Help With Acoustic Guitar Mid Side Miking!

J

jimmy77611

New member
I'm new to mid side miking on acoustic guitars, and I need a little help. I'm using a SCD for the mid mic, and a LCD in figure 8 for the side. I have everything set up as per all of the instructions online. My mid mic sounds good and my side mic sounds good, but when combined, they sound weird. When listening to the 2 side tracks, panned hard left and right, with the right phased reversed, they sound as if some of the frequencies are filtering. If I center them, they cancel out completely. When I bring up the level on my mid mic, the left channel sounds like some of the frequencies are filtering (thats the side mic with the phase not reversed) as If my mid mic and side mic are having some phase issues from the start. Is this normal? The mid mic mixed with the side mic that is phase reversed sounds good (right channel).

My mid mic is pointing at the body of the guitar at the neck joint, and the side mic capsule is directly under it turned sideways 90 degrees, as close as I could get the capsules together.
 
I think if i remember right i had some similar issues when i started doing mid/side experiments.
as much as i could i checked for phase issues before recording first and made sure i had a comfortable recording level.
Bearing in mind i am using a ribbon mic for my recvordings, so it's true fig 8.
I made sure the front of the of the mic was facing left.
and the mid mic was positioned as closely as i could comfortably achieve.
Recorded the piece into the daw thn the troubles started lol
I'm still not sure what it was exactly or if my theorem is correct but it solved the issue eventually so
here goes.
Make sure you record mid mic into channel 1 (expecting left side recording)
Make sure the fig 8 side mic is also recording into channel 3 (expecting left side recording)
when you make the duplicate track (to be phase inverted ) put it into channel 2 (even numbers) (expecting a right sided recording)
Invert its phase
and link (group)channel 3 and 2 . so that when you bring the volume up on either channel they follow each other.
pull the volume control on the linked channels all the way down
and if i remember right i bought the volume down slightly on the mid mic (channel 1)
then as you raise the volume and blend in the side mic channels you should hear the stereo image widening.
it worked for me and i hope i havent made this explanation totally incomprehensable.
good luck mate i hope you work out what the problem is.
 
jimmy77611 said:
... My mid mic sounds good and my side mic sounds good, but when combined, they sound weird.
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jimmy77611 said:
... as close as I could get the capsules together.
Click to expand...

I wonder if physically separating the two mics a bit would help with their phase issue.

Here is my reasoning...
If they are pointed in different directions then they are technically recording different sources, (one being direct sound, the other being reflected room sound.) If they are recording different sources then they can be moved about to correct naturally occurring phase problems. No?

For example, what if the mid mic was set 1 foot away from the guitar and the side mic is set 4 or 5 feet away from the guitar?
 
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I wonder if you sit the player closer to a reflective surface the Sides mic may have some more ambience to work with, also check how you decode the technique, I've seen that affect the overall phase.
 
Isn't that something that happens in M/S anyway? Don't the two sides cancel, then when you bring the mid up the canceling is lessened and that's where the stereo field comes from? Right?
 
If people would stop using "phase" when they mean "polarity" it would make discussing this much easier. You can't invert phase.

Separating the mics will only cause phase problems.

It may simply be that the mic array is picking up what it actually sounds like. Mid-side micing up close at the 12th fret will sound lopsided because most of the sound is coming from the body which is almost completely to one side.
 
You have phase issues between the 2 mics. When setting up your mics monitor them in mono and move them about until you get a full sound taking care to listen to the low end. As the mics go out of phase you will hear the low end dropping away.
It's just a matter of taking your time setting up the mics so they are in phase as much as possible and so they achieve a good stereo spread and also sound good. :)

Also you may not want to flip the polarity on 1 of the mics. If you mics are in phase then flipping 1 mics polarity will most likely result in you loosing a lot of the low end when monitoring in mono.

G
 
ecktronic said:
You have phase issues between the 2 mics. When setting up your mics monitor them in mono and move them about until you get a full sound taking care to listen to the low end. As the mics go out of phase you will hear the low end dropping away.
It's just a matter of taking your time setting up the mics so they are in phase as much as possible and so they achieve a good stereo spread and also sound good. :)

Also you may not want to flip the polarity on 1 of the mics. If you mics are in phase then flipping 1 mics polarity will most likely result in you loosing a lot of the low end when monitoring in mono.

G
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We're talking about a mid-side setup here. Monitoring them in mono makes the side mic inaudible and inverting polarity is part of how it all works.
 
It's not impossible that comb filtering is happening at the spot in the room based on how far the reflective surfaces are from the mics and source so I would try moving the array around and see what happens

also as bouldersoundguy noted as this is a stereo mic technique the position of the instrument vs the mic will affect the image
 
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