Crybaby original to jerry Cantrell mod?

[Chris oej]

yeah it is true bypass (that's what the 5 or 6 components on the left of the board are. the brown wire goes to the 5k pot which works as a kind of tone control.

[joegagan]

so, is that 5k pot wired between the ground lug on the wah pot like this thread suggested?

the dearmond 1800 wa-wa volume from 73 74 was mostly a boomerang clone, but had better biasing on Q2 and a 330 ohm resistor between the ground lug on the 30k wah pot. paul marossy has also discovered that some replacement pots in boomerangs can have the treble side scratch remedied by this same resistor placement. makes me wonder if dearmond added this R to solve pot consistency probs. richard mintz of all test devices has reported that he had huge consistency problems with the centralab 25k pots that gibson made him use in the 60s/70s boomers. he had to reject many due to noise probs.

(BTW i have also found some boomerang replacement 25k pots to have this same defect on treble side, must be something to do with he way the traces are manufactured.)

sorry for the derail.

[Paul Marossy]

the dearmond 1800 wa-wa volume from 73 74 was moslty a boomerang clon, but had better biasing on Q2 and a 330 ohm resistor between the ground lug on the 30k wah pot. paul marossy has also discvoered that some replacement pots in n boomerangs can have the treble side scratch remedied by this same resistor placement. makes me wonder if dearmond aded this R to solve pot consisteny probs.

Yeah, I suspect that is the reason why they put the 330 ohm resistor in the circuit. That works fine AFAIAC.

[zombiwoof]

Here's the pic of my friends Jerry Cantrell. As you can see, it's almost identical to the GCB-95

http://i728.photobucket.com/albums/ww286/chris-oej/lpb1/jccrybaby.jpg

I can tell from the way the DPDT is wired that it is wired for true bypass, but it isn't the method that I prefer, which is the one that disconnects the board input in bypass.  Still it is true bypass wiring.

There is an article on bypass on the Dunlop Blog pages that lists every pedal they make, and what type of bypass they have.  This is Dunlop's wording for the bypass on their pedals:  if it says in the description that it is "hardwire bypass", it is not really true bypass - if it says "true hardwire bypass", it is true bypass.  Their wording is somewhat misleading, and some guys think their pedal is true bypass, when it is really just "hardwire bypass", which is the same old tone-sucking bypass that the vintage wahs had.  However, usually those pedals have the input buffer that is Dunlop's cure for tone-sucking.  Some of the "signature" wahs have true bypass and some don't, I assume that the artist picks which type he wants in his sig wah.  I'll try to post that article, if I can find it.

Al

[Chris oej]

I've done the mods. The 12nf cap sounds awesome. However, the tone knob (4.7k) doesn't work. Instead it works as a volume knob. Is this because I removed the input buffer when I true bypassed it?

[ChanchoPancho]

Here's the pic of my friends Jerry Cantrell. As you can see, it's almost identical to the GCB-95

http://i728.photobucket.com/albums/ww286/chris-oej/lpb1/jccrybaby.jpg

From the picture i noticed every resistor and pot value is the same as the gcb95, i can see the two 0.22uF caps which i believe are C6 & C8 from gcb95 pcb.
The other cap values remain unkown. My main question here is: Are you sure that c5 (12nF) is making a real change in the pedal tone? original is 10nF and this change will lower the gain and also the frequency response, but i think it'll be very subtle.
can you look at other cap values? and confirm that they are the same values as the gcb95? I don't know if you already did it.

[joegagan]

a 20% change in c5 can be quite drastic.

[DiscoVlad]

There may have been a schematic (and other gutshots) posted either here or the... other site
But anyway, this:



shows the effect on the frequency response - that of lowering the sweep range, changing that cap from 10nF (green line) to 12nF (blue line) makes to a standard crybaby...

Albeit with a few caveats (different transistors - which aren't the thing under consideration anyway, R25/R26 represent the potentiometer at some position in the sweep, which just happened to centre around 1kHz... lucky guess ).

[ChanchoPancho]

i modded my wah. Changed C5 and instead put a on-off-on dptd switch to select different C combinations.
In the off position I put a 12nf Cap. In the other switch pins I used 8.2nf & 22nf. So i got 3 combinations

on 1: 12 + 22 = 34nf
on 2: 12 + 8,2 = 20nf
off: 12nf

I liked it better with 20nf.