Guitar Amp Hum

At some point, we have all experienced unwanted noise from the amplifier. It can be very annoying part of using amplifiers, and the pestering buzz produced by an amp can drive us crazy.

In this guide, we identify the potential causes of amp hum and address ways to help you reduce the noise.

What Causes Amp Hum?
Before we dive into individual causes, it’s worth mentioning that all amplifiers have some noise floor.

In other words, no matter what amp you are using, it will inevitably produce some sort of noise – whether a hiss, buzz or hum.

It’s something that can depend on the type of amp you use, but it’s an unavoidable part of an amplifier’s design. But it’s not all doom and gloom though, as below we take you through the causes of unwanted amp hum and ways to battle against it!

Type of Amp:
Different amps can have different noise issues. For example, valve amplifiers are coveted for producing a more analogue, warm sound with natural-sounding and musical saturation. However, they are susceptible to overheating and can therefore be unreliable.

Amp Tubes
You may face more noise issues with a valve amplifier.

This does of course depend on the brand and the quality of the valves used, but most preamp valves have a lifespan of between usually 1-3 years, and when they get towards the end of their life they become noisier and more distorted sounding.

This is a common cause of amp noise, and if you’re wondering why your precious tube amp has started producing strange persistent buzzing, this may be the cause.

Solid state amplifiers do not require valves to work, but rely upon a combination of transistors to deliver their sound. They are considered far more reliable than valve amps, and produce a consistent tone as they are less likely to overheat.

Despite this however, they still produce low-level noise and can annoy you just as much!

Amount of Volume and Gain:

As we said before, all amps have some noise floor. So, the quieter you have the amp set then the less noise will be emitted. This means that the higher you turn up your amp, more noise will be audible unfortunately, as you are technically raising the noise floor.

The same goes for Gain (the amount of distortion), which will only produce more hiss and noise the higher it’s cranked. So, if you’re a metal player then noise is an issue you will have to battle more than jazz cats.

How you set your EQ:

Treble/Presence Control
Don’t max out the treble or presence control, you’ll make it worse!

The way you set the EQ can also affect the noise, or rather the type of noise produced.

For example, if you want a guitar tone that really cuts through a mix, then naturally you would increase the amount of treble/presence on the amp. However, doing that will obviously turn up the amount of top-end and develop into a hiss, exacerbating the problem by making the noise more prominent and audible.

Types of Pickups in your Guitar:

The types of pickups in your guitar can also affect the amount of hum coming out of your amplifier. Single-coil pickups (most commonly found in Strat-style guitars) tend to generate noise due to their design,

which is far more noticeable when playing into a distorted amp. A single coil pickup is a single magnet wrapped with copper wire, creating a magnetic field. Hum is caused when this field is interrupted by power frequency currents in surrounding electrical equipment. And an amplifier only, well… amplifies the problem.

Humbucker-equipped instruments dramatically reduce hum, hence their name. The dual-coil design means that the two magnets essentially cancel each other out, so noise is significantly diminished.

You could also try “stacked” single-coils such as Lace Sensors (pictured beneath) or the popular Seymour Duncan Hot Rails series pickups, which are humbuckers in a single-coil casing.
Single Coil Pickups.

Single-coil pickups cause more noise than humbuckers due to their single magnet design. This is more noticable when using higher amounts of gain.

Active pickups such as EMG’s use batteries to work and are generally very low noise.

However, they can become noisy when their source of power (the battery) runs out and becomes flat. So before you panic and think about replacing a preamp valve, check that your active pickup equipped guitar hasn’t just got a dying battery.

AC Supply and Interference:

The quality of your mains supply can also have a huge impact on the potential noise that the amp may or may not produce. If the AC supply

In your area is fairly poor and inconsistent, then this can cause the amp to generate and emit far more noise as it isn’t getting a sufficiently clean supply of power. It’s generally a good idea to plug your amp directly into a mains socket if you can, and not through something like a multi-socket.

Radio frequency interference can affect any amp too. Have you ever noticed a weird electrical noise coming from your amp when you’ve received a text?

That is what this is. Some manufacturers find ways to combat and minimise this problem, but unfortunately it can’t be fully prevented.

Static noise can also be caused by lights and surrounding electrical products or appliances. This is why at rehearsal you could be satisfied with your quiet rig, and then you turn up at a venue only to suffer horrible noise issues. It’s just the way it goes…

How Do I Reduce Amp Hum?

So after identifying many of the causes, in this next segment we provide you with ways to tackle noise issues head on. Some people can live with the noise, and some purists think it’s old-school, but for most us we just want to do everything we can to reduce hum.

Good Cables:

It may sound daft, but good cabling can do wonders in terms of reducing that annoying hum. If you’re running a large pedalboard with many stompboxes connected together, make sure to use only high-quality cables to ensure a clean signal is delivered.

Evidence Audio SIS2-B Pedalboard Cable Kit.
High-quality cable kits such as the Evidence Audio SIS2-B are great for connecting your pedals and keeping your signal chain quiet.

Cheap patch leads are okay if you’re using only a couple, but if you’re joining all the pedals in your chain with cheap and nasty patch cables, then you are only going to exacerbate the noise issue. This is because the majority of patch leads are poorly shielded and are therefore more susceptible to interference from external power.

Look into the D’addario Patch Cable Kit or high-end Evidence Audio SIS2-B Cable Kit if you want good-quality cables that keep your signal clean. These ergonomic solderless cable kits allow you create your own cables and cut them to the lengths you require. This means you can make your pedalboard as neat and efficient as you like!

Even if you’re not running into a pedalboard, just a great cable connecting your guitar to the amp will help. It may seem underwhelming spending around £20+ on just a guitar cable, but a well-made cable will deliver the purest tone and will last. You’ll thank us later…

Noise Gates:

Even if you’re using well-insulated cables and taking into account all of the aforementioned advice, sometimes hum and noise cannot be totally eliminated.

Noise gate pedals are the best things to use to battle against unwanted hum, and are life-savers for guitarists that use high amounts of distortion.

They basically work by attenuating signals that register below their threshold, and silence that signal (the noise) so that is no longer audible.

Boss NS-2

Noise gate pedals such as the classic Boss NS-2 are great for getting rid of unwanted hum.

Most noise gate pedals feature a threshold that you can adjust, so if only a little bit of noise is present then you can set it low and not affect the sustain. However, if you have a lot of noise coming from the amp then the threshold needs to be set higher, so it is registered by the pedal. Many noise gate pedals also offer a decay/release control, which lets you set how quickly the gate will cut off.

This is a feature that again is more suited for metalheads who like a tight response for precise riffs.

• Here are the main noise gate pedals we think you should check out:
  TC Electronic Sentry
  Boss NS-2
  MXR Smart Gate
  Electro Harmonix Silencer
  So what do you guys think? Do you have any other useful tips or recommendations for reducing amp hum? Let us know and leave a comment below!