Chasing Down Noise Problems

In a perfect world, running all of your gear off of a unit that's supplying good, clean, consistent power and having everything on a common ground would eliminate noise issues. Unfortunately, from venue to venue and room to room there will still be a time you'll have grief from something not being 'properly earthed.' I'm thankful that for the last couple of years, my main use for those little gray ground lift adaptors has been to make up for the lack of rubber feet under one of my amps. Although, on things like TV appearances where I typically just have a few stompboxes instead of my rack, I still may have to lift an amp or two so that they'll play well with others—no big deal.

As I mentioned last column, we most recently had Brad’s rack rebuilt by David Friedman of Racksystems. Now for quite a while after having the rack rebuilt, we were noise free. Even when we quite a bit of gain dialed in on the amps, they wouldn't be any noisier than if they were sitting idle with no input.

Then one day, out of nowhere, the noise came. There seemed to be no getting rid of it no matter what I tried. The cleaner sounds had ground buzzes, and the distortion patches were all but unusable. Even the wah pedal would vary from not very good to terrible. As I'm sure you all have experienced, ground problems are some of the worst to track down. They seem to come from anywhere, and it feels like the slightest little thing will cause them. I'm not the type of person who just accepts things and moves along—I have to fix it. I just about drove myself crazy looking for an answer to why my brand new rig was noisier than the old one. I was searching at every show from the time my gear was set up until soundcheck with no luck. Nothing worked, nothing helped and I successfully shocked myself three times.

There had been no change in the rack whatsoever, so I could rule that out. I tried ground lifting each amp and the rack one at a time with no luck. To make sure I wasn't overlooking something, I talked through every step of my entire routine with our monitor engineer Mark Gould. I remember telling him that I had even tried lifting the wireless and it either made no difference at all or it was worse. I had just about settled into the idea that there was a cable going bad, and to make it all the worse, that it was somewhere inside of the rack.

Now that I’ve brought up the wireless, I have to address two things. First, the Shure UR4D wireless has a ground lift for each channel on the backside of the receiver—and flipping this switch didn't help either. Second, I have another UR4D receiver for my acoustic guitars mounted in my workbox. Both electric and acoustic wirelesses share a pair of paddle antennas by way of Shure's antenna combiner. This was the only connection that these two wirelesses have, and even breaking that caused no improvement.

By a sheer stroke of genius, Mark took the two acoustic wireless output cables and disconnected them from the sub snake. Just like that, my rig was dead quiet! Two cables that have absolutely no direct contact with my guitar rig had caused me more grief than I've ever endured in my ten years of touring.

Now this is where it gets interesting. There was nothing wrong with these mic cables at all. The problem was elsewhere. Have you ever, in an effort to keep noise levels down, grounded your fourth pin on an XLR connector? You jump your ground wire over to the fourth lug, which is generally left open and sometimes it can quiet down a noisy mic line. These had been wired this way from the factory, I'm certain for the same reason, but none of us had ever dreamed two centimeters of wire would cause such a massive ground loop through my amps. Just like a vasectomy, one quick snip made all the difference in the world. Thank you again Mark for all your help!

So remember, next time you have some noise issues and you've exhausted every avenue you can think of... it may not be your rig.