Guitar Amp Gain & Volume Explained
What is Gain? What is Volume? Are they the same?
In this blog post we will attempt to demystify the difference between Gain and Volume. We will approach this from the world of electric guitar, as this is no doubt where most of you will encounter these parameters. It will hopefully give you a better understanding of each, which will in turn aid your decision making process when choosing between gain or volume for a specific intended purpose.
Gain and Volume Simplified
Now imagine two identical boost pedals. Both of these pedals just have a single knob that says 'Volume' (or Master) - Now we are going to plug our guitar into the first boost pedal, then into the second boost pedal. With both boost pedals turned on - this is a fine example of Gain and Volume. But wait - I said both pedals were identical, how can one be gain and one be volume - well, that’s completely dependent on the order it appears in the signal chain. What determines which is gain and which is volume is their placement in the chain - and how they interact with each other in these positions. So by this logic - our first boost pedal is controlling the gain, as it is feeding the signal into our second boost pedal - which is now controlling the volume. The reason for this example is to think of gain and volume as 2 similar ways of achieving a stylistically different result - not better or worse.
Gain - is how loud the INPUT signal is. It controls tone and not loudness
Volume - is how loud the OUTPUT signal is. It controls loudness and not tone
Gain & Volume in Guitar Amps
Let's look at the electric guitar amplifier circuit. Much like our 2 boost pedal example, they are comprised of stages that cascade into each other in the same way. The signal from your instrument hits the first stage of the amp, which is then sent to the second stage of the amp until finally it hits the speakers and you kick a hole in the sky with your lightning hot rock and roll. You may have heard people talk about gain-staging - this is exactly what they are talking about - being aware of the order of your signal chain and where in that chain to make changes that will give you the desired effect you are looking for.
Preamp Gain Stage
So let’s talk about the first stage - this is often referred to as the 'Preamp' stage, and this is also where you will find most controls relating to 'Gain' - some amps will also call this 'Drive' - Much like an overdrive pedal circuit - increasing your gain at this stage pushes more volume from the first stage into the second stage. The result is a more distorted grittier sound due to pushing the level of that signal beyond the limits of the second stage. In a nutshell, think of the preamp section of your amp where the 'gain' lives, it's the tone-shaping section - where we decide how 'clean or dirty' we want to sound. This is where we are going to craft the character of the tone that we want. We do this early in the chain so that we can send this signal on to the next section.
Power Amp Gain Stage
Now, let’s move on to the 'Power-Amp' stage (AKA our second boost pedal ;)) - being second in the chain will take the signal that we shaped in the preamp section and apply a sheer linear volume control, making our perceived volume go from almost silent to deafening without changing the fundamental character of the tone we shaped in the first preamp section. The volume control in the power-amp is the final stage of your amp and this volume will often stay set at its level even when increasing the gain before it.
One main point of difference between the preamp and gain stage is that the preamp takes your relatively low output instrument signal and increases the strength of the signal and adds singal colouration by clipping the signal, and the power amp section which boosts the signal further then that sound comes out of the amplifier.
Something to consider: ‘Headroom’. You may have heard this term thrown around before - but as we are talking about gain and volume, we need to talk about headroom because it greatly affects how gain and volume effects tone and volume.
Here's a very basic example using the model of preamp and power amp we have already been talking about: If you want your sound to be cleaner, you need to turn down your preamp section, and then turn up your power amp section, and if you want your sound to be dirtier or grittier, you need to turn up your preamp section and turn down your power-amp section.
The 'headroom' of an amp is based on how early an amp takes to distort or clip the signal when turning up the gain.
For example, say we have a preamp that is feeding into two power amps - one is 20 watts, the other is 100 watts. If I turn up my pre-amp gain knob to 50% in this scenario we would find the sound coming out of the 20 watt power amp would be far grittier and dirtier than the sound coming from the 100 watt power amp and this is due to the 'headroom' of the amp. because our second stage is 100 watts and not 20 we are going to be able to push it harder for longer before it starts to clip and distort the signal. Basically, the more headroom an amp has, the cleaner the tone will sound.
Conclusion: The Difference Between Gain & Volume Explained
We hope that this blog simplifies gain, volume and how they interact together - also - if you do have 2 boost pedals - try our little trick with cascading them into each other for a unique overdrive tone! (this is basically how many many overdrive circuits are set up and you can achieve some really cool results by using underwhelming utility gear for different purposes - like overdrive!)
Remember the only rule - There are no rules!
[Editor's note: except for these rules - Ohm’s Law, Nyquist Theorem, Coulomb’s Law, Kirchhoff's law, Faraday’s Law of Induction, Watt’s Law, Lenz’s Law, Gauss’s Law, Lorentz force, Ampere’s circuital law] 🤯