Checking Monitoring Level

[JeffLancaster]

OK, so I just got a new SPL meter and I thought I'd use it to check the db level at my mixing position. My understanding is that it's a good idea to monitor at around 85 dba. So, playing a reference track I had loaded in Sonar with the fader set at 0db, I adjusted the trim on my monitors so I would get an "average" of 85 dba with the control room output on my interface set at the 1 o'clock position. I say average, however, because that was my best guess - the actual meter readings were fluctuating from around 80 dba all the way into the 90's.

Is this the way this is normally set? It seems like I had to do a lot of guesstimating as to where an 85 dba average was (I assume the 85 is supposed to be average spl, not peak?) The other thing I was hoping to check is that I was getting a perfectly equal signal level from each side. But with the constant variation in signal level, getting this perfect would be nearly impossible. So, I was wondering, should I be using some sort of a reference tone instead? And if so, what frequency? Finally, since different material plays at different actual volumes, should I be trying to compensate for this? Or should I be aiming for 85 dba from each side when my meters in Sonar are holding steady at some particular level (and what would that level be)?

Thanks in advance, folks. Perhaps I'm just making things more complicated than they need to be, but I have a tendency to sweat little details. Once I get this worked out, I hope to use the meter to try to identify variations in acoustics throughout the room (won't that be fun ).

 

[SouthSIDE Glen]

Perhaps I'm just making things more complicated than they need to be.

Yeah, Jeff, you're in real danger of doing that.

You have your overall volume set close enough. A dB or two here or there is fine; the 85dB reference is just a theoretical guidepost, not operational gospel. Once you get your technique in the groove with the new monitors, you'll find yourself throwing that fader all over the place while your mixing. But it's a good idea to set the zero fader point to around 80 or 85dB as you have.

As far as setting the balance between the two monitors, there it would probably be best to use a test tone or pink noise to guarantee that the source signal is identical on both channels.

There are two schools, though, as to how your should actually set the balance on nearfield monitors. The common wisdom way is like you describe, with the meter. And this is the way to do it in studios where the engineering personnel can change. For home project studios or CRs with a regular, full-time engineer, though, some folks recommend that for setting the balance that you put the meter down and use your ears instead. The idea there is there is no guarantee that your own ears' stereo perception is perfectly balanced; if your left ear is a little weaker, for example, you might want to make the left channel a little stronger to keep the perceived balance in the middle. I personally see pluses and minuses to both sides of that story; make your own choice there.

G.

 

[mshilarious]

The idea there is there is no guarantee that your own ears' stereo perception is perfectly balanced; if your left ear is a little weaker, for example, you might want to make the left channel a little stronger to keep the perceived balance in the middle. I personally see pluses and minuses to both sides of that story; make your own choice there.

My audiologist tells me my right ear is down about 6dB, centered around 6kHz. But I don't adjust my monitors for that. Sometimes I move my head

 

[ermghoti]

My audiologist tells me my right ear is down about 6dB, centered around 6kHz. But I don't adjust my monitors for that. Sometimes I move my head

I haven't seen the Dr, but I have my suspicions about my meat mics. I would much rather slide my chair over, and have my mixes panned propery, than to be the only person in the world that hears the center of the mix in the center of the sound field, Or am I missing something?

 

[bennychico11]

here is a link with some test files and instructions:
http://www.abluesky.com/p_s_gb/p5s10.html
The link is for surround monitoring and with a sub, but you can adapt it.

If you're running out of your computer analog into a mixer of some sort, you'll want to run a test tone first to each channel at -20dBFS (panned hard L/R) so that you set it appropriately. If it's an analog mixer, -20dBFS=0VU

like Glen said, use pink noise. Set your meter to C-Weighted/slow response
you set it the pink noise to -20dBFS and you do each channel separately.
For music and film it's suggested to monitor 82-85dBSPL
For TV (commercials, DVD, etc.), 79-82dBSPL....Dolby says 79dbSPL
Put the meter at ear level, in the middle of your monitoring position and pointing about 45 degrees upwards

Theoretically, if both faders are at unity...both channels should read 85dBSPL separately. However, some people have found that one speaker is louder than the other even if they both are set the same. Make sure you also look on the back of your monitors to see if there is a knob back there as well. You may find in a home setting, 85dBSPL can be pretty loud.

Then for fun, set a 100Hz tone and walk around your room slowly...it can be interesting to see what the meter reads

 

[mixsit]

I haven't seen the Dr, but I have my suspicions about my meat mics. I would much rather slide my chair over, and have my mixes panned propery, than to be the only person in the world that hears the center of the mix in the center of the sound field, Or am I missing something?

Going through this here again, new speakers, new ear test, moving things around, the whole nine yards. I believe the whole point is two-fold; One is to get the system into the best possible balance, the other is to identify and then find ways to adjust for the things you can't change.
Personally, I can hardly believe how long I dicked around on this where a few simple changes were needed. In this case getting the frickin' mackie out of the path and getting a stable monitor path in it's place, simplified simple balance issues. The amount of guess work goes way down..
Isn't hindsight great?

 

[mshilarious]

like Glen said, use pink noise. Set your meter to C-Weighted/slow response
you set it the pink noise to -20dBFS and you do each channel separately.
For music and film it's suggested to monitor 82-85dBSPL
For TV (commercials, DVD, etc.), 79-82dBSPL....Dolby says 79dbSPL
Put the meter at ear level, in the middle of your monitoring position and pointing about 45 degrees upwards

That methodology seems too loud for popular music. Perhaps they are assuming classical music, which has about that dynamic range.

However, If you calibrate both L and R channels to 85dBSPL with a -20dBFS signal (doesn't say peak or RMS, I'll assume RMS), then for a -14dBRMS mix, that's an average level of 94dBSPL (+6dBRMS and +3dB for two channels). If the -20dBFS is a peak measure, it's probably more in line.

I just use full spectrum pink noise at peak of 0dBFS on both channels (something like -6dBFS RMS) and calibrate to 85dBSPL. If you want to set each channel, use 82dBSPL.

Katz has a bit in his book about calibrating monitor levels for different styles of music.

 

[bennychico11]

That methodology seems too loud for popular music. Perhaps they are assuming classical music, which has about that dynamic range.

However, If you calibrate both L and R channels to 85dBSPL with a -20dBFS signal (doesn't say peak or RMS, I'll assume RMS), then for a -14dBRMS mix, that's an average level of 94dBSPL (+6dBRMS and +3dB for two channels). If the -20dBFS is a peak measure, it's probably more in line.

I just use full spectrum pink noise at peak of 0dBFS on both channels (something like -6dBFS RMS) and calibrate to 85dBSPL. If you want to set each channel, use 82dBSPL.

Katz has a bit in his book about calibrating monitor levels for different styles of music.

that's the problem with a standard....everyone makes their own up

here's something from Bob Katz off his site:

Appendix 2: SMPTE Practice
All quoted monitor SPL calibration figures in this paper are referenced to -20 dB FS. The "theatre standard", Proposed SMPTE Recommended Practice: Relative and Absolute Sound Pressure Levels for Motion-Picture Multichannel Sound Systems, SMPTE Document RP 200, defines the calibration method in detail. In the 1970's the value was quoted as "85 at 0 VU" but as the measurement methods became more sophisticated, this value proved to be in error. It has now become "85 at -18 dB FS" with 0 VU remaining at -20 dBFS (sine wave). The history of this metamorphosis is interesting. A VU meterwas originally used to do the calibration, and with the advent of digital audio, the VU meter was calibrated with a sine wave to -20 dB FS. However, it was forgotten that a VU meter does not average by the RMS method, which results in an error between the RMS electrical value of the pink noise and the sine wave level. While 1 dB is the theoretical difference, the author has seen as much as a 2 dB discrepancy between certain VU meters and the true RMS pink noise level.
The other problem is the measurement bandwidth, since a widerange voltmeter will show attenuation of the source pink noise signal on a long distance analog cable due to capacitive losses. The solution is to define a specific measurement bandwidth (20 kHz). By the time all these errors were tracked down, it was discovered that the historical calibration was in error by 2dB. Using pink noise at an RMS level of -20 dBFS RMS must correctly result in an SPL level of only 83 dB. In order to retain the magic "85" number, the SMPTE raised the specified level of the calibrating pink noise to -18dB FS RMS, but the result is the identical monitor gain. One channel is measured at a time, the SPL meter set to C weighting, slow. The K-System is consistent with RP 200 only at K-20. I feel it will be simpler in the long run to calibrate to 83 dB SPL at the K-System meter's 0 dB rather than confuse future users with a non-standard +2 dB calibration point.
It is critical that the thousands of studios with legacy systems that incorporate VU meters should adjust the electrical relationship of the VU meter and digital level via a sine wave test tone, then ignore the VU meter and align the SPL with an RMS-calibrated digital pink noise source.

*Bob Katz

 

[SouthSIDE Glen]

I just use full spectrum pink noise at peak of 0dBFS on both channels (something like -6dBFS RMS) and calibrate to 85dBSPL. If you want to set each channel, use 82dBSPL.

This is how I was raised to do it also.

But I'll also re-state that the numbers should not, IMHO, be taken too rigidly. It's like a cooking recipe; it's a guideline, not a scientific formula.

Skip the math for a minute. To keep the understanding (over?)simple, the idea is to try and set one's mains fader so that when it's set to zero or thereabouts, one's monitors are outputing an optimum volume for the typical program material one is likely to be working. Here optimum is commonly defined as loud enough to avoid deficiencies in the human ear's response characteristics, but not too loud to cause damage to them. This volume "sweet spot" is usually considered to be somewhere around 80-85dBSPL.

But notice that the above statement already introduces two huge variables into the "equation": first, the phrase "typical program material", and second, "human ear's response." As both Ms and Benny point out, program material type, whether it's music genre or program type will affect the calibration gain required to acheive the desired level. Typical RMSs of -18dBFS and -8dBFS will require entirely different "calibrations". And everybody's ears are different in terms of sensitivity to volume and frequency response. For many, including myself, extended listening of typical rock at 85dBSPL does little but harsh the mids in the short term and cause early ear fatigue. For others, they just can't hear the nuances that I can at 70 or 75dB unless they crank up.

And we haven't even considered such factors as room acoustics and ambient noise levels, which also will affect the "ideal monitoring level".

For those of us who work across genres in music and in media both the RMS values and the ideal monitoring levels change. This renders such numbers as pink noise levels and SPL levels fluid. One has to just try and pick something that will get one close enough to zero on the fader most of the time to provide what we need to hear on the monitors. From there we can adjust as needed for the situation.

This is why God created faders! When's the last time you mixed an entire song at a single volume without touchingthe fader? When's the last time that you mixed two different performers at the exact same volume?

So, IMHO, is that both Benny and MS are equally correct with their numbers, but neither is absolutely correct...because there is no absolutely correct. I agree that for me Benny's -20dBFS/RMS pink noise reference seems a bit low; OTOH, for others the -6dBRMS reference that me and MS like level may seem high.

The bottom line is to use the reference level that both gives you somehwere around your optimum level when the fader is near the middle or near zero (2/3rds or so up) *AND* that gives you the right amount of "headroom" or flexibility in volume on the fader. That is you need to be able to adjust the volume range to meet your current working needs without having to run your fader too close to the top or the bottom of the control.

That's all that really matters. The exact numbers are guideposts only and can optimally change from studio to studio, engineer to engineer, and God bless the volume control.

G.

 

[JeffLancaster]

Thanks everyone, for your contributions to this - a lot of useful info here! With the rock material I'm currently working on, when my master fader is set at 0db my meters are typically fluctuating between -6db and -3db with occasional peaks towards 0. So it seems that if I used a -20db signal to calibrate my monitors, if I then when back and listened to my material with the fader set at 0, I could quickly blow my ears! I don't think that's what I want to do

I think I'll start by using the meter to ensure the left and right channels are at even volume, however as you pointed out, SG, sometimes our ears may not be in perfect balance with each other, so once I know that things are right at a technical level, I'll sit back and analyze the balance with my ears and decide if I want to make any further adjustments.

Would any of you know where I might find any other good reference tones I could load up for doing this analysis? I looked at the link that you provided, Benny, but noticed the tones were recorded at -20db. I'm guessing those would be good if I was calibrating for say, a movie soundtrack, but with high volume rock material, I think I'm going to want reference tones recorded somewhere between -6db and 0. Would you all agree that I'm correct in this assumption? Better yet, does anyone know of something (perhaps a plugin) that would generate steady tones at user specified frequencies and output levels?

 

[mshilarious]

Would any of you know where I might find any other good reference tones I could load up for doing this analysis? I looked at the link that you provided, Benny, but noticed the tones were recorded at -20db. I'm guessing those would be good if I was calibrating for say, a movie soundtrack, but with high volume rock material, I think I'm going to want reference tones recorded somewhere between -6db and 0. Would you all agree that I'm correct in this assumption?

You can simply change the gain in your DAW to whatever level you like. Digital noise floor is irrelevant when calibrating monitors.

 

[bennychico11]

That methodology seems too loud for popular music. Perhaps they are assuming classical music, which has about that dynamic range.

After doing some more reading, I guess this would fit in with the K-14 standard for popular music....which they suggest turning down about 6dB.

more quotes from Bob Katz off of prosoundweb.com forum:

Hi, guy(s)....there is a bit more to pay attention to in the "K-System". First, referring to the above, make sure that the pink noise you generated is RMS-calibrated. But since you are trying to roll your own pink noise and filter it to 500-2 kHz, it's VERY important that you use an RMS-responding meter to guarantee its level is still -20 dBFS.

You could be as much as 6 dB off without an RMS-calibrated source or analyser, depending on the crest factor of your pink noise.

OK, that takes care of the first part!

The second part: YES, probably most of the stuff you will listen to will be intolerably loud at that calibration! And the reason is that by calibrating your system in the above manner you have established the "0 dB reference gain" on your monitor control. Approximately -6 dB monitor gain (reference the above 0 dB) will work well with true K-14 material, approximately -8 dB with true K-12, and so on. Considering that Red Hot Chili Peppers' RMS level is MUCH hotter, you might find your "comfort listening level" listening to the most squashed masters at as low as -14 dB on the monitor gain with the hottest stuff that's out there.

For a really good picture of how to use a calibrated monitor, visit the CD Honor roll at www.digido.com. It will show you examples of well-recorded material that fits within the various attenuation guidelines. And finally, as described on the "honor roll page" your mileage will vary depending on the transient response of your monitors, the size of the room, and how close the monitors are to your ears!

What I found interesting is when Mr. Katz referred to his quote in the article he published which said:

For the most accurate measurement, use narrow-band pink noise limited 500-2kHz, whose RMS level is -20 dBFS. This noise will read the same level on SPL meters with flat response, A weighting, or C weighting, eliminating several variables.

I'll admit, I work on much more TV, DVD, film projects than I do music. And our standard is -20dBFS=0VU. Which is why -6dBFS seem way too hot for me. I throw up pink noise at -20 and peaks are around -14, I think (I need better meters still...ugh)
Music is another ball game all together, which I guess could be one of the reasons there is no standard for CD and why many people just push their levels to as close as they can get it to 0dBFS.
But I also calibrate my montiors to 79dBSPL (and individually) for broadcast TV reasons.

Glen, nicely worded as usual.
I guess we can all agree what you set everything at depends on the material you are mixing as well as what medium the final product is going to end up on. Not to mention where it's going to playback as well.

 

[JeffLancaster]

You can simply change the gain in your DAW to whatever level you like. Digital noise floor is irrelevant when calibrating monitors.

Aah...good point. I'm not sure if I'm thinking too hard or not hard enough!

 

[SouthSIDE Glen]

I think I'll start by using the meter to ensure the left and right channels are at even volume, however as you pointed out, SG, sometimes our ears may not be in perfect balance with each other, so once I know that things are right at a technical level, I'll sit back and analyze the balance with my ears and decide if I want to make any further adjustments.

That sounds like a solid plan to me . Good luck with it all!

Would any of you know where I might find any other good reference tones I could load up for doing this analysis?

There are several sources available on the 'net.

A quick search yielded these example d/l sources:

http://www.nch.com.au/tonegen/index.html
http://www.softplatz.com/kw/pink-noise-generator/
http://www.newfreedownloads.com/MP3-Audio/Misc-Plug-ins/Test-Tone-Generator.html
http://www.timelyweb.com/free/pinknoise.html

Some of the listed generators synth their own tones; you'd have to capture them and save them to a wav of your desired volume. Others simply play back loops from a library of included wav files. As Ms says, you can change their apmlitude to your desired RMS yourself with no worries bout noise levels or that sort of thing.

G.

 

[bennychico11]

another interesting read, in case no one has yet. Kind of shows how much CDs vary without a monitoring standard in place:

Bob Katz's CD honor roll (boy, I seem to be quoting him left and right today )

edit---
oops, I forgot I quoted him above in my last post where he told people to listen to it....soooo, I'm just reiterating what he said

 

[SouthSIDE Glen]

I'll admit, I work on much more TV, DVD, film projects than I do music. And our standard is -20dBFS=0VU. Which is why -6dBFS seem way too hot for me. I throw up pink noise at -20 and peaks are around -14, I think (I need better meters still...ugh)

WARNING: Quick off-topic sidebar: Ben, do you work with the audio-only aspects of that stuff or you into the video editing as well? Put another way, you strictly a PT guy or you do the Avid stuff too? [End of sidebar]

I guess we can all agree what you set everything at depends on the material you are mixing as well as what medium the final product is going to end up on. Not to mention where it's going to playback as well.

And the biggest variable of all the is the most often forgotten; the specifications of the human engineer him/herself . The ears/brain are the two final links in the signal chain; the monitors should be tuned to them as much as anything else .

G.

 

[bennychico11]

WARNING: Quick off-topic sidebar: Ben, do you work with the audio-only aspects of that stuff or you into the video editing as well? Put another way, you strictly a PT guy or you do the Avid stuff too? [End of sidebar]

lol, strictly audio in Pro Tools. I hardly know anything about the Avids we use....they scare me

why do you ask? you gonna make fun of me 'cause of my metering comment? I'm still beggin' for the company to buy them!!!!! Get off my back!

 

[SouthSIDE Glen]

lol, strictly audio in Pro Tools. I hardly know anything about the Avids we use....they scare me

why do you ask? you gonna make fun of me 'cause of my metering comment? I'm still beggin' for the company to buy them!!!!! Get off my back!

No no no, nothing like that at all!

Just that it took me close to a year of talking with you on this board before I found you you worked mostly on sound for pictures (probably my own myopia at work there.) As you probably already know, I work with video as well as audio, which is an extreme rarity on this HR board. So when I found out that your work was related to the visual stuf as well, it caught my interest and curiosity, that's all.

As far as I'm concerned, you are THE Man for PT on this board and certainly no slouch outside of PT either, you know your stuff; I'd not jump on you back lightly...well, maybe except for the occasional well-intentioned noogie...

G.

 

[bennychico11]

No no no, nothing like that at all!

Just that it took me close to a year of talking with you on this board before I found you you worked mostly on sound for pictures (probably my own myopia at work there.) As you probably already know, I work with video as well as audio, which is an extreme rarity on this HR board. So when I found out that your work was related to the visual stuf as well, it caught my interest and curiosity, that's all.

As far as I'm concerned, you are THE Man for PT on this board and certainly no slouch outside of PT either, you know your stuff; I'd not jump on you back lightly...well, maybe except for the occasional well-intentioned noogie...

G.

lol, I was just kidding about the meters.
I didn't know you did video either. Yeah, I do just audio at our post facility...one of the few facilities in town that actually has both audio and video. So many video guys just do the audio on their own in the Avids...which I don't know how they do it all working with just 30 samples a second.
my background is originally music before I decided to enter the recording world. Eventually found out that post production side of things pays better (and with more regularity) than music....and it can be fun at the same time Audio for video used to be one of my weaknesses, but I'm slowly starting to catch on to it all.

Thanks for the kind comments, Glen. I find your contribution to this forum to be of great importance as well. Especially when they are well worded and concise as all of them usually are.

 

[SouthSIDE Glen]

Further apologies for the thread hijack...

So many video guys just do the audio on their own in the Avids...which I don't know how they do it all working with just 30 samples a second.

They are working at 30 video frames per second, but their audio tracks are really no different than what you and I work with in pure audio; they are still using uncompressed audio at at least 44.1k.

And you gotta be thinking of a different SSG. "Concise"??? I have to be guilty of the highest quantity of extra-long posts of anyone this side of ez-willis' thesis-paper-generator posts to walters.

G.