MS mics placement

[Teejay41]

Hi chaps and chapesses,
I have a query on mic placement. But first, a bit of background. I wish to record organ recitals, and at the same time, to gain experience in mic techniques. So I propose to use a single tall stand (max height around 6m) placed roughly centrally with a large mic mounting bar, about 650mm long. At its centre point I propose to put a Blumlein pair comprising two active Marantz ribbon mics. Next, on each side of the ribbon pair, I want to place an ORTF pair of Samson SDC pencil mics, for which I have matched-pair capsules, both omni and cardioid. My last pair, I want to be MS. I propose to use a CAD LDC hyper-cardioid (can't remember the model No.) for the M mic, and a t.bone RB 500 ribbon with in-line FET preamp as the S. All 6 mics will be input to a Zoom H6 with phantom power available on all channels, including the dual-input adapter which replaces the H6's native mics. The thing is though, in order to preserve a manageable weight balance on the stereo bar, I propose to put the M mic on one side of the existing mics and the S mic on the other. Frontal sound (i.e. the organ) will arrive simultaneously to both the M and the S mics (not that the S will pick up much frontal sound anyway) but the ambient sound will arrive at the S at a different moment from the M - one side slightly early, the other side, late. As every example of MS mic placement I've ever seen shows the M and the S mics coincident, I wondered if there would be any unforseen phase problems I might have overlooked.
Thank you in anticipation for any words of wisdom.
Best regards, Tony.

 

[emrr]

Go find Rolo46's various posts in the remote recording section of Gearslutz. He does some things with MS that look problematic, but sound excellent. Nothing like you propose though.

If you have the option, I don't think I'd do both Blumlein and MS. Look again to Rolo46 and consider MS with the figure 8's. Instead, especially with organ, I'd want to try wide AB omni. Then MS can sit in the middle and omni's to the outside.

 

[Teejay41]

Go find Rolo46's various posts in the remote recording section of Gearslutz. He does some things with MS that look problematic, but sound excellent. Nothing like you propose though.

If you have the option, I don't think I'd do both Blumlein and MS. Look again to Rolo46 and consider MS with the figure 8's. Instead, especially with organ, I'd want to try wide AB omni. Then MS can sit in the middle and omni's to the outside.

Thank you Doug, for your extremely prompt reply. The reason I wanted to do all three classic techniques was to compare their resultant sounds and make a decision for the future. I wasn’t proposing to mix them at all unless I could hear a distinct advantage of so doing. I like your suggestion of spaced omni AB though. Now I'm spoilt for choice on which to use. I will certainly follow your advice for further reading. Thanks again.

 

[RoadrunnerOZ]

The thing is though, in order to preserve a manageable weight balance on the stereo bar, I propose to put the M mic on one side of the existing mics and the S mic on the other. Frontal sound (i.e. the organ) will arrive simultaneously to both the M and the S mics (not that the S will pick up much frontal sound anyway) but the ambient sound will arrive at the S at a different moment from the M - one side slightly early, the other side, late. As every example of MS mic placement I've ever seen shows the M and the S mics coincident, I wondered if there would be any unforseen phase problems I might have overlooked.

There’s a reason the two mics are placed one on top of the other - If you separate the two mics you will get phase cancellations - eg. a distance of 300mm equates to 1/2 wave cancellation at 500Hz, or summing at 1000Hz but one wavelength out of phase. The side facing fig 8 mic does pick up front/side signal as well as the forward facing Cardioid mic picks up sides and you are asking for problems separating the M/S mics. Placing the two mics in the same vertical plane shifts the phase error to well above the human hearing range for a few millimeters of placement error, which you will always have anyway.

Suggestion, if you want to do both Blumein and M/S, is to make a “U” frame above the Blumein pair to mount the M/S pair - a bit top heavy but with a bit of simple metalwork not too difficult. (A true A/B/C test really wants all three sets to be at the same centre of focus.) If that’s not possible then maybe put each pair slightly either side of centre to balance the weight distribution.

 

[ubxf]

or get a pair of schoeps and be done with it

 

[Teejay41]

There’s a reason the two mics are placed one on top of the other - If you separate the two mics you will get phase cancellations - eg. a distance of 300mm equates to 1/2 wave cancellation at 500Hz, or summing at 1000Hz but one wavelength out of phase. The side facing fig 8 mic does pick up front/side signal as well as the forward facing Cardioid mic picks up sides and you are asking for problems separating the M/S mics. Placing the two mics in the same vertical plane shifts the phase error to well above the human hearing range for a few millimeters of placement error, which you will always have anyway.

Suggestion, if you want to do both Blumein and M/S, is to make a “U” frame above the Blumein pair to mount the M/S pair - a bit top heavy but with a bit of simple metalwork not too difficult. (A true A/B/C test really wants all three sets to be at the same centre of focus.) If that’s not possible then maybe put each pair slightly either side of centre to balance the weight distribution.

Many thanks, Roadrunner. Good advice and much appreciated.

 

[RoadrunnerOZ]

No problem. I’ve done quite a few M/S sessions and the real issues come from sounds to the left/front and right/front fields where the polar responses of the mics overlap. These cancellations are a bit like the problems encountered when miking drums with overheads.

 

[Barry Hufker]

In my experience, the problem with multiple mic arrays in one location is that the position is probably only optimized for one array at best. While M/S will give you post-recording flexibility, the other mics will be in a position that probably won't be to their best advantage. Omnis will pick up more room than cardioids and will have low frequency extension (which can be important for an organ recording). Directional mics will be a little "bass light" in unless positioned closely and will need to be further away than omnis to pickup the same amount of "room." Blumlein will give a very wide stereo image and will be a roomier sound than a coincident/ORTF pair... And it just goes on like that.
My suggestion is to use one pair at a time in its best position and evaluate each recording on its own best results.
I hope you have a lot of fun and learn a lot from your experiment!

 

[RoadrunnerOZ]

True - if you’re A/B/C’ing mics against each other to see which mics sound best they need to be at the same location, but I f you’re miking up an instrument to get the best sound each array will require experimentation with position to get the best response. Different arrays, different image.
I normally start with closed headphones and position mics with them running through the console and back to me - when roughly right I monitor in the control room and get an assist with moving the mics for optimum placement - assistant on cans being directed on talkback. Monitoring M/S you’ll need to set up your out of phase 3rd channel (for the “S” mic) to get a proper image in the cans

 

[Barry Hufker]

I think recording pipe organ is especially rewarding. I've had the pleasure of doing it many times over my career. I prefer to use as few mics as necessary -- two if that's the right number, and more if that isn't. My work is almost exclusively on location and I relish the opportunity to do more studio work. I often tell people I'm not so much in the "recording business" but more in the "moving business." In the 1970s and '80s when I was production manager at KWMU-FM, St. Louis, MO, I was the recording engineer/producer for a weekly pipe organ series, "King of Instruments." Each week host, Joseph O'Connor and I would travel to a different church in the STL area recording the instruments about town. It was a lot of fun to do. I learned a lot in those years...

 

[k brown]

I would note that very few commercial organ recordings are done with anything other than spaced omnis as the main pair; sometimes with a spaced or near-coincident cardioid pair to bolster some sections of pipes.

The majors almost never use/used any coincident technique for organ - they just don't provide the enveloping spaciousness most listeners expect in a pipe organ recording.

Blumlein can sound pretty spacious on loudspeakers, but produces a very artificial soundstage on headphones, which has become a very important consideration, now that much, if not most, music listening is now done with earbuds/headphones.

 

[Barry Hufker]

While I've tried a lot of mic techniques over the years, I admit my favorite technique is "Spaced Omnis." Blumlein is the technique I've used/liked least.

 

[k brown]

My favorite spaced omni array for many different things is Onno Double AB; developed purely by ear, and not by theory, by Onno Scholtze while an engineer at Philips. It's a 1' spaced pair on the same bar as a 10' pair; both pairs aimed 90 degrees apart, ideally all the same mic (he used DPA 4006s/silver grids), and all at the same level. For reasons I've never been entirely clear about, he always aimed the mics straight ahead, not aimed down.

No other array I've tried has a Decca Tree-like spaciousness on loudspeakers and almost binaurally real imaging with heaphones. Quite magical.

 

[Barry Hufker]

That's interesting… I used that exact technique for recording a recent orchestral concert, but I didn't know it had a name. It just seemed as if that was what was going to work (and it did)…

 

[k brown]

That's interesting… I used that exact technique for recording a recent orchestral concert, but I didn't know it had a name. It just seemed as if that was what was going to work (and it did)…

Sometimes referred to as an 'Onno pipe'; one old book named it the OHNO Array - don't know where they got that from; probably a typo. Used quite frequently by the guys at Soundmirror.

 

[RoadrunnerOZ]

My favorite spaced omni array for many different things is Onno Double AB; developed purely by ear, and not by theory, by Onno Scholtze while an engineer at Philips. It's a 1' spaced pair on the same bar as a 10' pair; both pairs aimed 90 degrees apart, ideally all the same mic (he used DPA 4006s/silver grids), and all at the same level. For reasons I've never been entirely clear about, he always aimed the mics straight ahead, not aimed down.

No other array I've tried has a Decca Tree-like spaciousness on loudspeakers and almost binaurally real imaging with heaphones. Quite magical.

The DPA 4006 Silver Grid has a linear frequency response on-axis - I guess pointing straight ahead may be at the combined best delivery height of the sound source in a theatre or auditorium with acoustic reflective ceiling surfaces above an orchestra, coupling this with the direct sound. Or, maybe more likely, by not pointing directly at the sound source taking advantage of the diffuse field off-axis softening of the top end - a very gentle roll-off.

 

[RoadrunnerOZ]

I think that M/S recording is more suited for small ensemble, backing vocal groups or multi M/S arrays for small choirs. It does work with a B3/Leslie organ as it emphasises the rotary speaker stereo image reflected from surrounding walls/surfaces but for a pipe organ with massive bottom end in the bass pipes and the reflections within a large church or cathedral, considering also rear reflections, the stereo imagery from M/S would I think be maybe marginal - possibly even confused. This may result in a less than pleasant soundstage - but worth a try though if you have the opportunity - maybe trying the M/S pair with a spaced Omni pair as a combination.

 

[Barry Hufker]

The late Marc Aubort of NYC' "Elite Recordings," once said, "M/S stands for 'Maybe Stereo'." And I agree with him. I've used it quite often to good results but I always feel "dirty" after --- ; >)

 

[emrr]

"Maybe stereo" is what happens if you use the wrong mics, or blend it wrong, or place it wrong, or.....I could go on, but it's wasted. Most people never drive it enough to get the training wheels off, and are blaming their own lack of technique when they blame MS.

 

[Barry Hufker]

I've used it plenty of times and have used the "right" mics. I've had success with it and it's been fine. Marc Abort preferred spaced omnis (and as I said I do too) and M/S (IMO) comes off second best in a lot of ways. That was Marc's (and my) point... No offense meant to those who use and enjoy the technique. It does indeed have many advantages. And I'll be the first to tell you the flaws spaced omnis have...