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

Bside2234 · Post by **Bside2234** » 08 Jan 2009, 20:22

I will keep you guys updated.

I was going to throw a couple of different caps on my breadboard and run some wires from the 4.7uf to it to see what sounded best.

I also replaced the 510 ohm (It's a Vox) resistor with a 1K trimpot and that does make a nice audible difference. I set the trimpot at 510 ohms, marked it so I knew where 510 ohms was. I found I liked it with just a little bit of a turn up. I haven't measured where it's at yet.
You could make this an external knob if you wanted as it might be fun to play around with. It does crackle when you turn it. You can have your own "crackle ok" knob on your wah

jrose · Post by **jrose** » 09 Jan 2009, 16:04

Anyone know where i can get a replacement for the 4.7uf capactior? I recently bought a cry-baby for cheap and it had been removed to be used as a volume pedal. Radio-shack possibly?

Bside2234 · Post by **Bside2234** » 09 Jan 2009, 16:13

The 4.7uf is a very easy part to find. Very common value.
RS has them: http://www.radioshack.com/product/index ... Id=2103622
Expensive but if you only need one it's not worth doing an online order with anyone.

jrose · Post by **jrose** » 09 Jan 2009, 16:16

Thanks for the quick response.
Really wanting to get this thing up and going.

Bside2234 · Post by **Bside2234** » 09 Jan 2009, 16:39

No problem. Just make sure you put it in the right way. It's polarized so the negative leg goes to the ground (towards the bottom of the board).

Bside2234 · Post by **Bside2234** » 12 Jan 2009, 23:49

Well as promised. I soldered some wires to the 4.7uf and ran them to my breadboard. I added 1uf - no difference, 2uf - no difference, 4uf - no difference, 6uf - no difference, then I jumped to 10uf - no difference. I heard absolutely no difference in adding any of them. Maybe I don't have a good enough ear. I tried toe up with each capacitor, toe down, and checked to see if the treble to bass sweep moved with each change. Nothing. Raising the value did nothing for mine.

analogguru · Post by **analogguru** » 15 Jan 2009, 16:29

Bside2234 wrote:Well as promised. I soldered some wires to the 4.7uf and ran them to my breadboard. I added 1uf - no difference, 2uf - no difference, 4uf - no difference, 6uf - no difference, then I jumped to 10uf - no difference. I heard absolutely no difference in adding any of them. Maybe I don't have a good enough ear. I tried toe up with each capacitor, toe down, and checked to see if the treble to bass sweep moved with each change. Nothing. Raising the value did nothing for mine.

No wonder....
changing this cap only results in an illusion for cork sniffers...

analogguru

Bside2234 · Post by **Bside2234** » 15 Jan 2009, 17:10

Well I guess I am glad I didn't hear any difference then

pz · Post by pz » 15 Jan 2009, 17:13

analogguru wrote: No wonder....
changing this cap only results in an illusion for cork sniffers...

analogguru

I couldn't hear the difference either, so i did some tests.
Typical Crybaby circuit, 1M input Z Fet buffer added.
Testing rig:
Compact4 headphone out -> 1M input Z wah
Wah output -> Compact4 300k input Z
3u3 vs 4u7 at pedal max position:

3u3 vs 4u7 at pedal min position:

Ok, the difference between 3u3 and 4u7 isn't that big, so let's try 3u3 vs (3u3+4u7)

Bside2234 · Post by **Bside2234** » 15 Jan 2009, 17:24

Looks like my ears are pretty good then

floris · Post by **floris** » 15 Jan 2009, 19:01

@pz: What is the software that you used to measure the frequency transfer function?

pz · Post by pz » 15 Jan 2009, 19:23

floris wrote:@pz: What is the software that you used to measure the frequency transfer function?

https://www.freestompboxes.org/viewtopic.php?f=21&t=2845

floris · Post by **floris** » 15 Jan 2009, 19:41

Thanks, it works great.

devastator · Post by **devastator** » 20 Jul 2009, 20:45

Hi guys,

I bump that thread instread of creating a new one.

i've just received that crybaby and I'd like to mod it, improve the sound possibilities. What cool mod do you recommend me ? I think installing trim pot to mid control (1k5 changed for 2K2trim) and 1K instead of 470resistor (maybe with pot after, if the controls have a real impact to the sound).
Something else to do with that circuit ? (I'm not really sure doing the Q control, I saw videos and that don't really change the sound, at least, nothing that justify drilling a hole installing a pot)

a little pic of my pedal , what thinking about those caps ? (It seems look like panasonic, right ? I found the same type in an old Pionner HI-FI)

lolbou · Post by **lolbou** » 21 Jul 2009, 08:06

Man, your unit is identical (pcb, components, inductor) to my JH-1... I guess that the name Hendirx does sound better somehow...

devastator · Post by **devastator** » 21 Jul 2009, 17:30

Sure ?

It's written "original crybaby" in the front, Dunlop can't lie about that

What's different compared to the regular crybaby ? I think there's some aditional cap around the wah pot , and the 0.01cap is 0.022. But in mine the values seem to be like classic crybaby

.

I noted That pedal is really noisier than my Dunlop 535Q. transitors are MPSA18.

Dr Tony Balls · Post by **Dr Tony Balls** » 21 Jul 2009, 17:40

wow.....so giving it a once over, the GCB-95 schematic seems to be about the same as the original Vox Clyde, minus some value differences. I just bought a crazy cheap crybaby on ebay this morning, so i'm looking forward to trying to return it to (approximate) vox specs.

crybaby: https://i532.photobucket.com/albums/ee3 ... 1248197982
vox: http://fuzzcentral.ssguitar.com/mccoy/m ... ematic.gif

One question:

Does anyone know what has changed with the gcb-95 over the years? Ive found a number of schematics online and all of them seem about the same. were there ever radical differences from that one schematic?

Bside2234 · Post by **Bside2234** » 21 Jul 2009, 18:16

Rev. C and earlier did not have an AC adapter jack ('89 and earlier); Rev. D incorporated an AC adapter jack ('89 - '90); Rev. E was the first to have pc-mounted jacks ('90 - '91); Rev. F incorporated buffered circuitry for improved performance ('91 - '92); Rev. G switched to the coaxial (barrel -style) AC adapter jack ('92 - present). You can determine the revision number of your Crybaby pedal by looking at the bottom of the PC-board (you may have to remove it from the housing to look under it) and look at the ECB-25 (letter), this represents the revision number of the pc-board. If there is not an ECB-25#, then you have a Crybaby manufactured earlier than 1990.

devastator · Post by **devastator** » 21 Jul 2009, 18:32

any marks on mine, just REV.C and Dunlop wrote in the top of track side.

lolbou · Post by **lolbou** » 21 Jul 2009, 19:37

My pcb is rev c with ac adapter too (around 1990 then)...

I does have the capacitor on the pot and an extra diode added on the inductor corner resistor. An hendrixian mod, really?