M/S recordings tilt to the right???

[lasso]

Hi slutz....lately I've been diggin M/S recording on acoustic guitar.

It's by far the best sound I've ever got on acoustic, BUT...when decoded in my DAW, the sound tilts to the right!!!

I simply can't figure out why...but it's a fact.

Everything is done by the book....cardoid condensor for mid, figure of eight for side. Mid channel panned dead center, side channel copied, one track phase reversed and the two side tracks panned hard Left / right.

What the heck is going on???

[Roland]

It could be that you are simply getting more sound from the right. If as you say you are doing everything by the book this should be the only explanation unless your side signal is unbalanced level wise, this should be easy to check.

Regards


Roland

[lasso]

Well, it couldn't be more sound from one side issue as the side mic is recorded in mono, as well as the mid mic.

Strange.

[toolskid]

put your head where the mic array is.. get the performer to play..

do you hear a balanced sound?

[lasso]

Originally Posted by toolskid

put your head where the mic array is.. get the performer to play..

do you hear a balanced sound?

Let's say the player's closer to one wall than the other. That side of the side mic would ofcourse be louder than the other. But I can't see how that would make the summed M/S signal tilt to either side, as the side mic is mono....I just don't get it.

[toolskid]

Technical Background - Sum & Difference Signals

MS Recording Techniques


hope that helps!

All the best

[d_fu]

Originally Posted by lasso

Let's say the player's closer to one wall than the other. That side of the side mic would ofcourse be louder than the other. But I can't see how that would make the summed M/S signal tilt to either side, as the side mic is mono....I just don't get it.

M/S is not mono... Of course a signal from the right will tilt to the right in the decoded stereo signal.

[lasso]

Originally Posted by d_fu

M/S is not mono... Of course a signal from the right will tilt to the right in the decoded stereo signal.

Ofcourse. I think I'm getting closer to understanding why....almost ZEN

[af_analog]

hmmm...what figure 8 are you using? Not all of em are symetrical, could be the problem?

Also, in Bob Katz mastering book, he explains M/S decoding as 4 tracks:

track 1 : Fig 8 (+) panned hard L
track 2 : Mid mic panned hard L
track 3 : Mid mic panned hard R
track 4 : Fig 8 (-) panned hard R

I have also heard of people decoding the way you have done it...with only one mid track, panned up the middle...which way is "correct" ?

[lasso]

Are you sure about Katz...I read the exact chapter last night. Well, usually it's the way I descripbed, never heard of to M channels.

Anyway...last time I tried I used an AKG c414 as side mic. I've also tried a Thomann Ribbon

[af_analog]

Hi Lasso, I also just read that chapter the other day for the first time and it really caught my attention when I read that...thats why i remembered. I will definately have to read this again when I get home to make sure...

[af_analog]

Oh..and I am not positive, but I dont think the Thomann is symetrical...

[d_fu]

Originally Posted by af_analog

I have also heard of people decoding the way you have done it...with only one mid track, panned up the middle...which way is "correct" ?

I don't see the need to split the M track. Apart from that, both will produce identical results.

Daniel

[gainreduction]

This can occur if the mics are not placed properly and you get minor phase issues.

[lasso]

Originally Posted by gainreduction

This can occur if the mics are not placed properly and you get minor phase issues.

Ah! That sounds more likely to be the issue. I paid no particular attention to aligning the diaphragms of the M and S mics when setting up, so that might be the problem huh? Maybe inches do matter afterall

[gainreduction]

Originally Posted by lasso

Maybe inches do matter afterall

[af_analog]

I don't see the need to split the M track. Apart from that, both will produce identical results.

Thanks d_fu..thats what i figured, shouldnt make a difference either way.

I think also it will depend on the angle and position of the guitar in relation to the M/S mic setup...if the guitar player sits or "angles" himself one way or the other the result will be slightly off center...I think some engineers use this to their advantage when using M/S...they "pan" something to tape...no?

[d_fu]

Originally Posted by af_analog

I think also it will depend on the angle and position of the guitar in relation to the M/S mic setup...if the guitar player sits or "angles" himself one way or the other the result will be slightly off center...I think some engineers use this to their advantage when using M/S...they "pan" something to tape...no?

I think this effect is commonly referred to as "Stereo"

[Gonzalo]

Another point (IMHO) is that micking in front of an acoustic guitar with M/S you get more high-mid frecuencies content from right side than the left side. Psychoacousticly, the hearing is more sensitive to panning/locating sources as the frecuencies goes higher. SOmaybe you think you get more level from the right side because of that.
Maybe (as someone said) can be the reflections in the rooms that are uneven.
AND of course, mic's positions
Cheers

PS: Sorry about my english, I hope I made myself clear

[af_analog]

I think this effect is commonly referred to as "Stereo"

Thanks..I was wondering what that was called

Someone above was saying that it could be slight phase problems...well I'm just trying to say that it could also easily just be "off center" in reality, except instead of being intentional, he has done this by accident...

[andychamp]

A non-symmetrical fig.-8 shouldn't cause such problems, either.
Since the side signal is hard-panned left and right, such a mic would only result in a signal that's more or less wide, but not one-sided.

You did remember to flip the polarity on the 2nd side track, right?

You should have:
- mid mic signal panned center
- side mic signal fully panned to the side it was aiming at while recording
- side mic signal, polarity-reversed, fully panned to the other side

If the problem persists, my guess is that it's somewhere in your playback chain.

[5down1up]

Originally Posted by lasso

It's by far the best sound I've ever got on acoustic, BUT...when decoded in my DAW, the sound tilts to the right!!!
What the heck is going on???

funny, i had the SAME problem some month ago.
the solution was real simple ...

BAD WIRED CABLE !!!

good luck

p.s ms rocks !

[max cooper]

Originally Posted by lasso

Well, it couldn't be more sound from one side issue as the side mic is recorded in mono, as well as the mid mic.

Strange.

It's sum and difference and therefore the result is true stereo. Here's a good explanation:

Summing the outputs of the two microphones will produce an addition of signals coming from the front left since the microphone outputs are in-phase in that direction. Similarly signals from the front right will be cancelled. This can then be used as a left signal. Subtracting the figure of eight signal from the cardioid signal will produce cancellation of signals from the front left and give a right signal.

Technical Background - Sum & Difference Signals

[soundbarnfool]

Originally Posted by lasso

Well, it couldn't be more sound from one side issue as the side mic is recorded in mono, as well as the mid mic.

Strange.

Dead wrong. It absolutely could be more sound from one side and probably is. I am betting it is the side closest to the sound hole. I have dealt with this issue by tweaking the side mike angle so that it gets a bit more of the side that is weaker. But then you MAY run into phase issues. but such is life.

[myoshida]

Hi,

Pull the fader down a little on the polarity-flipped side signal. That will pull the stereo image more towards the center (mono).

[lasso]

Thanks for all the good info - think I got it and I'll pay more attention to placement next time...wuhuuu...me likes M/S recording. Now, on to Blumlein

[lasso]

update....did another session with a wonderfull Martin acoustic...same problem...

Tried very possible combination of placements...same...the stereo image shifts to the side.

Strikes me it might be the side mic that's the issue. And yes - the back of the c414 it 4 dB down in relation to the front. Arg....at least I now why now...

And now you know if you run into the same problem.

Here's a clip if anyones interested.

[d_fu]

Originally Posted by lasso

Tried very possible combination of placements...same...the stereo image shifts to the side.

If at all, this recording "tilts" ever so slightly to the left. But then, the picking and strumming takes place on the left side of the M mic, so this is only to be expected. Sounds like a nice stereo recording of a guitar to me, with no obvious imbalance.
How are you playing this back? Do you see any level meters showing an obvious imbalance (more than e.g. 2 or 3 dB)?

Strikes me it might be the side mic that's the issue. And yes - the back of the c414 it 4 dB down in relation to the front

If that were the case with equal signals hitting the mic from both sides, the thing would be defective... Otherwise, I'd call it "stereo". M/S is based on loudness differences between left and right entirely, and depending on how close you are to the guitar, there will be a difference. If you don't want that, I'd suggest you record it mono...

[lasso]

I like stereo...think I just needed a second opinion.

Thanks...these are my first m/s recordings so it's nice to get feedback from others.

Edit: oh - and yeah, it was the level meters that tricked me the most - somtimes showing a 3 - 4 dB difference, but mostly pretty much center. I'm relaxed now

[Oroz]

Originally Posted by af_analog

hmmm...what figure 8 are you using? Not all of em are symetrical, could be the problem?

Also, in Bob Katz mastering book, he explains M/S decoding as 4 tracks:

track 1 : Fig 8 (+) panned hard L
track 2 : Mid mic panned hard L
track 3 : Mid mic panned hard R
track 4 : Fig 8 (-) panned hard R

I have also heard of people decoding the way you have done it...with only one mid track, panned up the middle...which way is "correct" ?

This formula is used to decode a stereo/already mixed recording into M/S for Mastering, do you what I mean? By the way, af_analog is correct (Katz's book right here ).

The other decoding (one MID) it's used when recording an instrument (in this case the guitar obviously)