What Does a Limiter Do on a Bass Amp?

Limiters are included in a number of amplifiers, or available as separate pedals to place in your audio signal chain. A lot of bassists don’t fully understand the role of a limiter. Why do we use them and how do they impact upon the sound of your playing?

A limiter effectively lowers the sound when it hits a certain level. If the volume or the signal of the input reaches a certain level, the bass amp limiter will cut the signal to provide a more even sound. This ensures we don’t have huge peaks and troughs in the audio signal. A limiter will also prevent the audio signal from ‘clipping’ which is something all musicians want to avoid.

In this guide, we explain in detail more about limiters, why they are important for bass amps, and what sort of impact they can have on the sound.

Why is a Limiter Important for Bass?

Limiters can be used for all sorts of instruments and amplifiers. So why is it specifically implemented for bass guitar?

Certain types of playing can provide huge variation in the sound levels. This is known as the dynamics of the sound. Think of playing slap pass, or popped notes. They will sound much louder than ordinary picking. Also, if you use a guitar pick to play bass then this can have a similar impact, as the sound can have a loud attack, before dying down to a quieter level. 

If you don’t have a limiter on your bass and have this kind of uneven signal, it can sound inconsistent, and generally pretty unpleasant.

Compared to other instruments such as playing the piano or guitar chords, there are more instances of spikes in sound when playing bass, and these might require a limiter to prevent clipping or peaking.

Why is a limiter important for bass? It can protect your audio from becoming distorted due to clipping, or having huge uneven peaks that make it sound inconsistent, like a volume knob is being constantly adjusted.

Why Does Clipping Happen on a Bass Amp?

Clipping occurs when you get close to running out of the usable power of the amp. It can happen when your gain and volume knobs are cranked.

If your limiter is constantly having to kick in while you play your amp, it could be that the amp is simply not powerful enough. You may have to turn down the gain, and if this leads to a volume that is just too quiet then it could be time to consider a higher wattage amplifier.

If the limiter is only having to kick in periodically, you don’t necessarily need more power. You probably just have problems with the attack, or with the style of playing, and levelling out the audio by using a limiter can be all you need to give a consistent tone.

Can You Hear a Limiter?

How much work a limiter is having to do depends on how loud the signal is, and whether the amplifier can handle it. If the limiter is having to kick in a lot, to prevent the clipping and peaking of an amp, then it is likely that you will hear the impact it is having to have on the sound.

This itself can sound unnatural, so it doesn’t really solve the problem. It can sound like someone is suddenly having to turn down the volume every time a loud note is played.

If it is implemented well, then you won’t need to worry too much about the limiter occasionally triggering. If it is just having to drop a fraction off of the sound level then you will not hear it doing its job. Remember, the goal is always a more even tone overall, so a drastic limiter having to kick in every few seconds will not improve the sound.

Difference Between a Compressor and a Limiter

If you know anything about compression then you might see some similarities between a compressor and a limiter. Both do some similar jobs on the audio, but they have some distinct differences, too.

Both have a threshold, or an audio level at which they kick in and start to impact upon the sound. However, a limiter’s threshold is what we call a “brick wall”. It automatically cuts the level of audio to what the threshold is set to. 

You may have control of a limiter. If you set it to 0dB, this means that no sound will get louder than 0dB. No exceptions.

With a compressor, the threshold of where the effect kicks in doesn’t necessarily mean the audio has a hard cut. This depends on the “ratio” that is set. A ratio of 4:1 would mean that if the signal went 4dB above the threshold set, the output only increases by 1dB. With a limiter, that output won’t increase at all. Hence, the “brick wall” analogy. 

To continue the brick wall analogy. A compressor makes the audio (or the gain increase) slow down. A brick wall limiter stops it completely, even if it is abrupt.

Completely understanding the science of how the limiter works is not required, as long as you know how it impacts upon the sound you are creating.

In Summary

If you want to become an audio engineer then you might want to know specific detail of what a limiter does and how it works, but most bassists are satisfied with a simple and practical “explain like I’m five” description.

In effect, a limiter is truncating the audio signal when it reaches a certain level, to provide a more even overall sound, without huge peaks that can sound unnatural and uneven. A limiter is often a failsafe, put in place to avoid “clipping” or “peaking”, a nasty distortion that can occur when the power of an amp is overloaded.

Rob Wreglesworth

Rob has come to terms with the fact he will probably never be a famous rock star....but that hasn't stopped him from writing and recording music in his home studio. Rob has over 15 years experience of recording music at home.

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