Fun With Stereo Pairs!

    • January 21, 2023 at 2:27 pm #4424
      Mary Mazurek
      Moderator

        Stereo Recording Techniques

        I love stereo pairs, and they’re not just for classical music recording, think drum overheads, pianos, choirs, sections, etc. This past Thursday I took my Classical Music Recording class through a series of stereo pairs. I also had them work with the acoustic of the recital hall at the University of Lethbridge by balancing the direct and ambient sound through placement.

        What you see on the stage are the following stereo pairs: coincident, near coincident, and spaced pairs.

        Coincident pair consists of 2 identical, directional microphones (not Omni) with the diaphragms in the same space and angled some degree. In this instance the diaphragms are 90 degree, so they might be referred to XY as well as coincident. This pair is mono compatable

        as the sound reaches both capsules at the same time. The overall sound tends to be present and maybe even a bit bright due to the fact that the capsules are next to each other.

        The next pair is near coincident pair with 2 identical directional (not Omni) microphones spaced a few inches apart and angled some degree. This pair is 20cm (About 8”) and 90 degrees so this pair is known as DIN (Deutsch Institut für normung or Deutsch Institute for Normals/standards). This pair is not mono comparable due to the space, but this pair creates a great sense of depth and spaciousness.

        The other pair is a spaced pair. The microphones can be any pattern but Omni is commonly used. They are spaced several feet apart, and pointed directly at the ensemble. These provide the greatest sense of width across the stereo field.

        BlumleinWe then decided to add a closer pair to the guitar using two Royer ribbon microphones. Ribbons are inherently figure 8 (unless the housing is changed), so they are great microphones for the Blumlein technique, 2 figure 8 pattern microphones 90 degree with no space in between. These also fall within the coincident pair family.

        We then compared, contrasted, and blended the various pairs. I believe that we found the close Blumlein pair blended with the spaced omnis the most pleasing in this circumstance. Though this combination is not mono comparable, it was pleasing. We still check all combinations in mono. We expect a bit of loss in airiness in mono as that component of the sound is created by the space between the microphones, but if it’s changing the frequency response more drastically, you might rethink your mike placement.

        Binaural

        And because we could…Meet Fritz the Neuman KU100 binaural head. We wanted to find out what 6th row center (an ideal audience listening position) sounded like, so we employed Fritz for the task. The binaural head is spatially accurate over headphones, but he’s sometimes also used for rear surround channels.

        We found that we liked our stage miking better than listening in 6th row center as it provided more detail, but not so much that it sounded unreal.

        So there are some of the basics for stereo pairs. What stereo pairs have you tried and in what context?

      • January 21, 2023 at 6:19 pm #4430
        Bob Katz
        Keymaster

          Cool. I’ve used Blumlein with Omni outriggers to extend the angular pickup. Technically, it’s verboten when there’s audience applause you want to pick up on the back but since the back side of the Blumlein is inverted polarity but the omnis are not you’d think they wouldn’t mix well. But if you space the omnis wide enough the cancellations are vague and random enough so you still get a pretty specific stereo applause track! It can sound great. Use your ears and listen for anomalies muting and unmuting the supplementary omnis.

        • January 21, 2023 at 6:25 pm #4431
          Bob Katz
          Keymaster

            There are some transforms available between binaural and miking for speakers. I recorded a jazz ensemble with my own custom binaural head. And I have access to all the close mikes. The piano is too soft and distant on the binaural. The question is whether I can convincingly mix in the close mikes to get a binaural mix. I’ve had to table the project as it’s too challenging right now to find the best tools for that.

          • January 31, 2023 at 11:30 pm #4498
            Michael Heitmanek
            Participant

              Has anyone tried the bluberry mics in ORTF set up?

              • February 1, 2023 at 2:34 pm #4535
                Mary Mazurek
                Moderator

                  Hi Mickey!

                  No I haven’t tried ORTF (17cm, 110 degrees, cardioids), but I have with other large diaphragm cardioid condensers. It should work just fine.

              • February 3, 2023 at 10:12 pm #4707
                David Streit
                Participant

                  Great post! I completely agree that stereo pairs aren’t just for classical music recording (although that is the context in which I really learned about them.) This week, I used a spaced pair of cardioids to close mic a piano (SM57’s that worked very well in the specific context), an ORTF pair of cardioids for drum overheads and a small choir (Mojave MA-201), and an ORTF pair of cardioids for room sound (Ear Trumpet Labs Edwina). They all sounded great. A well placed stereo pair can add a sense of depth and realism to a recording.


                • February 3, 2023 at 10:47 pm #4709
                  Mary Mazurek
                  Moderator

                    Thanks David! And you’re so right, they produce a nice field of depth as well as width.

                  • February 3, 2023 at 11:01 pm #4714
                    Michael Heitmanek
                    Participant

                      I am not a professional recording engineer, but I have found that a pair of cardioids, large condensers of small diagram condensers in ORTF configuration work well in a lot of situations, especially if you’re recording in a small space. You might have to move amps and instruments, but it gives an over all good impression combined with spot mics. I am a bigger fan of Mid-Side recording. What kind of stuff do you record David?

                    • February 4, 2023 at 1:12 am #4722
                      David Streit
                      Participant

                        Hi @Mickey242! I use ORTF a lot. (I often eye-ball the setup, so I guess it’s near-ORTF.) Mid-side is good too. One cool thing about M-S is that the mics don’t need to be the same, which allows some interesting combinations. I record a variety of pop music (as opposed to classical, although I would enjoy doing that too.) Mostly multi-miced, multi-tracked stuff, often with group members all playing together at the same time, and then some added overdubs.


                      • February 27, 2023 at 9:49 am #5010
                        Charles Lawson
                        Participant

                          The ORTF arrangement is a wonderful general pickup, especially for small ensembles.  I have always been aggravated by the the limited low end of the directional mics required in an ORTF, but you can use a good omni pair (such as the Schoeps MK2 series or DPA 4006) with acoustical directional accessories (a 30mm slip on “ball”)  to give you the required directionality yet preserve the marvelous low end of a good omni.  Since the Neumann TLM-50 is now a “legacy” item, the Schoeps and DPAs with the spheres can work very well in place of them.

                        • February 27, 2023 at 9:54 am #5011
                          Bob Katz
                          Keymaster

                            I started out life using a lot of ORTF but I really abandoned it because I found that plain cardioids did not have the dimensionality I sought. As you may recall, Stanley Lipschitz was a purist and insisted that coincident miking was the ONLY way to go. But the slightly added time delays of ORTF can help with the sense of dimensionality. Still, in my opinion that is not enough. If you change to hyper or super in a semi-ORTF spacing you begin to get some of the out of phase bounce from the rear. If you change to Figure 8 blumlein the magical dimension really begins to happen! Mr. Blumlein had it right decades ago and it still rules! Usual caveats: In the right hall, with the right ensemble and included angle. Which is why supplementing Blumlein with a couple of cardioid or omni outriggers is an amazing way to have your cake and eat it, too.

                          • February 27, 2023 at 10:14 am #5013
                            Charles Lawson
                            Participant

                              If I am using ORTF, I typically supplement with flanking omnis (if conditions permit).  It does, indeed, help a great deal with that element of “dimensionality.”

                              I really can’t take Blumlein because of all the out-of-polarity stuff…at least in a concert hall setting.  However, I have heard some remarkably good work done that way.  The right person can pull off nearly anything.

                            • February 27, 2023 at 1:28 pm #5015
                              Len Moskowitz
                              Participant

                                (I tried posting here yesterday. After a few edits, the forum deleted my post. So per Bob’s suggestion I’m trying again.)

                                I record with higher-order ambisonic (HOA) microphones that allow for virtual stereo pairs and more.

                                A single HOA mic allows for any coincident mic array that you can imagine. The polar patterns and pointing directions are selected in post, and from a single recording you can do as many virtual coincident arrays as you like, including Blumlein, XY, LCR, binaural (both headtracked and fixed-head, with computed ITDs), and many others.

                                With two spaced HOA mics, I do ORTF and bilateral ambisonics (for binaural recordings with a true ITD).

                                All the parameters of the virtual mics are decided in post-production, except for the spacing in spaced arrays.

                                The HOA mics retain their full frequency response specs, even when decoded to directional polar patterns.

                                Here’s a link to a short clip of the Montreal Symphony Orchestra playing Dvorak’s New World Symphony, recorded with a single HOA mic decoded to Blumlein:

                              • March 1, 2023 at 8:02 am #5037
                                Mary Mazurek
                                Moderator

                                  ORTF or other near-coincident pair with Omni flanks is a great way to go @clawson. I like to use this combination for large ensembles like orchestras and choirs.

                                • April 1, 2023 at 5:36 pm #5668
                                  Henry Grimmius
                                  Participant

                                    Regarding ORTF, are there many people still using the Shuffling technique that’s been around a long time and how I found out about it via Michael Gerzon? I remember in my early attempts at recording via 2 microphones, starting with X-Y.

                                    Soon tired of that, although more phase coherent, was very, for lack of a better term, boring. Then started experimented with ORTF. My recording career took me further away from classical recording, and less use and experimenting with other techniques.

                                    That said, I’ve recently had opportunities to experiment with ORTF with shuffling, ORTF with omni outriggers, and even Gerzon’s mic technique. Been fun to get back into it. So, anyone using shuffling anymore?

                                  • April 1, 2023 at 9:10 pm #5670
                                    Michael Heitmanek
                                    Participant

                                      Please tell me of the “shuffling” thing. I have never heard of it.

                                    • April 2, 2023 at 4:18 pm #5675
                                      Henry Grimmius
                                      Participant

                                        Hmm. Replied to Michael but it didn’t post. So, Shuffling. This actually started with Mr. Blumlein and his stereo mic technique. I read about it via something from Michael Gerzon, either from a couple of web boards, the Mastering web board, of which, Bob Katz was a part, or maybe even earlier in the old rec.pro.audio days. Anyways, Mr. Gerzon expounded on it and there are some plugins built with shuffling built in, one of which is from Waves. Mr. Gerzon also developed his own take on stereo miking, using almost half X-Y and half ORTF.

                                        I tried to attach a link to a pdf written by Michael Gerzon. Maybe that link kicked my post out? Don’t know. Anyways, I’ll post the URL via this post. Just copy and paste. Will see if that let’s my post through.

                                        https://www.audiosignal.co.uk/Resources/Stereo_shuffling_A4.pdf

                                      • April 9, 2023 at 11:21 am #5746
                                        Mary Mazurek
                                        Moderator

                                          Thank you @Henry the article. It was very interesting.

                                        • April 9, 2023 at 11:27 am #5747
                                          Mary Mazurek
                                          Moderator

                                            MS Technique

                                            I definitely teach MS technique, and my students seem very enamored with it. Here they used an AKG 414 in cardioid (though it could technically be any pattern) for the mid mic and a Royer R121 for the figure 8 side. They sent the mid mic to a track and panned it center and the side mic to two tracks panning hard left and right and then phase flipping the right channel.

                                            Though, I  rarely use the technique in my professional work. Where do you find the MS miking technique useful in your work?

                                          • April 10, 2023 at 12:06 pm #5748
                                            Phil Koenig
                                            Participant

                                              I’ve used M/S micing in two situations.  One was capturing an exceptionally wide soundfield.  I wanted to add an ambient stereo track of distant thunder, frogs and crickets in my back yard to a song about being in a bayou. Sounds were coming from directions up to 200 degrees apart so I thought M/S might work well.  I used a Studio Projects B3 for figure-8 side pickup and an AKG D8000 cardoid dynamic for the mid.  It came out with a nice spacious sound, I thought.  The song is streamable  – Track #2 (‘Lady Of The Bayou’) from https://www.soundclick.com/artist/default.cfm?bandID=1157871

                                              The other situation was my desire to get realistic stereo imaging of 3 harmony vocal backing parts.  I set up the M/S pair in the studio. then marked 3 different positions (masking tape on the carpet trick) that were 6 feet back from the mics and 8 feet apart laterally across the floor.  I sang and recorded each harmony part separately, standing in a given position for each part, rather like you might position a small choir.  That produced pretty stellar stereo imaging when soloed, though some of the finer detail ended a bit buried by the rest of the mix.  The harmonies are used in the chorus of this song: ‘Life Song’ (Song #15 on this list) https://www.soundclick.com/artist/default.cfm?bandID=74019&content=songs

                                              • April 10, 2023 at 6:11 pm #5756
                                                Bob Katz
                                                Keymaster

                                                  Hi, Phil. There was another advantage to the way that you overdubbed your voice. Not specifically because of the MS, but important. You used the identical gain for each overdub. As a result, the same perspective of the stereo miking integrates them all.

                                                  Reminds me of when I recorded Stravinsky’s L’Histoire Du Soldat in two parts and mixed them later in post. Part one was the instruments and part two the narration and the acting. I insisted to the producer that we keep the same Blumlein pair mike up (An AKG C24) for the narration, at the identical gain used for the instruments. I positioned the actors in front of the mike at positions that sounded good — in the same hall. As a result, everything just flowed together in post. What happens if you decide to record the narration/acting at a different time, is you get a discontinuity, the ambience and the perspective changes. But instead, we got a continuous presentation that makes it sound precisely like the actors are there on stage with the musicians.

                                              • April 10, 2023 at 3:13 pm #5749
                                                Gregory Pastic
                                                Participant

                                                  I’ve used Blumlein fig 8s with small ensembles successfully, and have only needed to use a pair of omni outriggers to capture some additional ambience a few times.  I’ve also used Tony Faulkner’s setup which uses a pair of Fig 8’s spaced 20cm apart parallel to each other.  I hung out at a couple of his recording sessions in London, England, and observed him using that setup for a large choir and a chamber orchestra.  The recordings turned out very nicely.  I’ve tried (unsuccessfully) using EBS and a slightly modified ORTF setup, but ended up using a Jecklin disc with two omnis in one case, and the Faulker setup in the others, both of which yielded more satisfying results.  Has anyone else used Faulkner’s setup?  If so, were you happy with it?  And, under what conditions did you use it?

                                                   

                                                  • April 10, 2023 at 6:16 pm #5757
                                                    Bob Katz
                                                    Keymaster

                                                      Faulkner’s setup reminds me of the late David Hancock’s approach to spacing a pair of figure 8 ribbons. I haven’t tried it, but the idea seems dangerous as coincident figure 8’s already have tremendous separation. But David told me that he called coincident pairs “monereo”. And since I have frequently supplemented Blumlein with spaced omnis I’m no purist either 🙂

                                                  • April 10, 2023 at 9:33 pm #5761
                                                    Gregory Pastic
                                                    Participant

                                                      Here’s a link to an interesting article about Tony Faulkner’s mic setup.

                                                    • October 31, 2023 at 1:28 pm #5957
                                                      Barnaby Bristol
                                                      Participant

                                                        In the mid ’90s I produced/engineered a science, educational, radio drama for children titled Kinetic City Super Crew. The specification was to produce in mono, but I convinced staff to produce in stereo. I recommended MS microphone technique for the ensemble cast recording for primarily mono compatibility but also to eliminate multiple mic source pre-mixing and to minimize issues of mic technique. Benefits realized after were that the cast had to work in close proximity and even block some scenes to stay in the sweet spot, and because stereo information was attained by L/R amplitude and not time delay, the recording worked well in post production with digital reverberation. One thing to be aware of for this mid-atop-the-side pair was for sound sources (actor voice) being significantly below the horizontal plane of the mic pair. The voice would become “wide and phasey,” presumably from the time difference and arriving at the side capsule first. A few short blocks for the short actors to stand on fixed this.

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