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Author Topic: Don't have a wide mic bar? Give PAS with figure 8's a try  (Read 5347 times)

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Offline Gutbucket

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Don't have a wide mic bar? Give PAS with figure 8's a try
« on: March 30, 2016, 05:37:24 PM »
Was messing around with setups on Michael Williams' multi channel microphone array design website and clicked over on the good old 2-channel arrays (the original Stereo Zoom stuff) and pulled up the Stereo Zoom table for figure 8s (linked below).   I remember thinking about near-spaced figure-8s but only really trying Blumlein.  Then I remembered all the LD mics (many switchable to fig 8 ) I see on standard narrow-width mic bars (can't space those mics much anyway, they are big and heavy), often setup inside the SBD cage for protection, but not in optimal configurations (like switched to omni pattern, but only 10" apart or whatever).  Looking at the figure-8 table for a while, I realized that figure 8's would be an excellent solution for tapers using standard mic bars which aren't wide enough to space the mics sufficiently as recommended by the improved PAS with optimal spacing table which is intended for cardioids or supercards (threads on Improved PAS are here, and here).

Here's the basic principle in a nutshell-
For a given PAS angle between mics, the more directional the pickup pattern is, the less spacing is required between them for a decent stereo image.

Omnis require the most spacing, figure-8s require the least. The progression of first-order microphone directional patterns, which are simply points along the directional sensitivity continuum, goes like this: omni-subcardioid-widecardioid-cardioid-supercardioid-hypercardioid-figure-8.  So when you aren't capable of spacing the mics much, and want to use a minimal angle between them to Point At Stacks, patterns closer to the fig-8 end of the directional spectrum are a wise choice.  Why not leverage that as far as possible and get a great stereo-image? Especially outdoors where there is no room verb or back wall reflection?  Using 8's allows for the least amount of spacing required between the mics of all mic patterns.

Note that switched to fig-8 pattern, the mics will exhibit more low bass rolloff, but that bit of built-in low-cut may be a good thing for taming overactive subwoofer boom.

So break out those ADK TL's, ADK 414's, or the big Neumanns and and give this a try at an outdoor fest if you are setup at the board or stuck behind it and can't get very FOB.  You'll get reach, you'll get improved stereo imaging, you'll get something sort of Blumlein-like in it's "airiness" but with a narrower SRA window focusing on the stage, which will produce a wider, less monophonic stereo image on playback.

http://www.mmad.info/MAD/2%20Ch/SRA%20Bi.pdf

^ Example: mics spaced 7" (~18cm) apart, which is totally doable with common mic bars, and angled ~50 degrees apart, which is probably a typical PAS angle from back there, provides a Stereo Recording Angle of a bit more than +/- 45 degrees or 90 degrees total.  Figure-8 nulls maximally reduce audience noise pickup from below and greatly off to the sides.   SBD is in back where the rear lobes point, and those lobes provide a welcome diffuse ambience.  Win!
« Last Edit: April 02, 2018, 01:22:55 PM by Gutbucket »
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Offline F.O.Bean

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #1 on: March 31, 2016, 07:36:35 AM »
I wish I had [2] mk8's, because I would DEF try that outdoors :) Or run Blumlein FOB/DFC :)
Recording Rigs:
Schoeps MK4's & MK41's ->
Schoeps & NBob 250/05 KCY's ->
Naiant +60v/Low Noise PFA's ->
DarkTrain Right Angle Stubby XLR's ->
Sound Devices MixPre-6 & MixPre-3

Portable Playback Rigs:
Sony NW-A35 Walkman & Shanling M0 ->
Linum G2 SuperBax & Bax & Westone Bluetooth MMCX Cables ->
Campfire Audio Andromeda & Westone UM Pro 30 (G1 & G2) IEM's -> Comply Isolation+ Memory Foam Tips

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Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #2 on: March 31, 2016, 10:13:47 AM »
Should work nicely, although I doubt very many tapers have two mk8 on hand.  However, a good number of tapers use LDCs with switchable patterns that include fig-8 and cannot easily space them further apart than a standard near-spaced micbar.  I imagine this will be most applicable for them.

And yes, one way of thinking of this is a modification of Blumlein (figure 8s arranged in coincident X/Y with a 90 degree angle between them) by using a bit less angle and a bit more spacing between the mics.  That should help it to work better from a position further back than straight Blumlein.

It won't sound exactly like Blumlien, probably sounding something like a near-spaced config. And it won't have the same omnidirectional 360 degree pickup sensitivity as Blumlein due to the narrower included angle between mics.  Instead it will have more of a forward facing fat8 shape without the deep side nulls, sort of a fat oval, or a forward pointing "jelly bean" if you like  ;) with less sensitivity to the sides.

Because the directional sensitivity of the forward lobe of a figure 8 is tighter than any other pattern as a source moves from on-axis to 90 degrees off-axis, that allows for the use of less angle and spacing of the stereo pair than using any other pickup pattern, while still getting sufficient difference information between the two channels. 
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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #3 on: March 31, 2016, 10:56:20 AM »
So you would point the 0* left lobe facing forward at an angle like a front address capsule like my mk4x, but using the side-address side of then caps, with the rear lobe facing behind the mic setup pointing towards the SBD area, like pointing hypers/supercards PAS?? I'm trying to picture this in my head lol ;D

Sorry if that's really confusing GB
Recording Rigs:
Schoeps MK4's & MK41's ->
Schoeps & NBob 250/05 KCY's ->
Naiant +60v/Low Noise PFA's ->
DarkTrain Right Angle Stubby XLR's ->
Sound Devices MixPre-6 & MixPre-3

Portable Playback Rigs:
Sony NW-A35 Walkman & Shanling M0 ->
Linum G2 SuperBax & Bax & Westone Bluetooth MMCX Cables ->
Campfire Audio Andromeda & Westone UM Pro 30 (G1 & G2) IEM's -> Comply Isolation+ Memory Foam Tips

http://www.archive.org/bookmarks/diskobean | http://www.archive.org/bookmarks/Bean420 | http://bt.etree.org/mytorrents.php

Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #4 on: March 31, 2016, 11:37:55 AM »
Exactly.  Figure-8's are "side-address" type mics.  They have one positive polarity side and one negative polarity side just like a supercard or hypercard does, the primary difference is that the front/back lobes of an 8 are the identical in size and shape, symmetrical front/back, where as with a supercard or hypercard they are different sizes, larger in front than in back.  With the Schoeps mk8 I think the positive polarity side is the one marked with the '0' (the side you'd point towards the left if using it as the Side mic in a Mid/Side setup).

Think of this as PAS using two mk8 in place of two side-address mk41v, with the positive polarity lobes of both figure-8's facing forwards.
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Offline 2manyrocks

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #5 on: March 31, 2016, 02:37:29 PM »
Hmm, wide mic bar vs. two mk8sand two CMC6 bodies.   And the bill comes to ....ouch.   ;D

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #6 on: April 16, 2016, 02:59:55 PM »
I ran a "Faulkner Array" with my Milab DC-196's at 20cm in figure 8 pointed straight ahead,  at DSO outdoors at the Cuthbert Amphitheater and was impressed how it sounded especially in comparison to Phish at  the Les Schawb in July that I ran Blumlein.
I'd do it again in the right outdoor venue.
see:
http://www.sengpielaudio.com/TonyFaulknerPhasedArray01Engl.pdf
« Last Edit: April 16, 2016, 03:02:13 PM by ArchivalAudio »
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Offline Bruce Watson

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #7 on: April 16, 2016, 05:00:18 PM »
I ran a "Faulkner Array" with my Milab DC-196's at 20cm in figure 8 pointed straight ahead...

Yep, that Tony Faukner guy is pretty cleaver. AB-8s works really well in spaces with reverb problems like stone shoebox churches that are just a bit too small, so the reflections from the walls/ceiling are just a little too quick, and/or too loud. Calms them right down. I'm not surprised it works in the opposite -- outside where there are basically no reflections. Point them down a bit so the rear node is pointing up toward the sky, and you essentially loose the rear node entirely. Unless a plane flies by.  ::)

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #8 on: May 11, 2016, 10:14:58 PM »
I wish I had [2] mk8's, because I would DEF try that outdoors :) Or run Blumlein FOB/DFC :)

You get close to blumlein with an mk8 and one of your mk41 as M/S which your tascam can decode on the fly.
Recording:
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Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #9 on: May 11, 2016, 11:19:15 PM »
Yep.

As long as you're okay with a slightly wider recording angle / narrower playback stage and with sharp coincident imaging as opposed to near-spaced phase goodness.
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Offline down2earthlandscaper

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #10 on: May 15, 2016, 04:15:46 AM »
I ran a "Faulkner Array" with my Milab DC-196's at 20cm in figure 8 pointed straight ahead,  at DSO outdoors at the Cuthbert Amphitheater and was impressed how it sounded especially in comparison to Phish at  the Les Schawb in July that I ran Blumlein.
I'd do it again in the right outdoor venue.
see:
http://www.sengpielaudio.com/TonyFaulknerPhasedArray01Engl.pdf

I'd still love to hear how your recording turned out, Ian :)
Is it posted anywhere? Dropbox link, perhaps?
Mics: CA-14(cards & omnis) and CA-11(cards & omnis) ; AT853's(cards, hypers, mini shotguns); Busman BSC-1 (cards, hypers, omnis)
Nakamichi CM300's (CP-1,2,3,4) Nakamichi CM700's (cards, omnis)
Tascam PE-120's (cards, omnis) Peluso CEMC-6 (cards and subcards)
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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #11 on: May 28, 2016, 03:18:40 PM »
I ran a "Faulkner Array" with my Milab DC-196's at 20cm in figure 8 pointed straight ahead,  at DSO outdoors at the Cuthbert Amphitheater and was impressed how it sounded especially in comparison to Phish at  the Les Schawb in July that I ran Blumlein.
I'd do it again in the right outdoor venue.
see:
http://www.sengpielaudio.com/TonyFaulknerPhasedArray01Engl.pdf

I'd still love to hear how your recording turned out, Ian :)
Is it posted anywhere? Dropbox link, perhaps?

No It's still not posted... I will try soon to up it to LMA .... I'm slacking too many other things to share  where I was the only taper.
~ Archival Audio ~
Archiving Worthy Music
since 1986 & digitally since 1995

https://www.facebook.com/ArchivalAudio/

Main Mics: Milab VM-44 Links • Milab DC-196's (Matched  Pair)  • Line Audio CM3's
PreAmps:  Naiant LittleBox • Naiant [Milab VM44] TinyBox • Naiant PIPsqueak
Recorders: MixPre 10T •  Tascam DR-100 mkIII • Sony M-10 

macMini 3Ghz i7 16GB Ram 500GB SSD • MOTU UltraLite
Naiant MSH-2's •   TOA K1's • Beyer TG 153c's •  AT 853 (4.7kmod darktrain) • Countryman B3's (1 k mod)  + other assorted mics

Offline F.O.Bean

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #12 on: May 29, 2016, 04:20:23 AM »
Exactly.  Figure-8's are "side-address" type mics.  They have one positive polarity side and one negative polarity side just like a supercard or hypercard does, the primary difference is that the front/back lobes of an 8 are the identical in size and shape, symmetrical front/back, where as with a supercard or hypercard they are different sizes, larger in front than in back.  With the Schoeps mk8 I think the positive polarity side is the one marked with the '0' (the side you'd point towards the left if using it as the Side mic in a Mid/Side setup).

Think of this as PAS using two mk8 in place of two side-address mk41v, with the positive polarity lobes of both figure-8's facing forwards.

Gotcha, thanks GB! So the 0* lobe[Red Dot] of an mk8 would face FORWARDS towards the stage just like an MK4v/MK41V? Check, now I got it 8) Now I just need [2] mk8's :P ;D

Hmm, wide mic bar vs. two mk8sand two CMC6 bodies.   And the bill comes to ....ouch.   ;D

Actually, I just need the [2] mk8's, that's all ;D

I wish I had [2] mk8's, because I would DEF try that outdoors :) Or run Blumlein FOB/DFC :)

You get close to blumlein with an mk8 and one of your mk41 as M/S which your tascam can decode on the fly.

True that Noah 8) Id probably decode that in post in WaveLab 6 though, but DEF badass that the 70d can do the on-the-fly MS decoding on both stereo channels[1/2 and 3/4] :)

I ran a "Faulkner Array" with my Milab DC-196's at 20cm in figure 8 pointed straight ahead,  at DSO outdoors at the Cuthbert Amphitheater and was impressed how it sounded especially in comparison to Phish at  the Les Schawb in July that I ran Blumlein.
I'd do it again in the right outdoor venue.
see:
http://www.sengpielaudio.com/TonyFaulknerPhasedArray01Engl.pdf

I'd still love to hear how your recording turned out, Ian :)
Is it posted anywhere? Dropbox link, perhaps?

No It's still not posted... I will try soon to up it to LMA .... I'm slacking too many other things to share  where I was the only taper.

Id LOVE to hear this too 8)
Recording Rigs:
Schoeps MK4's & MK41's ->
Schoeps & NBob 250/05 KCY's ->
Naiant +60v/Low Noise PFA's ->
DarkTrain Right Angle Stubby XLR's ->
Sound Devices MixPre-6 & MixPre-3

Portable Playback Rigs:
Sony NW-A35 Walkman & Shanling M0 ->
Linum G2 SuperBax & Bax & Westone Bluetooth MMCX Cables ->
Campfire Audio Andromeda & Westone UM Pro 30 (G1 & G2) IEM's -> Comply Isolation+ Memory Foam Tips

http://www.archive.org/bookmarks/diskobean | http://www.archive.org/bookmarks/Bean420 | http://bt.etree.org/mytorrents.php

Offline jazzgtrl4

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #13 on: June 08, 2016, 03:37:56 PM »
hi
thanks

i might try this with my 414s this weekend at Huck Finn Jubilee, outdoor bluegrass fest. ill let you know what happens if i do.
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Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #14 on: June 08, 2016, 04:27:04 PM »
Cool.  Please post your thoughts about it here.  The greater bottom end roll-off inherent with figure 8's shouldn't be any drawback at all for that music genera, but sensitivity to wind-noise could be an issue if it's breezy, so dust off your fatty windscreens and/or miniature fur muumuus so you're sufficiently prepared.
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Offline MattH

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #15 on: July 09, 2016, 12:27:21 PM »
Here is my first experiment with PAS figure 8's. I was FOB about 2/3 back and spaced the mics 30 cm. I realize this is closer and wider spaced than OP's suggestion but I wanted to try it anyway. I'm glad I did ;D

http://bt.etree.org/details.php?id=587549

mics: Soundfield ST450, JW mod Milab VIP-50's, Milab VM-44 Links (Matched Cards, Matched S-Cards), BR mod Nak 700's
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Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #16 on: July 11, 2016, 09:41:35 AM »
Hi Matt, thanks for the link.. just jumped on the torrent with the intention of listening tonight. I'm somewhat confused by your etree note mentioning "PAS Blumlein", which I interpret as "coincident fig-8s pointed at the PA (no spacing between mics)", yet above you mention a 30cm spacing. When you say "closer and wider" do you mean recording from a position close to the stage with the microphones spaced apart more widely, or a relatively wider angle between mics in order to point them directly at the PA stacks?  What do you estimate the angle between the two microphones to have been?


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Offline MattH

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #17 on: July 12, 2016, 09:06:39 AM »
Hi Matt, thanks for the link.. just jumped on the torrent with the intention of listening tonight. I'm somewhat confused by your etree note mentioning "PAS Blumlein", which I interpret as "coincident fig-8s pointed at the PA (no spacing between mics)", yet above you mention a 30cm spacing. When you say "closer and wider" do you mean recording from a position close to the stage with the microphones spaced apart more widely, or a relatively wider angle between mics in order to point them directly at the PA stacks?  What do you estimate the angle between the two microphones to have been?

I was closer in that I was FOB and not at the SBD or behind. I was wider in that the mics were separated more than the 18 cm you suggested. It was closer to 30 cm due to my mic bar and the way my LD's mount. I would estimate the angle was about 60 degrees.

I feel like I got something sort of Blumlein-like in it's "airiness"
mics: Soundfield ST450, JW mod Milab VIP-50's, Milab VM-44 Links (Matched Cards, Matched S-Cards), BR mod Nak 700's
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Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #18 on: July 12, 2016, 11:35:26 AM »
The spacing you used is pretty much right in line with what this proposed method suggests as optimal for that particular mic angle.

The closer spaced example in the first post of the thread (fig-8's spaced about 7" (~18cm) and angled ~50 degrees apart) was mean to be something doable with a typical mic bar width, for a what I suspect will be a common PAS angle.  I chose that particular example because it represents an improvement over using cardioids with the same spacing and angle by just switching the mics to bi-directionals.  In that case the 50 degree angle between microphones and the resulting SRA of 90 degrees doesn't actually match up with each other, so it's not an optimized PAS configuration in terms of the Improved PAS idea I initially pitched here at TS a few years back as typically implemented using cardioids and supercards.  It's just something close to what tapers are already doing for PAS.  I later later realized that the fig-8 pattern provides an advantage at narrow mic angles in requiring somewhat less spacing which lead to this thread.  Your spacing is close to the Improved PAS concept of matching the SRA and mic angle by modification of the spacing.

With the Stereo Zoom, the correct amount of spacing between the two mics corresponds to the angle between them (or vice-versa), and in the case of PAS, the angle between mics is going to be the angle between the stacks, or at least pretty close to it.  Attached below is the same Michael William's Stereo Zoom table for a pair of figure 8s I linked in the first post of the thread, on which I've added some red dots along a red line.  The red line indicates all the combinations of mic spacing and angle where the angle between the mics is the same as the the stereo recording angle (SRA), just as we'd like it to be for PAS.  The appropriate spacing between mics can then be read from the bottom of the graph below where the red line intersects with and the horizontal line indicating the angle between mics:


For the left-most red dot, the angle between mics is 80 degrees and the spacing between mics is zero or coincident.  That combination produces an SRA of +/- 40 degrees or 80 degrees total, which is the same as the angle between mics. (This is pretty much the standard coincident Blumlien setup*)

For the second red dot from the left, the angle between mics is 70 degrees and the spacing between mics is ~19cm. That combination produces an SRA of +/- 35 degrees or 70 degrees total, same as the angle between mics.

For the third red dot from the left, the angle between mics is 60 degrees and the spacing between mics is ~35cm. That combination produces an SRA of +/- 30 degrees or 60 degrees total, same as the angle between mics.

The fourth red dot is just off the edge of the graph, but indicates an angle between mics of 50 degrees and a spacing of ~55cm, for an SRA of +/- 25 degrees or 50 degrees total.
And so forth..


According to this figure-8 PAS hypothesis, the spacing you used is very close to the 60 degrees ~35cm combination and pretty much exactly what you'd want for that particular mic angle.
« Last Edit: July 13, 2016, 09:04:59 AM by Gutbucket »
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Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #19 on: July 12, 2016, 12:56:24 PM »
*A foot note on Blumlein config, Williams, and my own experience..

For the left-most red dot, the angle between mics is 80 degrees and the spacing between mics is zero or coincident.  That combination produces an SRA of +/- 40 degrees or 80 degrees total, which is the same as the angle between mics. (This is pretty much the standard coincident Blumlien setup*)

The standard traditional Blumlein setup of coincident figure-8's crossed at right angles to each other is typically used with all sound sources placed comfortably inside the 90 degree front quadrant.  Interpreted in terms of the Stereo Zoom, the instruction for making sure all sources fit "comfortably inside the 90 degree front quadrant" is acknowledgement that the total SRA is somewhat less than 90 degrees.  William's table indicates an SRA of about +/- 35 degrees or 70 degrees total.  Also notice that on William's graph, 90 degrees with zero spacing, lies within the upper grey shaded area.  The grey areas indicate combinations with increased angular distortion near the edges or center of the playback image.

For those reasons, a slightly narrower angle of 80 degrees between coincident fig-8's and the resulting matching 80 degree SRA angle, represents something of an "improvement on standard Blumlein".  And indeed over the years I've found I've found I prefer a slightly narrower angle than 90 degrees for Blumlein, partly because it provides a somewhat more solid center.

Playing with Image Assistant on the hauptmikrofon website http://www.hauptmikrofon.de/stereo-3d/image-assistant/ima-3-app, one can see the effects on the curves in reducing the angle between coincident 8's by 10 degrees, or by leaving the angle at 90 degrees and spacing the mics apart slightly.


I feel like I got something sort of Blumlein-like in it's "airiness"

Unfortuantely I didn't get to listen last night, hope to tonight..
« Last Edit: July 12, 2016, 02:40:59 PM by Gutbucket »
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Offline Gutbucket

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #20 on: July 13, 2016, 09:26:49 AM »
 I like it.  Open, clear, natural.   The low frequency roll-off of the 8 pattern can be compensated for pretty easily.  Diffuse field correlation sounds significantly low (good), which helps it sound enveloping and not closed in.  Some listeners might prefer a stronger and more monophonic center, which could be achieved with slightly less spacing or the same spacing but slightly less angle.

I quite enjoyed listening to this.  Did you notice any significant difference in the pickup of audience noise immediately nearby verses what you expected?  There is of course lots of rearward sensitivity due to the rear lobes of the bi-directional pattern, yet the overlaping null planes of the two patterns should significantly reduce pickup of noise arriving from immediately below (your noisy self  ;)), and somewhat to the sides depending on mic angle.

Thanks for trying this out and posting the link!
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Offline EmRR

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #21 on: December 21, 2017, 10:24:48 PM »
For those reasons, a slightly narrower angle of 80 degrees between coincident fig-8's and the resulting matching 80 degree SRA angle, represents something of an "improvement on standard Blumlein".  And indeed over the years I've found I've found I prefer a slightly narrower angle than 90 degrees for Blumlein, partly because it provides a somewhat more solid center.

I've found MS matrix of a pair of fig-8's (same pattern as 90º Blumlein, if mixed correctly) to give a more solid center than Blumlein in many cases, and better retention of highest frequencies when summed towards mono.  80º or less could be very useful with some distances and PA widths.  I need to try the Faulkner approach.   

I am liking, at least for my purposes, the flatter than normal bottom response of the MKH 30's and MKH 800 Twin, much more like what I get from ribbon mics.  Big, non-stealth mics though. 

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #22 on: December 22, 2017, 09:16:25 AM »
^^^^^^^^^

For the record Blumlein himself used two figure 8 microphones in a M/S array.....
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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #23 on: December 22, 2017, 09:30:12 AM »
Yes, so I hear. It would seem one of the strongest arguments to make to the person skeptical of MS. 

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #24 on: December 22, 2017, 09:30:31 AM »
There is much to be said for Mid/Side getting the center correct.  The mid mic points directly forward, taking best advantage of the mid microphone's on-axis response and minimizing off-axis response irregularities for the center response.  Even though PAS it's not (usually) coincident, it's the same in that way - each mic on-axis with the PA speaker on each side.

Also there should be less response variation due to minor phase cancellations at very high frequencies in the mono sum.  With Mid/Side Blumlein the Side signal cancels out in the mono sum, and what remains is the signal from the Mid microphone alone.  With X/Y Blumlein the Side signal also cancels out in the mono sum, but the remaining Mid signal is not just the signal from one mic alone but the common signal of both mics in combination, with slight response variations due phase differences from not quite perfect coincidence above some frequency.
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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #25 on: December 22, 2017, 09:34:43 AM »
For the record Blumlein himself used two figure 8 microphones in a M/S array.....

Don't forget he started with head-spaced baffled omnis. Before figure 8 pattern microphone was available to him.

Yes, so I hear. It would seem one of the strongest arguments to make to the person skeptical of MS.

I don't follow, why so?
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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #26 on: December 22, 2017, 02:45:05 PM »
Here is my first experiment with PAS figure 8's. I was FOB about 2/3 back and spaced the mics 30 cm. I realize this is closer and wider spaced than OP's suggestion but I wanted to try it anyway. I'm glad I did ;D

http://bt.etree.org/details.php?id=587549

Is there a chance that any of you could seed this torrent posted on bt.etree for 30 minutes?  I should be able to snag it in that amount of time.  Thanks!!

Snagged it!!  Thanks!
« Last Edit: December 23, 2017, 09:39:35 AM by dactylus »
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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #27 on: December 22, 2017, 09:06:05 PM »

Yes, so I hear. It would seem one of the strongest arguments to make to the person skeptical of MS.
I don't follow, why so?

In that Blumlein's use of MS authenticates the legitimacy of a technique that a lot of people don't believe can work, because they haven't researched it or tried it.  If you need an argument for a skeptic of MS, it seems the best one to me....if they know anything about Blumlein.....hope that makes sense. 

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #28 on: December 22, 2017, 11:44:04 PM »
Dug into the pattern charts a bit.  I see that MS with two figure 8 gives you the ability to virtually change the angle of a pair of Blumlein figure 8, after the fact, with a change in the blend.  Another win.   When you change Blumlein width with panning you only change the presented width between playback speakers, as opposed to a virtual pattern repositioning.  This would seem to change the expected relationship of the combined pattern nulls, and explains the changes in the high frequencies.  It ideally shouldn't be panned anywhere between outputs at all.  All theories with ideal poor patterns across all frequencies, of course.  The real world will treat us differently. 

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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #29 on: December 26, 2017, 04:26:38 PM »

Yes, so I hear. It would seem one of the strongest arguments to make to the person skeptical of MS.
I don't follow, why so?

In that Blumlein's use of MS authenticates the legitimacy of a technique that a lot of people don't believe can work, because they haven't researched it or tried it.  If you need an argument for a skeptic of MS, it seems the best one to me....if they know anything about Blumlein.....hope that makes sense.

Yes, quite.  I'd misread your statement as stating the opposite (overlooked the 2nd "to"), reading it as stating the argument would make a person skeptical of Mid/Side, rather than it would make for a good argument to convince someone otherwise skeptical of Mid/Side.
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Re: Don't have a wide mic bar? Give PAS with figure 8's a try outdoors
« Reply #30 on: December 26, 2017, 04:36:10 PM »
Dug into the pattern charts a bit.  I see that MS with two figure 8 gives you the ability to virtually change the angle of a pair of Blumlein figure 8, after the fact, with a change in the blend.  Another win.   When you change Blumlein width with panning you only change the presented width between playback speakers, as opposed to a virtual pattern repositioning.  This would seem to change the expected relationship of the combined pattern nulls, and explains the changes in the high frequencies.  It ideally shouldn't be panned anywhere between outputs at all.  All theories with ideal poor patterns across all frequencies, of course.  The real world will treat us differently.

Yes, Mid/Side using two figure-8 pattern microphones is unique in that the shape of the resulting virtual polar patterns doesn't vary along with a change in Mid/Side ratio, only the virtual angle between patterns varies.

We're getting quite off-topic discussing Mid/Side here though.  This thread is specifically about a spaced Point-At-Stacks microphone arrangement using bi-directional (fig-8) pattern microphones, not about about Mid/Side.  I'd prefer not to confuse those who may not be familiar with both techniques.  Plenty of threads about Mid/Side here at TS, lets keep this one focused on PAS figure-8's,  Thanks!
volition > vibrations > voltages > numeric values | numeric values > voltages > vibrations> virtual teleportation time-machine experience
made easy- >>Improved PAS table<< | made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

 

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