New member here with A/B box questions!

[xxxplorer]

Hello everyone,

I have frequented this site several times over the last few years and found it to be a great source for information when trying to fix stuff or mod it.

I have modded a few crybaby's, a few boss sd-1s and a big muff or two.  Decided I am better at playing than modding lol. 

My question is about a/b boxes.  I use a Marshall JCM800 for my dirty tones, and a Roland JC-120 for my clean tones.  I made the a/b box that is all over the web like on fulltone's site, beavis audio, and apparantly the same layout even Eric Johnson uses.  I don't use both amps at the same time, so I have no need for a/b/y or anything else.

I built it, it SEEMS to work, but if I set it up to: guitar - a/b box - Side A - overdrive and marshall - side b - tuner and JC-120, I get some weird stuff going on.  First, if I switch the overdrive on while playing clean through the JC, there is a buzz and noise.  Second if I keep the overdrive on and hit the tuner while on the clean side, you can hear some sound coming throuh the marshall side.  I'm guessing the switch or something has some crosstalk or something isn't grounded quite right, but I tested with a multi meter and all seems good in the switch.

I tried it with several different amps, overdrives, and even guitars and cables.  Same results.  Any ideas?  Thanks a bunch!

[CurtisWCole]

Did you ground the inputs of the amp not in use? Also ground loop issues can make a mess. So look into grounding the inputs and try plastic jacks or a more complicated hum free aby over at geofex.  I might be way off so take my advice with a couple grains of salt.

Curtis

[xxxplorer]

I ground the input of the amp not in use yes.  Used a Carling dpdt switch.  I will try some plastic jacks. for the outputs, I did search here and see some people use those.  Thanks for the input.