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

boxnix · Post by **boxnix** » 30 Sep 2008, 04:04

The whipple wah is installed, it's really nice. I upped the gain resistor to 620 which made it pretty thin but I am loving the 100% clean tone. I need to find the balance between beefy and clean. I already upped the Cin cap from .1 to .22 so I guess the gain resistor is the only other option for extra beef right?

Oh and I put two Tropical Fish caps in. I am enjoying this mojo I have heard you all speak of.

ChristoMephisto · Post by **ChristoMephisto** » 02 Oct 2008, 09:05

modman wrote:
floris wrote:
ChristoMephisto wrote: http://www.diyguitarist.com/DIYStompboxes/Boomerang.htm
I get a: "404 Not Found error"
I don't and I hadn't looked at that page in a long time Some good info there which supports my case of "wah loves low gain transistors"

I honestly don't know how mine sounds compared to the real thing, but it sure sounds good with the reissue yellow Fasel inductor. After playing this for a while, it appears that the 2N5089 transistors may have slightly too much gain for clean wah sounds, but it does sound great with distortion! I tried out some MPSA18s in it to see if that would get a little better clean sound,

Update 11/20/05: For clean wah sounds, the MPSA18 transistors still had too much gain as some distortion would occur, especially with a humbucking pickup. I can find no data on the transistors originally used in the Boomerang, but I am guessing that they are general purpose transistors with an Hfe of around 200-250. I had some 2N3569s lying around that were within that range, and those work better still.

Update 12/26/05: I still wasn't completely satisfied with the 2N3569 transistors, so I decided to try some BC109s with an Hfe of around 400, and now I am finally totally happy with it. It actually sounds a little more vocal with these transistors, to my surprise.
Hfe400 is really high for a BC109, and in the US without BCs around, I would try 2N2222 metal cans.

I'm using simple 2N3904 with a low gain of 200-250, had to filter through about 20 trannies before i could find low ones, and the second trannie is biased with a 4k7, as suggested.

wildschwein · Post by **wildschwein** » 03 Oct 2008, 13:07

My GCB-95 Crybaby is a pcb version which I bought S/H - Rev F or G from memory. I've done most of the usual cap and resistor mods on the pedal and changed the pot, modded it to true bypass, etc and it sounds great; but the problem with it is that the plastic-housed jacks have cracked/deteriorated and I want to replace them with some standard 6.5mm jacks like they used to have on the pre-1990 Crybaby; as they're obviously more heavy duty. I have this pic (below), which is of some type of pcb-wah circuit that differs slightly in layout from my Dunlop. I got the image from an online auction site and it seems to show how the mono output jack connects to the board - but it unfortunately only shows the original pcb-mounted input jack and doesn't tell me where or how to wire up a new jack to the input side of the circuit. The pcb-mounted jacks are soldered at 6 points - I assume 3 lugs on each jack are probably running to ground and also give the mounting more physical strength. I just want to see if anyone can confirm for me that the R, T and S input jack terminals of a new stereo jack should be wired to the 3 bottom facing holes in the picture - sort of parallel to where the output jack is wired up to in the pic? I personally assume that they would be but just want a second opinion before I commit to the job.

PS: Sorry for this very obvious super-Noob question, I'm primarily a guitarist trying to save a buck and I'm still pretty new to electronics, although I've done a reasonable amount of pedal modding - by carefully following clear instructions. I've looked around a lot online for some info from others but there doesn't seem to be anything at all on the net about how to delete the pcb-jacks and replace them with standard jacks, and I want to get it right the first time without frying the board too much.

Bside2234 · Post by **Bside2234** » 03 Oct 2008, 13:51

If you hold your board like the picture above, you want to hook up the R, T, S on the bottom 3 solder pads (I memory serves me correct).

wildschwein · Post by **wildschwein** » 03 Oct 2008, 14:12

Bside2234 wrote:If you hold your board like the picture above, you want to hook up the R, T, S on the bottom 3 solder pads (I memory serves me correct).

Thanks heaps for that - I'll give it a go.

boxnix · Post by **boxnix** » 05 Oct 2008, 03:48

I have gone around the world with this stupid circuit and I cant get a fat clean sound out of it.

Current mods:
Inductor: Whipple
Boost mids: 2.2K resistor
Q: 100K pot + 33K resistor in series
Cap upgrades: Tropical Fish .22's (measured.24)
Orange drop 10nF
Put a good 10nF back where the .22 bass boost was.
Wah Pot: 100K Blackbear
Gain: 1K res series with 1K trimpot, currently about 1.5K total
Volume: 50K pot, down to 25K now to compensate for such high value for gain reducer resistor.
True bypass mod and removed buffer circuit.

So at this point I cant boost the bass or gain any more without getting loads of distortion. The bass mod actually makes a horrible honking sound about 1/4 of the way thought the sweep. So I guess the only thing left to do is change the transistors right? I read some other posts on this sub but I was hoping I could squeeze a little more info.

The only transistor in there I can read is marked Q2 on the board and is a Fairchild MPSA18. According to the datasheet it has a minimum hFE value of 400.

http://www.datasheetcatalog.org/datashe ... MPSA18.pdf

wildschwein · Post by **wildschwein** » 05 Oct 2008, 07:44

I haven't changed out the trannies on mine but there is some info here about it, if you haven't seen it already:
http://fuzzcentral.ssguitar.com/axiswah.php
Here's the short quote:
"Changing the Transistors
The transistors that come in the Vox V847 and Dunlop Crybaby pedals are the high gain, general purpose MPSA18. I personally think that these transistors are way too high gain to make a good sounding wah pedal. The toe-down position is quite ear-piercing and unpleasent. To help make a more mellow wah pedal, I've chosen to use a pair of nice BC109C transistors that I ordered from Steve Daniels of Small Bear Electronics a while back. For Q1 I chose a unit with a gain of 400, and for Q2 I chose one with a gain of 388. The end result was a very nice, a bit more mellow sounding wah that's not as ear-piercing when toe-down, and the heel-down is still nice and fat...the bass response actually made the springs in my Twin Amp's tube shields rattle!"

Fuzzer · Post by **Fuzzer** » 05 Oct 2008, 15:45

I don't think the gain matters much in the second transistor, I would swap one at a time.

ChristoMephisto · Post by **ChristoMephisto** » 25 Oct 2008, 12:44

Fuzzer wrote:I don't think the gain matters much in the second transistor, I would swap one at a time.

The Technology of wah (at geofex.com)has it as:
Q1
Voltage gain transistor. Open loop voltage gain is partly determined by this. Has some effect on the overall sound. Its distortion, if any, contributes to the tone of the pedal. There is some tone change to be had by substituting for this transistor as a result. This is the one to substitute if you can only find one "5117" transistor.

Q2
Emitter follower transistor. Very little effect on tone as long as the Hfe is large enough. Gains of 200 or greater will all sound pretty much the same.

Is he saying the "5117"s are good or bad to have at Q1?

dai h. · Post by **dai h.** » 25 Oct 2008, 13:23

I think he is saying if you have some mojo/rare transistor, then since that position has some effect that would be the place to put your old stock BC109, 5117, etc.

Fuzzer · Post by **Fuzzer** » 25 Oct 2008, 17:50

Yes man, what I suggest to you is to change either Q1 or Q2 at a time, (mostly Q1, I haven't found a really noticeable difference changing Q2, but that's me), because if you change both at the same time you won't know which change really influenced an improvement, or on the contrary, a deterioration on sound.

kyoungsteadt · Post by **kyoungsteadt** » 27 Oct 2008, 03:24

bajaman wrote:Third - replace the 390 ohm resistor with a 510 ohm ( or parallel 2 x 1k ohm)

This is what I have done to my GCB-95:

Added RG Keen's buffer since my rev. D model sucked tone bad in the off position. I left the 82k resistor at that value since the buffer tied into that resistor.

Changed the 33k resistor to 56k (I had been playing with this value for a long time. I stuck with 68k for quite a while but it just didn't feel quite right).

The 390R resistor quoted above was a 330R in my model changed it to 510R. This really helped the tone.

The pedal sounds really cool with these changes.

Thanks!

Tom5150 · Post by **Tom5150** » 26 Nov 2008, 12:01

Hey guys, i dont post much, but i lurk quite alot here,

Ive in the past, tried a couple different component values in my wah, but not really liked them,

Im in University now, and ive spyed some decent looking film caps in the Electronics rooms component boxes, i think im gunna have to give Baja's tips a go and replace all the ugly little square caps with films. im also going to put a 3pdt in too. I was also thinking of swapping out Q1 for something with a bit better quality, ill have to see what the uni has.

I have two questions though

1) i'd ideally like to change the 33k into a 100k trimmer so that i can tune in the inductor, just like Baja said, but because the jacks are pcb mounted, the space between the jacks and the inductor is a little tight for a trimmer, where have u guys put yours? (im going to keep the original circuit board btw)

Also

2) Mine is a rev H board, and all the leads have connecters on them, which makes it look like something off a computer or something

I dont really see the point in replacing these? i cant imagine them having any effect on the sound??

Thanks

Tom

ryanuk · Post by **ryanuk** » 05 Dec 2008, 18:34

wildschwein wrote:My GCB-95 Crybaby is a pcb version which I bought S/H - Rev F or G from memory. I've done most of the usual cap and resistor mods on the pedal and changed the pot, modded it to true bypass, etc and it sounds great; but the problem with it is that the plastic-housed jacks have cracked/deteriorated and I want to replace them with some standard 6.5mm jacks like they used to have on the pre-1990 Crybaby; as they're obviously more heavy duty. I have this pic (below), which is of some type of pcb-wah circuit that differs slightly in layout from my Dunlop. I got the image from an online auction site and it seems to show how the mono output jack connects to the board - but it unfortunately only shows the original pcb-mounted input jack and doesn't tell me where or how to wire up a new jack to the input side of the circuit. The pcb-mounted jacks are soldered at 6 points - I assume 3 lugs on each jack are probably running to ground and also give the mounting more physical strength. I just want to see if anyone can confirm for me that the R, T and S input jack terminals of a new stereo jack should be wired to the 3 bottom facing holes in the picture - sort of parallel to where the output jack is wired up to in the pic? I personally assume that they would be but just want a second opinion before I commit to the job.

PS: Sorry for this very obvious super-Noob question, I'm primarily a guitarist trying to save a buck and I'm still pretty new to electronics, although I've done a reasonable amount of pedal modding - by carefully following clear instructions. I've looked around a lot online for some info from others but there doesn't seem to be anything at all on the net about how to delete the pcb-jacks and replace them with standard jacks, and I want to get it right the first time without frying the board too much.

Appecriate that this is an old thread but this caught my eye - what dunlop board revision is attached to wildschwein's post?? NEVER seen a dunlop/vox wah with more than 3 trannys!
Dunlops are also marked accordingly - no idea what this is. Anybdy any clues. Curious to know what valve the last tranny adds??

pz · Post by pz » 06 Dec 2008, 08:34

ryanuk wrote: Appecriate that this is an old thread but this caught my eye - what dunlop board revision is attached to wildschwein's post?? NEVER seen a dunlop/vox wah with more than 3 trannys!
Dunlops are also marked accordingly - no idea what this is. Anybdy any clues. Curious to know what valve the last tranny adds??

It looks like a pcb from those cheap wahs sold by musicstore.de (got one some months ago). It has an input buffer made around a discrete darlington (Q1,Q2). It can be easily replaced by a decent FET.

kyoungsteadt · Post by **kyoungsteadt** » 06 Dec 2008, 12:41

RG Keen's buffer uses an FET I implemented that quite easily.

rutledj · Post by **rutledj** » 18 Dec 2008, 00:29

I've been modding a crybaby and was searching the web for some schematics of the boutique wahs. Not much luck but I was wondering what makes the Fulltone or Teese RCMs special. Is the the inductor only or have they added other circuitry around the basic wah ckt that works some magic?

Thanks,
Rut

devastator · Post by **devastator** » 19 Dec 2008, 21:29

Just carbon resistors and some cheap mystic parts from 70's

Bside2234 · Post by **Bside2234** » 08 Jan 2009, 19:04

So I finally tried the 4uf cap. It didn't really change the sound of the wah too much. Not so noticable that it would be worth swapping it out. It did make a spot in the sweep that was a really fast bass to treble transition that I didn't like. It wasn't a smooth sweep anymore. I put the 4.7uf back in there and it was gone. I like the 4.7uf better. Now to try a 6uf to see what happens!

bajaman · Post by **bajaman** » 08 Jan 2009, 20:12

It did make a spot in the sweep that was a really fast bass to treble transition that I didn't like. It wasn't a smooth sweep anymore

Interesting - please keep us posted - perhaps this is the "mojo" part that we have all been looking for - perhaps try paralleling the existing 4.7uf capacitor with additional .1uf polyester film capacitors and take it up to 4.8, 4.9,5, 5.1 etc.
You could also try the 4uf again and do the same - perhaps there is a sweet spot for your particular wah where the smoothest transition from bass to treble occurs - it may be 4.5uf

thanks
bajaman