Sub60hz mixing...

All I gots to say about mixing lows… the wave lengths are too long to effectively reproduce in most home studios. A 60hz wave is rougly 19 feet long… aka, you need to be 19 feet from the sound source to hear the wave. Not very many folks have a room that can deal with such things… that’s why super low end sounds like mud so much of the time and folks tend to roll it off and studios go through a lot of trouble to build traps to stop low frequencies from bouncing in the room. Your listeners don’t normally have the room or equipement to reproduce such things either… so unless this is some sort of an academic endeavor, I wouldn’t spend too much time messing with it (Aka, worrying about that stuff is a waste of time IMO for most things unless you liek to blow the speakers out of $30 boomboxes with frequncies folks can’t hear. Worry about sub 60 hz once you are mixing Foley for a Jurrasic Park movie.)

40hz ~ 28.25 ft
20hz ~ 56.5 ft
16hz ~ 70.6 ft


You’re gonna need one heck of a big room or stand outside to hear this stuff. (And much below 35-40 hz most folks can’t hear anyway.) What one feels as punch in the gut from a kick drum is generally in the 80-100hz range. Below that is rumble and mud.

Yeah, the thing is, you don’t want “oomph” when you are mixing, you want accuracy.

But shouldn’t you know whether or not the “oomph” is there?

Bubba, I am still curious about something. Remember how I said i added a bunch of 30Hz to something? It wasn’t that I set the EQ to 30 and cranked it up; I used a plugin (mda SubSynth) to synthesize a 30 Hz tone when the bass drum hit. If I turned that 30Hz tone really loud, I could hear it – or at least perceive it – on my boombox and my ATHM30 headphones and it sounded cool. But then, when I went out to the car with a subwoofer in it, it was way too loud. I guess I can see that in a car, which is outside, the low frequencies had plenty of room to develop. But that it happened at all does seem to go against your statement that most peoples’ equipment can’t reproduce such low frequencies (unless the plugin was lying and was creating frequencies higher than 30Hz).

I guess I’m getting off topic, though, and it boils down to my ignorance about low end and subwoofers. Thanks for the info and wavelengths; I’ll try to do more research before I become annoying :)

I think what you are missing is how harmonics work. When you hear the low B of a 5 string bass being played, in close proximity, you hear nearly none of the fundmental which is something like 30-35hz (low A on piano is 27 hz if I remember correctly). You are hearing the harmonics which are multiples of the frequency… perhaps two or three times the fundamental. I can almost guarantee the mda plug is adding harmonics above and beyond those in the subsonic level… I actually happen to think the sub part is probably the least of what the plugin does.

<!–QuoteBegin>

Quote
Distort
Takes the existing low frequencies, clips them to produce harmonics at a constant level, then filters out the higher harmonics. Has a similar effect to compressing the low frequencies.


This tells me it is mostly upper content that it is adding.

<!–QuoteBegin>
Quote
on my boombox and my ATHM30 headphones and it sounded cool


This confirms my thoughts even more. There is no way on god’s green earth you are hearing much 30 hz in headphones. 1/2" of air space ain’t enough, plus the drivers/cones in headphones are tiny so they are not going to put out much 30hz tone even if you did have the air space.

You have added harmonics which make the bass sound fatter, but it doesn’t necessarily add much low bass. I’m tellin ya, roll off the lows and forget it. High pass at 40 or 60 hz on the 2 bus and be done with it. For the sake of experiment, take your sub harmonic mix and run a high pass that chops off the low end. Then by sweeping the cross over frequency upwards, see at what point in head phones you actually start to notice the lows disappearing. Maybe even make a similar experiment to hear in the car… It makes me nuts the folks who have subs blaring in their car producing frequencies they can’t even hear … I can hear them just fine 50 feet away in my house upstairs, in bed, at 3 AM.

As for knowing if the oomph is there, use a spectral analyzer and get rid of it. You’re just going to burn up a lot of your friends’ $30 boom boxes with your mixes if you leave a lot of low bass in. Plus, you’ll know you have too much low end when you go to master your mix and it sounds all mushy from the limiter/compressor kicking in every 2 seconds because the low is controlling the mix.

Listen to the Bubba. :)

Sure, aikan, you want to know what the mix sounds ike, but that was my point - you don’t want a monitoring situation in which the music is presented in a way that falsely emphasizes anything. You want accuracy, not (added) oomph. You demonstrated why with your experiment - the car system had more low end in it than the headphones, and the result was not good. BTW, most of us listen to mixes on as many different systems as we can, for this reason - to see how well our mixes work in different contexts, on different systems, because there is no ideal monitoring environment, there is no such thing as “best” when it comes to monitor speakers, there is no “correct” way to monitor. There is simply what “works” in a given case for a particular person, and even that changes…

:D

To take TomS’s point a step further… let’s think about the effects of a system that makes things sound like more than they are…


You have a sub that makes you bass sound like God. Things rumble and thump to the point your bowels can hardly stand it. So this mix engineer would say “Gee whiz, there is way too much bass in this mix!” and I would take some of it out. Then, on every other sytem the bass would sound whimpy becuase I took too much out. I took too much out because my monitoring system told me, falsly, that there was a lot of bass. See what I am saying? Yeah, guys say “Learn your monitors.” That is true to a point. Learn your monitors, but don’t make the learning curve harder than it needs to be by introducing all sorts of extraneous output.

As we discussed earlier, half of monitoring is the room you are in. Bass frequencies are hard to deal with as it is. To take a bad room (which most of us have), add a sub (especially one that is not properly calibrated), and then try to mix, you are setting yourself up unless you are really willing to put the time and money into doing it right.

Great topic guys, I’ve been observing the discussion.

Quick question…

Quote (Bubbagump @ July 13 2005,10:10)
half of monitoring is the room you are in.

Then do headphones make sense? This is what I use, however the freq response is not flat, so I’m in the same boat. But I can buy flat headphones, and not worry about the room, correct?

Headphones have their problems.

1. Most headphones are not very accurate, even the “accurate” ones.
2. As I mentioned above, you simply do not have enough air space to hear bass, any bass, correctly.
3. Headphones give you a phoney perception of stereo space.


The reason folks use near fields is that they are designed to try to compensate for all the problems we have mentioned. The idea is to over whelm the reflections in the room with the direct field of the nearfields. That’s why we use near fields as opposed to mid or far fields like you would find in a high end mastering house or movie mix room. Mid and far fields REALLY suffer from being in a poor room. You can get away with more with near fields. (ie, less room treatment, not so critical placement…) There is a reason you see near fields in every catalog and every studio.

so, Bubba, maybe this is a good point for someone (ie you? :D ) to sort out the differences between near field and reference monitors while we’re here, and point out the good ones to consider?

Near field and reference monitors are more or less what the maker wants to label them. Same thing, different words. As far as choosing them, the method I always advocate is to use your ears… Make a CD compilation of professionally done tunes that you are very familiar with and know what they should sound like. Take you handy compilation down to the store and listen to it over and over through the monitors and find te ones you believe are giving you an accurate picture of what the tunes on your compilation sound like. On my CD I put a mix of styles and music to check certain areas. The Brandenburg Concerto (balanced), a Prodigy tune (very bass heavy), an Oasis tune (wall of sound mid range) , a Terje Rypdal tune (lots of high end), a Sting tune (love or hate the guy, you gotta love his production…) and a few others. DOnt’ expect your best to be the same as anothers. I think it was clark_griswald, he got KRKs. I listened to the KRKs and hated them. I got Events. Whatever. For what he is doing he felt the KRKs were what he needed and I found what I needed in the Events. Just get away from the hype and advertising and actually listen to them.

Which Brandenburg recording, Bubba? :)

Christopher Hogwood

Quote (Bubbagump @ July 12 2005,06:24)
A 60hz wave is rougly 19 feet long… aka, you need to be 19 feet from the sound source to hear the wave.

Ok, Bubba, this part has me a puzzled. I generate a 60Hz sine wave tone using Audacity, play it back, and I can hear it coming through the subwoofer 2 feet away. It’s like the 60-cycle hum people complain about. It makes sense to me, since sound is just air-pressure variation over time, and I imagine the subwoofer can vary the air pressure and wiggle my eardrums at 60Hz even at close range, unless some room reflections or something interfere. What’s going on here?

Tony

let me see if I can clarify that.

it is generally thought that a low frequency sound is not completely FORMED until it reaches the full length of the wave. Therefore you’re not gonna’ hear an accurate picture of the low end unless you’ve given the bass time to develop and not be interferred with by walls etc…

So you’re right, you CAN hear a low frequency sound even right next to the speakers because all it is is a air-pressure variation, BUT, that same sound will appear different (probably in timbre) from listening 20 feet back.

Think of a club. you can stand next to the speakers and hear all the bass, but stand back some more and it’ll sound more articulate and probably better.


On a side note…

I have nearfield monitors (event 20/20’s) and they are unfortunately right next to my wall. I mix in my bedroom and really can’t move them away from the wall in any permanent fashion. I wonder if most would agree that applying, say 4" foam directly behind them would help with the situation. Obviously the super low end won’t be relieved by the foam, but it might clear up the low mids a tad-and I roll off at 50hz or so already so those aren’t a problem.

Quote (Bubbagump @ July 13 2005,12:38)
Christopher Hogwood

Beautiful! :)

Kristi has this whole Baroque collection from him. It is swell.

You bet.

Would you believe that my first recordings of the Brandenburgs were Otto Klemperer’s 1960 recordings made in Abby Road? You can imagine what kind of performance those are. :)

We like Hogwood. :D

<!–QuoteBegin>

Quote
I have nearfield monitors (event 20/20’s) and they are unfortunately right next to my wall. I mix in my bedroom and really can’t move them away from the wall in any permanent fashion. I wonder if most would agree that applying, say 4" foam directly behind them would help with the situation.



My copy of The Master Handbook of Acoustics (you know, the one I suggested we all should have…) tells me that 4" open cell foam has an absorbtion coefficient of 0.2@125Hz and 0.7@250Hz (where the absorbtion coefficient is the fraction of sound that is absorbed at a surface). So basically this material may do some good in the low mid range. My bet is that, depending on the width of your listening space, it may do more good off to the sidses of the speakers, but without any information on the size of your room, I couldn’t say for sure. Depends on what “situation” you need help with.

Some of this placement stuff you can almost test by playing tones through you monitors, recording them at your mixing position, then analyzing them on a spectrum analyzer. Pink noise will probably give you the best results, but I’ve also done a slow sweep with an oscillator. Play back some noise and record it with an omni microphone. You’ll need it loud to make sure you get your room excited at all frequencies. See what kind of frequency response you get. Now put up some foam somewhere and do the test again. What changed? Try another location and do it again. This trial and error method may be a drag, and may not get you better results, but you could get lucky. Do some research beforehand on the size and shape of your room and the placement of your monitors and you could get lucky quicker. Every room is different, so every solution is going to be unique…

What is “pink noise”? Sorry, perhaps an amatuer question…

Quote (guitars69 @ July 13 2005,11:02)
it is generally thought that a low frequency sound is not completely FORMED until it reaches the full length of the wave. Therefore you’re not gonna’ hear an accurate picture of the low end unless you’ve given the bass time to develop and not be interferred with by walls etc…
…that same sound will appear different (probably in timbre) from listening 20 feet back.

The thing that threw me to begin with was, “you need to be 19 feet from the sound source to hear the [60Hz] wave.” Maybe I was taking it too literally, but I was reading this as saying I wouldn’t hear anything if I was less than 19 feet away! :D

As I said, I can understand how room reflections can cause issues with harmonics, cancellation, etc., but room aside–in some open space outside, for example–I can’t see how sitting 2 feet or 20 feet from the subwoofer could affect the accuracy because the “sound is not completely FORMED”; the only thing I can see happening is the sound weakening over increasing distance. Your eardrums are points in space, and eventually each “wave” will “pass by” in its entirety as long as you’re standing still within earshot, no? Yes? Again, what I’m saying doesn’t deal with room reflections–once you’re in a room or put some closed-back headphones on or whatever, yes, I understand that all kinds of weird things start happening. :)

Tony