Master volumes are probably the oldest approach to solving the ‘tone/volume problem’ and are still a very popular feature used by many builders today.
In a very basic sense, the idea behind a master volume is to be able to adjust the pre-amp and the power amp volumes individually, thus giving guitar players the chance to control how much the amp is ‘breaking up’ or overdriving, while still keeping the volume at a respectable level.
By and large, one of the most discussed topics when it comes to tube amps is volume. The first question most people ask is ‘how loud?’ an amp is.
Unfortunately, this question is kind of difficult to answer with any sort of clarity. There are just so many variables, and honestly, when you think about it, it is hard to find a scale to really quantify it.
This puts guitar players in a tough spot because it really does matter how loud an amp is for a number of reasons.
If a player wants to push the amp a little harder, they can just increase the ‘normal’ volume and back off on the ‘master’ volume and now, the player will be able to push to amp into overdrive without adding too much volume.
The reason for this is that by increasing the ‘normal volume’, the amp’s pre-amp is producing more gain, but since the power section ‘master volume’ is set lower, the signal isn’t amplified too much. This makes the amp considerably more flexible.
Not familiar with master volumes yet? Keep reading to learn more.
Master Volume Description
What is a master volume?
Basically, a master volume allows users to turn up the pre-amp section, while controlling the signal going to the power amp, thus controlling the overall volume of the amp.
In a non-master volume amp, this control doesn’t exist – its volume is the same control as the gain, drive, or pre-level control on an amp with a master volume.
Master Volume Benefits and Features
Can I add a master volume? Will the amp sound the same? What’s the difference between master volume and non-master volume amps?
Here are a few answers to some of its common questions and the benefits of using them.
What effect does a master volume have on the sound?
Generally, non-master volume amps are more dynamic. Plus, they are more responsive to the player’s touch since the pre-amp is interacting directly with the power amp.
The overdrive is typically a power tube breakup or a combination of the power amp and pre-amp breakup which sounds different.
The semi-clean and clean tones are one of the places where these amps really shone. A guitar player can control breakup by adjusting the knobs on the guitar and varying their pick attack.
However, this isn’t really practical in many locations a player would use the amp.
For distortion and overdrive in master volume amps, the pre-amp is high gain. The pre-amp overdrive is usually a bit buzzier but also more of a square wave.
Some players prefer this, while others don’t; however, it is a practical way to get distorted tones without high volume.
There are several ways to shape a distorted pre-amp to match a player’s needs. The rise of high-gain amps gave players distortion tones without overly loud volumes, but it changed the tone too.
What’s the difference between Pre-Phase Inverter vs. Post-Phase Inverter Master Volumes?
Basically, these two types of masters place the master volume in different places in the amp. Many Post-Phase Inverter Master Volumes have the advantage that when turned all the way up, they are out of the circuit.
Therefore, the amp retains its function as a non-master volume amp. However, when using a Post-Phase Inverter Master Volume, you need the amp to be turned up more to sound good.
Standard master volumes work well in amps designed for them. No matter what it affects the tone – they sound different when in use and you should choose one based on your needs and preferences.
Can you add a master volume to a non-master volume amp?
Some vintage amp designs can have master volumes added; however, most behave differently with a master volume installed. In others, adding a master volume has no real benefit so this must be evaluated on a case-by-case basis.
For instance, when it is installed to are Marshall Plexi amps. Some Plexi amps are very loud and the classic Plexi crunch sound can vary based on power tube breakup and speakers being pushed hard.
A master volume may help quiet things down, but you will still have to play quite loud to get the sound that people usually associate with those amps.
The sound is simply not the same with the master volume as without. However, that’s not to say that it won’t sound good with a master volume – it will just sound different.
Typically, a combination of an attenuator and a master volume is necessary for such an amp.
Master Volume User Reviews
Here are some reviews from people who use a master volume:
“Ayos sya, sukat yung knob sa pinaglagyan.” – Christian Villano, Konzert/Sakura Amplifier
“Knob works great once you remove the metal clip from your old knob. This works great, the failure that most are seeing is caused by this metal clip left behind by the previous knob.
When I first slid on the knob it fit but didn’t allow me to turn the radio off and on. I could adjust the volume but that was all.
Turned out that there was a small clip that was part of the knob. In my case when I lost the old knob it left the previous clip on the knob stub.
I easily pulled the metal clip off and slid the new part on and everything works great.” – Cat, ACDelco 16199583 GM Original Equipment Radio Volume Control Knob
“These are high-quality aluminum knobs. They have knurled edges and rubber o-rings to provide a good grip for push/ pull switches.
Both my switches are pushed/pulled and these knobs work perfectly. They attach to the stem with an Allen headset screw and the wrench is included.
They look great and work great.” – Elizabeth, mxuteuk Black Aluminum Alloy + Blue Rubber Ring Potentiometer Control Knob Volume
“These knobs are very well machined and look great. These fit my standard 1/4″ split-shaft American guitar pots just fine.
A great price on them here, too. FAST shipping.” – LHBassist, Taiss/ 4pcs Silver Color Aluminum Rotary Electronic Control Potentiometer Knob for 6 mm Diameter Shaft, Volume Control Knob
“Very nice knobs. Nice finish matching and good for form 6mm potentiometer. I used this for the master volume on a custom boombox.
My only complaint is because it uses an Allen screw on one side, it tends to push on the pot stem unevenly and sits a little crooked.
An easy fix was to wedge a small piece of zip tie between the two halves of the pot stem so that when you tighten down it doesn’t compress the stem and become uneven.
Otherwise, a very nice knob and then rubber ring covering the Allen set screw is a nice design.” – Ryan, mxuteuk Black Aluminum Alloy + Blue Rubber Ring Potentiometer Control Knob Volume
“I bought 15 different variations of the knobs and feel ko ito yung nag fit so ito lang ung ire-rate q, so sana makatulong din sa iba =) Fit siya sa Sakura Karaoke Amplifier AV-5023. Thanks seller!” – Maruyakeri, UNIVERSAL Amplifier Knob
“The knobs look and feel good. The smaller diameter works perfectly with my home made guitar amp.” – Sucker, Taiss/ 4pcs Silver Color Aluminum Rotary Electronic Control Potentiometer Knob for 6 mm Diameter Shaft, Volume Control Knob
“It’s a control knob, not a whole lot to say. Purchased to replace the jog wheel on my MPC Live II for aesthetic purposes. Great fit, has no sharp burrs, and the knurling is good.
I will add, I didn’t pay attention that the rubber ring was off for a reason when I got it. The set screw is in the recess, so screw it in place before putting the rubber o-ring in its place.
Was a pain in the butt for some reason, getting it off as I tried to be careful not to rip it while digging it back out.” – Tony, mxuteuk Black Aluminum Alloy + Blue Rubber Ring Potentiometer Control Knob Volume
“I put these knobs on both my Ibanez bass and my Rogue lap steel. I really like the way they look, the position indicator is easy to see and they are cleanly machined.” – Willie, Taiss/ 4pcs Silver Color Aluminum Rotary Electronic Control Potentiometer Knob for 6 mm Diameter Shaft, Volume Control Knob
Master Volume Price
Prices for master volumes range from Php 5 to Php 100+ based on the brand and where you buy it from.