Double-Mic'in'

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SafeandSoundMastering
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Post by SafeandSoundMastering » Tue Jul 05, 2011 3:15 am

There would only be phase cancellation if the distance from the mic's to source
was different and did not follow the 3 to 1 rule when using a stereo set up.

The diaphragms of mics side by side would pick up a very similar part of the cycle so that is a not issue.

For more distant micing sum your 2 mics in mono when panned hard left and right (close and distant) and find out, this should be common practice when recording anyway. Or at least pan hard left and right and see if the "stereo" image created is greatly lacking in low frequency energy or not compared with a single mic on it's own. If it is move the distant mic around until you lose less bottom end.

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Post by chris harris » Tue Jul 05, 2011 7:34 am

The mythical "3 to 1 rule" is so useful! Sometimes I use it when recording multiple sound sources in the same room. Sometimes, I use it when I'd rather use a tape measure than my ears for mic placement. Sometimes I use it to get the temperature right in my espresso machine. Sometimes I use it to determine how much water to add to my rice. Sometimes I use it to decide how long I can really go before an oil change. Sometimes I use it to comprehend erections. Sometimes I use it to make vinaigrette.

Wait a minute.... that's not right....

The reality is, I've never, EVER even considered applying the "3 to 1 rule" for mic placement. Yet, somehow, I've been able to record bands with multiple mics for 10+ years without phase problems.

The best application of the "3 to 1 rule" is in convincing people that there are shortcuts to actually learning how to HEAR something. I can't even imagine ALWAYS having my second mic three times further from the source just to avoid something that I hadn't taken the time to learn to identify with my ears. What a weird world of useless rules to have to exist in.

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Post by ceylon » Sat Jul 09, 2011 11:22 am

i've been double micin since i started recording to 1" 16 track (now 2" 24 track) tape. phase cancellation never seemed to be a big deal--i just flip the phase on a mic and all's good. on a slant cab, i usually mic a top speaker and a botom, since they always sound different. i reckon that's the depth of the cab behind the speaker? i always use my ears because replicating placement one session to the next does not replicate sound. one guy inthe control room, one guy in the tracing room moving a mic around until it wounds good. then we do it to another mic. typically i'm using 57's and beta 57's or an akg equivalent. sometimes i've used this really cheapo mic, superlux eco-88, and gotten some good sounds.

the other day i doubled up with a stock mxl990 and shinybox w/ lundahl. placed each mic 12-14 inches away from a diff speaker, facing the speaker directly. no phase issues (why?) and sounded wicked awesome. was really surprised to hear THAT much of an improvement. took 2 min and no hassle.

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Post by ceylon » Sun Jul 10, 2011 5:37 pm

oops! -i got the chinybox w/ cinemag.

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Re: Double-Mic'in'

Post by ofajen » Mon Jul 11, 2011 10:00 pm

vvv wrote:Anybody into double-mic'ing a source?
No, I lack the patience (and track count) to do that much, but sometimes I kinda do the same thing with a single figure 8 or omni mike. I'll adjust the direct and reflected sound by the angle (at least for a figure-8 ) and distance of the mike to the source, so I'm thinking of capturing those two components of the sound, just with one mike.

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Post by mikoo69 » Fri Jul 22, 2011 7:08 am

this brings me to another question about compression techniques while using multiple mics on a source. let's say I'm recording kick drum and blending 2 mics to a single track on tape. one mic is inside the hole and another mic is outside the drum, 3 feet back to pick up more of the air, and the natural sound of the kick in the room.

should i run just one of the mics through a compressor, let's say a distressor, or is it fine to blend them to one track, and then compress the entire thing as one track?

Same goes for bass. If I am using an RE-20 to capture the low frequency information and an AT Pro37 SDC to focus on the high frequency, could I run these both through the same compressor as a blended track, let's say a CL-1B or MC-77? Or should I compress them separately (or only one of them) prior to hitting a single track on tape.

I know each situation is different, though I am looking for some general recommendations about using compression on sources with multiple mics, specifically when these mics will be blended into a single track on tape while tracking.

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Post by vvv » Fri Jul 22, 2011 8:35 am

I usually default to blend and then compress, but if that ain't work, I change it.

It really does depend on the situation, like if the bass sounds good uncompressed but needs more deepness, I might compress just the D.I. (I don't double mic bass, you get the idear) to get the big bottom, but leave the mic to keep more of the player's dynamics.
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Post by goose42 » Fri Jul 22, 2011 7:43 pm

mikoo69 wrote: I know each situation is different, though I am looking for some general recommendations about using compression on sources with multiple mics, specifically when these mics will be blended into a single track on tape while tracking.
As long as you can link the two detector circuits, so that a peak in either signal will trigger both compressors, you're in pretty good shape, I'd think. But this is different than compressing a stereo mix or stereo drums...
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Post by mikoo69 » Wed Jul 27, 2011 6:20 am

what about using one mono compressor on a source with 2 mics (i.e. bass mic 1 and bass mic 2 go to subgroup 1 and a mono compressor goes on the subgroup insert)?

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Post by Sean Sullivan » Wed Jul 27, 2011 6:24 am

mikoo69 wrote:what about using one mono compressor on a source with 2 mics (i.e. bass mic 1 and bass mic 2 go to subgroup 1 and a mono compressor goes on the subgroup insert)?
I usually do this on upright bass with a LA-2A style compressor, just to smooth out the playing.
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Post by weatherbox » Wed Jul 27, 2011 4:11 pm

I gave a Super Reverb that gets used pretty heavilly on everything I do, and I'll almost always jam an 87 and an m88 on the top left speaker unless I specifically want something else - it's just become the standard sound for that amp. I'll sum them via auxes in PT or through the board and print to a single track for sanity.

Snare is another one. I lot of it I guess is being able to alter blends song to song to tweak the tones w/o having to set more stuff up or repatch when it's a seriously tome crunched project and I wanna have a little variance built in from the get-go.

I mic'd a vocalist this week w/ a cm7 and an ev666 and it ruled. Significantly better than either alone. When dual mixing I usually jam the caps as close together as possible - if that's physically not doable on a multiple speaker amp I'll set up on different speakers, get a tone for the priority mic, and w/ cans on listen to the hum if the amp cranked and move the other mic around til the white noise sounds in phase.

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Post by trodden » Thu Jul 28, 2011 10:47 am

mikoo69 wrote:what about using one mono compressor on a source with 2 mics (i.e. bass mic 1 and bass mic 2 go to subgroup 1 and a mono compressor goes on the subgroup insert)?
This is how I do it. Usually a condenser and a dynamic on bass cab, blended via board, sent to a comp then to recorder. Mics are usually an re20 and CAD e100 or re20 and u87 depending where I'm at.

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Post by bannerj » Sat Jul 30, 2011 2:59 pm

subatomic pieces wrote: The best application of the "3 to 1 rule" is in convincing people that there are shortcuts to actually learning how to HEAR something. I can't even imagine ALWAYS having my second mic three times further from the source just to avoid something that I hadn't taken the time to learn to identify with my ears. What a weird world of useless rules to have to exist in.
I don't use the 3:1 rule either, but my ears must not be as good as yours because I have had phase issues. In fact Larry's opener to last month's mag about phase reminded me to be more careful. My issues usually get bad when I go overboard with panning.

I'm wanting to go back and re-do a few songs for practice. This time I want to either not pan double miced sources or put them at more narrow settings. Also, I think it is a good idea to not double mic everything if you are trying to pan the mics. Its like this with reverbs/delays. I'm trying to keep it to maybe just one or two stereo fx and the rest in mono. Likewise for stereo micing and mono. If you use stereo mics on the drums and pan them hard, then don't do the same with the acoustic guitar etc.

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Post by losthighway » Mon Aug 01, 2011 8:01 am

I have found in using two mics on one speaker cabinet there are several steps that are essential in avoiding phase problems. First I eyeball the mics to make sure they are equidistant from the source. Second I record a sample and then zoom way in to the waves to visually check for phase coherence while listening. Often times when mixing a condenser with a dynamic the condenser needs to be millimeters further away from the speaker than the dynamic because it responds so much faster.

On the sonic side, it seems double mic'ing almost always adds some kind of low mid girth to my electric guitar sounds. Which can make things sound heavier or richer when needs be. I have been doing this a little less since getting a Chandler Germanium since you can add a lot of low mid heft with the mic pre. It's also nice to to have to worry about phase as much.

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