Why Does My Pedalboard Hum, and How Can I Fix It?

Pedalboard hum can be one of the most frustrating and annoying issues to deal with and diagnose.

Let's set the scene. You've just spent hours building your ideal pedalboard, plugged everything in ready to dial in your dream tone and as soon as you hit the power switch on your amp, you're greeted with a loud hum.

Pedalboard related noise can be a low frequency drone or a high pitched sharp buzzing sound. Regardless of the type, it becomes a frustrating mess very quickly.

In this article we're going to look at the different types of noise you might experience and learn how to diagnose and eliminate them.

Identify the Type of Hum

The first step is to work out which type of hum you're suffering with. Knowing what the issue is will be the first step in resolving it. Although hum and noise is a very broad spectrum of things, we can mostly group this into 3 main categories:

• 50 / 60 Cycle Hum: This is a low pitched hum that is caused by alternating electrical current at 50Hz per second (Or 60Hz per second in the US). This can also be caused when situated too close to power lines.
• Buzz: This is a little more aggressive and higher pitched. This is often caused by digital interferences or grounding issues.
• Ground Loop Hum: This is caused when multiple devices are trying to reach ground through different paths. This is common in older buildings where various power outlets have different ground potentials.

To also help you diagnose the type of noise and the source of the noise, you can troubleshoot segments of your rig with a few simple questions:

Is the hum always there or does it change when various pedals are switched on or off? 

If the hum is persistent, it would imply a wider power issue, more likely a power issue relating to the power source itself rather than your specific pedalboard. To figure that out, test your rig in another room with a different power outlet, or if possible, a different building.

If the hum goes away when certain pedals are switched off, that could be a more localised issue with that specific pedal.

Does the hum go away with the guitars volume rolled back?

If the hum goes away when you roll the guitar volume down, this could be related to an interference issue, or a grounding issue on the guitar. Check that your grounds are connected properly and that your pickup cavity is correctly shielded. Single coil and p90 loaded guitars are more prone to this sort of noise.

Does moving your rig or pedalboard to another room, or power outlet, fix the issue?

If the answer is yes, the issue is a power supply issue for the first place you tested. If the answer is no, this could be a wider power issue, or an issue with your rig. This is where you can start troubleshooting individual segments of your rig by pulling things out one by one to see if that resolves the issue.

Common Causes of Pedalboard Hum

Now that we've talked about a few of the types of hum you might experience, it's time to figure out what actually causes these issues to manifest in the first place. Thankfully, a lot of the reasons are common things that you'd probably experience on a day to day basis which makes it easier to figure out how to fix it,

Ground Loops

This is a very common noise issue for most guitarists. If you're a gigging guitar player, you will most likely have encountered ground loop issues when playing in older venues.

Ground loop noise is caused when devices are grounded through multiple different grounds, instead of a single ground. This often happens when plugging different pieces of your rig into different power outlets.

Type plugging everything into the same power source, or using a power conditioner with ground filtering built in.

Non-Isolated Power Supplies

When building a pedalboard, having an isolated power supply is very important. An isolated power supply allows each pedal in the chain to have a dedicated source of power. While non-isolated supplies, and daisy chain style supplies are cheaper, they are more prone to noise issues.

When pedals share power off a daisy chain, they can often introduce noise to the signal path. This is especially true with some digital pedals.

 Always use a high quality power supply with isolated outputs to minimize this risk.

Poor Quality or Damaged Cables

When it comes to tone, and noise issues, we often overlook the humble cable. Something so simple, yet essential, can create a world of problems when it is not performing the way it needs.

If you are using a cheaper unshielded cable, or a cable with significant damage,  you are opening the door for a plethora of potential problems. Cheap cables with poor shielding can introduce noise.

Always try to use the highest quality cables you can and ensure they are shielded for maximum interference rejection.

High Gain Pedals

We all love gain pedals. It's in our blood as guitar players, but we do also have to accept the reality that gain introduces noise. The more gain we use, the more noise risk we face. Higher gain and fuzz pedals can considerably boost noise issues.

This isn't to say that these pedals are the sole cause of your noise, but if you have noise issues, a fuzz is going to make it more obvious.

Try adding a noise gate after the high gain pedals to catch any noise created by the pedals. Some noise gates will also have a built in loop that you can run gain pedals in.

Pedal Placement

This might not be an obvious one, but it's worth considering. Sometimes, the placement of pedals and their proximity to other pedals can cause issues. For example if you have a fuzz pedal on the board, which are particularly sensitive to interference, and you have this next to a digital delay, in some cases they can interfere with each other. 

This is not a set in stone rule, but just something simple to be mindful of.

Electromagnetic Interference (EMI)

EMI causes a high pitched interference, often with a slight beeping sound to it - If you grew up in the 90s, think of the sound of dial up internet! EMI is caused by anything that emits electromagnetic radiation. The good news is, your home is FULL of things that do.

Your wi-fi router, laptops, desktop PC, fluorescent lights, screens and more.

Try not to position your board too close to anything that emits a major source of EMI.

Troubleshooting Your Pedalboard

If you find the issue is being caused by your pedalboard, the next step is to isolate the issue on the board. This can be done by running a few tests:

Start Minimal

Plug your guitar straight into your amp with no pedals. Is the hum still there? If not, start by plugging in one pedal at a time, in the intended order, until the hum appears. Once you find the pedal causing the hum, remove it from the chain, keep adding the rest of the pedals to see if the hum comes back. If not, then the issue is with a specific pedal, this might need a repair/modification.

Use Batteries

Sometimes, as we mentioned earlier, your power supply can be the culprit. To test this theory, run all your pedals on batteries. If you use a very large pedalboard, this can be an expensive test to run because 9v batteries aren't cheap anymore! 

If this resolves the hum, you can safely deduct the issue is power related.

Check Cable Shielding and Routing

Patch cables and power cables under your pedalboard can also cause issues when they have shielding or routing problems.

When routing cables, it's best practise to keep your power and audio cables separate. Try not to run them parallel to each other where possible, and when you do need cables to cross, try to cross them at a 90 degree angle.

If you suspect a cable is causing the noise, replace cables with a spare, one by one, until the noise stops.

Experiment with Pedal Order

Try mixing up the order of your pedals by putting your digital pedals (your delays, reverbs etc) after the drive section of the board. Try to keep them further apart to ensure they are not causing issues by interfering with each other.

Solutions and Preventative Measures

Once you've finishing troubleshooting your board and taken steps to fix the issue, it's time to consider future proofing the whole thing. There are some long term solutions and preventative measures you can take onboard to keep your pedalboard noise free for many more gigs to come.

Use a High Quality Noise Gate

Pedals like the ISP Decimator, Boss NS-2 or the TC Electronic Sentry are great for cutting that unwanted noise out of the chain. They can work wonders to reduce noise caused by high gain pedals and keep everything sounding tight and clear. For best results place them after your high gain pedals or put the high gain pedals in the noise gate loop.

[product=lichtlaerm-audio-the-key-and-the-gate]
The Key and The Gate is at first glance just a noise gate with a super-easy to dial in one-knob design. The pedal splits your signal internally and uses your unaltered guitar-signal as a reference for its gating: absolutely no tone sucking and no loss of sustain! You can even inject another signal into the "Key" input to control the Gate, giving you unlimited opportunities for side-chain operation in the studio or live.
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Upgrade to an Isolated Power Supply

We've mentioned this a few times, but if you are not using an isolated power supply, it's worth considering one. Sure, it's an investment and spending a lot of money on power isn't the most fun upgrade you can make to your pedalboard, but this will benefit you greatly in the long run,

A good isolated power supply with deliver clean, balanced power to each pedal and reduce the risk of noise.

Invest in High Quality Shielded Cables

Must like power, cables aren't the most fun way to spend your money, but they are very much overlooked in their importance. You're spending a lot of money on great pedals and a good amp, it doesn't make sense to connect it all up with cheap, low quality, unshielded cable.

Buy the best shielded cables you can afford and they will help your quest to reduce noise.

[product=ne-electronix-patch-cable]
High quality Van Damme Pro Grade Classic XKE silver-core cable and right angle jacks. The cable has enough flex to cope with bends and features a noise rejecting construction, while the dual-conductor core provides a balanced frequency response.

Good pedals need good cables, and these patch cables look great and sound superb!
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Maintain a Clean Signal Flow

This is more of a housekeeping idea. Keep your pedals in the best possible order, keep your digital and analog pedals apart to avoid any overlap, place high impedance pedals closer to the front of the chain, ensure all the connections are  clean and secure, check your power and audio cables don't overlap too much.

These basic housekeeping rules will help keep your board in top working order.

Always Use Proper Grounding

Where possible, use the same outlet for all your gear. In an ideal world you'll also be running all your rig through a power conditioner to keep interference at bay. Try to avoid daisy chaining things, especially pedal wall wart style plugs, across multiple power outlets.

Try to avoid using anything that breaks the ground connection such as a ground lift or a three prong to two prong plug adapter.

Now It's Your Turn

So now that you know most of the common causes of noise and what you can do to resolve and avoid them, it's time to put this into practise in your own rig.

If you're experiencing any noise issues, these steps will help you get your tone back on the correct path. Go and implement these steps and enjoy years and years of hum free guitar tone!