Wednesday, 4 February 2015

GCB-95 Crybaby Wah MODS

Another big one! Here is the famous crybaby GCB-95 wah pedal. A lot of people have this one, therefore, even more people are looking to mod this thing until the cows come home. A simple google search delivers a wide array of mods that is enough to boggle the mind of anybody trying to choose which ones to do. 

I'm not doing anything revolutionary here but I did some common mods that, in my opinion, sound great! The general theme behind all of these mods is that they push the circuit harder and drive the transistors to work harder than they should. Some resistor values are lowered to increase the gain going into the transistor, effectively increasing the gain of the circuit. This however gives a great sounding wah sound!

Here are some pics of the changes I did to the board:

There's a nice little picture of the PCB. There are some variations between the different years. I believe this is one of the most recent GCB-95's. 

R5: Changing this will change the Q of the effect. The Q is the width of the bandpass filter. Lower resistance, more subtle wah sound. Higher resistance will give you a sharper more vocal wah.  
Stock: 33k
Mods: -47k
           -68k  -  (This is the one I choose) 

R1: Increasing this will smooth out the transition between heel to toe. Sometimes the stock wah can transition quite rapidly and doesn't sound too good. This should smooth out that transition and increase the mids.  
Stock: 1.5k
Mods: -1.8k
           -2.2k  -  (This is the one I choose)

R9: This resistor change will increase the gain of that transistor and add more bass response.
Stock: 390ohm
Mods: -270ohm
           -330ohm - (The one I choose)

R15: This is the input resistor. Therefore, if you decrease it, more signal will pass through the circuit and as a result, it will give it a little volume boost
Stock: 68k - (I stuck with this value because I found it had no huge difference with the 47k)
Mods: 47k

List of mods done on my wah:

  • Resistor       Stock        Mod
  • R5               33k           68k
  • R1               1.5k          2.2k
  • R9               390ohm    330ohm
  • R15             68k           68k

Everybody has their own preference of wah pedal. I like the way mine turned out, but I encourage you try different values and find out what works well with your rig. In general, all of these mods increased the gain going into the transistors. You can definitely hear the difference, my wah sounds more vocal, louder, and more gainier.

Happy modding!

Tuesday, 27 January 2015

Been a long time

1 year and 2 months,
or  28 fortnights if your into that kind of stuff.
That is how long it has been since I've last posted on this blog. 

I'm not too sure why I stopped posting. To be fair, it has been a pretty long and strenuous school year. But I'm sure most of you care not for it. In this new year I want to start this back up again. but with a little twist...

As much as I enjoy building guitar pedals, and will continue to do so, my focus has shifted onto another realm of audio...recording. In the time since I've last posted, I obtained the materials needed for a nice little analog home studio. I've translated some of the stuff I've learned from building guitar pedals to this other side of audio electronics. I still want to keep this blog alive but I think the name might not be fitting for the new stuff I want to post.

I really just wanted to give the frequent viewers of the site a little update. I'll be definitely posting some very exciting stuff, very soon. Stay tuned!

Analog on,