#1682584 - 06/28/05 07:53 AM
The fine line of 3D Imaging
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Keyplayer
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Registered: 11/19/01
Posts: 410
Loc: Maryland, USA
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Recently, I've been reworking my approaches to mixing stereo projects. The more you learn the more adept you become, right?
Blending, I've got down cold. You can hear all the parts clearly without any one part fighting for space or attention across the L, Ctr, R field. Where things get tricky is getting the back to front imaging.
I'm getting okay results with the usual techniques: delays, reverb and volume for recessing and compression, eq and volume for pulling forward. What I'm looking for now is some tips on "REALLY BUILDING A ROOM." You know, a mix where you close your eyes sitting in the sweet spot between the monitors and you can tell that the drummer is 10' back LC, the bassist is right across from him RC, the brass section is on 3' risers 4' behind the bassist, etc, etc. How do you get that kind of precise clarity?
The best case scenario that I'm looking for is an all acoustic imaging (NO PA OR MICS OR ANY KIND OF AMPLIFICATION INVOLVED) ranging from a living room or coffe house intamacy to a small 350 seat theater hosting an acoustic group. How do you guys get those kind of results?
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#1682585 - 06/28/05 12:27 PM
Re: The fine line of 3D Imaging
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philbo_Tangent
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Registered: 10/08/00
Posts: 1175
Loc: Iowa
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Well... the best way is to set up mics in a room of the desired size, and put all the musicians in there and have them play after you hit the record button.
But you might be able to record a convolution sample of the room you want to use and apply that to the mix. The SIR reverb (a free VST plugin) can do that kind of stuff easily.
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#1682586 - 06/28/05 01:05 PM
Re: The fine line of 3D Imaging
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theblue1
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Registered: 02/06/04
Posts: 4537
Loc: Long Beach, CA
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Don't forget echo, when used correctly, can actually push the object in question forward in the mix.
A long delay suggests to the mind that the original source is far away from whatever the wall is bouncing off. So a dryish vocal or guita with a long delay (or predelay leading to a bit of highly defused 'verb.)
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You know, I spent a lot of time growing up listening to classical music and I've been a subscriber to my local symphony for most of the last 16 years or so. I also keep my ear out for new classical recordings.
One thing I feel like I'm noticing are problems in some contemporary classical recordings. Yes, everything is clearly defined -- perhaps overly so at times -- sometimes it seems like you're hearing more resin than bow.
But I feel like there are phase and time issues in many of these recordings from the last decade or two that didn't surface in the orchestral recordings of the past. I suppose it's from over-mic'ing and I wouldn't be surprised if the timing issues come from 'collapsing' the naturally regulated time-space of the orchestra... by that I mean that orchestras that play together live accomodate for the relatively slow speed of sound... if the percussion section is, say, 30 feet behind the conductor, that means it takes 30 ms or so for the sound from their instruments to reach him. That's one reason why the visual cues presented by the conductor are so important. A music theory teacher (who had been a marching band director most of his early career) told my class that this problem is greatly magnified for marching bands, who are often spread out as much as 100 feet from side to side and end to end. (Which is, perhaps, why so many marching bands sound more like marching trainwrecks.)
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#1682587 - 06/28/05 06:27 PM
Re: The fine line of 3D Imaging
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Philip O'Keefe
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Registered: 12/17/00
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Loc: Riverside,CA,UNITED STATES
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Bump... I can't respond right now, but I don't want to forget about it... 
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#1682588 - 06/29/05 11:21 AM
Re: The fine line of 3D Imaging
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gaotu
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Registered: 01/10/04
Posts: 211
Loc: Indianapolis
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How does pre-delay factor into the imaging placement of a sound source?
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#1682589 - 06/29/05 02:55 PM
Re: The fine line of 3D Imaging
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Lee Knight
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Registered: 10/19/01
Posts: 1077
Loc: Encinitas,CA,UNITED STATES
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Originally posted by gaotu:
How does pre-delay factor into the imaging placement of a sound source?
Think of each foot of space as roughly a millisecond. If you have a predelay set at 30ms, that implies that the nearest refective surface (a wall, most likely) is 15 feet away. 15ms to get to the wall, and 15 to get back to your ear... or your mic. So, the predelay is telling your mind something about the space where the recording took place.
Bear in mind, as Bruce has pointed out, that if you've recorded something in a smaller space and have a longer predelay than what's present on the recording, you'll be sending the brain info about the space you recorded in, not the faux space you're creating with the digi verb.
The way around this, if you really DO want to get around this, is to deaden all the closer refective surfaces, to kill the early refections, masking the size cues of your environment.
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#1682590 - 07/01/05 02:55 PM
Re: The fine line of 3D Imaging
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Philip O'Keefe
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Registered: 12/17/00
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Loc: Riverside,CA,UNITED STATES
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For me, depth of field is extremely important, and I work pretty darned hard on getting it. There are various different tools and techniques that can be useful...
For me, it starts with mic technique and the room(s) you're recording in. If you're going for the sound of a small combo in the same room, but at different distances, then by all means consider using a good sounding room and addressing the depth at the sources - IOW, if you want something to sound more distant in the final mix, consider a more distant mic placement for it when tracking. Of course, that's assuming you like the sound of the room. Once you've captured the room ambience, you can't go back later and get rid of it.
As Lee mentioned, sound travels at about 1,130 FPS... IOW, about 1.13 feet per ms. That can be useful information to know when you're trying to set up reverb predelays and so forth. If you close mic everything (due to a less than stellar sounding room) and then want to simulate a specific acoustical environment with delays and reverb, the longer the predelay, the further away the reflective surfaces of the simulated room will appear to be.
The greater the ratio of delayed and reverbed signal to the direct sound is, the further away the sound source will appear to be when you listen back. IOW, if you have two instruments (or vocals), and you're using the same predelay and reverb on each, but one has less of that predelay and reverb dialed in, it will sound "closer" or more "forward" in the mix, but still sound like it's in the same "room".
Also, EQ and level can be useful for simulating placement within the room. High frequency sounds are more easily attenuated by air with greater distance, so rolling off a bit of highs on something you want to sound "further away" can help with the illusion.
As far as levels go, the Inverse Square Law can be useful to know about. Basically what the Inverse Square Law says is that volume in a free field environment (IOW, in a open, outdoor area - acoustic reinforcement and reflections messes with this and makes the level drop less dramatic) will drop by the inverse of the square of the distance from the source. In simple English, that means if you double the distance from the source of the sound, the level drops by approximately 6 dB. Remember, that's in a free field environment, and it's not going to drop as drastically in a highly reflective room. In a "deader" room, the loss will appear to be a bit more than in a highly reflective room, but in neither case will it be as much as you'd get in a completely unreflective environment, such as outdoors. What all of that means is that if you drop the level a bit, a sound source will appear to come from further away from you.
So there you have it - the four main tools I use to adjust apparent depth of field - mic placement, levels, EQ and delay / reverb.
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