Modding a Crybaby CGB-95 to buffered bypass

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
Post Reply
User avatar
Silvio55
Information
Posts: 11
Joined: 03 Jul 2014, 21:09

Post by Silvio55 »

Hi! I have a bunch of pedals, all of them are true bypass, except for the crybaby that´s hardwired bypass. The problem I have is that I need a buffer in my effects chain, with all the pedals off I notice a loss of high end, istead of buying or building another pedal/buffer, I was wondering if I can use the input buffer of the Crybaby as an "always on" buffer. Here´s the schematic:
Image
I'll have to add a cap between the end of the buffer and the 68k input resistor, make that cap the output of the buffer, and put the switch conection after that cap. But my question is if the Crybaby input buffer good for this or it´s not a good buffer for my effects chain? Thanks in advance!

User avatar
mictester
Old Solderhand
Information
Posts: 2915
Joined: 11 Sep 2008, 20:29
my favorite amplifier: Mesa Boogie, Roost Sessionmaster, AC30
Completed builds: Hundreds! Mostly originals, a few clones and lots of modifications.
Location: Somewhat closer to Amsterdam than before!
Has thanked: 32 times
Been thanked: 825 times
Contact:

Post by mictester »

Take your buffered bypass signal from the emitter of the buffer stage through an electrolytic capacitor (4µ7 should be enough). The input to the wah filter shouldn't load down the emitter of the buffer if you want to leave it in circuit, but to be absolutely rigorous, you should disconnect the input of the filter stage. The input buffer there will be perfectly good enough - it has a good high input impedance so that it won't load down the guitar, and a reasonably low output impedance, so it will be able to drive cables.
"Why is it humming?" "Because it doesn't know the words!"

User avatar
Silvio55
Information
Posts: 11
Joined: 03 Jul 2014, 21:09

Post by Silvio55 »

Thanks mictester! Yeah, that was my idea, to disconect the inpunt of the wah filter with the bypass switch, the pedal already has a DPDT switch, so it´s easy to completely bypass the wah filter circuit.

User avatar
Silvio55
Information
Posts: 11
Joined: 03 Jul 2014, 21:09

Post by Silvio55 »

I have a question: what would be the output impedance of that buffer?

User avatar
mictester
Old Solderhand
Information
Posts: 2915
Joined: 11 Sep 2008, 20:29
my favorite amplifier: Mesa Boogie, Roost Sessionmaster, AC30
Completed builds: Hundreds! Mostly originals, a few clones and lots of modifications.
Location: Somewhat closer to Amsterdam than before!
Has thanked: 32 times
Been thanked: 825 times
Contact:

Post by mictester »

Silvio55 wrote:I have a question: what would be the output impedance of that buffer?
Roughly 10k - the same as the emitter resistor.
"Why is it humming?" "Because it doesn't know the words!"

User avatar
Silvio55
Information
Posts: 11
Joined: 03 Jul 2014, 21:09

Post by Silvio55 »

Thanks again!

Post Reply