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Author Topic: 3 mic (LCR) distance  (Read 15512 times)

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Offline Billy Mumphrey

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Re: 3 mic (LCR) distance
« Reply #30 on: December 11, 2022, 08:42:58 PM »
Best sounding might be just two channels.. or six, or whatever.  Too many variables to predict best sounding, and a lot of it is how you set things up and how you use whatever you've got.  Mostly I think using more than two microphone channels can help to stack the deck in your favor, making it more likely you can produce a great sounding recording given all the real-world constraints under which tapers record.

I wanted to note an experience this weekend that applies to anyone thinking of adding more mics or currently doing it. I showed up early to a local jazz jam, hoping to get some good 3-4 mic onstage action. Due to multiple circumstances I made the smart decision to ditch all the new gear and just run a simple stereo setup in the sweet spot of the room. Very glad I did. I could just tell the onstage mix would be skewed; they mic'd the quieter instruments through a small PA so out in the room would get the best mix of all instruments and thus the best recording. Ended up with an excellent recording that is very listenable.

My point is don't be afraid to master the art of 2-mic stereo recording as well. I thought of doing 3-mic LCR in the audience, with the center channel picking up some sweet sound direct from the stage, but 2 discrete mics just felt better than a larger 3 mic setup as I was right in front of the majority of the viewing audience. Real-world constraints. I ran at853rx cards PAS straight into the XLR's of the warm mod pmd661 and I couldn't be more pleased.

Side note I'm getting fatigued with the at853 hyper capsules, I think I'm gonna save them for the shittiest of venues and/or extra chatty situations. This is my first time using the warm mod 661 and I think it is just as smooth but more detailed than the mp2. I personally find these mods to be subtle yet still adding pleasing frequency bumps in the right areas. They (usually) make raw files more listenable, skipping tedious post work IMHO. I can't wait to try the CM4's into it.

Also that Schoeps app is VERY cool.
« Last Edit: December 11, 2022, 10:03:09 PM by Chanher »
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Offline Gutbucket

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Re: SAMPLES: 3 mic (LCR) distance
« Reply #31 on: December 12, 2022, 03:50:12 PM »
-I should definitely mention that even though I had the center mono hyper ~1 inch AHEAD of the CM4's (as recommended), I ended up visually lining up snare hits on ALL sources/feeds. I did some quick listening to the 3 mic mix with the center mic left alone and then with it visually aligned (the actual difference was miniscule) and if I'm being honest I didn't hear any difference so I left it lined up. I know Gutbucket talked about moving the center mic forward more in relation to the distance of the outside (left right) stereo pair and perhaps in future recordings I can experiment with that.

Saturday I installed smaller Movo windscreens in place of the big Shures in my recording rig for a day of recording Sunday. While doing that I was checking the 3-microphone L/C/R portion of the array against what is suggested by the Schoeps Visual Assistant for this combination of pattern, spacing and angle.  In it, playing around with the center forward spacing mostly affects how correctly the imaging links up between the L/C and C/R segments of the array.  I found that given the pattern, spacing and angle I'm using between the L/R microphones (supercards, 24" [61cm], 45 degrees), Visual Assistant suggests more center forward spacing than the ~6.5" I am using currently.  Alternately or in combination with that, I could push L/R farther apart and/or angle them wider.  Shifting L/R a bit farther apart is what I think I'll do when I rewire everything at some point, as that's when I have the opportunity to adjust wire-lengths and move things around more freely.  The current L/R spacing was originally setup for use with a wider L/R angle, but I found I like the L/R pair more on-axis with the PA so I now angle them +/-45 degrees, and should increase the spacing to compensate for that change in angle.  Ideally I'd like to figure out a way to easily adjust the angle of the L/R pair to anything between, say, +/-30 deg and +/-90 deg when setting up in the field, then adjust spacing to fit the angle.  Would be super slick to build the bar-clamp mechanism in such a way that things are mechanically linked, so the angle would change simultaneously as spacing is adjusted, and all incorrect combinations are automatically avoided, but that's more mechanical complication than necessary.

The only 3-mic arrangements in Visual Assistant that work with no center spacing at all are super-wide arrangements of omnis (typically) in a line. For relatively-narrow arrangements with L/R spacings closer to that of typical 2-channel near-spaced arrangements, the only solution via Visual Assistant is to push the center microphone position much farther forward, something like 1 to 2 meters or more (in plan view the LCR triangle becomes very tall with a narrow base, rather than wide at the base with relatively minimal height), which then requires the application of delay or manual time-position shifting of the center signal in the DAW such that an impulse from the stage is time-aligned across all three channels.  That's not a practical taper arrangement at all though, as front back spacing is usually more difficult to achieve in taper situations than left/right spacing.

As mentioned earlier in this or in another thread, if free to adjust pattern, spacing and angle, the sweet spot for tapers with regard to forward spacing of the center microphone position might be to use whatever arrangement achieves good image linking while placing the baseline of the L/C pair perpendicular to a line to the left PA stack,  and vice-versa for the C/R pair and the right PA stack.  Sort of PAS with regard to the each baseline on either side of center.  That should optimize imaging as well as transient arrival from each stack to each side.  It will also tend to produce a triangle arrangement that is significantly wider at the base (L/R) with relatively minimal forward spacing of the center.


musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Billy Mumphrey

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Re: 3 mic (LCR) distance
« Reply #32 on: December 16, 2022, 02:41:21 PM »
My very crude visual depiction of gutbuckets “triangle” explanation of how to place the forward Center mic in an 3-mic LCR arrangement. As I understand it, you want to make an imaginary triangle (math people plz tell us the type of triangle) with the Left mic, Center mic, and left PA speaker, and then a second triangle with the Right mic, Center mic, and right PA speaker. I plan on trying this the next chance I get.

Please correct or add anything.
« Last Edit: December 16, 2022, 02:46:02 PM by Chanher »
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Offline Gutbucket

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Re: 3 mic (LCR) distance
« Reply #33 on: December 18, 2022, 05:37:44 PM »
Yes, that's what I'm proposing as a reasonable, relatively easy to apply rule of thumb that aims to get time-alignment right natively without needing to do anything in the DAW, while also achieving about the right forward-center spacing needed for good image linking.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Gutbucket

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Re: 3 mic (LCR) distance
« Reply #34 on: December 18, 2022, 07:12:19 PM »
Below is a screen-shot of the L/C/R microphone arrangement currently comprising the center portion of in my rig, simulated in Image Assistant after measuring it up last weekend.  The angle of the L/R microphones in the rig are currently constrained to +/-45 degrees.  From the Image Assistant curves it appears this arrangement would benefit from a bit more center forward spacing so as to achieve optimal image linking.

So in the second image, I've shifted the center mic 5cm farther forward, which visually improves linking in the graph, but also widens the SRA a slightly by doing so.

BTW, it sounds good as is, without using any time alignment - and the forward spacing is pretty close to achieving the geometric alignment Chanher and I discuss above.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Billy Mumphrey

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Re: 3 mic (LCR) distance
« Reply #35 on: January 30, 2025, 12:12:46 PM »
Following up, I made a handful of 3-mic LCR recordings in 2024. Following Gut's advice, and against my own instincts, I placed the center mic around 4-5 inches ahead of the flanking Left-Right pair. Pics below. Long story short, I REALLY enjoyed the results. I'll post samples soon.

(2) Line Audio CM4 55cm apart, PAS
(1) Studio Projects C4 MKII hypercardioid ~5 inches ahead
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Offline Gutbucket

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Re: 3 mic (LCR) distance
« Reply #36 on: January 30, 2025, 12:41:30 PM »
Right on. I'm happy to hear it worked out to your satisfaction.

BTW you may be aware of this-  Since we last talked about all this here, I've updated the Improved PAS technique to extend it from two mics to three (or four if using a coincident pair in the center), and it now also includes adjustments for closer verses more distant recording positions for some of the configurations.  It might be of interest to you even if only as a general guide.  If you are happy with the setups you've been using then there is no need to modify them.  A link to the thread with the revise PDF covering both 2 and 3 position PAS and a bit about what it does and why is in my signature.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline aaronji

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Re: 3 mic (LCR) distance
« Reply #37 on: January 30, 2025, 04:37:14 PM »
Following up, I made a handful of 3-mic LCR recordings in 2024. Following Gut's advice, and against my own instincts, I placed the center mic around 4-5 inches ahead of the flanking Left-Right pair. Pics below. Long story short, I REALLY enjoyed the results. I'll post samples soon.

If you have the mounts and a four-channel recorder (not to mention the time and inclination), it would be interesting to mount one hyper 5" ahead and a second in-line with the CM4s. The time of arrival distance is so slight (about a third of a millisecond, I think) that I (and maybe others) would be curious to hear the difference.

Offline Gutbucket

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Re: 3 mic (LCR) distance
« Reply #38 on: January 30, 2025, 06:28:04 PM »
^ I'd certainly be interested in hearing that.

I'd expect the difference in such a test to be subtle, mostly likely heard in the smoothness of the imaging handoff between the mics across the playback stage and possibly a difference in the perception of depth.  If you do decide to make the comparison Aaron suggests, the closest data point from Improved 3-mic position PAS diagrams is this one:
  • PAS angle = 100° (outside mic pair angled +/-50°)
  • If close to the source, say <4m away- Outside pair spaced 54cm (21") apart and center mic or pair 17cm (6.5") forward
  • If far from source, say >6m away- Outside pair spaced 58cm (23") apart and center mic or pair 20cm (8") forward.
The setup you mention with the outside pair spaced 55cm (22") apart and the center mic pushed 5" forward is already close to that.  If you do decide to make such a comparison recording, I'd increase the forward spacing of the center mic a bit more to 7" or 8" if easily doable.  Partly because that's what the calculations suggest is best, but also because doing that would be expected to make any audible difference between the arrangement with the center mic positioned forward verses the one with all mics positioned along the same line more apparent.


However.. If the musical performance is important to you and you have a second hyper and an extra recording channel available for it, the stronger motivation for me would be to place that extra mic coincident with the other center mic to form and X/Y pair in the center.  Doing that will almost certainly make for a more dramatic difference, which in my experience makes for an even better recording.. even if it doesn't help us confirm the forward center positioning thing. 

That said, the initial attempt at trying an X/Y center pair and/or making this comparison test is probably best reserved for something you don't care quite as much about and are willing to sacrifice the channel currently dedicated to mono SBD.  If recording something important to you, probably best not to take chances and make the best recording you can using an arrangement you already know and trust.

/not volunteering you, but if you find yourself motivated to make such a comparison please report back!
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Billy Mumphrey

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Re: 3 mic (LCR) distance
« Reply #39 on: January 31, 2025, 12:10:02 AM »
I also expect the difference to be subtle, and possibly non-existent (to my ears). One of my first thoughts before even trying this was that I should do a control, just like you said, where I use NO forward spacing. But after starting to wrap my head around Gut's triangles explanation (that I posted a [crude] drawing of earlier in this thread) I really wanted to try it!

If I have time, I'll happily try to get a 4th hyper aligned with the LR mics. May not happen soon though.

I am also of the opinion that an XY pair in the center would increase the enjoyment for me. Do you place that pair forward as well?

In the samples below, I was fortunate to be close to the stage for pretty much all of them. I thought that allowed the center hyper to actually get great onstage sound from the actual amps and drums. Suuuper fun to play with in post. LOTS of ability to manipulate the mix etc. These may not be great representations of LCR recordings from the section, but it demonstrates some cool results with only 3 mics. Would love to one day replace that C4 hyper with a single mk41 cap > active cable.

https://samply.app/project/BHDbKcmpsQCtDSXnq5O3/

Track 01 is at a brewery, but it's not as bad sounding as most breweries. I ran at a front row table, about 20-25 ft out, slightly ROC but pretty close to the sweet spot.

Track 02 is the same venue but different group (except keyboard player) but they did this super quiet but juicy opening track I wanted to share. Pretty much only keys are coming from the PA, so the CM4's are PAS getting great keyboard sound, while the hyper is pointed straight at the stage, getting drums, stand-up bass amp, and horns.

Track 03 is at a small stage in an enclosed back patio and is essentially indoors; but there's a tree literally in the sweet spot (pic below). It was an improv hosted by a popular drummer, so I decided to angle the hyper right at the drums (they were off to the left) as I wanted to feature him a bit in the mix.

Track 04 was outdoors, like 25-30 ft from the stage. bonobeats got a great onstage recording that's on the archive.

These were all recorded with a Zoom F6. The files are essentially raw except for normalization and dithering to 24bit (from 32fp). And mixing the amount of center mic of course. I did some mastered versions for the artists, but I also enjoy raw files, especially when discussing LCR technique.
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Offline VibrationOfLife

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Re: 3 mic (LCR) distance
« Reply #40 on: January 31, 2025, 03:31:30 AM »
Thinking about shows that I go to that I want to record, last night I actually came up with a game plan for tomorrow night which is so similar to this.  I'll use the x/y built in mics from my recorder clamped in the center, slightly forward, with a cardioid pair pas.  I figure if it all fits within 1.5' 20' back from the stage and 30' high from the "balcony", I might get a good recording in a very very crappy place to record.  We shall see.  Or I'll do my normal which is boom some pas and add in the sbd, but I want to go sbd free on this one just to test my theory.

Offline Gutbucket

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Re: 3 mic (LCR) distance
« Reply #41 on: January 31, 2025, 09:17:31 AM »
Yes, when substituting an X/Y or M/S pair for the single Center mic, just place that pair in the same position as the single mic.  Unlike using an X/Y pair by itself, it will be safest to use a relatively narrow X/Y angle, say 90-deg or even less, rather than the 120-deg or so I'd usually prefer for a non-close-mic'd X/Y pair used on its own.  It will be adding additional "stereo-ness" to what you are already getting from the wide-spaced pair.  I like using a M/S pair partly because the single Center mic remains the same, and its more compact and easier to setup.  I can point it directly at the snare drum or whatever, and add as much Side "width" afterward as I like, including none at all.  But I almost always use some of it. Requires a fig-8 though, or a dedicated M/S stereo mic.

What you say about recording from on or near stage about picking up the direct sound from the amps and drums many tapers will relate to - love that pure, direct, real and dynamic sound, and the wider, well-defined instrument placement in the resulting stereo image. And I certainly relate to what you say about playing around with it afterward to find and the best sound. The increased flexibility that these kinds of properly arranged multiple-mic recording methods provide is not only a lot of fun, but is also valuable in taper situations where we need to be able to pretty much just walk in and set up, under a lot of constraints, assess things by eye and past experience, and are unable to really sound check things properly and reconfigure based on that if needed before recording.

Thanks for the photos.  I love a good tree in the sweet spot!

I look forward to giving your samples a listen, hopefully this weekend.

VOF-
Grab the SBD too if you can and not a hassle, just in case.  Feels really good when no SBD is needed, but also good to hedge the bet.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Billy Mumphrey

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Re: 3 mic (LCR) distance
« Reply #42 on: February 01, 2025, 09:00:15 PM »
Someone said Samply is making them sign up before viewing the files, I did NOT know that (I hate that shit) so here's a dropbox link:

https://www.dropbox.com/scl/fo/w3p6up6lcfoczub7g810l/ABbAdHD5ZuoKx4-PajXb6Vo?rlkey=9qesfo54wqclgcx39z0kz3a7f&st=zjclqpk8&dl=0

Samply is pretty cool though, I personally recommend it as it has a setting for lossless playback.


Some other random slightly off-topic thoughts on 3-mic setups:

-I absolutely plan on doing more of this setup, but following along with what was being discussed in the OMT thread, sometimes it's just not practical to get all these mics up in the air. ESPECIALLY in regards to pissing people off. Gotta respect the artists, staff, and fans. I recently had a show where I brought this setup and upon looking at it, the owner of the venue expressed the slightest hesitation at it's size and I immediately switched to my low pro u853r setup (more on this in another thread). They were pumped that I was taping so it was a no-brainer to scale it down. A cardioid stereo setup in the sweet spot still sounds great.
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Offline Gutbucket

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Re: 3 mic (LCR) distance
« Reply #43 on: February 03, 2025, 09:14:52 AM »
-I absolutely plan on doing more of this setup, but following along with what was being discussed in the OMT thread, sometimes it's just not practical to get all these mics up in the air. ESPECIALLY in regards to pissing people off. Gotta respect the artists, staff, and fans. I recently had a show where I brought this setup and upon looking at it, the owner of the venue expressed the slightest hesitation at it's size and I immediately switched to my low pro u853r setup (more on this in another thread). They were pumped that I was taping so it was a no-brainer to scale it down. A cardioid stereo setup in the sweet spot still sounds great.

Spot on. The OMT setups are an exploration of advantageous multichannel setups that be used to great advantage when not in people's way or upsetting anyone.  Perhaps useful to a majority of tapers simply as a data point of what might be done when pushing the edge of excess. A practical concession in applying it is how to achieve those things while making the setup as minimally imposing as possible, and how to further reel in its visual/spatial foot print by varying degrees without overly compromising what it sets out to do when necessary.

Didn't get a chance to check out the Samly link over the weekend, thanks for the drobox link.  Hope to get a chance over the next couple days.
« Last Edit: February 04, 2025, 05:37:39 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Billy Mumphrey

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Re: 3 mic (LCR) distance
« Reply #44 on: February 04, 2025, 12:26:30 PM »
Thanks for all the advice and theory.

One day, when I win the lotto, I have visions of a couple 4060's, spread 2-3' with coat hanger wire, and an MK41 + active cable in the center for the ultimate low-pro 3-mic rig.
formerly known as "Chanher"

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