The Difference Between Gain, Volume, Level, and Loudness

Topics: OBB/Personal

When working with sound amplification equipment, we often misuse these terms. Probably because you’ll see them often, and two or three on the same piece of equipment! That can seriously make your brain want to go flip upside-down and jump into a pool of boiling acoustic particle velocity soup. On top of that, you might have channel volume, master volume, guitar volume, fader levels,  guitar amp gain, mixer board gain … etc. But, it’s pretty important stuff to understand if you want to get a good sound from your equipment.

Gain

Gain is one of the harder terms to define, mainly because its used in a lot more places than just the audio world. Quite simply it means an increase in some kind of value. So for example, you can have a power gain, voltage gain, or current gain; and they all increase those respective values. Typically when referring to gain, we refer to transmission gain, which is the increase in the power of the signal. This increase is almost always expressed in dB (decibels). This could be the increase in the raw signal from your guitar or microphone before it goes into any of the other electronic components. For the curious, here’s the equation to calculate gain:

Gain = 10 x log (Power out/Power in)

expressed in dB.

Practical Use of Gain

For all non-rocket scientist purposes, you’re probably going to see a gain control in two places. One of them is on your mixer board or PA, and the other is on a guitar amp. These both mean the same thing as far as electronics go, but serve different purposes in each.

On the mixer board, you’ll see the gain at the top of the board. It’s the first control that the raw mic signal sees, and it will boost the signal to a sufficient level for the rest of the controls to work properly. You’ll want to set this gain level high enough to bring up the level of the signal, but not so high that you’ll get clipping or distortion in the signal. For this purpose, many boards come with a PFL (Pre-Fader Listen) button. This button will let you see the actual signal strength by looking at the LEDs on the board. Use the mic at normal sound levels and set the gain knob so that the peaks in sound don’t send the signal into the red, and you’re good to go.

On a guitar amp, the gain’s main intention is to create distortion (as my blood tingles with ground shaking delight). You already know what it does, so there’s no point in telling you, but I do have a small tip – turn your gain down! Yes, I also love the gut wrenching melodies of face-meltifying solos, but you seriously don’t need your gain sitting on 10 all the time. Novices will go into the recording studio thinking their sound is redonkulously awesome, only to have the sound engineer take their distortion down to a 5 or 6 cause they sound terrible. The distortion shouldn’t hide your skills, but accentuate them. IMHO.

Volume

Besides defining three dimensional space, volume can also be used to describe the power level of a signal. So when you turn up the “master volume” knob on your amp, it simply means you’re increasing the amount of power used by the amp to increase the signal. This term is quite ambiguous since it’s used in so many different places, mainly to mean the actual sound you perceive in your ears, which is not exactly true. Use with caution.

Level

This term is used to describe the magnitude of the sound in reference to some arbitrary reference. More specifically we use SPL (sound pressure level) to describe sound waves. SPL is a term calculated from the log of the rms sound pressure of a measured sound related to a reference value. Basically meaning we create a measurement scale with zero starting at the lowest threshold of human hearing. The SPL scale is shown in dB and goes up to 130 dB (well, infinity, but whatever), which is the threshold of pain for the human ear. Now I just need to find a way to rock as loud as Krakatoa (180 dB standing 100 miles away).

Loudness

Loudness, even though similar to volume and level, is another whol’nother monster. Since human ears are not able to hear each frequency at the same level, perceived loudness is different as we move up and down in frequency. The following graph shows the level that a human ear “thinks” its hearing, which as you can see is not correct most of the time.  The lower frequencies, like the bass guitar at 40-220 Hz, need more sound pressure for us to believe it’s equally as loud as a sound at 1 kHz.

Equal Loudness Contours

Equal Loudness Contours

Here we introduce a term called a “phon“, which is used to describe loudness.  You can see on the graph that the phon contour is different for each dB level.  The 120 phon contour requires less boost in the low frequencies than the 10 phon contour.  Mostly because of the shape of the ear, you can also see from the graph that we hear the 3-4 kHz range the best, which happens to be on the slightly higher end of human speech.  If you lost it, you’d have a hard time understanding people.

In Conclusion

Now the whole point of this article is to get you all learned up about music terminology, and how to use it.  But don’t go around hitting people on the head with your “terminology hammer” and pretending like you own the universe now that you know this stuff. Know-it-alls are annoying. The point is the ideas behind the words, so don’t get so hung up on the specific words unless you have to go writing text someplace.

So that’s it, no more. I was gonna say “As always, yada yada”, but realized that this is only the second article I’ve written so far, so I can’t exactly say “As always”. Well, hold on a sec. Why the heck not? Yeah. There’s no rules for writing blogs right?

As always, stay cool, and hash it up in the comments.

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5 Responses to “The Difference Between Gain, Volume, Level, and Loudness”

  1. Rob Drscoll says:

    Thanks for the lucid explanations. Maybe you might want to answer this one. Or Not!

    I’m a musician and have a Vox Tonelab for guitar FX.

    My problem is all my recordings sound like mush but not so bad when I monitor live out the back of the unit with headphones.(I don’t know where to set all the knobs)

    The tonelab models most of the best equipment from the past 50 years and has in this sequence: pedal / drive & level, amp with gain, pre-amp, valve reactor gain / power amp / channel volume / cabinet model / modulation / delays / reverb / output level.

    Could someone please add another knob? After reading your article I went and looked at the schematic for Tonelab and realized for the first time channel volume is between the power amp and the cabinet model. (Who knew?)

    My question is: with my guitar set to say 7, what knobs should I set at 50% and leave there (if any) and then should I use the master volume / vr gain (of the amp / not the level knob on the back of the Tonelab) to control the overall level I am hearing in my headphones?

    Or should I be saving myself a load of heartache and learn how to run the thing while monitoring through pro-tools? (so the sound I am hearing is most definately the sound I am recording?

    Clear as mud? I hope so because I’ve decided to go to NIMBUS recording school here in Vancvouver and maybe then I can figure out how to use and record with the Tonelab.

    The Gizmo Itself is a pure work of art with tubes and everything, but for people like me who are developing their talent a little later in life it can be mildly vexing to get the best sound possible.

    Thanks for your great article, it helps a lot.

    Rob Driscoll / Musician / Vancouver BC

    ps: I had my head stuck out a window at 8 am in the morning at Victoria BC facing south down Puget sound the day Mnt ST Helenes blew up. That was LOUD, very loud, as in… turn down the gain loud, and then lower the volume a bit. Stay Well. I’ve book marked your site. http://www.myspace.com/robdriscoll

  2. John says:

    Ha ha ha, I wish I could have been there for St Helens man; it sounds like something straight out of a movie!

    As for your question, usually when you’ve got a “mushy” sound you’re losing frequencies somewhere. You said it sounds good out of the headphones right? It might be the headphones that are giving you problems, because you’re probably changing the settings on the Tonelab while listening to the headphones (I’m assuming), but your headphones might not be giving you the full frequency spectrum. Then you head over to record, and the Tonelab is set up to sound good on your headphones, and will sound like crap on the computer recording.

    I don’t know if that answers your question, but the best option is probably to take your own advice and just monitor through Pro Tools. Then you’ll know for sure the sound you’re getting is what you want. Or at least set up the sound you want while listening to Pro Tools, and then you can switch back to the headphones when you want to play. Good luck at NIMBUS, and tell me if you solve your sound problem. Oh, and thanks for the bookmark.

  3. Randall Hughed says:

    I have a line six ux2 which is also a digital audio interface like the vox tonelab and i also own a vox valvetronix vt40+ and that mushy sound you are talking about they seem to be proud of it. My setup for the valvetronix is almost the same. The guitar input then the preamp which is of course at first the gain to set the amount of input im allowing into the preamp then an eq like and other amp than a volume then it gets a little weird like your tonelab. After the signal leaves the preamp it goes through two banks of 11 fx pedals (22 in all) then through a 12ax7 ruby preamp tube making the amp a hybrid sort of. The 12ax7 tube is 2 vacuum tubes in one. The signal passes through the tube to supposedly make the sound “warmer and fuller” and also like a tube amplifier the signal is sent through an output transformer with a master level control (somehow the valve reactor tech takes a normally 40 watt amp and pushes it to 60) then to the speaker. I havent had nor have heard any other vox equip so i started to figure out a way to get rid of the “mushiness”. At first in the first set of fx there was a treble booster or top boost and that got rid of the mushiness but added too many highs. I then used the metal distortion fx. It helped the most. But what i found what works the best and the reason of this is the excessive amount of head room these amps tend to have im guessing because of the tube but i always run it with the master level set atleast to 40% because also like you when i play through headphones it sounds amazing. I am almost convinced its because the valve reactor technology needs to be PUSHED in essence pishing the tube harder and in effect getting the sound i desire. Oh and the stock speaker “SUCKS MAJOR”. Replace with either a 10 or cut the hole to fit a 12″. I have installed an output jack to drive a cab with it if wanted and an eminence governor 12″ which drastically improves the tone and characteristics of the amp making it sound more professional and not like a cheap practice amp. My advice which worked for me is drive the valve reactor as high as you can. Just think of a 50 watt tube amp with the preamps set to normal but the master is low. It sounds muddy becuse not enough electrons are passing through the tube. Give it a try and let me know how it turns out.

  4. oldfartatplay1320 says:

    I’m curious as to why I have to keep turning down the volume on my computer. I run the line from my computer into a 10-band equaliser, then into a Pioneer home entertainment system amplifier, which plays through Optimus 25 and Carillon 100 speakers. It doesn’t matter what medium is playing, YouTube, CD, DVD, videos from other sources, I keep having to turn down the sound. I thought this might be ‘gain’, but apparently I’m wrong. The sound doesn’t distort, it just gets louder (and how!). Being a technoshlub, I thought I should ask an expert (that’s you). Any handle you can give me on this will be appreciated.

  5. FretBubba says:

    I recently purchased the Vox Stomplab IG – I’m confused as to whether I can connect the output (meant for headphones as well) to my home theater amplifier.

    If so, should I be careful about the gain/level settings on the amp modeler and/or the volume level on the home theater? I’m just scared I might bust my speakers since the product’s meant to be used with passive speakers such as headphones…

    Any thoughts?

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