exactly what I did. I don't even remember what the wah circuit looks like, it's been so long. What I do remember is I increased the gain of the amplifier, and played with the resonance/Q of the inductor filter. I seem to remember something about a 33k resistor near the inductor that I fooled with, but that may not be right.

What I will tell you is that Bajaman is exactly right. I haven't tried his "quality upgrades" :D but the Q of the filter is exactly where you want to concentrate your efforts. I would read R.G.'s article and focus on the areas that control the Q of the filter. I believe I made my filter sharper and narrower IIRC. The extra gain helps too.

After making my changes I suspect that having a killer sounding wah has little to do with inductors and other esoteric parts made of unobtainium, and everything to do with just tuning the filter properly. And that just requires simple resistor & cap changes and a willingness to experiment a little. The article can save you some time by helping you make some educated guesses towards getting you where you want to go.
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Postby Aharon » 14 Sep 2007, 21:46

As I previously posted I made a new board for my JH wah (for details read my other post earlier in the thread),the only thing left to do was to tune the pot 's range and that's what I did today.....big improvement,you can really tell it's not an off the shelf wah (at least to me ears)and the sound is a distinct wah....not woh or weh. 8)

I have a couple more really nice inductors I pulled from some old equipment that I already tested in a generic wah circuit and they work,bought some old wahs at my music store for peanuts and I will be building some more,each one with a diferent sound flavour,diferent colour case,maybe a dual inductor board etc ....I don't know. :?:
I have re-discovered the wah and I'm loving every minute of it. :D
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Postby Barcode » 28 Sep 2007, 02:24

i've been trying to get my bad horsie just right for about a year now. basically i want the range and sound of the crybaby (post mod, of course) but i like the horsie because of the auto-on optical switching. any ideas?
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Postby bajaman » 28 Sep 2007, 06:47

Hi Barcode - like I said in the beginning of this thread (before folks started talking about those shitty behringer wahs), change the capacitors - put in some higher quality film types - then tune the feedback cap to the inductor you WILL here the difference :wink:
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Postby mibu » 11 Oct 2007, 12:19

hi guys! this is my first post here (after lurking for awhile...). just got my chrome wah from tube amp in germany. it's chinese, of course, but it's a sturdy case - just what I needed because my old dunlop wah from the '80s crashed (the case) at a recent show...
the original sound of the chrome is very thin and lifeless and the pot is a pretty stiff one, not good for the foot. I will try some mods on the original circuit and will post my findings.

thanks
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Postby ~arph » 14 Dec 2007, 13:55

MoreCowbell wrote:heres a link to reviews.... http://reviews.harmony-central.com/revi ... h+Wah/10/1


Gotta love this one "The whole thing is like an Electro Harmonix effect, very simple and efficient, nothing complicated to kill your tone." :lol:
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Postby Uma Floresta » 20 Jan 2008, 05:45

Here's another Wah mod - lifting the negative end of the 4.7 uF cap in order to make your Wah into a volume pedal. Easy, and works except the volume on my Vox V847 won't go all the way down, even after disconnecting the gear from the pot and turning it all the way down. Any ideas on getting the volume to go all the way down?

Here's a schematic:

http://www.geocities.com/j4_student/voxwah.gif
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Postby stephenxvp » 21 Jan 2008, 01:52

Steve,
hi, you were right this is the most fascinating forum on the web.

Where do I get the MKT caps in Chch?
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Overview of available wah pots

Postby guiltyspark » 14 Feb 2008, 16:39

Just for fun I thought I'd run down every available wah pot for reference:

Dunlop Hot Potz 2: Avail. on Ebay for OK prices, this type is black and has 3 lugs on the BACK of the pot.

Fulltone Clyde: This one is supposed to have the ICAR taper, made by Diva, kinda pricey at $25 or so.

"Clyde" Avail. on Ebay for about $15, also made by Diva, appears to be identical to the Fulltone. I've used this and the Fulltone w/good results.

Blacktop: marketed by New Sensor (EH), this one has an ICAR type modified taper but is 200K for some reason. Never tried one. Fairly cheap in quantity.

Blacktop "Small Bear", same as above but 100K, only sold by SB to my knowledge. About $17

"Blue" pot: I've seen these at wholesalers and in some Roger Mayer wahs, looks kind of like a Bourns w/a squarish plastic body. Not common in the US

Teese Pot: only available in Teese wahs, I'm sure they're ICAR.

Dunlop Hot Potz 1: Big, fat sealed pot seen in 1 trillion Crybabies, doubt this is mojo ICAR taper, seems like a quality pot. USAish made industrial part. I don't think these are made anymore.


So there you have it, if you're modding a wah this is what's available that I know of, feel free to amend or correct.

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Postby bajaman » 14 Feb 2008, 22:16

I put a WHIPPLE inductor in my Wah - very worthwhile improvement - US$20.00 from Mike on Ebay - search for Whipple on Ebay - you will find him :wink:
cheers
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