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Gear / Technical Help => Ask The Tapers => Topic started by: Limit35 on April 20, 2016, 11:27:59 PM

Title: Card+Omnis from the lawn
Post by: Limit35 on April 20, 2016, 11:27:59 PM

I don't usually go to amphitheatre shows but will taping a few soon and have been trying to figure out how I am going to tape from the lawn. I was thinking I could run spread omnis (naiant x-x) somewhere around 1-1.5m to get a little ambiance and the stacks at the front of the lawn. Since I have two channels open I am between two options and hope for some opinions.

  A. I could run 853 cards x/y at the stage.
  B. I could run one 4033 at the stage.

Ideally, I will be around front center lawn, if not I can see omnis for the stacks and x/y working for any spot, left/center/right. Preferred in the center I imagine from back there.  The 4033 with a mono center channel will be the same in either third. So I guess the question is which would people prefer from a distance with the rear stacks a) split omni with x/y, or b) split with a single card, or c) just use the better card and fill out the stereo with the naiants.

Title: Re: Card+Omnis from the lawn
Post by: kindms on April 21, 2016, 11:46:07 AM

I don't usually go to amphitheatre shows but will taping a few soon and have been trying to figure out how I am going to tape from the lawn. I was thinking I could run spread omnis (naiant x-x) somewhere around 1-1.5m to get a little ambiance and the stacks at the front of the lawn. Since I have two channels open I am between two options and hope for some opinions.

  A. I could run 853 cards x/y at the stage.
  B. I could run one 4033 at the stage.

Ideally, I will be around front center lawn, if not I can see omnis for the stacks and x/y working for any spot, left/center/right. Preferred in the center I imagine from back there.  The 4033 with a mono center channel will be the same in either third. So I guess the question is which would people prefer from a distance with the rear stacks a) split omni with x/y, or b) split with a single card, or c) just use the better card and fill out the stereo with the naiants.

do you happen the have a super card or shotgun available ?

We have been having very nice results running split omnis with a short shotgun center. We have also run M/S as the center as well.

Given your choices I would run omni split with a center card. You could point the other card facing to the rear for some mixing possibilities (crowd reaction etc). Ha now i sound like Gutbucket
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 21, 2016, 02:39:28 PM
Ha! That's what I'd do!
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 21, 2016, 03:28:59 PM
But actually this is an excellent question and a difficult choice.  I'd probably go with the better quality single cardioid (4033) in the center, and point one of the 853s directly rearwards.  If you do that, it's best to space the two center mics a couple feet apart from each other if you can manage it- placing the 4033 a foot forward and the 853 a foot back from the center-line between the omnis.  If not no sweat.  The fore/back spacing isn't nearly as critical L/R spacing.

I'd likely choose to do that for two reasons- 1) using the better quality cardioid where it counts most  2) I really like having the backwards facing mic to work with most of the time, which sort of ends up serving a similar purpose as using a X/Y or M/S pair in the center.
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on April 21, 2016, 03:51:19 PM
Since I am kindms running buddy I will second what he said and third what gutbucket says. I will add that as long as it is open taping be prepared to put the stand up as high as it will go within reason. Last year for Phish at SPAC we were at least 10 feet up. If you have two stands, you can do what gutbucket is saying: run the 4033 in the middle of the split omnis on the one stand, then place the other stand 12-16 inches back and aim the 853 toward the rear.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 21, 2016, 04:11:39 PM
^ or just gaff tape the rear-facing 853 to a chopstick or something similar sticking backwards, an advantage of tiny lightweight microphones.  I was only about 8.5' up last weekend without much near-crowd noise problems, but that was as high as I could go.  Most of the chatter I picked up was tapers talking friends who stopped by underneath the mics! Bastards.  :P

Here's a photo of a setup similar to what I'm suggesting above-
(This is front/rear facing Microtech Gefell M94/MV692 cardioids between wide spaced 4061 omnis.)
[edit] You can see the mic bar on which the front/rear facing Geffs are mounted is oriented sort of diagonally, allowing the mics to be mounted side-by-side instead of back-to-back and making the arrangement compact enough that both mics fit under a small umbrella.  I can still shift the mics in the mounts to extend them somewhat further forward and back, but they need to be in the position below to use the umbrella effectively)

(http://farm9.staticflickr.com/8477/8161220180_f1d3fa81b9_c.jpg)


Here's the same using front/back facing AT853 cardioids in some ratty looking furs in place of the MGs-
(actually those were AT933 I'd borrowed to test the concept, later replaced with 853 which I liked better, later superceeded by DPA 4098 hypers)

(http://farm9.staticflickr.com/8198/8189307572_029a22f65a_z.jpg)
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 21, 2016, 04:18:54 PM
I do like what an X/Y or M/S pair does between the wide omnis, as long as you are into tweaking the Mid/Side ratio of either for best effect in addition to playing with the level balance between the center pair and the omnis.  But that's sort of gravy on top of the main course of the omnis + single center mic. Just putting any mic between the two omnis goes a long way.  Bringing up some of the rear-facing mic in your mix effectively does something similar to what adjusting the M/S ratio of a forward facing center pair does- it opens up the sort of "hard-panned SBD sounding" center somewhat and blends it with the wide open and deep ambient base which the omnis are providing.

I was experimenting with using a M/S pair in the center between omnis just last weekend outdoors, and to do so I gave up my usual rear-facing mic channel to be able to run the Side figure-8.  However, I don't think I'll move to doing that regularly, partly because I also was running a sideways facing pair of near-spaced supercards which also do something sort of similar in combination with the single center mic as turning it into a M/S or X/Y (m/s adjusted X/Y) pair does.  I just I like the spaced sideways-facing supercard pair a bit better in a stereo mix, and a whole lot better with discrete multtchannel surround playback do to improved L/C/R channel separation.

Here's that arrangement as a full 8 channel array with both center forward and backwards facing M/S pairs hidden inside the big Shure windscreens, the omnis are cropped off out of frame, the mics at the edge are the sideways-facing supercards.  Last weekend's setup looked identical to this, except the rear facing M/S pair wasn't hooked up so I only needed to record 6 channels.   A good test, but I missed having that rear facing mic!

(http://taperssection.com/index.php?action=dlattach;topic=96009.0;attach=121524;image)


But if I had a wall reflection directly behind me or a noisy beer tent something, I'd not use the rear facing mic and switch to an X/Y or M/S pair in the center instead.

Hope that helps more than it confuses!

Link to the thread documenting the evolution of these crazy setups- http://taperssection.com/index.php?topic=96009.msg1279052#msg1279052 (http://taperssection.com/index.php?topic=96009.msg1279052#msg1279052)
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on April 21, 2016, 11:56:55 PM

Thanks, a lot of good information there for me think about for the future too! I didn't think about a rear mic, I think I'll try that out with the 4033a and naiants.  I imagine increasing the angle on the rear mic would help so as not to mic the guy 10' up slope. In fact the rear mic should use the angle of the lawn now that I think about it.

I really want to do forward/rear 853s in a different setting now. That's something I never though about.

And here I was all stoked when I just figured out 853s can inserted in backward AT8438 mounts on a K&M 23550 to do x/y setups. I'll have to save that for another time.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on April 22, 2016, 01:26:05 AM

In regards to spacing the cards. Is that in relation to each other, or in relation to the spacing of all 4 mics?  I could throw the rear 853 on a small diameter tent pole gaffed to a 8438 mount straight back to get that spacing between the cards easily. I'm maxed out at about 6" forward in the 4033.

Interesting, a lot of things to think about. Such as a single shotgun, hyper, or omni cap would open opportunities that I never thought about before. 
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 22, 2016, 09:02:17 AM
The front/back mic spacing isn't critical, but some distance between them producing a bit of time difference is good.  8" forward is fine.   If you can place the rear facing one a foot or two behind the front one you're good.

I encourage you to try the 853s as forward facing X/Y in the middle too, and ordinarily that would be my first suggestion.  Partly because each of the two stereo pairs (wide omnis, X/Y cards) may be listened to alone, and compared, as well as mixed together.  Partly because it's a bit less odd, making that setup generally more understandable and acceptable to other tapers.  Which is more appropriate somewhat depends on the situation.  Using the 4033 in the center is a significant enough quality jump to sway me to suggesting the front/back facing pair before the 853s in X/Y.

My general working premise for a single forward facing mic in the center is that I want a directional mic there which focuses on the direct sound form the stage and minimizes pickup of ambient sound from all other directions.  It's sort of like using a soundboard recording in a matrix mix- the clean clear direct sound fills the center of the stereo image, and the wide omnis provide the ambient bed for it, with wide bass, and audience reaction spread out to the edges of the playback soundstage.
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on April 22, 2016, 09:06:51 AM

In regards to spacing the cards. Is that in relation to each other, or in relation to the spacing of all 4 mics?  I could throw the rear 853 on a small diameter tent pole gaffed to a 8438 mount straight back to get that spacing between the cards easily. I'm maxed out at about 6" forward in the 4033.

Interesting, a lot of things to think about. Such as a single shotgun, hyper, or omni cap would open opportunities that I never thought about before.
Oops. I didn't see Gutbuckets post in front of mine. Of course, he has the best explanation!  8) Also, doing the XY and split omnis gets you a "safety" 2 mic XY or Omni recording in case you don't like the single card in the middle.
We did this the first couple of times we tried side fig 8 and MId short shotgun. Now, we are comfortable not running the safety rig.!
If you can get the cards any amount forward or rearward of center, in the middle of the Omnis. and as Gut would say, 3 feet spread on the Omnis is minimum. That is the widest spread our Manfrotto mount does, I believe he has been running his Omnis at 6 foot apart.
Here are rig pic links to our setups kindms described:
http://taperssection.com/index.php?topic=177186.0                         Our recent Omni split with Forward facing fig 8 and side facing fig 8
http://taperssection.com/index.php?topic=176841.0                        we were running 6 mics in this pic, but what we chose to mix was the 2 outside Omnis and the AKG ck8 shotgun in the middle
http://taperssection.com/index.php?topic=176719.0                     the third pic is the M/S set up using AKG 414 XLS-II in figure 8 as the S and an AKG 460/ck8 as the M
http://taperssection.com/index.php?topic=175276.0                     we ran this as a first try without any Omnis: AKG C414 XLII-ULS as a figure 8, and my AKG C460B w/ck8 capsule as the mid  (in fact, this was the       
                                                                                                run when we decided to start using spread Omnis with a middle mic following Gutbuckets recs)
                                                             
Title: Re: Card+Omnis from the lawn
Post by: lsd2525 on April 22, 2016, 09:46:56 AM
I got a question for you math wizards......trying something new tonight and this weekend. Picked up a set of Nak 300's (using the Omni caps); going to run them along with my AT4041 cards. At the time, my bar is around 2 feet. Was going to run the Nak Omnis on the outside so I could get the biggest amount of split, with the AT's as the inside set in more of a DIN/PAS configuration. Since I can only split the omnis a couple of feet (at most), should I do something different? I would run them as the inside set if I had a Jecklin disk, but I don't. any advice?
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 22, 2016, 10:12:00 AM
You can probably get a few inches additional spacing on each side for the omnis by pointing them directly out to either side and pushing the mic bodies out as far out as you can in the mounting clips, as long as they are still securely held.  The mic bodies then extend beyond the length of the bar with the capsules at the outermost limit.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 22, 2016, 10:26:18 AM
^^ That will be another good comparison for you.

Listened to on their own, I usually prefer near-spaced stereo configurations like DIN/PAS over X/Y.  But in combination with the omnis, I prefer X/Y in the center over a near-spaced config.  In addition X/Y is Mid/Side tweakable without weirdness, so the center of the image can be dialed in optimally if you care to make the effort to adjust that.  Near-spaced configs are Mid/Side tweakable too (any stereo recording is) but the bit of time/phase difference which makes them sound better in isolation can do some weird things if you shift the M/S ratio by more than a little.

X/Y PAS isn't normally anything I'd want to listen to on it's own, but works as an excellent counterpart combined with the spaced omnis. 
Title: Re: Card+Omnis from the lawn
Post by: lsd2525 on April 22, 2016, 10:32:12 AM
You can probably get a few inches additional spacing on each side for the omnis by pointing them directly out to either side and pushing the mic bodies out as far out as you can in the mounting clips, as long as they are still securely held.  The mic bodies then extend beyond the length of the bar with the capsules at the outermost limit.

And, being omnis, they don't need to be pointed at the stage/stacks.......won't I lose some top end? Or probably not enough to matter?

I'll be doing this a lot this summer. Might be time to invest in another stand. Or a really wide bar:)
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on April 22, 2016, 10:58:37 AM
You can probably get a few inches additional spacing on each side for the omnis by pointing them directly out to either side and pushing the mic bodies out as far out as you can in the mounting clips, as long as they are still securely held.  The mic bodies then extend beyond the length of the bar with the capsules at the outermost limit.

And, being omnis, they don't need to be pointed at the stage/stacks.......won't I lose some top end? Or probably not enough to matter?

I'll be doing this a lot this summer. Might be time to invest in another stand. Or a really wide bar:)
This is the Manfrotto we own. At $80.99 it looks to be $20 less than when I bought it: (for the Nak's you'll need something like this, for lighter weight mics, you can always do a telescoping bar like Gutbucket uses.)
http://www.fullcompass.com/prod/165942-Manfrotto-154B
http://www.bhphotovideo.com/c/product/503258-REG/Manfrotto_154B_154_Triple_Microphone_Holder.html
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 22, 2016, 11:06:18 AM
Probably not enough to matter, especially in combination with whatever you are also running in the center.  Mixed with the center mic(s) it may actually be a slight advantage to have them pointed away from each other (bit more level difference, opening up the center for the other mics), and not at the stacks, but again, it's probably not significant enough to matter much or worry about.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on April 22, 2016, 09:06:28 PM

What kind of angle are you guys using in x/y? I am wondering when further back would it be beneficial or matter to close up the angle below 90* to get a more narrow field and let the omnis do their thing? Obviously 60-90* may not yield a useful recording on its own and the center card can be used, just curious how narrow and wide x/y fits into the pair.

I'm just trying to wrap my head around the possibilities here. With summer coming up and plenty of music, I really look forward to playing around with these 3 and 4 mic setups.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on April 22, 2016, 09:10:56 PM
^^ That will be another good comparison for you.

Listened to on their own, I usually prefer near-spaced stereo configurations like DIN/PAS over X/Y.  But in combination with the omnis, I prefer X/Y in the center over a near-spaced config.  In addition X/Y is Mid/Side tweakable without weirdness, so the center of the image can be dialed in optimally if you care to make the effort to adjust that.  Near-spaced configs are Mid/Side tweakable too (any stereo recording is) but the bit of time/phase difference which makes them sound better in isolation can do some weird things if you shift the M/S ratio by more than a little.

By M/S tweakable, you are just referring to how much of the image is brought up into the mix?
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on April 22, 2016, 09:57:40 PM

What kind of angle are you guys using in x/y? I am wondering when further back would it be beneficial or matter to close up the angle below 90* to get a more narrow field and let the omnis do their thing? Obviously 60-90* may not yield a useful recording on its own and the center card can be used, just curious how narrow and wide x/y fits into the pair.

I'm just trying to wrap my head around the possibilities here. With summer coming up and plenty of music, I really look forward to playing around with these 3 and 4 mic setups.
I defer to Gutbucket here, but I'd say the closer to the source 110, farther away 90. anything less than 90 isn't worth it. IF you are super close to the stacks, you can try 110 NORTF (spaced 17 cm) or stay with X-Y 110.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 25, 2016, 12:53:22 PM
^^ That will be another good comparison for you.

Listened to on their own, I usually prefer near-spaced stereo configurations like DIN/PAS over X/Y.  But in combination with the omnis, I prefer X/Y in the center over a near-spaced config.  In addition X/Y is Mid/Side tweakable without weirdness, so the center of the image can be dialed in optimally if you care to make the effort to adjust that.  Near-spaced configs are Mid/Side tweakable too (any stereo recording is) but the bit of time/phase difference which makes them sound better in isolation can do some weird things if you shift the M/S ratio by more than a little.

By M/S tweakable, you are just referring to how much of the image is brought up into the mix?

I'm referring to re-adjusting the Mid/Side ratio of the stereo X/Y recording. 

When recording using an X/Y microphone setup, one doesn't need to do any conversion to listen to Left/Right stereo directly.  Most recordists simply use that direct output and call it a day. Essentially the ratio Mid to Side in the the resulting stereo recording is determined by the X/Y angle between the mics.

When recording using a Mid/Side microphone setup, you need to convert the Mid/Side stereo info to Left/Right stereo info at some point, and the ratio of Mid to Side can be adjusted to preference when doing that.  One can use equal amounts of Mid and Side, more Mid than Side, more Side than Mid.. whichever sounds and works best.  Using all Mid and no Side produces a monophonic output with no stereo width information.

Now here's the thing- once recorded, X/Y and Mid/Side are interchangeable.  You can re-adjust the ratio of Mid to Side in an X/Y recording in the same way that you do with a Mid/Side recording.  Essentially, that allows you to re-adjust the "virtual angle" between the two X/Y microphones after the recording has been made.  To do that you convert the X/Y recording to Mid/Side, make whatever Mid/Side manipulations you want - in this case changing the amount of Mid verses the amount of Side* - then convert back to Left/Right stereo again.

Just like converting Mid/Side to Left/Right, that can be done via routing on a mixer (hardware or software) but is easiest using a simple Mid/Side plugin, most of which are free.  Some Mid/Side plugins include the option to use two Mid/Side conversions in series, with adjustment of the ratio between the two.  That way the input can be L/R stereo, a change can be made to the Mid/Side ratio, and the output is L/R again with the ratio adjusted.  The Voxengo MSED plugin has the option to work that way and is a free download- http://www.voxengo.com/product/msed/ (Disclaimer- I've no association with Voxengo, but I do use this and some of their other plugins and like them)


*In addition to making simple Mid/Side ratio adjustments, you can also make other manipulations before converting back to Left/Right stereo.  By EQing the mid and side differently you can manipulate both stereo width by frequency and the tone of the center of the stereo image verses the outer edges of the stereo image.  By altering the dynamics of one verses the other, you can manipulate the stereo width by level and the dynamics of the center of the stereo image verses the outer edges of the stereo image.  That kind of more advanced Mid/Side manipulation is a common mastering technique.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 25, 2016, 01:43:53 PM

What kind of angle are you guys using in x/y? I am wondering when further back would it be beneficial or matter to close up the angle below 90* to get a more narrow field and let the omnis do their thing? Obviously 60-90* may not yield a useful recording on its own and the center card can be used, just curious how narrow and wide x/y fits into the pair.

I'm just trying to wrap my head around the possibilities here. With summer coming up and plenty of music, I really look forward to playing around with these 3 and 4 mic setups.
I defer to Gutbucket here, but I'd say the closer to the source 110, farther away 90. anything less than 90 isn't worth it. IF you are super close to the stacks, you can try 110 NORTF (spaced 17 cm) or stay with X-Y 110.

Ordinarily I'd not choose to run cardioids X/Y by themselves for an AUD recording.  Instead, I'd run a near-spaced cardioid configuration. 

If I were to run X/Y on it's own, I prefer supercards, hypercards, or 8's, but if running X/Y cardioids by themselves I'd probably use a rather wide angle like 120 degrees between microphones to achieve a more satisfactory stereo image.  If I didn't want the mics angled that wide, I'd space them apart more, but then that would no longer be X/Y.

In this situation however, the X/Y isn't intended to be used by itself, but intended to work as a team along with the wide omnis.  Combined with the omnis, we don't need to try and achieve sufficient stereo width from the X/Y pair alone.  I actually want the X/Y cards to be more monoish and forward/center focused and less angle between microphones is appropriate.  How much less?  Instead of choosing an X/Y angle which best optimizes stereo image and width, I'd choose an angle that best optimizes forward focus and collection of direct arriving sound with optimum clarity- I'd point them directly at the stacks- PAS.

X/Y PAS is probably going to call for a rather minimal angle between mics, usually significantly less than 90 degrees.  In isolation, the X/Y recording will sound center heavy and not have much stereo spread.  But it is probably going to work best in combination with the omnis- providing good clear forward focus with just enough stereo width to smoothly fill the center of the stereo image between the omnis.  A bit of stereo width helps keep everything that is being contributed by the X/Y pair from being simply clumped together dead center like a single forward-facing center mic would do, but it doesn’t need to spread fully out to the sides like it would without help from the omnis.

Aside- This is why 4 channel AUD mic setups which combine two stereo configurations that are each designed to work optimally on their own, will often produce less than optimal results.  Each pair needs to contribute something different from the other so they don’t conflict with each other.   Optimally configured for use in combination with each other, the X/Y or M/S pair in the center needs be significantly narrower than if it was to be used by itself, and the omnis should be a bit wider than one would want for them if used on their own.  That's the logical extension of the idea to optimize the combination of the two pairs.  So strive for that if possible, but no big deal if not- like if you can't space that far).

I think I mentioned previously that I've been playing around with a Mid/Side pair in the center between omnis.  When listened to by itself in isolation, that M/S pair sounds best with plenty of Side in used in the Mid/Side to Left/Right conversion.  Let's say it sounds best with a 50%/50% Mid/Side ratio or even more Side than Mid.  When used in combination with the omnis, I’ll first determe a good level balance between the omnis and the Mid microphone (using 100% Mid and no Side).  That’s exactly the same as if recording using just three mics- the two omnis plus the center Mid mic.  Then, with both the omnis and center all playing back, I'll begin to play around with the Mid/Side ratio of the center pair, adjusting the ratio it until I find the smoothest imaging across the playback soundstage, where the center is still clear and direct, but evenly blends into Left and Right with more distinct image placement just off center and half-left/half-right.  That may be a Mid/Side ratio closer to a ~90%/~10%.  Mostly Mid, with just a touch of side. 

So a narrow X/Y angle is equivalent to using more Mid and less Side.  Point At Stacks X/Y with a narrow angle is going to be Mid heavy with little Side information to begin with, and will focus on other qualities which are desirable in the center (the clarity of direct sound from the stage and PA), while still getting sufficient Side information to provide a bit of width and work well in combination with the omni pair.  The Mid/Side ratio can be always be adjusted further either way as needed, but PAS X/Y already gets us closer to the ideal, and may be close enough for those who don’t want to go to the trouble to adjust it.

If you are tweaking the Mid/side ratio of the X/Y pair, I suggest setting the ratio to 100% Mid while finding your initial balance adjustments between the omnis and center.  Once you have a balance you like, then play with the Mid/Side balance of the center pair by bringing in more Side.  You may want to go back and forth a bit to find the best balance between the center level and center Mid/Side ratio.

This kind of flexibility after recording is partly what makes these techniques so useful. 
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on April 25, 2016, 02:09:59 PM
^^^^^^
glad I said to defer to you! So, to be more specific about the X-Y angle while running the Omni XY four mics: even if the PAS is a 45 degree angle, go for it? Secondly, what if you are on the lawn of an amphitheater with only the outside repeaters, aim at them or just do a narrow 45-60 degree XY for the middle?
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 25, 2016, 03:53:20 PM
Yep, I'd have no problem at all with a 45 degree X/Y angle if the plan was to mix that with the wide omni pair, and in fact I'd probably find such a narrow angle preferable, for more reasons than "being closer to what we want without having to re-adjust things later" as described above.  I'll try and explain-

When changing the X/Y angle (either physically during setup, or virtually by adjusting the M?S ratio) we're also changing the combined pickup pattern of the pair. I mentioned above how re-adjusting the mid/side ratio changes the "virtual angle" between the X/Y microphones.  Well, unless you are using figure 8 mics in X/Y (or using the Mid/Side equivalent to that with a figure-8 Mid), that re-adjustment also changes the virtual polar patterns simultaneously along with the virtual microphone angle.  Virtual angle and virtual pattern are linked.

The combined pickup pattern of the pair is the Mid signal.  You can derive Mid from X/Y easily.  Simply sum the Left and Right channels together.  You then have all Mid and no Side.  If you sum a 90 degree X/Y pair of cardioids together you don't end up with a single forward facing cardioid, you end up with a single forward facing sub-cardioid.  Think about it this way- if you sum two coincidentally arranged cardioids which have a 180 degree angle between them, each facing the opposite direction, you produce a virtual omnidirectional pickup pattern (which is how microphones with electrically switchable patterns produce their omni pattern output).  If you sum two coincident cardioids which have no angle between them and are both facing the same direction, you produce a cardioid pattern with twice the sensitivity of either mic alone, but the same cardioid shape sensitivity pattern.  For angles in between zero and 180 degrees, the combined pickup pattern morphs through the sub-cardioid shaped patterns which lie between cardioid and omni.

If one goal is to maximize pickup of direct stage and PA sound and minimize pickup of reverberance and environmental audience noise in the center microphone pair, then we probably want a rather directional forward facing mic in the center. But a wide X/Y angle makes for a rather wide virtual Mid pickup pattern, the most directional it is able get (using no Side at all) is only as tight as the two mic patterns summed together.  So by using less angle between the X/Y pair, we immediately tighten up the Mid pattern if we do nothing else, and we gain a range of adjustment which includes a greater exclusion of room and audience sound at the combined (Mid) end of the available adjustment range if we want to tweak things.

Using supercards for the X/Y pair (or as the Mid microphone) is another way to tighten up the Mid sum.  That works the same way, but then the range of pattern is between something closer to a single forward facing cardioid (100% Mid) and a single sideways facing 8 (100% side).  Rocksuitcase- your use of a shotgun Mid pushes that to it's logical extreme.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 25, 2016, 04:38:05 PM
Secondly, what if you are on the lawn of an amphitheater with only the outside repeaters, aim at them or just do a narrow 45-60 degree XY for the middle?

Hmm, hard to say.  Let's see..

I'd probably treat it like an off-center situation, trying best I could to ignore what my eyes are telling me and point the array as if I were blind, using only my directional hearing sense.  I'd rotate the primary axis of the entire array (that is both the omnis and center pair together, the primary axis being perpendicular to the line between omnis) to face directly towards the apparent acoustic center determined by listening, even if it looked like it was pointing off at some weird angle.  I'd then try and determine which direction(s) the clearest direct sound was coming from.  If the whole array ends up pointing at a repeater stack, and that repeater stack is the closest source of clean, direct sound, then I'd use a pretty narrow X/Y.   

If I were positioned midway between repeater stacks, and the apparent center was in the center between them, I'd point the entire array at that apparent acoustic center, and angle the X/Y pair wider so that they faced the repeater stacks more or less directly.  The two X/Y mics will focus on as much direct sound as possible individually, and if their included angle is very wide, their sum will form something like a very wide cardioid shape.. which is appropriate in that case, as the most direct sound is arriving from off to either side, producing a phantom image center somewhere closer to the middle.   If using supercards, you can still angle them upwards towards the repeaters to help limit pickup of audience noise even if the horizontal angle between them is rather wide.

Basically- Point the array at the apparent acoustic center and angle the directional center pair to point at the close sources of clear direct sound.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on April 25, 2016, 07:23:50 PM

Thanks Gutbucket.  I had a 'feeling' of what I wanted to do but was not quite sure why exactly I wanted to do it, if that makes any sense.  I've never run X/Y before but, it makes sense from the location I will be in with a smaller angle.  However, with my limited recording experience and knowledge it is just guess work.  The explanation really clears things up.

As far as treating X/Y like M/S, that is totally new to me and need to research this more. I want the end result to be well blended, as it will be when I am there, so tuning the X/Y pair with omnis seems like the way to go for me.  It seems like a lot post work but I would think the end result would be worth it.  I really like the flexibility of this option a lot more over just the omni-card-omni setup. 
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on April 26, 2016, 09:15:53 AM
Glad to help.

Try both in similar situations but different times to begin to determine if it's worth it to you to use the X/Y pair in the center instead of a single cardioid, along with the associated extra options that makes possible.  Keep in mind that you don't have to make any mid/side adjustment to the X/Y pair, especially if the angle is rather narrow.  In that case you're only balancing the levels of each pair individually first, then finding the appropriate mix level of the two pairs, which is pretty much the same as balancing the levels of the omni pair and then finding the appropriate mix level of the omnis and the single cardioid.  But sometimes having extra options can be as much a curse as a blessing and simpler can work out best.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on July 29, 2016, 01:30:58 AM

I would like to say thanks for all the input in this thread. I decided I am going to run 853s and X-Xs on outriggers tomorrow and see how it sounds, maybe switch to x/y on the next night. I feel on the lawn a 4033 clamped off the stand with a small footprint to dig into the turf a bit is too unstable. So I came up with a similar result as above with 853 cards or hypers on 8438's front and back with another perpendicular Tbar and funky mounted telescopic outriggers (1.4m). I kinda looked at what I had and went with it. I played around with it and the X-X/card option seems pretty bassy and dark so perhaps I will try hypers and see how that goes in the first set at least.

What I was really surprised about was the control of space with the mix. The front hyper was mono of course, dialing in the back gave an 'expanded mono' since that mic was picking up room reverberation, both being enter mixed. Bringing in the split omnis was really nice, I was home 'PA' testing but the thickening on the four channels was nice to hear.  Not the PAS/DIN/NOS/AB I am used to, crowd sound will be icing on that for sure.

I was also surprised to see moving the stand around the room and panning how insanely directional the rig is. With the center card of course it is, but I am not used to that, so some thinking will be involved on the best rough angle before swinging that spread around to stage or stacks or somewhere in between.  I didn't really understand what the whole 'using your ears' concept until I panned the rig and heard  how radical the changes were. I've tweaked spacing or moved a little but never had the whole sound scape change, it makes sense though... 4 mics, a lot of different sound coming in.  It does seems like a fun rig. I figure there are going to be some good mics out there so I might as well have some fun and do something different and learn some things. I can always download a good pull or recreate a surround sound experience to relive the day if nothing else.

Thanks again, I've been re-reading this thread for awhile and hitting the archived ones to figure this situation all out. I'll let you all know how it went.

Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on July 29, 2016, 08:58:49 AM
Limit35- We just finished 3 Phish and 3 days of Greyfox Bluegrass running split omnis (AKG ck22's) with a combo of inside mics (ck61 card, ck8 short shot, c414 fig 8, c414 cards- 414's in MS.)
It is fun AND the listening experience is different. instead of "in your face" directional sounds like ck61 cards PAS, it is much more spacious with a wider soundstage and to my ears more "realistic" in many ways.
Now, mixing the sets can be a challenge and oddly enough I've already found from mixing Greyfox sets that even with the same mic setups, I've put different amounts of Omnis vs center forward vs center rear. with some mixes, I've eliminated the rear channel all together, and with others, I've left it in without any reduction of level.
Like you said, experiment with the center channels if you can and you will have  a bunch of different sounds to mix together.
Have fun!    :headphones:
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on July 29, 2016, 10:28:04 AM
I'm so glad you guys are having fun and getting good results with these techniques.  I've been posting about this stuff for years and although others seemed interested in the threads I was starting to think nobody was interested in actually giving this stuff a try.

What I was really surprised about was the control of space with the mix. The front hyper was mono of course, dialing in the back gave an 'expanded mono' since that mic was picking up room reverberation, both being enter mixed. Bringing in the split omnis was really nice, I was home 'PA' testing but the thickening on the four channels was nice to hear.  Not the PAS/DIN/NOS/AB I am used to, crowd sound will be icing on that for sure.

It is fun AND the listening experience is different. instead of "in your face" directional sounds like ck61 cards PAS, it is much more spacious with a wider soundstage and to my ears more "realistic" in many ways.

Quote
Now, mixing the sets can be a challenge and oddly enough I've already found from mixing Greyfox sets that even with the same mic setups, I've put different amounts of Omnis vs center forward vs center rear. with some mixes, I've eliminated the rear channel all together, and with others, I've left it in without any reduction of level.
Like you said, experiment with the center channels if you can and you will have  a bunch of different sounds to mix together.
Have fun!    :headphones:

For me, this is what makes this kind of approach so powerful- we gain a huge amount of creative control over the final results, and can choose how we want things to sound.  We can focus on different aspect as we see fit and then dial it just right to make the best of them- More dry and direct or more open and spacious? More solid center or more stereo width?  More enthusiastic audience reaction from all around enveloping the listener or less ambience and a more upfront forward focused presentation?    What ends up being the best subjective choice for one set may be very different from what we end up with for another set.   

Although this stuff can be more complicated than just running two mics in a standard mic config, it actually makes producing a really good recording less reliant on making a good and often simply 'lucky' educated guess at setup time, and we are no longer simply stuck with what we happen to get.

Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on July 29, 2016, 10:37:38 AM
Lee,
I owe this thread a longer explanation with some mixes to audition. kindms and I will be finishing the mixes soon and figure out the best trackers or LMA to post them in.
Also, as I mentioned, I would love to offer you the unedited files for a set or two that you may be musically interested in - i.e. you choose the sets/artists. we can put these on kindms ftp site for you to access if he agrees.

Finally, for those who wonder- a photo of the largest set up we did at Greyfox:
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on July 29, 2016, 11:41:06 AM
^ Impressive!

Thanks Kyle, I'll take you up on that, I'd love to play around with some of the raw files.  For me that's where the rubber meets the road and where all this comes together. At a gross level it's where I can determine if whether the hypothesized ideas work the way I expect of if something perhaps unexpected happens- and either way that's a positive learning experience.  On a finer-grained level I find I learn a lot about the nuances of the real world relationships and how they influence what I end up with as a best final choice.

And big thanks to you guys for posting these examples!  That's the main area where I've been lacking with all this.  I can't reasonably expect many to try this stuff without samples to listen to in order to decide if the effort is worth it.



Random comment on something I've found interesting recently, stereo mix-wise for these spaced omnis plus front/back pair recordings:

One thing I've been messing around with over the last couple weekends, while away from home playing files recorded using these methods directly from the DR-680 using it's built-in monitor mixer to dial in a stereo mix for headphone listening, is trying switching on the Tascam's M/S monitor mix decoder for the front/back facing mic pair.  That may seem odd, since the recording was not made using a M/S mic setup, but it's actually worked nicely.   

Obviously if recorded using a center M/S pair, you'd want to use a M/S decoder for that center channel pair to turn it into L/R in the resulting mix, tweaking the M/S ratio to taste.  A ratio of all mid and no side would be identical to a three mic recording with just the center mid mic between omnis and and no side mic.  As you change the M/S ratio more side mic gets added until it's eventually all side and no mid between the omnis.  Okay, that's standard M/S stuff.

But I'm talking about using the M/S decoder after recording using a front/back mic pair.  Normally when bringing up the level of the front facing center mic and mixing in some of the back facing center mic, both are panned to the center of the playback image.  We get the 'expanded mono' you mentioned above, limit35.  We gain depth and spaciousness in one sense, but in another sense all the stereo information comes from the omnis.  When using the M/S decoder, the rear facing center mic is no longer "panned center", but is mixed in with reversed polarity on one side.  That allows for dialing in a sort of different type of "stereoness" which can be played against the wide omni "stereoness".  It unlocks the "stuff coming from behind" from the center - the reverberant stuff, the audience stuff from back there - and spreads it more diffusely in the playback image.  Using 100% Mid is the same as not using the M/S decoder and not bringing up any of the rear-facing mic.  Changing the ratio to 100% side makes for super-over-wide stereo with none of the rear-facing mic filling the center, very ambient and diffuse, with the only remaining mid information being whatever is provided by the sum of the omnis.

Like usual when finding the most appropriate mix, I'll bring up the omnis first and balance that on its own. Then I'll bring up the center using a 100% mid ratio, and find a good balance for that with the omnis.  I'll then play around with the M/S ratio, listening for what it sounds like dialing in 100% side, and eventually settling on a good M/S balance which works best in combination.  It's interesting comparing this against mixing the center pair in directly, both panned to the center.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on July 29, 2016, 12:09:34 PM
I played around with it and the X-X/card option seems pretty bassy and dark so perhaps I will try hypers and see how that goes in the first set at least.

Keep in mind that you can break free of needing to have the tonal response and spatial responses inseparably linked.  This stuff is at it's most powerful when one fine-tunes the spatial response by way of the choice of mic setup, and fine-tunes the tonal response afterwards using EQ.

Nothing wrong with choosing mic setup which gets closer to the tonal response you want.  That's the way most tapers work in choosing both the mics and the mic setup they prefer.  It's certainly simpler.  But if one is not averse to using EQ afterwards to get the tonal balance right, one can more or less 'forget about tone' when choosing mics, mic pattern and mic setup, and focus instead on what cannot be as easily adjusted later- the resulting spatial aspects of the mic patterns and their relationships determined by the mic setup.

There is no hard line here though.  By recording this way we do gain significant spatial control after the fact where we previously had very little, just as we've been talking about.  And obviously we can change tonal aspects at the front end by selecting different mics, mic pickup patterns, and mic configs, just as most tapers do.

It's simply the greater freedom achievable by un-linking these tone and spatial aspects which I'm arguing for here.  Approaching it that way isn't necessary, and it is more complicated, but it's also more powerful.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on August 01, 2016, 03:10:49 PM
I am a convert on this mic setup and it's going to be my go to method when the conditions allow. It really captured what I expected, not all all like a near spaced pair, big full sound.  The audience reaction is well captured and accurately represented. 

Quote
One thing I've been messing around with over the last couple weekends, while away from home playing files recorded using these methods directly from the DR-680 using it's built-in monitor mixer to dial in a stereo mix for headphone listening, is trying switching on the Tascam's M/S monitor mix decoder for the front/back facing mic pair.  That may seem odd, since the recording was not made using a M/S mic setup, but it's actually worked nicely. 

That is funny, I was playing around with this at the hotel room after the show. Doing this adds some really nice openness to the recording. For the Wheatland Dead & Co show I recorded this adds a little and opens it up, I noticed it really isn't needed though, good location. The following night at Shoreline I found this really helped out the recording, poor location. The latter sounded a bit flat, playing with the M/S decoder opens up the recording a bit more. I think the change was more noticeable on headphones than it is on speakers now that I listen to it at home.

That is surely a tool I am going to be using more because adding that little amount of "air" to the recording sounds really nice.

edit: spelling
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on August 01, 2016, 03:50:12 PM
^^^^^^ To Limit35's point:
I am not 100% sure of kindm's thoughts, but I do feel each of us, myself for sure, is committed to using this spread omni plus 1 or 2 as the go-to set up when conditions permit as well.
We may not be certain of exactly which mics to run etc, but the overall concept has been proven to me over several different types of music, indoor and outdoor venues, and on playback in different situations as well.

To my ears, the "accuracy" or "realism" is so much more present with these recordings as compared to even the very best of coincident, 2 channel recordings. The fact I even say this is monumental as I am the guy for over 30 years that used to tell people, we only have two ears, we don't need more than two microphones to record from the audience. Thanks GB, and I am working my way through Greyfox almost finished with the raw mixdowns to 2 channels and will get them posted, even if it is just private server or soundcloud for you guys. then I will offer up the raw files for the sets you might like to hear/play with.

Another snap from Greyfox: (THU 7-14)(AKGck22 spread 36 cm with AKG c414 XLS/ST Cardiod forward 0', AKG c414 XLS/ST Cardiod rear facing 180'

Title: Re: Card+Omnis from the lawn
Post by: Limit35 on August 01, 2016, 04:51:18 PM
^^^^^^ To Limit35's point:
I am not 100% sure of kindm's thoughts, but I do feel each of us, myself for sure, is committed to using this spread omni plus 1 or 2 as the go-to set up when conditions permit as well.
We may not be certain of exactly which mics to run etc, but the overall concept has been proven to me over several different types of music, indoor and outdoor venues, and on playback in different situations as well.

To my ears, the "accuracy" or "realism" is so much more present with these recordings as compared to even the very best of coincident, 2 channel recordings. The fact I even say this is monumental as I am the guy for over 30 years that used to tell people, we only have two ears, we don't need more than two microphones to record from the audience. Thanks GB, and I am working my way through Greyfox almost finished with the raw mixdowns to 2 channels and will get them posted, even if it is just private server or soundcloud for you guys. then I will offer up the raw files for the sets you might like to hear/play with.

Another snap from Greyfox: (THU 7-14)(AKGck22 spread 36 cm with AKG c414 XLS/ST Cardiod forward 0', AKG c414 XLS/ST Cardiod rear facing 180'

I couldn't agree more. What I found with the X-Xs is they seemed to want to be at around 1.3m and out 180 degrees to open things up a bit, I was really happy with their performance. The front 853 hyper added to that pulled in what we were hearing well. There wasn't much stereo information coming from the PA, the "stereoness" or openess was environmental. When taking off and on the monitor headphones there was very little sonic difference, the sound was being accurately represented. The rear hyper  picked up some PA and nice audience color from behind. It was really nice.

I can buy a soundboard and listen to the band but I don't think I could have captured the amphitheater experience better any other way.

I may switch to a card front and rear hyper and see how that works for Moonalice later in the week.
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on August 01, 2016, 05:49:25 PM
Limit35
We have used Hypers facing forward (Beyer M201, and the 414 in Hyper just once). Not done it facing rearward. Of course, it's the old math theory trick. If two cards pointed 0 and 180 respectively are basically an Omni, what would two Hypers facing 0 and 180 act like? a figure 8 with a mini bulb in the middle of the pattern where they meet at the rear of each cap? I'm not 100% certain here.

The onetime we did the 414 Hyper facing forward we used ck61 card facing 180. I don't recall if we liked it or not in that config.
Also, don't forget with a Hyper, the rear lobe will pick up a bit of rear audience or house more than the cardiod.

We have run an MS pair with fig 8 at 0 and fig 8 at 90 (true Blumlein) as the inside pair. that is interesting and even without mixing it to MS, I did use the center channel fig 8 facing at 0 mixed in with the ck22's only those three tracks for one of the Phish shows.

I do agree, we can always buy one of the Soundboard recording if we need to hear what the SBD had, but all our recordings with the spread Omni, plus 1 facing forward and 1 facing rear (cards typically) have some realism and accuracy of ambiance you rarely find with coincident recordings.
Title: Re: Card+Omnis from the lawn
Post by: HealthCov Chris on September 01, 2016, 12:10:10 PM
I'm jumping into this thread since I've already had some similar discussions with some of you about this recently.  I am committed to running spaced omni's when possible too.  So I have a few questions for advice as I have already inquired about some center channel mic options (shotgun, hypercard, ext). 

Here are my current gear options:  AKG 460 (ck61); Studio Projects C4 (cards, omni's); CA-14 cards
Purchase considerations: CA-14 omni's (very likely); Shotgun mic

I recently ran my C4's with omni caps split ~ 3ft with my AKG's in the middle at PAS.  EX)   https://archive.org/details/DP2016-06-30.highberry_24bit

However, after reading this I should consider running AKG's in X/Y.  My dilemma is that I really like the sound of my AKG's as a separate pair in PAS or DIN or NOS.  So, I want to run them that way as a separate recording in case it rocks or the omni rig does not turn out well!  That currently leaves me with the C4's and CA-14 cards.  So, should I split the C4 omni's and run the CA-14 cards in the middle in X/Y?  How even do I set CA-14 cards into X/Y?  What if I pointed 1 CA-14 forward and the other backward?

Next, assuming I purchase CA-14 omni's, I can run them split wide with a retractable TV antenna and have my C4's in the middle as X/Y.  This will allow me to also have my AKG's as a standalone pair.  Thoughts?  Do you think I can expect similar results from the CA-14 omni's as the C4 omni's?
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on September 01, 2016, 12:23:30 PM
I'm jumping into this thread since I've already had some similar discussions with some of you about this recently.  I am committed to running spaced omni's when possible too.  So I have a few questions for advice as I have already inquired about some center channel mic options (shotgun, hypercard, ext). 

Here are my current gear options:  AKG 460 (ck61); Studio Projects C4 (cards, omni's); CA-14 cards
Purchase considerations: CA-14 omni's (very likely); Shotgun mic

I recently ran my C4's with omni caps split ~ 3ft with my AKG's in the middle at PAS.  EX)   https://archive.org/details/DP2016-06-30.highberry_24bit

However, after reading this I should consider running AKG's in X/Y.  My dilemma is that I really like the sound of my AKG's as a separate pair in PAS or DIN or NOS.  So, I want to run them that way as a separate recording in case it rocks or the omni rig does not turn out well!  That currently leaves me with the C4's and CA-14 cards.  So, should I split the C4 omni's and run the CA-14 cards in the middle in X/Y?  How even do I set CA-14 cards into X/Y?  What if I pointed 1 CA-14 forward and the other backward?

Next, assuming I purchase CA-14 omni's, I can run them split wide with a retractable TV antenna and have my C4's in the middle as X/Y.  This will allow me to also have my AKG's as a standalone pair.  Thoughts?  Do you think I can expect similar results from the CA-14 omni's as the C4 omni's?
Chris, I can only speak to the AKG part of your question since I have no experience with using the SP's or CA's.
I hear you re a backup config. for many shows, kindms and I would run our ck61 actives in DIN or DINA in the middle of our split omni experiments (Omni's were AKG c414's split 3 feet, with middle a 460/ck8 or 460/ck1) in order to have a "safety copy" in case things went awry with the rest. Since we now have the ck22's mated to our 460's we have run a middle channel coincident 90 degree figure 8 with the 414's as well as the ck8 or ck61 facing forward (3 channels) OR the ck8/ck61 forward (0') and a ck61 rear (180') [4 channels].

The only other thing I can add is: we use what we own, but the 414's are a bit large or heavy as the split omnis, and if you have a choice, I'd go with gutbuckets concept of light weight mics on an antennae as you mentioned.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 01, 2016, 03:07:45 PM
My dilemma is that I really like the sound of my AKG's as a separate pair in PAS or DIN or NOS.  So, I want to run them that way as a separate recording in case it rocks or the omni rig does not turn out well!

[my bolding above]

This is important!  In more ways than one.  In addition to providing a 'safe recording' in case the new technique doesn't work out as hoped (which to my way of thinking is what minimizes the risk inherent in trying out new configurations), it also provides a key 'known good' standard stereo reference to which the results from the new technique can be compared carefully and critically.  The ability to compare the two resulting recordings made at the same time, from the same location on the same mic stand, by the same taper who is aware of all the setup details, is critical for making well informed decisions about what truly is better and what isn't in an honest and objective overall sense.  It also allows one to get an far more accurate handle on all the subtle qualities which collectively make one sound better than the other, which helps greatly in considering what adjustments or changes to the new technique may be appropriate moving forward.

For me, the limits on doing that are: How many channels I can record, and how complicated I care to get with additional mics, rigging, and wiring.  I'm always using whatever gear I have at the start, until I determine I actually need something else, or have tied and refined the technique to the point where I'm happy with it and don't feel as much need to play around with it so extensively, at which point I move on to fine tuning things to optimize practicality. 

This gets back to a tension between two essentially different approaches in experimenting with multiple mic stereo audience recording-  Either starting from a favorite 2-channel stereo setup and adding additional mics to that in an attempt to make it better, verses starting with a whole new approach and a clean slate.  The former is safer, while the later is potentially more fruitful.. yet if you have enough channels and don't mind the complication, you can do both!

More on this later.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 01, 2016, 04:51:04 PM
Of course, it's the old math theory trick. If two cards pointed 0 and 180 respectively are basically an Omni, what would two Hypers facing 0 and 180 act like? a figure 8 with a mini bulb in the middle of the pattern where they meet at the rear of each cap? I'm not 100% certain here.
 
Two back to back coincident cardioids sum electronically at an equal ratio produce an omni.  Two back to back coincident hypercardioids summed electronically at an equal ratio produce..... an omni! (with lower sensitivity). 

Lets walk through it- Think of the pickup pattern of a microphone as mathematical combination of an omni component and a bidirectional (figure-8) component mixed together at a particular ratio.  That ratio determines the pickup pattern.  An omnidirectional microphone is 100% omni component and 0% bidirectional component. A cardioid is equal amounts omni and bidirectional.  The hyper is less omni and more bidirectional.  A figure-8 is all bidirectional and no omni.  Good so far?

A bidirectional mic has a specific orientation polarity. It's front side produces a positive polarity signal and back side a negative polarity signal.  An omni has no specific orientation polarity.  Summing any two opposite facing coincident mics, the omni components double, and the bidirectional components cancel out (positive lobe + negative lobe | negative lobe + positive lobe).  If the mics were to face the same direction, the omni components would still double, and the bidirectional components would double as well (positive + positive | negative + negative). 

So with two summed back to back cardioids, the bidirectional components cancel, and the omni components double.  Given the 50/50 ratio of omni/bidirectional components in a cardioid, we're left with a doubling of the two 50% omni components, yielding 100%, or equal sensitivity to one of the single cardioids we started with.

With two summed back to back hypercardioids, the bidirectional components cancel, and the omni components double like in the previous example.  But given that a hypercardiod is made up of a higher ratio of bidirectional component to omni component, we're left with less omni component to add together, yielding less than 100% of the original sensitivity compared to that of the single hypercardioid we started with.

Summing a pair of coincident but opposite facing bi-directional mics leaves nothing, as there is no omni component provided from either microphone. If we want to combine opposite facing coincident directional mics to produce a figure-8 instead of an omni, we need to polarity invert the signal from of one of the microphones.  Then the bidirectional components double and the omni components cancel. Two summed coincident yet opposite facing directional mics produce a pseudo figure-8, and two summed coincident omnis leaves nothing.

This is how the signals from two opposed cardioid capsules inside in a multi-pattern electrically switched microphone can be combined in various ways to produce any pickup pattern from omni through cardioid through bidirectional.

That's the mathematics of it at least.  In the real world, it's never that clean and neat.  Capsules arranged so as to be as coincident as possible won't cancel entirely even if levels and responses are precisely matched, and if we introduce any significant spacing between the mics then the resulting time/phase interactions insure that none of the clean theoretical mathematical stuff above holds true anymore.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 01, 2016, 06:12:04 PM
Also, don't forget with a Hyper, the rear lobe will pick up a bit of rear audience or house more than the cardiod.

Yeah, maybe.  Although I haven't found that significant in my experience. May depend on how hyperish/ figure-8ish your hypercardioid actually is, but I think it's more about average sensitivity across the entire back, than the existence or lack of lobe.  I think what matters is having a minimum average sensitivity across the entire rear hemisphere, actually across a greater arc than just the rear hemisphere wrapping around towards the front a bit.  Of the several supercards I've used in the center facing forward, all of them have excluded more surrounding audience noise than using cardioid, despite their small rear lobe.   

Selection of the forward facing center mic for me is primarily about getting the best quality pickup of sound I can from the PA and stage, and then secondarily about the ability to minimize pickup of the surrounding audience and reverberant ambience as much as possible without overly compromising the sound pickup from the front.

Selection of an appropriate backwards facing mic is sort of the same, but with the primary and secondary goals reversed.  Most important to my way of thinking for the backwards facing mic(s) is getting as much isolation as possible from sound arriving from in front (which is going to be the loudest direction by far, often burying the audience and reflected sound arriving from behind), and only secondarily about getting a good sound from what arrives from behind.  The usefulness of a rear mic is leveraged by maximally excluding the PA/stage sound from that channel, which is a difficult task.  That's why when recording on stage and using a rear facing mic or mic pair, I prefer to hang the rear-facing (room/audience) mics below the stage-lip, so the the entire stage acts as a baffle further reducing pickup of the on-stage sound beyond the attenuation achievable by mic pattern alone.*

It's interesting to solo and listen to just the sideways facing bidirectional mic (my most recent experiments involve adding those to determine if turning the front and back facing center mics into Mid/Side pairs is useful) and comparing that to a solo'd rear facing cardioid, and to a solo'd rear facing supercardioid.  A sideways bidirectional has a far deeper null facing directly towards the stage than a rear facing cardioid, and the supercards actually have their small rear lobe facing forward.  Yet when listening to that channel alone, the bidirectional has the most PA sound in it.  I'm tempted to say the cardioid has less, and the supercardioids the least, but I'd need to double check that with more listening.  In practice a rear facing cardioid or supercard may be about the same. That's partly what confirmed in my mind that it's more about the integrated response sensitivity across the entire back side of the mic which is more important than the particular shape of it's pickup pattern.

[*edit- soloing the audience/room facing mics of my on-stage setups lead me to the same conclusions as soloing the back facing mic in these audience setups.  Minimizing pickup of the main PA/Stage sound is the most important thing for making those channels useful.  With on-stage taping, I began with my additional room/audience mic experiments by attaching omnis to the rear wall facing forward, behind the audience, then switched to using cards or supercards as part of my on stage setup facing out into the room and away from the stage (better), before hanging those same mics below the stage lip (best).  That game turned out to be all about achieving sufficient isolation in the audience/room channels from pollution by the stage and PA sound.  It was something of a mental hurdle to realize that exclusion of good direct sound as much as possible was the most appropriate goal for those channels, since conversely getting good clean direct sound is usually the most significant challenge for tapers!]
Title: Re: Card+Omnis from the lawn
Post by: Chuck on September 01, 2016, 08:50:51 PM
The way you guys are talking... I'm wondering if using my LD in figure 8 (side) and my AKG Ck-63 hyper facing forward (mid) with spaced omnis A-B might give me the most options for mix down. 4 channels total. I'm recording an amplified folk group (with drummer) outside this weekend and looking for something new to try. My last try at mid-side was disappointing, because the figure 8 pattern is so thin sounding. But, with the omnis to mix in later it would fill it out.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 02, 2016, 11:09:13 AM
I think so, especially if you want to try something new.  Give it a try let us know what you think.  If you can arrange it so your M/S pair is slightly forward of the omnis that's probably best (I shoot for something like 8" to 12"), but no worries if setup is easier having all the mics in a line.

When mixing it, bring up the omnis first and get that sounding right, then bring up the center and balance it with the omnis, then introduce some center stereo width from your LD and play with the M/S ratio until you get the most seamless image across the playback stage.  You may end up using very little Side or you may use a lot, it all depends on what the specific situation calls for and the sound you like.  The omnis and center mic are doing most of the heavy lifting here, and the Side mic helps blend those primary components seamlessly, by whatever amount is appropriate.

I consider the omnis + a forward facing center mic the basic core of this technique.  Making the center a M/S pair brings the gravy and pulls it all together.  I wouldn't suggest M/S alone without the omnis.
Title: Re: Card+Omnis from the lawn
Post by: Chuck on September 02, 2016, 11:18:48 AM
I wouldn't suggest M/S alone without the omnis.

Yeah, that's what I've discovered too.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 02, 2016, 11:52:21 AM
On making gravy..

As I just mentioned, I consider the omnis + a forward facing center mic the basic meat & potato core of this technique. 

From there the next step towards sonic deliciousness and increased flexibility is the gravy addition using any one of these things:
1) Turning the center mic into a M/S pair by adding a coincident bidirectional.
2) Substituting an X/Y pair for the single center mic.
3) Adding a rear-facing near-spaced center mic.
4) Adding near-spaced, 180-degree opposed sideways-facing supercardioids.

For most tapers I'd suggest the first two options.  They are familiar, and sort of direct extensions of what adding a center directional mic to the spaced omnis does by addressing what is most deficient in a pair of spaced omnis on their own.

Option 3) is sort of more of an extension and way to fine-tune what the omnis are bringing to the table.  It's more about the natural sense of space, ambient depth, the "you are there" stuff, rather than upfront stereo imaging, yet still helps glue the center and sides together up front, just not in a sharp stereo imaging sense.  It's a great addition to the other 3 options, yet useful on it's own without them.  Still I think I'd recommend the first two options first for most tapers. [edit- Fans of straight up spaced omnis and "you are there" imersion junkies might do this first though.  This was what I ran for quite a while before going further exploring these other options.]

Option 4) does both those things.  Like a M/S or X/Y center, this expands imaging across the center.  Difference there is sort of the near-spaced pair verses of coincident imaging thing, except this retains the center mic position which I feel is a key element, and instead of a normal 2-mic near-spaced pair it's a "3-way near-spaced pair".  I really like what this does, it's quite magical in providing a sense of up-front presence and excitement for the main, primary-focus sound.  [Edit- at the same time, it provides a more ear-perking sense of "you are there" imersion, with a true sense of direction for the audience, ambient reverberance.] For my uses, this option is more important than using an X/Y or M/S center because I'm using this to provide discrete 3-channel front stereo for surround playback, while it also works well for mixing to 2-channel stereo. Unlike the other options this requires a 5th channel since it's adding two mics instead of one, so a recorder with more than 4 channels is required.  I don't find a compelling need to do this and use an M/S or X/Y center pair, instead I'd add the rear facing mic as the 6th channel. 
Title: Re: Card+Omnis from the lawn
Post by: HealthCov Chris on September 02, 2016, 02:33:59 PM
On making gravy..

As I just mentioned, I consider the omnis + a forward facing center mic the basic meat & potato core of this technique. 

From there the next step towards sonic deliciousness and increased flexibility is the gravy addition using any one of these things:
1) Turning the center mic into a M/S pair by adding a coincident bidirectional.
2) Substituting an X/Y pair for the single center mic.
3) Adding a rear-facing near-spaced center mic.
4) Adding near-spaced, 180-degree opposed sideways-facing supercardioids.

For most tapers I'd suggest the first two options.  They are familiar, and sort of direct extensions of what adding a center directional mic to the spaced omnis does by addressing what is most deficient in a pair of spaced omnis on their own.

Option 3) is sort of more of an extension and way to fine-tune of what the omnis are bringing to the table.  It's more about the natural sense of space, ambient depth, the "you are there" stuff, rather than upfront stereo imaging, yet still helps glue the center and sides together up front, just not in a sharp stereo imaging sense.  It's a great addition to the other 3 options, yet useful on it's own without them.  Still I think I'd recommend the first two options first for most tapers.

Option 4) does both those things.  Like a M/S or X/Y center, this expands imaging across the center.  Difference there is sort of the near-spaced pair verses of coincident imaging thing, except this retains the center mic position which I feel is a key element, and instead of a normal 2-mic near-spaced pair it's a "3-way near-spaced pair".  I really like what this does, it's quite magical in providing a sense of up front presence and excitement.  For my uses, this option is more important than using an X/Y or M/S center because I'm using this to provide discrete 3-channel front stereo for surround playback, while it also works well for mixing to 2-channel stereo. Unlike the other options this requires a 5th channel since it's adding two mics instead of one, so a recorder with more than 4 channels is required.  I don't find a compelling need to do this and use an M/S or X/Y center pair, instead I'd add the rear facing mic as the 6th channel.

Perfect summery to this thread!  I just printed it. 
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on September 02, 2016, 03:56:50 PM
I thought I should update here since I have been playing with this awhile, its been my go to setup this summer.

From the options available to me I really like X/Y 90* cards with the omnis spread out 1+ meters, up to 3m at stage lip.  I found I like the sound a bit more than using a single center card. The single card didn't really add enough to justify using only one mic, maybe at stage lip perhaps but i wasn't impressed at 10m back. I'll stick to near coincident cards with an omni center for a three mic mix.

I really like the cards 0/180* with the omnis 1m+ out, really nice. The only drawback I found with this setup so far is it needs a good recording environment. I used 0/180* cards and hypers at a few chatty shows and the result was little distracting.  The sound stage was great but the chatter was being picked up by 3 mics. I find it really amazing how even a slight amount of rear mic in the mix really fills out the sound.

I still want to play with hyper/card, card/card, or hyper/hyper front and back more. My area is pretty windy so I don't get the hypers out to much but like what I heard so far.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 02, 2016, 04:26:00 PM
..From the options available to me I really like X/Y 90* cards with the omnis spread out 1+ meters, up to 3m at stage lip.  I found I like the sound a bit more than using a single center card. The single card didn't really add enough to justify using only one mic, maybe at stage lip perhaps but i wasn't impressed at 10m back. I'll stick to near coincident cards with an omni center for a three mic mix.

I really like the cards 0/180* with the omnis 1m+ out, really nice. The only drawback I found with this setup so far is it needs a good recording environment. I used 0/180* cards and hypers at a few chatty shows and the result was little distracting.  The sound stage was great but the chatter was being picked up by 3 mics. I find it really amazing how even a slight amount of rear mic in the mix really fills out the sound.

[snip..] like what I heard so far.

Thanks for the feedback and your impressions, and so glad this stuff is working out well for you!  As I see it, one may as well record a 4th channel if doing 3, so the question becomes whether to do X/Y, M/S, or the rear facing mic.  My impressions agree with yours concerning when the rear facing mic is most useful.  I'm fortunate to have some quite good sounding locations in which I use these things so I'm rather fond of that channel and don't want to give it up, plus with multi channel playback it makes for excellent surround when the omni channels are dedicated Left/Right channels without the sideways facing supercards.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 02, 2016, 04:26:57 PM
Perfect summery to this thread!  I just printed it. 


Thanks!  Just added a couple minor edits in italics to clarify the descriptions a bit, no major change though.

BTW, my current avatar photo shows what options 3 and 4 look like as realized in my rig.  The smaller windscreens to the sides are on the sideways facing supercards (4), mounted a bit less than half-way out the same telescopic antenna arms which support the omni, which are cropped from view in that photo.  The big Shure windscreens are on the front and rear facing center mics, which in my case are also supercards.

..except there is more than meets the eye in that photo.  That was taken when I was testing adding a bidirectional to the front center mic to make it a M/S pair (1), and the listening comparisons which that allowed are what informed the conclusions I'm talking about here.  A big Shure windscreen is large enough that it fit over both the supercard and the bidirectional.  So it's actually showing all these options except (2) X/Y.

.. and actually there is also a bidirectional mounted with the rear facing center mic make that a M/S pair in that photo as well.  I consider that a less important experiment and haven't even assessed the recordings using that option yet, but figured I should go ahead and try it since I had to move from 6 to 7 channels anyway to test center M/S without giving up the side-facing supercards (since they are part of my current "reference rig") so might as well record 8.  And I had the extra bidirectional on hand, so why not?  I hope to determine if a rear-facing M/S pair in combination with the omnis is useful for deriving a wide stereophonic ambience across the back for surround playback (instead of a pair of spaced rear-facing surround mics), and for adjusting width of the rear ambience for 2-channel stereo mixes.  But that's probably pushing the limit of what makes sense.  I'll probably settle on my current standard of 6 channels using options 3 and 4, maybe switching to 1 and 4 for some things, which is what I ran for Wanee a month or so after that photo was taken.  But if I were to pickup an F8, who knows.  I may never end the experimentation with variations, but I do feel I've determined where the efforts are best placed and where diminishing returns become significant.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on September 02, 2016, 05:11:22 PM
Ill have to put up a picture of my current set up. At the moment (version2), I have AT8438s mounted backwards, one with riser, on a K&M bar. Along the edge is two telescopic antennas that are zip tied to the K&M edge. The AT853s can be mounted in the backward AT mounts and run X/Y, with a little gaff tape to secure them when using screens. The inverse of this I noticed is NOS so it can be setup near coincident if needed, just did that when I was late for a bluegrass band last weekend.  The omnis are out 90* (180* as pair) spaced up to 1.5m on the telescopic outrigger. Until I replace the telescopic antenna I found on axis at 0* they can droop in the heat, I guess tape can solve that. But that isn't a concern since I am wanting the low end and ambiance from those omnis anyways.

I've also ran the same mic setup on 3 stands on stage with the great results; omnis 4m apart on separate stands with the X/Y pair in the center.

What is nice with the spaced omnis is they don't really effect the lack of low end if I choose to run hypers since I am just filling in the center space with that 0/180* or X/Y pair. That allows one to tune the X/Y part of the recording +-90*  or cards/hypers, which is great because you get freedom to setup wherever and tune the X/Y pair as narrow or wide as needed.

As also mentioned MS decoding can stand on its own with a fill in from the omnis. I don't see a plug in for Linux Audacity so I will have to learn that by hand or decode during recording. But on the DR60 playback it sounds good, yet with its own totally different sound experience. I think I want to experiment with that for small indoor acoustic ensembles at on stage/stage lip and keep straight X/Y for when on stands from distance. So far that was the only experience I had that seemed to benefit from the addition of MS decoding.

Pretty versatile setup I think. More work in post however but, it is something to do between shows.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on September 02, 2016, 05:22:53 PM

Thanks for the feedback and your impressions, and so glad this stuff is working out well for you!  As I see it, one may as well record a 4th channel if doing 3, so the question becomes whether to do X/Y, M/S, or the rear facing mic.  My impressions agree with yours concerning when the rear facing mic is most useful.  I'm fortunate to have some quite good sounding locations in which I use these things so I'm rather fond of that channel and don't want to give it up, plus with multi channel playback it makes for excellent surround when the omni channels are dedicated Left/Right channels without the sideways facing supercards.

Agree, I recorded a Moonalize show that was a free family friendly event, so a lot of chatter. I couldn't drop the rear mic in post because what it did add sonically was beneficial even with the chatter. I don't really understand why, but even at really low dBs it filled out the sound of the other three mics. You could barely hear it on its own, but if I muted that channel when all channels where mixed it was obvious it dropped out.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 02, 2016, 06:55:43 PM
Yep. You totally "get it".  Congratulations!
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 02, 2016, 07:31:07 PM
Okay you guys.  Now that you have some 4 channel recordings using these techniques in hand, if you have a home theater setup you might as well play these recordings through it to what that sounds like.   It's fun to hear, even if your HT setup is sub par. Through a quality surround system it can be amazing.. the musical teleportation time-machine.  And I think listening this way helps to further understand what's going on with all this even if your intention is just mixing to 2ch stereo. If your home theater receiver/amp has multichannel analog RCA inputs for a DVD player or whatever, you basically just plug the the discrete channel outs from the recorder in there and play the files back from the recorder.  Of course if you have multichannel output capability from your from your DAW machine, by all means plug that into the receiver and gain far more control.

Here's the basic routing to the receiver inputs, depending on the mic setup you used-

Omnis + one center mic:
Route the center mic channel to the Center speaker
Route the omnis to the Left and Right speakers
(result = three channel LCR stereo)

Omnis + X/Y:
Ignore the center speaker
Route the X/Y pair to the Left and Right speakers
Route the omnis to the Surround speakers
(result =four channel quad surround)

Omnis + front and rear facing center mics:
Route the center mic channel to the Center speaker
Route the omnis to the Left and Right speakers
Rout the rear facing center mic to the Surround speakers, using a Y-cable (or 3)
(result = four channel LCRS > 5 channel surround)

Omnis + center Mid/Side pair (option 1):
Route the Mid mic channel to the Center speaker
Route the omnis to the Left and Right speakers
Rout the Side channel to the Surround speakers, using a Y cable (or 3)  For extra credit, swap the wiring to the surround speaker(s) on the right side to invert polarity)
(result = four channel LCRS > 5 channel surround)

Omnis + center Mid/Side pair (option 2, probably not doable directly from the recorder):
Either ignore the center speaker or better, route the Mid mic channel there
Decode the Mid/Side to L/R and route that to the Left and Right speakers
Route the omnis to the Surround speakers
(result = four channel quad, or five channel LCRLsRs surround)



What I do with my 6 channel recordings:
Center mic to Center speaker
Sideways facing supercards to Left / Right speakers
Omnis to side surround speakers
Rear facing center mic to rear center surround speaker(s)


A few things-
> You'll have overall volume and probably EQ control via the receiver.  You may or may not have individual channel level control, depending on the reciever (I don't when using the 5.1ch RCA inputs).  But balancing levels channel to channel is very important for good results. You may have control over individual channel level and possibly EQ on your recorder:
      DR-680 provides no control over individual channel level balance or EQ.
      Not sure about the 4ch Tascams except the DR2d which has only stereo playback (I use an DR-680 or R-44 to playback 4ch recordings made with the DR2d)
      R-44 provides both level and EQ for each channel.
      F8 (I don't have one) provides only 4 outputs unfortunately, but I think provides level, EQ, delay, etc, by channel.
     
> I sometimes route the surround channels through another recorder (an old R-09, line-in > headphone out) which provides level control and introduces a short delay which can be useful in the surround channels.  Don't do that for the front channels or the delay messes things up.
>Using a small mixer between the output of the recorder and the input of the receiver can provide easier control of individual channel level balance and EQ.
>Way more control and flexibility if you have a multichannel output card or interface for your DAW! But this method works.
Title: Re: Card+Omnis from the lawn
Post by: Limit35 on September 03, 2016, 12:35:58 AM
Cool playback tip, thanks.
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 06, 2016, 09:18:30 AM
We'll, it's certainly not necessary, it's just something I enjoy greatly and hope others might enjoy as well.   I hesitate to suggest it here, simply because I don't want to scare anyone off who may have no interest in that stuff from trying these techniques purely for 2-channel stereo.  But besides being a lot of fun, I feel I've leaned a lot about recording and reproduction by listening that way.
Title: Re: Card+Omnis from the lawn
Post by: rocksuitcase on September 06, 2016, 09:30:16 AM
^^^^^^^^
Gutbucket, I was just telling an old friend of mine who used to tape about the mic techniques and he asked about multi channel playback. I showed him the above post and he really likes the possibilities this presents us when using the oddball mic techniques. His impression after hearing several shows recorded with the varying configurations we've been doing was that almost all of the recordings, even the ones with no rear facing mic had a "3d" presence, not just "flat stereo" (his words). (listening via 2 channel AudioEngine A2's with no subwoofer)
He was really impressed with the Phish from SPAC in that although you can tell it was made from the lawn, as opposed to 40 feet from stage, the quality of the vocals and less obtrusive audience noise made it one of the better Phish AUD's he's heard from this summer.

I wish I had a 5.1 system, I would be checking out these recordings that way for sure!
Thanks again for all the inspiration!
Title: Re: Card+Omnis from the lawn
Post by: Gutbucket on September 06, 2016, 11:00:39 AM
His impression after hearing several shows recorded with the varying configurations we've been doing was that almost all of the recordings, even the ones with no rear facing mic had a "3d" presence, not just "flat stereo" (his words). He was really impressed with the Phish from SPAC in that although you can tell it was made from the lawn, as opposed to 40 feet from stage, the quality of the vocals and less obtrusive audience noise made it one of the better Phish AUD's he's heard from this summer.
 
That's a good description of what I like to hear in general from any really good audience recording, what I was attempting to optimize by way of these techniques, and what I get more often from them when everything works out well.

Recording position is still the most important aspect we have some control over.  There is no substitute for placing the mics in the best sounding spot.   Not much we can  do to make a bad spot good, but this can help make the best of a decent recording position, making a good position better and a great one fantastic when it all works out.

Thanks again for climbing aboard this crazy train and generating enthusiasm for these techniques here at TS.