Master vs Volume! Cannot understand the difference

Hey people! I’m an acoustic guitar player and just started using an electric guitar, so I’m a complete beginner in that regard.

I’m trying to find a basis/foundation in terms of tone and get on from there, but I find all the knobs and internet info overwhelming to the point that my head hurts and I just go back to my acoustic guitar.

I bought a Boss Katana MKII 50 (already watched a bit of Justin’s video - I have unanswered questions, maybe I was tired, maybe it was my 3rd 4th video in a row, I don’t remember)

I understand the gain, bass, mid and tremble knobs, because they are obvious.

I DON’T understand the volume and master controls. In my head I’m thinking that I have two volume controls. Three if you add the volume knob on my guitar. Why do I have 3 volume knobs? What’s the difference? What’s the use?



On your amp the first volume (next to gain) is the pre amp part of the amp and the master is the power amp side which controls the overall volume.
The best way to use it is to put the master volume on fairly high and control the overall volume using the volume - it usually gives a nicer tone, if it’s too loud change the Power setting to a lower wattage.
You have a volume control on your guitar so that you can change the output of your guitar; lower volume on the guitar will yield a cleaner sound, increase the volume on your guitar will give distortion for the same amp setting.


This is my understanding of what the difference is. I assume that all modeling amps work the same(katana, fender, Spark, ect).

Use the volume and gain settings to control the amount clean vs distortion in your sound. Once you have a level of distortion that you like, use the master to control the loudness.

If you are in a small room the master would be at a low setting, if you need to fill a larger room you raise the master. Volume/gain are used to adjust the tone and the master is used to adjust the overall loudness. If you adusted the volume control up to fill a larger room you would change the tone.

Volume/Gain/Bass/Mid/Trebble/Effects creates your tone and the master determine how loud your tone gets. The Katana has a power setting .5/50/100. I don’t have a katana so I assume you could create additional distortion with the master control up and the selector in the .5 setting at a reasonable decibel level.

That is my understanding.


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It may be best to think of the channel volume to be the level of each individual patch, and the master to be the overall level.

So, with the channel volume you can balance patches to make them all roughly the same level, and then use the master volume to say how loud you want the amp over all.

It’s really just the gain control that’s used for clean/distortion. Channel volume is how loud the channel/patch is.




Found this on the blackstar website: Channel Volume vs. Master Volume - Blackstar.

I’m not sure I entirely agree with that description on the Blackstar site.

Gain definitely is about driving the input to the pre-amp stages and getting pre-amp overdrive. But the channel volume is the volume of the output of the pre-amp, and shouldn’t have a significant impact on the tone (with caveats).

The clue to the function of the channel volume is in the text: “If you have a single channel amp like the Studio 10, you will just have a single volume”

This indicates that channel volume is something that’s specifically a function related to having more than one channel on the amp.

To set some context, traditional guitar amps did not have “patches”, but might have multiple channels. These channels, typically, have different pre-amps gain structures (so you might have a clean channel and a “dirty” one).

In some case, these channels would have completely separate pre-amps with separate physical inputs, so to switch from the clean channel to the dirty one, you would have to unplug your guitar and plug it into the other input.

The idea of channel volume in this environment is to balance the output levels from these different channel pre-amps into the shared power amp. This is so that when you switch channels you don’t get a big change in volume.

With many modern amps, like digital modelling amps, you don’t have separate channels but, instead, have “patches”. However, these perform a similar function to channels, but they are software-based rather than being hardware-based.



Addendum: Some traditional amp circuitry may have characteristics such that the channel output level does impact the power-amp gain differently from the how the master volume impacts it. This might be due to, for instance, where the tone control circuit is in the amp circuit.

In those cases, the channel volume may have an impact on the tone, but this tends to be specific to certain amps.


Hi Keith, not sure about this in case of the Blackstar modelling amps. I use a Blackstar ID Core V20, which can be compared to the Boss Katana, see picture below:

The volume control can be seen at the left side and is described in the manual:

There’s no Master Volume at the panel, the “Level” knob on the right side is controlling the effect section.
Just wanted to add this, I’m on my way learning to use my amp and as a electric guitar newbie I had the same questions as @neophytosdm about controlling the volume(s).
I’m not sure how to control the overall volume without changing tones with only the volume on the pre amp section and the guitar volume. Didn’t see anything in the architect software to control the master volume too. :woman_shrugging:

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Interesting thread, I’ve never got my head around Master vs Volume. I need to have a real delve into this and play with my THR to finally understand.
When we’re talking about dialling in a tone using volume / gain where should the master be set at as you’re dialling in? half way?

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Andrea, I also have a Blackstar amp, though a different model that does have the additional Master volume to make the final output louder or softer.

Once you have selected the amp voice, then the Gain control will drive up the levels into the preamp, which creates more distortion on the tone, and the Volume control drives the level into the power amp which makes the sound softer or louder.

These controls can be used to different effect based on the amp voice you choose.

To experience effect of the guitar volume control, turn it up to 10, pick a crunch amp voice, set the gain and volume so you have a distorted sound. Then play with rolling back the guitar volume to see how that changes the tone. I have found on my amp that I use that approach and it reduces the level of distortion.

Based way to understand the amp controls is to keep playing as you have been doing.

Have fun.


On the THR, I would just use the Master volume to set the overall level, and the level control to adjust each patch so they are about the same level as each other.

There’s no hard and fast way to do this and it can be a bit of a balancing act, but I would use the factory default patches as a good guide as to where to set the master level, and then adjust any custom patches to match those levels.



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If your amp doesn’t have a “master” then the volume control will impact both the actual level and the power-amp overdrive (if it does this, not all amps do).

In this case, I assume there’s no way to balance the levels of different patches/channels?




Thanks, David for taking your time to explain! Due to reading a lot about guitar related stuff, I meanwhile learned the basics how an amp works, another step ahead :sunglasses:

That’s exactely what I’m doing :slightly_smiling_face:. I’m looking for the option to reduce the over all volume, without changing the tone. The volume knobs at the amp and at the guitar also change the tone. So, when I managed to get the right tone, it often tends to be too loud.

As already mentioned, I’m learning to run at the moment :slightly_smiling_face:, maybe there is a way, but I don’t know yet. But I neither found an option in the software.
So maybe there is somebody out there, who uses Blackstar amps?
Edit: Sorry, @neophytosdm I didn’t want to hijack your thread :see_no_evil:


I experimented with my GTX to see if the channel volume would alter the tone. I did not hear any significant difference if any so I would agree with this statement. I think this would asnwer the orginal question in regard to the boss katana and like you said there are caveats depending on the amp.


That’s exactly the way I understand it. If you have several pre-sets/patches you would set them all at the same volume. Then adjust the master to suit the loudness for the room size. Otherwise if you switched presets during a song you could have an unplanned change in volume.


Thanks for all the answers guys and girls @Helen0609 Hijack my post all the way, I’m glad it turned into a somewhat bigger discussion, it seems there are different opinions and “problems”, someone else might learn something too!


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