Double Bass Volume vs master volume

[turf3]

It's kind of embarrassing to admit I don't know this, but for most of my life I've either been unamplified or someone else handled it. But now that I'm playing bass I have to learn about amplification.

So on my bass amp, from left to right, there are "volume", "bass", "mid", "treble", "high" and "master volume". The EQ knobs are self explanatory, I understand "volume" controls the level of signal fed to the EQ portion and "master volume" controls the level of the signal after EQ is applied to it. But what I want to know is, what is the REAL WORLD difference in boosting at "volume" i.e., before equalization, versus boosting after, at "master volume". This is a one channel amp.

 

[KUNGfuSHERIFF]

Depends on who made it. MI-series Walter Woods amps should have the master volume dimed and have the overall level controlled by the input gain if maximum volume is desired.

Before anyone jumps on me, Walter told me that himself.

 

[5StringBlues]

It's really gonna depend on your amps individual preamp and how it works.

 

[Chris Fitzgerald]

It’s a great question, and an important issue that every bassist should have a feel for.

Since I came up as a guitarist in my early years during the 70’s and early 80’s, I was always trying to get the right level of distortion/saturation in my tone for whatever any given song required. In those days, especially on tube amps, those two knobs were often called “Gain” (far left, pre EQ) and “Volume” (far right, post EQ). You would dial in the amount of saturation you wanted using the Gain control, then regulate the volume with the Volume control.

In the guitar world, those amps were made to produce overdrive/saturation/distortion at the preamp level, then control volume with a dedicated knob at the end of the chain. Nowadays there are a million pedals and amp sims for this task, and even the solid state amps sold now can do this through electronic wizardry. Many people still argue that the old tube amps did it better, but that’s another story.

In today’s bass amp world, most of the amps are solid state and/or class D designs, which accounts for the smaller form factor and much lighter weight. But in spite of this, some of that old paradigm remains. These days, I think of the formula as Preamp Gain and Power Amp Level. Even with amps designed to put out a clean signal, there is still a certain art to dialing in a good preamp level for the sound you’re after.

In my experience, there is a sweet spot with the preamp gain. Set it too low, and the sound is too unfocused and ambient; set it too high, and there is distortion of a sort that I doubt any double bassist would find pleasing. But between those two poles, there is a wide range of colors, including an aspect I can only describe as “heft”. Heft is the sound of a preamp signal hot enough to maximize the capabilities of the amp, but not so hot that it makes the signal sound distorted or overdriven. It’s an extremely personal season to taste kind of thing, but well worth exploring, IMO.

TLDR: for a more old school ambient sound, back off the preamp gain and dime the master (think PC on Kind Of Blue). For a more modern, solid sustaining sound with lots of impact and punch, find the hottest preamp sound that won’t distort, and use the master as a volume control (think Bromberg on Wood). For everything in between, season to taste. As always, EEMMV, and EEMWCB.

 

[Wasnex]

When you have both Volume and Master, Gain is a usually a better term than Volume. Also Master is short of Master Volume

Gain controls come early in the preamp. The exact location varies. It might be right after the first gain stage, or it may later in the signal path.

One intent of a Gain control is to set the level passing through the succeeding circuits.

The way preamp circuits are designed determines how they overload. Some circuits cross quickly into harsh distortion and some transition gradually into compression, then light drive, and finally heavier drive.

The way you adjust a preamp that transitions quickly is to set the Gain just below clipping on your loudest notes. The idea is to adjust the signal level high enough for a good signal to noise ratio while maintaining enough headroom to avoid unintended distortion.

Explanation of signal to noise ratio. Circuits have a certain level of "self noise;" I.E noise generated by the circuit. Tone control in particular tend to generate a relatively high level of self noise. If the signal coming out of the tone controls is weak, then you have to turn up the Master, which makes the noise louder. To get a good signal to noise ratio, you turn up the Gain, so a nice hot signal hits the tone controls and passes through to the Master. Now you can turn the Master down, which lowers the noise floor.

A preamp that transitions more gently into overload can be adjusted to achieve the desired compression or OD.

After you set the Gain, you adjust the Master for the desired power level.

When amps only have Volume, it's usually placed in the circuit like a Master; the amount of gain in the front end of the preamp is fixed.

Masters are usually towards the end of the preamp. I.E. after gain, shaping filters, tone controls, compressors, etc. The output from the Master is routed to the power section of the amp.

 

[Tom Bomb]

Go easy on the gain — rule of thumb (unless you're getting ugly).​

 

[fdeck]

The explanations here are good. On electric guitar and bass, players can use the gain and master control to tailor the amount of distortion they want. Upright players rarely want any distortion, so it's not such a big deal, but you can follow a rule of thumb such as turning up the gain until it's just shy of distorting, and then setting master for how loud you want to be. I think that's consistent with what's been suggested above.

I've got kind of a compulsion for understanding how gear works, and have studied the designs of bass amps. But I admit that when I'm on stage, I just scoot both knobs up gradually until I'm happy with my volume, then play. Because we prefer less distortion, and are typically using amps with more modern circuitry, those controls are probably quite forgiving, and "if it sounds good, it is good."

My GK MB150E combo has 3 gain controls (gain, boost, and master) and a complex circuit for managing distortion. On the other hand my MB200 head has a single volume knob and it's perfectly satisfactory.

There's a confounding factor that makes it hard to judge the effect of our controls, which is that making it slightly louder makes it sound better and seem easier to play. That's really hard to account for when experimenting with controls.

 

[DoubleMIDI]

If your amp has a DI out, even when it is set to pre(-EQ) it would (typically) be affected by the gain setting.
So set the gain as high as possible without getting unwanted effects even on very loud notes and keep it there. Then set your volume with the master only.
Even if the DI is not used by FOH, it is a good practice in case it might get used that way any time later.

 

[Wasnex]

If your amp has a DI out, even when it is set to pre(-EQ) it would (typically) be affected by the gain setting.

? AFAIK, most Pre DI signals are derived before the Gain control.

Here's an example:

 

[afroblue]

In a high volume situation, I would have the volume (gain) set lower and the master higher to try and avoid feedback.

 

[Povl Carstensen]

In a high volume situation, I would have the volume (gain) set lower and the master higher to try and avoid feedback.

Why would it make a difference, when the resulting volume is the result of the combined gain + master settings?

 

[Lance Bunyon]

My Boogie 400+ has volume (two actually, one for each channel) and master Volume.
Volume on this amp sets preamp gain.
Master volume controls the power amp.
There's a school of thought in the tube amp world that the master should always be dimed and the volume should be controlled by gain. On this particular amp that could damage my ears, my house, and my speaker cabinet...

 

[brianrost]

In general, the idea is that the tone of the amp will change depending on how much signal hits the EQ. Whether it’s useful or even audible depends on the particular amp. Master volume knobs showed up on guitar amps first, where the application was to control the amount of distortion without needing to play extremely loud.

Before anyone jumps on me, Walter told me that himself.

The manual for the Electracoustic models (which still were named MI-xxx) suggests setting the master at “6” (I assume about 1:00) and then adjust the gain to set the overall volume. Increase the master only if you need even more volume.

Personally, I always dime the master on my amps unless playing at really low volumes.

My Boogie 400+ has volume (two actually, one for each channel) and master Volume.

I owned the earlier D-180 and the two gain controls allowed cascading channels for a wide range of adjustment of distortion, just like the Boogie guitar amps. This was unique to the Mesa bass amps, I never saw any other brand offering it.

 

[Wasnex]

Why would it make a difference, when the resulting volume is the result of the combined gain + master settings?

Higher gain in middle of the preamp can result in more compression and the generation of harmonics, both of which increase the tendency for feedback.

 

[Wasnex]

There's a school of thought in the tube amp world that the master should always be dimed and the volume should be controlled by gain.

This is nonsense of course. The correct setting varies by amp, the volume you require, and the type of tone and feel you are trying to achieve.

I have amps that sound great with the Master dimed. Orange AD200B is a good example. Max the Master if want a close approximation of Fender black face sound and feel. Dial the Master back if you want to push the preamp into drive.

Some of my other amp don't work well with the Master cranked. There is simply too much gain in the back end of the amp. With these amps, cranking the Master results in a lot of undesirable hiss and/or hum. Some of my tube amps are set up like this.

The scaling of the Master in the Mesa M9 Carbine is super aggressive. With the Gain set to about 10:00, the Master goes from almost off, to loud...there is no in between. You can lower the Gain, but I think it degrades the sound. Pretty sure the amp would be unusable with the Master cranked.

 

[Wasnex]

I owned the earlier D-180 and the two gain controls allowed cascading channels for a wide range of adjustment of distortion, just like the Boogie guitar amps. This was unique to the Mesa bass amps, I never saw any other brand offering it.

FYI, the 400 and 400+ don't have the D180's unusual Master and the two channels are separate rather than cascaded.

The D180 gives the best clean sound with the Master dimed. If you back the Master off, it starves the driver tube and the goes from clean to heavily distorted in a fraction of a turn.

I don' think either the 400 or 400+ work well with the Master dimed.

 

[DoubleMIDI]

My Genz Benz Shuttle has an bout overload indicator, but this seems to be rather the exception than the rule.

For a feedback risk free setting the fully open master seems to be the best option but with more EQ and input stage noise than needed.

To get the lowest noise and lowest feedback risk you have to find the best gain setting just below the increasing feedback risk. Easy with an indicator, more tricky to find out with a certain pickup/preamp (setting) combination.

 

[Jefenator]

Usually: Volume for the instrument, Master for the room.

 

[Michael Glynn]

? AFAIK, most Pre DI signals are derived before the Gain control.

Acoustic Image amps have the Pre-EQ DI signal taken after the input/gain control (I'm sure there are others out there as well). I've had occasions where I had to turn the input down and master up to give the sound people what they wanted.

 

[Wasnex]

Acoustic Image amps have the Pre-EQ DI signal taken after the input/gain control (I'm sure there are others out there as well). I've had occasions where I had to turn the input down and master up to give the sound people what they wanted.

Although the vast majority of amps take the pre DI off before the gain control, there are clearly exceptions.