How do I check in mono if my mix is out of phase?

Also when doing an eq, say I want to bring out the low E in a bass guitar which is 41 hz, Is it a good way to just boost the harmonics like 82 hz, 123 hz, 164 hz to keep the mix less muddy but at the same time making the low E more apparent?


Another thing I wanted to check is about Sound Pressure Meters. I've read that, to ensure the mix is not bass heavy or bass light, monitor sound between 80 and 85 db. Is there some sort of meter plugin to check the sound pressure?

Some, but not all, phase problems are more obvious in mono. The symptom is usually a thin, hollow sound. Just click the phase button on the master bus and listen.

Yes, harmonics are extremely important for bass guitar. Which frequencies to boost or cut depends on the guitar tone. Sometimes you may end up boosting at 1KHz and cutting at 300Hz. Depends on the makeup of the original tone.

SPL meters can be had at any Radio Shack for cheap. Get the analog version if they have them, but the digital version is OK too and, IIRC, slightly cheaper. Don't remember what I paid for mine, but I think it was $25-$30 (it was many years ago, though!)

The reason you use an SPL meter is so you can correlate levels on your interface or master bus meters to an actual sound volume coming out of your speakers. It's necessary if you want to adopt the K-meter system.

But mainly, it's important to mix at consistent volume levels. Whether that ends up being between 80 and 85db is up to personal preference. Some people like it to be a little quieter than that. The reason 83 or 85db is given is twofold: first, it's kind of the sweet spot in the Fletcher-Munsen curves, and second, it's the standard for motion picture exhibition. 

"Yes, harmonics are extremely important for bass guitar. Which frequencies to boost or cut depends on the guitar tone. Sometimes you may end up boosting at 1KHz and cutting at 300Hz. Depends on the makeup of the original tone. " 
 
I'm guessing for people new at this (myself), it would be trial and error on boosting and cutting harmonics until it the bass sits nicely in it's own territory? 
----
"SPL meters can be had at any Radio Shack for cheap. Get the analog version if they have them, but the digital version is OK too and, IIRC, slightly cheaper. Don't remember what I paid for mine, but I think it was $25-$30 (it was many years ago, though!)" 

So there is no such thing as a plugin that can be added in the master bus at the end of the fx chain? Though I'm probably guessing.

Low E on a bass guitar (without using an octave device) is 80Hz, and a bass drum is usually around 60Hz. If you need the frequencies I think maybe nowadays they can be looked up on the Internet, if not then buying the Handbook of Electronic Tables (formulae and a lot of things) then get ahold of one.

Though the ears are probably best, there are 'correlation meters' that measure this type of issue.

One thing that many people do is to get all of the EQ done in mono. Then start panning things and do the remaining tweaking. If you can hear everything and it sounds good in mono, then you know you don't have phase issues or frequency masking issues that are just being hidden by being on separate sides of the mix (i.e. they don't sound bad in the sweet spot but out in the room where it's effectively mono they are problematic.)

spacealf


Low E on a bass guitar (without using an octave device) is 80Hz, and a bass drum is usually around 60Hz. If you need the frequencies I think maybe nowadays they can be looked up on the Internet, if not then buying the Handbook of Electronic Tables (formulae and a lot of things) then get ahold of one.

Actually, low E on a guitar is 80Hz (82.407Hz specifically). The bass guitar is half that - 40Hz. Most octave devices don't work well on the low E of a bass guitar. I find mine won't start working till about a low G, but only properly working at about a low A. It's an EBS OctaBass.


My biggest question is WHY do you want to tweak the low E? Is it dropping out in the mix? Early in my mixing years I was mixing in a terrible, small, brick room. The bass of one note on a song kept popping out. So I automated it to be even. Then on headphones or other systems it was a missing note. I didn't realise how much the room was affecting my bass. Hence the question! Are you making this mixing decision in a good room or with headphones? If not, be careful and make sure you understand what's going on to your bass in your room!


SPL meters are physical, hand held devices which measure sound pressure. No plugin, I'm afraid. Good ones cost a LOT. But you don't need that. A cheap one would be suitable. If you play a song, it doesn't just have a single dB level in the room. Each frequency has it's own pressure level. If we measure the SPL at say 125Hz and find it to be 75dB, and then turn up the volume and measure 100dB, our ears won't hear it the same way. They might hear 60dB and 100dB. That's because at low levels, are ears don't hear bass well. We need to turn it up a little to hear it properly. Fletcher and Munson discovered this. So this means that if we use an SPL meter normally, it's going to measure HUGE levels of bass that we might not even actually be hearing! This makes the meter not very useful. If we have two songs, one is bass heavy, one bass light. We adjust the levels so the bass light one sounds louder and the bass heavy one sounds quieter. BUT if you measure it with the SPL meter, it might tell you the quiet one is actually louder. You don't hear the bass, but the meter still picks it up. Hence we need to put in a filter to basically mimic our ears. These are weight curves. Most common are A-Weighted and C-Weighted. They are simple approximations of how our ears hear. So this is why when you buy an SPL meter, it must have these curves! Fortunately they should all have them as it's very standard. I think for K-Metering you use A. It's most typical for quiet sounds. For louder sounds you tend to use C-Weighting. But do you actually NEED one? Probably not! I'd personally save the cash and buy a plugin ;)

Plugins do exist that emphasize or add harmonics, and are often used on bass precisely because 40 Hz is poorly reproduced on most playback systems. 

MaxxBass from Waves works on the principle that we will think we hear very low frequencies that aren't really there if the harmonics are raised. A simple distortion plugin or amp sim will do something similar. If you want to experiment, try the free Voxengo Boogex distortion plugin on bass, either in series or in parallel.

Thanks Bit. Does that plugin actually raise the harmonics? 
-------------------------------------------------------------------------------
I'll have a look at correlation meters. So do I just hit the phase button on the master track as suggested by Bit?


------------------------------------------------------------------------------------------
Thanks Al, I'll see if I can find one on the web.

Yes, it actually adds harmonics, as opposed to just turning them up as with an EQ.

Ok correct me if I'm wrong, but if that plugin "adds" harmonics, isn't that the same as turning up/boosting the harmonics manually in the eq except it does it for you?