GCB-95 Crybaby Wah Mods

phil esposito · Post by **phil esposito** » 24 Mar 2011, 13:28

Hi All,

I'm a bit of a noob at this so I'm hoping some one can give me a quick answer. I've done the mod's as listed:

http://www.diyguitarist.com/DIYStompboxes/WahMod.htm

390 - 330
1.5K - 1.8K
33K - 47K
.01uF > .022uF

I haven't performed the true bypass yet but plan to.

I'm getting some nice results. However, I'm still getting a sharp peak on the sweep from bass to trebles. Someone described it as the peak of the mountain be too high too quick which is a good anology.

I'm curious if that sharp peak is due to the original inductor being not so great? I'm going to socket the resistors and try to see if I can flatten it that way.

Thanks!!

Post by **azrael** » 24 Mar 2011, 15:49

Try raising the 1.8K more, to maybe 2ish kilo ohms.

Also, try reindexing the pot. That is, change which part of the taper it rotates through by physically moving the sweep a bit.

phil esposito · Post by **phil esposito** » 24 Mar 2011, 17:47

azrael wrote:Try raising the 1.8K more, to maybe 2ish kilo ohms.

Also, try reindexing the pot. That is, change which part of the taper it rotates through by physically moving the sweep a bit.

Thanks for the reply! I'll try that this eve and give you an update.

I was doing some more digging...from what I can gather it is the 1.5k resistor, Q1 transistor, or a bad pot. Maybe I'll try to do a sound clip if the resistor change doesn't help.

alnico · Post by **alnico** » 24 Mar 2011, 18:35

Put the 33K back if you want it less peaky?

phil esposito · Post by **phil esposito** » 24 Mar 2011, 18:51

alnico wrote:Put the 33K back if you want it less peaky?

Thanks! I just read that....I think I'm going to put it back to see if that helps. It was peaky before I made the made changes so that tells me there is probably something more to this.

D-Day · Post by **D-Day** » 24 Mar 2011, 19:18

Don't know if you read this one but I figure it can't hurt to link it up: https://www.freestompboxes.org/viewtopic ... &hilit=gcb

phil esposito · Post by **phil esposito** » 24 Mar 2011, 20:13

D-Day wrote:Don't know if you read this one but I figure it can't hurt to link it up: https://www.freestompboxes.org/viewtopic ... &hilit=gcb

Thanks! I've read that and now I'm thinking I might have to change the Q1 transistor...I'll have to see what I have in the parts bin for a sub. I know BC109 is the popular choice. Is there any alternates that people have used?

It seems most people bring the 33K resistor up in value and I'm having to go the other way...that makes me think I've got a different problem.

phil esposito · Post by **phil esposito** » 25 Mar 2011, 02:05

OK....so i've done a few more things and it's helped.

Re-indexed the pot.
Added TB.
Socketed the components for easy change and ended up with:
Lowered 33K > 22K
Raised 1.5K> 2.7K

This seemed to flatten the spike....however it could be smoother!!!!

I measure the transistors and
Q1 = 460
Q2 = 580

This seems a little high...I'm thinking I'm going for the BC109's....and then of course...a new inductor.

What have I started???

Mark_McQ · Post by **Mark_McQ** » 25 Mar 2011, 23:15

I put BC109's in mine recently. Made a huge difference. One of the few mods I've done that was immediately noticable. Made my fasels sound more 'full' too.
Got a vid here. Not the best quality, but gives a rough idea:

phil esposito · Post by **phil esposito** » 08 Apr 2011, 10:36

Mark_McQ wrote:I put BC109's in mine recently. Made a huge difference. One of the few mods I've done that was immediately noticable. Made my fasels sound more 'full' too.
Got a vid here. Not the best quality, but gives a rough idea:

Wow, sounds great! Nice job!

I've gone the full meal deal so far. I put in a Whipple, new pot, LED, and trim pots. I've got some BC109's on order so we'll see how that looks when they arrived.

I had an idea for the cap change (100n - 220n). I'm building a rangemaster clone and borrowed the idea of the tone pot for the 2 input caps: http://www.madbeanpedals.com/forum/inde ... pic=1165.0

I was thinking of doing the same for the cap on this...anybody try that move??

Satchmoeddie · Post by **Satchmoeddie** » 10 Apr 2011, 21:02

First I would try re-indexing the pt. This is done by taking the rack and loosening that strap that keeps it against the gear loose and turning the pot by hand so it does not go as far in the treble direction. My last mod used 4 inductors and lots cermets I can get to through small holes in the bass. I got a working regular crybaby for $15 with a bad on off foot switch. Since that and the buffer section get sacked straight away I had hit the jackpot. My other two are a really old European Clyde McCoy with the metal TO-18 housed transistors, and an old Thomas. Neither worked when I got them. The board in the Thomas is very brittle and tracks have come off everywhere. I used cat6 Oxygen free data cable to run between where the tracks came off. Wahs are pretty easy to work on. Maybe put a pot in place of the resistor in question and dial in what you like and buy what is close, or put the pot bushing through the side so you can adjust it. The mods for these are numerous, and endless.