Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #157495  by chipperj
 Mon Jul 17, 2017 11:01 am
Hi all,

I'm having an issue with a ground loop hum in my rig, and I think I've narrowed it down to the OBEL breakout box (Hub Bub). I unplugged all the pedals, and then started at the tuner and successively added pedals in. There was no hum until I returned to the Hub Bub. In other words, if I just plug the output of the guitar straight into the input of the Hub Bub, going through all the pedals, and then straight out of the last pedal, I get no hum. But as soon as I return to the Hub Bub and then go out of there to the amp, I get hum.

Does this sound familiar? Is the loop in the box or the guitar? Anyone have any ideas?

Thanks a ton!
 #157497  by chipperj
 Mon Jul 17, 2017 12:42 pm
Can you test by going out of the hub bub and directly back into the hub bub w/out connecting any pedals? Just connect a cable directly from send to receive?
Yep, did that, and no hum.
Just now, I took the breakout box completely out and just plugged my guitar into the 1st pedal and out the last. No hum.

Also, before I took the HubBub out of the chain, I plugged a non-OBEL guitar into it and it still had the hum.
 #157498  by lovetoboogie
 Mon Jul 17, 2017 1:36 pm
Make sure your signal and ground is phased properly on the OBEL out jack on the guitar. I don't quite know what a HubBub is but I am assuming it's like Jerry's early network box from the Travis Bean days. Using a DMM you can check for signal continuity and ground continuity. Make sure the in, out and send and return on the HubBub are equivelent to the hot and ground from the OBEL jack...

As well as make sure all jacks on the HubBub are grounded in phase...

Hope this helps

 #157500  by kurt eye
 Mon Jul 17, 2017 6:42 pm
I recommend checking the jack for the the loop return on your HubBub. Make sure the nut is nice and tight and there is good bare metal contact.

Also test the cable that went from the last pedal in your chain to the HubBub. I assume this is a different cable than the one you plugged directly into the amp in your troubleshooting?

I just reworked my pedal board and had to troubleshoot and test each of my D'Addario Planet Waves cables (the ones where you cut the cable to length and secure the plugs to the cable with a set screw).