Parallel spaced mics on a single instrument

[Don S]

Originally Posted by Marlan

An XY is also nice technique to use in this situation. It gives a nice stereo image, can be mixed in sparingly, and is not prone to phase problems.

While I'm not a big fan of X-Y as mains for ensemble, it works beautifully in that situation.

[sonicdefault]

As Plush has alluded to in his prior posts...
It's easy to become focused on issues with phase etc, whilst overlooking one of the most practical reasons for choosing a specific mic technique, and that is the panoramic soundstage. Because as we all know how a source may sound good on it's own, but when placed within an ensemble doesn't work. This is why choosing a specific mic position can be critical regarding the need for panning certain instruments while mixing. Therefore, the end result may prove more natural sounding, even though the mic technique may not have seemed ideal on its own.

And as others have mentioned, there's consideration for the 3:1 principles which is of primary concern with ensemble recording. For solo instrument pieces such as classical guitar, phase is not an issue for spaced pairs as long as both mics have their capsules at equal distances from the source, although it has been noted that acoustics are also a part of the equation.

Personally I always prefer the traditional Blumlein configuration for solo recordings which as many concur yields the most depth and realism. However, when recording multiple sources, everything changes and one must consider each situation differently.



-SD

[Yannick]

Originally Posted by mpdonahue

Yannick,
This seems to me to be a bit of a solution in search of a problem. The main reason I use a pair of closely spaced microphones as spots is to specifically get the sound of spaced microphones (usually not omni's for spot mics), much the same way I also use spaced omni array's for mains rather than coincident systems.
If you can get away without panning the spots, there is absolutely no comb filtering.....)
As always, YMMV.

All the best,
-mark

To each his own preferred technique of course.

But you still need to explain to me how the left ear does not hear the right spot coming out of the right loudspeaker ? Because I can hear phase (the source rarely does not move) and comb filtering issues when listening to spaced spots.

[dtf]

Hi Yannick,

You are giving the answer already yourself. With the same signal on both loudspeakers (mono spot) you will get comb filters during playback in the room. With two different signals much less and in a more natural way. This is clearly audible.

The real problem with mono signals lies on the playback side. Apart from that there are many other (e.g. dynamic) effects why I would always prefer spacing between microphones as opposed to coincident techniques.

That being said, I have heard fantastic recordings made with an XY.

Best,
Dirk

[king2070lplaya]

That's one place where the stereo spot technique, no matter what method you use, comes in super handy is translating dynamics.

[pkautzsch]

Originally Posted by studer58

3:1 rule violation ?

As spaced pairs usually are panned hard L/R, the 3:1 rule does not apply. 3:1 rule only applies when two mics' signals are being summed. So it does apply to the relationship between spot mic and main mic (or, to be precise, between Left Spot and Left Main / Right Spot and Right Main).

Originally Posted by Marlan

An XY is also nice technique to use in this situation. It gives a nice stereo image, can be mixed in sparingly, and is not prone to phase problems.

But it doesn't give the spaciousness typical of spaced setups. In XY, both signals always are correlated (just level differences), in spaced setups, they're not, and that's what gives us the sense of space.

Originally Posted by Plush

The answer to my question above is that Finckel moves a lot when he plays. That means that he is one time in the left mic and next in the right mic.

Narrowing the spacing of the spots would get rid of this tendency.

Another way would be to set the spaced pair up vertically. To "jump" between the speakers he'd have to physically jump up and down.

Originally Posted by Plush

(also a way to use this is to move both mics' panning to the left. One at hard left and the other at 9 o'clock.)

Wouldn't this introduce the comb-filtering trouble that's being talked about so much in this thread? In order to pan something, say, a little to the left side, what do you think about lowering the R signal by a few dB or delaying it by half a millisecond?

Originally Posted by Yannick

Narrowing the spacing would also worsen the comb filtering.
A narrow MS would also counteract the soloists movement, and you can even follow the anti-panning during mixdown

Originally Posted by Yannick

There is comb filtering, as there is inter-aural crosstalk between the two speakers, unless you listen on headphones.

Strangely, my case in favour of MS is exactly that: you can narrow it, you can pan it and you can place it, even rotate it and skew it.
If you can do all that with AB setups (in post !) without additional comb filtering (which will happen if you do not pan the two mics full L and full R) then you must know some secrets.

Any playback with two speakers and two ears (and air between them) will result in some comb-filtering, and I'm with dtf here: The more similar both channels are, the stronger the comb-filtering will be. I strongly prefer slight (!) comb-filtering with spaciousness to sound free of comb-filters but without space.
You can pan AB setups by the methods described in my reply to Plush a few lines above. Will only work for spots - you can't really adjust a main pair that way!

[dtf]

Originally Posted by pkautzsch

You can pan AB setups by the methods described in my reply to Plush a few lines above. Will only work for spots - you can't really adjust a main pair that way!

That is one thing that has been overlooked in this thread so far - a stereo main pair is a totally different thing than a spaced pair as a support.

Best,
Dirk

[JonesH]

Originally Posted by pkautzsch

In order to pan something, say, a little to the left side, what do you think about lowering the R signal by a few dB or delaying it by half a millisecond?

Lowering it feels more wrong than manipulating the inter-channel delay which the system was built on in the first place...
I experimented once with moving the performers in a chamber group around and placing their individual spaced pairs so that they appeared in the Spots where they were supposed to be in the main mics as well. No panning, but it took ages to move the mics and performers... Anyone tried that?

[Marlan]

"But it doesn't give the spaciousness typical of spaced setups. In XY, both signals always are correlated (just level differences), in spaced setups, they're not, and that's what gives us the sense of Space."

Sometimes it can in the right situation. Maybe not as much as spaced omni's, but tis is a fine compliment often when you are recording an orchestra with four omni's across the front. The solo instrument will be picked up naturally in the main array and this can be used to hone in on it a bit more and doesn't need to be used aggressively.

Yes, one can use m/s, ortf, omni's, etc...... There is no one rule.

[Larry Elliott]

Most of the acoustical research identifies comb filtering as a severe problem for speech and in some cases as an enhancement for music signals. After all floor reflections from most acoustical instruments will arrive at a mono mic with a delay that will be conducive for a comb filter. If this is a "stereo" mic there will be sufficient differences between the L&R signal that any cancellation will be at different frequencies for each mic.

Larry

[Yannick]

Hmmm. Very good arguments in favor of spaced technique versus comb filtering, caused by 2ch loudspeaker playback.

I have to think long and hard about this one, maybe test some more

Maybe here is another reason why some prefer coincident and others spaced techniques ?

[recordsalot]

The dispersion of sound from a given instrument can be very complex. I've found using the closely spaced/ coincident stereo techniques that have already been suggested for spot miking can sometimes give a more accurate tonal balance of the instrument than can be achieved with a single mic. However, this is not always the case, depending on instrument and mic- YMMV.
On the downside, adding more spot mics can lead to a higher noise floor and more opportunity for feedback in live settings.

[jnorman]

hmmm - other than acoustic guitar, i havent really found any instruments that sound good close mic'ed. for any solo instrument like violin, sax, etc, AB pair at around 4-6 ft works great. anything like 10-12" just screeches in my ears, even with ribbon mics. are you guys talking about spots in a large ensemble? - different thingie.

[pkautzsch]

Originally Posted by mpdonahue

I typically end up anywhere from 6" to 18" depending on the source and situation. As to patterns, it really can be anything..... depends on what I'm looking for soundwise.
All the best,
-mark

Originally Posted by jnorman

hmmm - other than acoustic guitar, i havent really found any instruments that sound good close mic'ed. for any solo instrument like violin, sax, etc, AB pair at around 4-6 ft works great. anything like 10-12" just screeches in my ears, even with ribbon mics. are you guys talking about spots in a large ensemble? - different thingie.

I think the 6" to 18" is the spacing between the two mics that make up our spaced pair, whereas 4 to 6 ft is the distance between source and mics.
Both are typical values...

[Brackish]

Originally Posted by jnorman

are you guys talking about spots in a large ensemble?

Yes, I think that has been what mostly has been discussed.

[king2070lplaya]

YouTube - ‪Gustav Mahler Songs - Recording Session with Angelika Kirchschlager‬‏

If by "Large" you mean "Heavy" or "Deep" I guess this CD of Mahler songs for Mezzo and Piano will qualify......

[JonesH]

I spent some time testing this now again with a chamber baroque ensemble, where each person was moved to our liking in the main pickup and then individually spot-miced with a narrow pair (18 cm or so). The pair was moved around until the phantom image correlated with the placement in the main mics.
Voila, good localization and no comb-filtering from panning the mics inwards or anything. Although I also agree that there is some slight diffuseness to this sound, however I almost prefer that to the pasted on quality of single mono mics.
Anyone else tried this "True stereo spot" technique? I can't be the first to do that....?

[chris319]

no comb-filtering from panning the mics inwards or anything

So you had one mic panned hard left and the other hard right?

[king2070lplaya]

Panning them in I think would imply moving them in from hard L and R. Like what you would do if you were trying to place the source somewhere other than in the center of the mix.

Correct it if that's not correct JonesH.

[d_fu]

Originally Posted by Plush

also a way to use this is to move both mics' panning to the left. One at hard left and the other at 9 o'clock.

I do this, too, at times... Some tonmeisters are very strictly against that, insisting that spaced pairs must be panned hard L/R.

It is nice to know that I am in good company with this, though...
I have not had any comb filtering problems as a result...

I have at times noticed the "pasted on quality of single mono mics", though. In some cases, a slight touch of stereo enhancement to the channel will help...

D.

[boojum]

Originally Posted by d_fu

I do this, too, at times... Some tonmeisters are very strictly against that, insisting that spaced pairs must be panned hard L/R.

It is nice to know that I am in good company with this, though...
I have not had any comb filtering problems as a result...

I have at times noticed the "pasted on quality of single mono mics", though. In some cases, a slight touch of stereo enhancement to the channel will help...

D.

In my ignorance I have been following in good footsteps. In a recent jump blues band mix I had a spaced pair of cards over the drumset. I put them in the mix in the space they were in reality and spaced the mics by panning with the left at the left edge of their sound field of the drumset and the right correspondingly. I may have adjusted it a bit but essentially that is what I did. It sounded about right. It was the only solution I could see. Wider panning was not working. Even a blind hog . . .

[radeng]

Originally Posted by JonesH

Anyone else tried this "True stereo spot" technique? I can't be the first to do that....?

"Professor" Keith Johnson of Reference Recordings has been doing this for many years.