All sound waves go through some kind of medium to get to your ears.
When you're talking about a guitar rig, each sound wave or "signal" will go through a number of manipulations before it actually hits open air where you can hear it.
Nearly all of those instances have the potential to change volume in some capacity.
If you don't understand how volume is impacted at each stage of audio signal processing in your guitar rig, you'll have a hard time setting amp EQ properly or contextualizing your volume for the environment in which you're playing.
In this article, I'll cover the basics of volume at the guitar, pedal and amp level.
A Broad View of Audio Signal Processing
If understood at a high level, audio signal processing simply takes a sound (either analog or digital) and performs some kind of operation on it. A boost or cut in volume is one of the simplest such operations.
At a high level view, it works something like this:
The strings on your guitar produce sound waves, which then pass through n mediums each of which perform operations on those waves, thus altering them in some way.
You have a signal (the sound waves from your strings) which is then processed by n number of entities on its way to being heard audibly through a speaker.
At every operating algorithm n1, n2, n3, etc, volume can be directly or indirectly impacted.
We'll examine the volume variance in three primary categories:
- Guitar Level (pickups, volume knob)
- Preamp and Effects Level (pedals, preamps and line level output)
- Amplifier Preamp and Power Amp Level (gain, master volume and final output)
At all three of those points, there are multiple operations that can occur and change the volume of your signal. We'll begin by looking at where this happens in the electric guitar itself.
Volume Impact at the Guitar Level
As mentioned, the source of your signal is your guitar string's vibration.
Anything that changes those vibrations after they occur, should be considered a processor of that original signal.
Thus, there are a number of factors at the guitar-level that impact your volume before it even leaves through the instrument cable.
...your guitar's volume knob doesn't behave like a master output as much as like a gain control.
A Volume Knob's Impact on Guitar Volume
The volume knob has the first and most substantive say in how loud your guitar signal is.
The thing to keep in mind is that your guitar's volume knob doesn't behave like a master output as much as like a gain control.
This means that if your guitar's volume gets cut, it's effect is similar to reducing the gain levels on a preamp. Thus, the signal strength going into your actual preamp (or your first pedal) won't be full.
This means that in most scenarios, the volume on your guitar should be maxed, allowing your pedals and preamp to control your gain.
The second factor that can impact volume at the guitar level are the actual pickups.
Pickups and Their Impact on your Signal
There are primarily two different pickup-related factors that can impact the volume of the signal coming out of your guitar.
- The type of magnet used in the pickup (usually ceramic or alnico)
- The distance of the pickup from the strings
While the variance in volume due to these features is far more subtle than the volume knob, it's still something you should be aware of.
A lot of times this will be described as "output" or a way to measure the intensity of a certain type of pickup. For example, if you go to Seymour Duncan's humbucker page, you'll notice a color pallet under each product display that indicates the output level of the different humbuckers they offer.
You can see that the output for the neck and bridge pickup are much higher in the Jeff Loomis Blackout set than for the other two.
Now, this is not to say that the intensity of the pickup is going to drastically change volume. However, it does have a subtle impact on the amount of signal being picked up from your strings. This is sometimes called the "voicing" of a pickup which is partly determined by the quality and type of magnets being used and how they're wound within the enclosure.
Of greater consequence, is the distance of the strings from the pickups, once they're installed.
Predictably, the closer the magnet gets to the strings, the more output they'll produce.
Again, this doesn't have the same impact on volume that you'll get from a volume knob, but it still counts for a measurable change in your signal strength.
While there are some pickup height and balance conventions, the actual distance you implement depends largely on the pickups and the guitar in question. Thus, most guides are specific to those factors.
Volume Impact through Pedals and Your Effects Chain
If you don't run a pedal chain in favor of going straight into an amplifier, you can skip this section.
For those who do run a pedalboard, each effect can have some degree of impact on your volume, depending on a number of a factors. The first and most evident variable is the type of effect.
I would break these types into two categories. First, effects that can have a significant impact on volume:
- Distortion (overdrive, fuzz, high gain, etc.)
- Boost (signal boosters or "lead" pedals)
- Volume pedals
Second, effects that have minimal or no impact on volume:
- Ambience (delay, reverb, echo)
- Modulation (chorus, phaser, vibrato, flanger)
- Filter (wah, envelope filters, etc)
Our focus will be primarily on the first list, where the most significant changes in volume can occur.
We'll look at distortion first, then address the other three (volume, compression, boosters) together.
Distortion Pedals Impact on Guitar Volume
The theory behind distortion is simple, in that it's merely manipulating the original signal to create a non-linear, musical form of high gain or "saturated" tone (per the Sound Reinforcement Handbook).
This means we're sending a greater amount of signal into a circuit that is then enforcing compression (also called a "threshold") and causing the signal to clip.
You can have three different types of clipping or "wave" types when a signal is compressed:
- Original Signal (agnostic of threshold)
- Soft Clipping (smooth overdrive)
- Hard Clipping or "Square Wave" (heavy, saturating distortions)
The difference between the last two is how abruptly the signal is compressed.
This means that the more a signal is boosted before it is compressed, the more intense your distorted sound will be.
The more volume your send into your distortion pedal's compression, and the more strict that compression is, the more distortion you'll have as your pedal's output.
This is why most distortion pedals have both a "gain" and "volume" or "output" knob.
The gain knob is essentially allowing you to boost or cut the signal going into the circuit, where the output is then compressed (establishing a threshold) by a master volume control.
While gain is an increase or "boost" in signal, it's not necessarily increasing the final volume because of the compression in a distortion pedal circuit.
Basically, you're overloading or "overdriving" the circuit with more volume than what is actually being output. This is how you get a fuzzy or "dirty" signal from your pedal or amplifier.
In a pedal chain, the distortion stompbox will only impact volume by where you've set the final level or master output control. In other words, if you don't want your signal boosted, you'll want to match the decibel level of the distortion pedal's output with that of your guitar and amplifier.
If you increase the LEVEL of your distortion pedal by 50% above the decibel level coming in from your guitar, you'll send an additional 50% boost to your amplifier, where the distortion will depend on how you have the GAIN set on the pedal.
The same rule applies if you cut the LEVEL on your distortion by a certain amount beneath the decibel level of the original signal.
In most cases you'll want the volume going out of your distortion to either match the volume going in or be slightly higher.
If you want to use your distortion pedal to provide a small boost, so that your distorted sound is louder than your clean sound, you can use the LEVEL or master volume control on the pedal to add a slight, perhaps 2 to 5db, boost to your original signal.
Obviously, the opposite is also true.
If you use the LEVEL knob to reduce the volume in your signal, you'll go to the amp with a cut in the volume of your guitar's original signal. Just keep in mind the difference between the GAIN and LEVEL or MASTER VOLUME controls.
Volume Pedals, Boosters and Compressors Impact on Volume
Understanding distortion goes a long way in helping you understand the implications for volume involving other three pedals.
Volume pedals, compressors and booster pedals all have functionality that's based on the same principles of gain, compression and clipping. This is why many distortion pedals have built-in compression as part of the effect.
In fact, you could say that a distortion pedal is essentially the combination of a booster and a compressor pedal in one box.
Thus, a signal booster pedal, like the Xotic EP Booster is akin to the MASTER VOLUME control on a distortion pedal.
Turning it up or down gives you a db boost or cut without compression.
On a compressor pedal, you'll typically have two controls.
Your primary concern here, as it relates to volume is the "Output" knob, which might also be labeled "volume" or "level."
This is where the compressor limits the volume of the pedal's outputted signal, which effectively allows you to set the volume of your compressor and, once again, either increase or decrease the db level coming out of the pedal. The main difference between a signal booster and compressor is that a compressor, with the addition of the "sensitivity" or "attack" knob, allows you to control how smoothly and strictly your signal responds to the volume knob setting.
For example, a compressor will prevent notes that are picked hard from exceeding the db level set by the output knob. Certain pedals, depending on where the sensitivity knob is set, will also amplify notes that are picked too softly to meet the aforementioned db level set by the master output.
In that respect, compressors and signal boost pedals are both very similar.
Not surprisingly, volume pedals, and their impact on your signal, are the easiest to understand of the bunch.
In most respects they simply function as a second volume knob, reducing gain as they reduce output. This means that they are most effective at the beginning of pedal chains and particularly useful in rigs where the guitar is without a volume control.
The most typical scenario in which this is true is with acoustic guitars that don't have a built-in preamp. In that case, a volume pedal becomes far more necessary.
While certain volume pedals are built with distinct swells and trigger points, most of them are comprised of simple technology and can be considered merely as a second volume knob control. For this reason, they can be used to control volume in conjunction with other pedals, allowing you to reduce gain without having to move the volume knob on your guitar.
VOLUME PEDAL USE WITH A DISTORTION PEDAL
For example, let's say you have a guitar with a volume knob, a volume pedal, a distortion pedal and an amplifier.
If you're using your distortion pedal as a +5db boost, and your guitar's volume knob is maxed, you can use your volume pedal to reduce gain while still maintaining your distorted signal.
For example, in the following graphic we have a volume pedal cutting the original signal by 8db before the distortion pedal adds 5db to the signal, for a grand total of -3db going to the amplifier. In this way, the volume pedal allows you to reduce the volume of your signal, without totally losing your distorted sound - handy for going from an intense and heavy distortion to a somewhat lighter and less aggressive saturation.
Note that volume pedals do not increase the volume of your original signal. They can only decrease what is already there, since they (at least most of them) do not come with any kind of signal boosting circuit.
Thus, a volume pedal that's "wide open" should maintain the signal strength coming from the guitar, without exceeding or amplifying it.
Modulation, Ambience and "Non-Volume" Effects
Outside of the aforementioned types of effects, there aren't many pedals that have a drastic impact on the volume of your signal.
Modulation, ambience and filters are the three remaining primary categories and in most cases, they're not going to significantly change your volume. Take modulation pedals for example, which would include things like chorus pedals, phasers and vibrato. None of these effects will cause significant volume shifts, though they might make your signal sound more full and distinct.
This is called layering, but is not the same as signal boosting.
In its purest form, modulation only has two controls.
Take the old Boss CE-2, for example:
The only two knobs you have are RATE and DEPTH, which are typical for most modulation effects. If you see an additional knob called "Level" or "Mix" that's almost always a control that allows you to mix the wet and dry (un-modulated) signal, like with the Boss CH-1 Super Chorus.
The same is true of ambient effects, which typically include reverb, delay and echo.
For these pedals, your primary controls are "delay time" and "repeats," where delay time is the amount of time a signal is recorded in order to be played back and repeats is the number of times that signal is played.
A mix or level knob on a delay pedal is simply controlling the balance between the wet/dry signal and has nothing to do with volume or signal boosting.
Understanding Volume in a Guitar Amplifier
Perhaps the most confusing aspect of guitar volume is how it's managed at the amplifier level.
To understand it properly you need to know these three terms, two of which we've already discussed:
- Preamp (Gain)
- Power amp (Master output)
These are the essential parts of what make a guitar amplifier. While some combo amps might have external speakers, all amps have at least a preamp, power amp and one or more channels.
Once a signal enters your amplifier, these are the three components that can directly impact the final volume of your signal.
The preamp and power amp function similarly to the controls in your distortion pedal, where the gain control sends a boosted signal at the preamp level and the power amp sets a compression level (for clipping) and then outputs a final, master volume.
The old Marshall JCM800s are setup this way.
In an amp without multiple channels, these are the only two controls you have to worry about, which typically means the preamp controls how clean or dirty your signal is while the power amp determines the output.
However, many amplifiers have between two and four channels, allowing you to set some variance of volume, gain and EQ for each individual channel.
Different amps will add different properties to each channel. For example, some will provide a designated "clean" and "dirty" channel, where the gain knob only exists on the dirty channel.
Take the Marshall DSL15H with two channels, for example:
Here's a summary diagram of what you're seeing on the DSL 15H front panel.
All of this allows you to establish a template for each channel, meaning you can set designated gain and volume levels for certain channels and switch to them (usually via a footswitch) as needed.
It also saves you from changing volume at the guitar or pedalboard section of your signal chain.
It's usually a better habit to make signal strength changes at the amplifier level. This ensures that you aren't losing gain unnecessarily by down-shifting your volume pedal or the volume knob on your guitar. In an ideal scenario, your signal should be at 100% until it gets to your amplifier's preamp.
To that end, a good protocol is to establish a median volume then make sure you have a method for both boosting and cutting volume. If you want your distorted signal boosted, use a distortion pedal or dirty amp channel to add the increase in volume. If you want the boost to be clean, use a signal booster, compressor pedal or a second clean amp channel with low gain for the volume increase.
Here's a graphical look at all three steps.
1. Establish a "median" volume by keeping your volume knob and pedals at 100%, then setting the gain and volume levels for your clean channel.
2. Establish a distortion volume using either your pedal or amp's dirty channel that is slightly louder than your clean signal.
3. Establish a method to cut volume using either your volume pedal or another amplifier channel if you have more than two.
It might seem weird that I called this an "abridged" explanation, because it's a lot of information.
However, addressing signal processing (even in terms of something as simple as volume) is much more in-depth and nuanced. There's a lot that goes into your signal, but thankfully, we can get a lot of mileage out of the spark notes version without ever having to take a class in signal processing (which I have and in which I faired terribly).
What we need to know is functionality at each level of our gear.
If you covered each section, you should have a pretty keen understanding of volume at the guitar, pedal, preamp and power amp level and how all those components react with one another to give your electric guitar its sound and decibel level.
Your Thoughts, Input and Questions
If you have questions about guitar volume or anything I mentioned in the article (perhaps a correction or constructive criticism), feel free to drop it in the comments section below.
For reference purposes, I've listed all of my sources in the works cited section.
Thanks for reading.
"Humbucker Product Section." Seymour Duncan. N.p., n.d. Web. 01 June 2017.
Davis, Gary; Davis, Gary D.; Jones, Ralph (1989). The Sound Reinforcement Handbook. Hal Leonard. pp. 201–102. ISBN 0-88188-900-8., June 1, 2017
"Distortion (music)." Wikipedia. Wikimedia Foundation, 24 May 2017. Web. 01 June 2017.
Fundamentals of Telephone Communication Systems. Western Electrical Company. 1969. p. 2.1.
"Audio Signal Processing." Wikipedia. Wikimedia Foundation, 28 May 2017. Web. 01 June 2017.