FIF : Troubleshooting A Noisy Signal Chain
January 19, 2021 12:50:00 PM PST January 19, 2021 12:50:00 PM PSTth, January 19, 2021 12:50:00 PM PST
At some point or another, we have all had an issue with unwanted noise coming through our gear. Whether the source is a bad cable, or crackly pot, or even just the inherent 60 cycle of hum of a single coil pickup, it is typically undesirable -- luckily, this sort of thing is manageable more often than not.
The fact is, there are so many elements bombarding our signal chain at all times, and they change from venue to venue, guitar to guitar, pedal to pedal, etc. Today we will discuss a few of the more common sources of noise and ways to help eliminate said noise -- serendipitously, this article should double as a general best practices outline for maintaining an efficient and healthy rig.
We have all played at that venue that notoriously has "bad power" or "dirty power," so we know that this is a real life issue. Unfortunately, we don't have time before every gig to commission an electrical team to rewire the whole building so we need to be as prepared as we can.
Amps with ground lift switches can prove useful here (See Image 1A), but this is not always a sure fire win. If you are experiencing a bad hiss at a new venue, try giving your ground lift a chance to shine -- hopefully this can do the trick in a number of places, but if not, it's time to take more drastic measures.
When it comes to touring and playing at multiple venues all over the map, it's always better to be safe than sorry, and to leave as few things up to chance as possible. This is why I always connect my pedal chain and amplifier (as well as any auxiliary electronic gear) through a well-built power conditioner. These often come as rack units and have multiple power inlets that provide clean(ed) power for your devices. The goal of a power conditioner (as, yes they are very often successful) is to not allow any excess noise to get from the venue's power into your rig's power. Furman makes different models of power conditioners that typically run anywhere from $50-$100 and are well worth it (See Image Below).
Pedal Chain and Cables
If you know you are running the cleanest power possible into your rig, and are still getting too much noise, it's time to move on to the next big bullet point -- pedals and cables.
Let's start by running our guitar straight into the amp and totally bypassing all of our pedals. If you're bypassing your pedal chain and the same noise is still present, you may have an issue with either the one cable you are currently using, or the guitar (but we'll get to that in a minute). However, if the signal cleans up and the noise disappears, we have a potentially long journey ahead of us depending on how many pedals and patch cables we have to sift through in order to find the culprit(s).
At this point let's connect back through our pedals and start removing them from the signal chain one at a time. If at any point, you remove a pedal (and its corresponding patch cable) and the noise stops, we have found the wicked one and it's time to do some investigating. First, try using a different patch cable to see if this particular cable is introducing excess noise. This can happen when cables are too long for the application or when they are not well-shielded.
Best practices note : using well-made, well-shielded cables (that are only as long as they need to be) for your patch cables, instrument cables, and speaker cables, is always always always recommended. Yes, they cost more, but they last longer and provide a much cleaner signal.
If changing out cables does not do the trick, then it may be time to have someone look inside the pedal. A number of things can happen inside a pedal, especially depending on how protected it is during travel, how much it's getting moved around, etc. A tech may change out the input and output jacks, double check all grounding points, or any number of techy wizardy things -- this should hopefully eliminate the unwanted noise. In the end, some devices are just inherently noisy and there is not a whole lot that can be done about them. If this is the case, you'll have to decide if keeping that particular pedal in your chain is worth the added noise -- sometimes it is, sometimes it isn't!
Guitar : Bad Ground and Shielding
Once we have eliminated the above, it is time to move on to our guitar. Now, bear in mind, if you are playing a guitar with single coil pickups in it, you will pretty much always notice your 60 cycle hum when you aren't in a hum-canceling pickup switch position. If this is the case and you still want to get rid of the noise, I suggest you check out Mojotone's Quiet Coil line of pickups.
If your issue is not an inherent 60 cycle hum from single coils, you can keep moving on down the checklist with me! Now, when we are on stage playing, our guitars are being berated with signal demons such as flourescent lights, wireless microphones, etc. All of these things can and will find their way into our signal if we let them. This is why shielding the inside of your guitar's control cavity is paramount. If you remove the screws from your guitar's pickguard or backpanel, and take a look inside, you may or may not notice that certain areas are covered in what looks like aluminum foil. This is our shielding, and it is used to prevent all of that weird static from lights and wireless signals from bleeding into our sound and finding its way out of our amplifier. In Image 3A below I have removed the back-mounted control panel cover from my guitar to demonstrate. Notice that the actual plastic panel itself has aluminum shielding tape covering it, but the floor of the control panel does not. Some guitarists/techs prefer to go the extra mile and apply shielding to as many areas as they can, even including the bottom of the pickup routes. If you want to try going this route, you can use copper shielding tape or aluminum shielding tape, either will do the trick -- have your tech install it if you'd like, but this is a pretty straightforward job that simply involves cutting strips of tape and lasying them in the areas of your choosing. If your guitar currently has absolutely NO shielding, this is something that must be addressed -- at the very least try to get some on the back of your pickguard or back-mounted control panel cover.
While we have our controls exposed, we might as well do a visual check for some obvious signs of a bad ground connection, as this could also be causing our noise. In Image 4A below, you will see a picture of a potentiometer with wires soldered straight onto the metal on the bottom of the pot. This is typically a grounding point for guitar electronics, so just make sure that none of these wires are disconnected, and you can even check for an obviously poor solder connection. Having your tech fish around inside the control panel is always a good idea as well, they will be able to test a number of points and check multiple connections to make sure everything is in pro shape -- there are a number of things in the control panel that can potentially introduce noise into your signal.
This last checklist item will be quick and easy...which is why I saved it for last. If you have checked every cable, every pedal, you're running your devices through a power conditioner, your guitar is shielded and well-grounded, and you've had your tech look at your rig a thousand times all to no avail...please just check to make sure you don't have a cellphone or iPad sitting on top of your amp or in your pocket. Yes, that seems silly and simple but I cannot tell you how many times I have had friends come to me at a gig complaining about weird noise coming through their rig only to walk over and find a phone full of brand new text massages sitting right on top of their amp. This is an easy one to take care of, so just double-check before crying wolf!
Alright, so that was our rundown for the day. This should cover pretty much anything that comes up, but if for any reason you are still experiencing inexplicable and undesirable noise coming through your gear, it may be time to have a tech thoroughly inspect the entire setup. I know it can be a pain, but it is well worth it if you want to have a clean and professional setup. Thnaks for reading this installment of Fix It Friday -- we'll see you next time!