Troubleshooting a noisy guitar rig
You might be surprised by noises, humming, unexpected grit, and the wrong kind of distortion when you take your guitar rig to a new place. For the touring guitarist, your overall tone can change night-to-night depending on a host of varying factors.
As you grow, you learn to troubleshoot your guitar rig to keep everything running cleanly and to squash any issue that might arise from a change in venue. Here are some troubleshooting tips for noise, humming, buzzing, the bad kind of distortion, and more.
When it comes to troubleshooting, it's important to isolate the issue. Isolation is the act of pairing down to pinpoint the root cause of a problem in your signal.
For many guitar rigs, the most efficient form of isolation is to start with the guitar straight into the amp, with an excellent power source and separation from interference of various kinds. Listen to your rig in this state to determine whether the issue is gone or not.
For example, I went to play in a church's student building several years ago and my amp made new noises I had never heard before. As it turns out, I had set my amp up below a massive TV screen and the noise I was hearing was interference (whirring and hissing).
I moved the amp to fix the issue for that worship service, but I was able to shield the amp later on using copper tape to fix the issue longterm.
In some large guitar rigs, the more efficient method of troubleshooting would be to split halves. Split halves troubleshooting is where you take a large group of components, split them in half, test for the issue, split them again, test again, split again, test again, on and on and on.
You do this until you're down to only two components, one experiencing the issue and one working properly. Some guitar rigs are so large and complex that it's inefficient and difficult to plug guitar straight into the amp and add back links in the signal chain one-by-one.
Split halves troubleshooting might be utilized to isolate an issue in a massive touring rig like that of Josh Klinghoffer from the Red Hot Chili Peppers. His signal chain is guitar via wireless unit into buffered splitter into stereo mixer into effects sends and returns into three amplifiers into cabs in an isolation area behind the stage.
To undo all of that and run guitar straight into amp would be a nightmare, and it'd be impossible to add back many of those components one-by-one, not to mention all of the time that would take when he and his guitar tech are under the gun to soundcheck quickly.
Most of the time—fortunately—at each stage in a complex professional rig like that, there's a way to defeat the stage before. For example, with an RJM Effects Gizmo handling the effects sends and returns, you can simply pull an effect out of the signal path by disengaging that loop, and all other loops will function normally.
Now that we've discussed two methods of troubleshooting, let me give you a sort of quick-and-dirty how-to to get started troubleshooting your own rig.
Starting with excellent power, that is, a fairly regulated and modern voltage with conditioning against surges and spikes, and with isolation from interference, you need to make sure that all of your gain stages are in proper order.
Signal leaving the guitar: Do you have active pickups or a preamp? Do issues persist in passive mode? Are you due for a battery change? Have your pickups been raised or lowered drastically recently? Your output jack—is it working correctly? Wiggle the cable around and listen for pops, crackles, or scratchiness. Any damage to your lead?
Signal entering a wireless unit: Your guitar lead to body pack can suffer strain. Does it have any knots, humps at the connector, exposed wire, or creases? The body pack: Batteries charged? Dialed to the right frequency?
The wireless unit is highly susceptible to interference from radio signals and other units. Try scanning for a new channel (if you're able) to find a setting with less noise, or consult your wireless tech at the gig (if they've got a dedicated wireless tech).
Only run wireless if you simply must. Cables will always sound and hold up better with way less fuss. I recommend that you never ever use digital wireless (Shure GLX-D) as it is highly susceptible to interference from interference from 2.4gHz (wi-fi) sources.
Signal hitting the front end of your amp: Do issues persist when you crank the master volume and lower the input volume (if you have a master)? Are you running straight in or do you have any pedals? Are the pedals boosting gain? Are their gain stages set as cascading?
Take away all of your pedals. Is the noise gone? Add them back one by one if you can. Does the noise return? With which pedal or patch cable? I'd recommend buying a cable tester. I have one from Behringer and it has saved me so much time before the gig on several occasions.
Signal at the power stage: Do issues persist when you open up any sort of power scaling or voltage limiting on your amp? Do you have an attenuator? Is it set correctly? Better check tubes—do any of them look like a blown lightbulb?
Signal at the speaker stage: Are you powering your speakers correctly? Are you using the right ohms for your cabinet? Are your speakers blurting or farting? Are they damaged or blown? Are they properly connected? Are you using the appropriate ohm rating for your cab? Do you have anything plugged into the amp's line out?
Hopefully these tips and steps will save you one day in the future! Reach out to me if you've got any further questions—I'd love to help. Or just talk tech.