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Author Topic: Binaural Recording (latest thinking from tapers?)  (Read 6184 times)

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Offline rocksuitcase

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #60 on: April 06, 2021, 02:28:28 AM »
Found this brief but nicely differentiating basic gem regarding microphone patterns.
https://www.sweetwater.com/insync/stereo-mic-techniques/

Of particular interest to me as we've done a small amount of 90 degree crossed figure 8's was this:
Quote
4. Blumlein Stereo

In a way, Blumlein stereo (named after Alan Blumlein) is a lot like XY, only with greater stereo separation and potentially better room ambience. This setup uses two figure-8 microphones positioned so that the elements cross at right angles and as close to one another as possible. Because the figure-8 polar pattern offers complete off-axis (side) rejection, these mics pick up an almost completely isolated (coincident) stereo field.

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Offline kuba e

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #61 on: April 06, 2021, 04:17:28 AM »
I also like blumlein recordings. I once read somewhere that blumlein sounds unique because fig.8 has half the polar pattern negative. Then the blumlein records the sounds coming from the front in phase (++). The sounds from behind are in a flipped phase (--). And the sounds from the side are in opposite phase(+-). I added phases to the picture.

Unfortunately, I do not own fig. 8. But I use pair of hypercardiods and they are at least a bit similar to fig.8. They have small negative lobe. Sometimes I tried to choose a smaller angle with the coincident hypercardiods and add a side in Mid/Side in post. Then it could be even more similar to the blumlein.
« Last Edit: April 06, 2021, 04:20:56 AM by kuba e »

Offline Gutbucket

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #62 on: April 06, 2021, 12:10:38 PM »
Quote
4. Blumlein Stereo

In a way, Blumlein stereo (named after Alan Blumlein) is a lot like XY, only with greater stereo separation and potentially better room ambience. This setup uses two figure-8 microphones positioned so that the elements cross at right angles and as close to one another as possible. Because the figure-8 polar pattern offers complete off-axis (side) rejection, these mics pick up an almost completely isolated (coincident) stereo field.

Well Blumlien is X/Y, just using fig-8s, even if Alan actually arranged his fig-8s in M/S.  But that's just picking nits (The better term for of describing that entire family of arrangements is coincident , thus differentiating them from near-spaced and wide-spaced arrangements in regards to what differences matter most)

What I feel compelled to disagree with is both halves of the last statement:

Fig-8's do not provide "complete off-axis rejection", but are exactly as sensitive to sound arriving from in back as from the front.  Nor do they offer anything like "complete side" rejection. They do provide reduced pickup to the side quadrants in comparison to the primary front/back axis, however the back half of a cardioid or supercard picks up significantly less than the side of a fig-8.  Blumlein does offer good off-axis rejection directly up and down, but I don't think that's what they're referring to.

"Completely isolated (coincident) stereo field" seems especially misleading.  No first order microphone pair can achieve that and Blumlein has is equal sensitivity across all horizontal directions, making it one of the least isolated configurations second only to omnis or something like back to back cardioids.  The imaging across the front quadrant (and of the back quadrant super-imposed on the front) is very precise if that's what they mean, but that is based in a particularly evenhanded "stereo bleed" hand-off between channels (rather than isolation between them) that is in essence identical to hand-off between the stereo channels of a stereo pan-pot.  The same amount of "bleed" happens between the front and side quadrants, and between the side and back quadrants.  Its not "isolated" at all really in any sense, except directly along the exceptionally narrow null-planes, which are generally much narrower than many folks imagine them to be.

Heading outside to shake my fist at a cloud now!  ;)

I guess I should actually follow the link to see what else they have to say now that I feel better.

I really like 8's but am with kuba e on generally preferring crossed hypercardioids to Blumlein most of the time for taping, sometimes with a smaller angle (applies to Blumlien fig-8s too), and like to do some M/S tweaking afterward to really tune it in either way.
« Last Edit: April 06, 2021, 12:13:17 PM by Gutbucket »
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Offline rocksuitcase

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #63 on: April 06, 2021, 01:41:25 PM »
Quote
4. Blumlein Stereo

In a way, Blumlein stereo (named after Alan Blumlein) is a lot like XY, only with greater stereo separation and potentially better room ambience. This setup uses two figure-8 microphones positioned so that the elements cross at right angles and as close to one another as possible. Because the figure-8 polar pattern offers complete off-axis (side) rejection, these mics pick up an almost completely isolated (coincident) stereo field.

Well Blumlien is X/Y, just using fig-8s, even if Alan actually arranged his fig-8s in M/S.  But that's just picking nits (The better term for of describing that entire family of arrangements is coincident , thus differentiating them from near-spaced and wide-spaced arrangements in regards to what differences matter most)

What I feel compelled to disagree with is both halves of the last statement:

Fig-8's do not provide "complete off-axis rejection", but are exactly as sensitive to sound arriving from in back as from the front. Nor do they offer anything like "complete side" rejection. They do provide reduced pickup to the side quadrants in comparison to the primary front/back axis, however the back half of a cardioid or supercard picks up significantly less than the side of a fig-8.  Blumlein does offer good off-axis rejection directly up and down, but I don't think that's what they're referring to.
LOL, I didn't read it closely enough to"nitpick" but I see your points and raise you this: Only discussing the off-axis part:
The Sweetwater description is very, "pedestrian" or basic. To err in their favor, MAYBE they meant a PAIR of COINCIDENT figure 8's would have side rejection due to the pattern, not the individual mic. but again, they specifically say "A fig-8", sooooooooooo     score gutbucket if you're keeping score!

What I know from listening to those recordings where we used 90' coincident fig 8's with an AKG c422, or 414 XLS's or kindms' c426 the front to back ratio is easily heard and I would assume to mathematically characterize. The location where the pattern sounds the best live stage wise is less than 20 feet from stage, preferably 10-15 feet from the onstage amps, and of course, vocals which may come from a PA can get lost this way. But often the instruments sound as if you were using a DI box out of a soundboard.
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Offline Gutbucket

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #64 on: April 06, 2021, 05:43:07 PM »
I assume they mean a single 8 and are misrepresenting "off-axis" as somehow not including response from the rear.  Technically that could be construed as correct in regards to a single bi-directional microphone (hence the "bi" label), but not with regards to the sensitivity of a Blumlein pair, because if they do mean a pair there is zero rejection to sounds arriving from the sides and that's a long way from "complete"!

I think it's poor wording, confusing various aspects of a single mic with a pair, and lack of a good (any?) editor who knows better reading for content.  Unfortunately that's typical of most explanations of stereo configurations found on the interwebs.  Most of them go on to claim the 3-1 ratio applies to spaced pair stereo mic'ing.  It not only doesn't, its geometrically impossible to apply it to that situation!  As Chuck Berry says, Roll over Pythagoras and tell Tchaikovsky the news.

Thanks for playing along and apologies for flogging a dead horse with my personal pet peeve for clarity on these things!  I don't care much about keeping score, but I do relish the participation ribbon.

What I know from listening to those recordings where we used 90' coincident fig 8's with an AKG c422, or 414 XLS's or kindms' c426 the front to back ratio is easily heard and I would assume to mathematically characterize. The location where the pattern sounds the best live stage wise is less than 20 feet from stage, preferably 10-15 feet from the onstage amps, and of course, vocals which may come from a PA can get lost this way. But often the instruments sound as if you were using a DI box out of a soundboard.

I find the same with regards to recording position with Blumlien, and with respect to the rather direct sounding quality that can be achieved from instruments in the front quadrant (probably due to reduced pickup of early reflections in the same channel as a result of the relatively narrow front lobes - not the same as the side rejection of the stereo pair collectively), while still retaining good depth and "air" from the back lobes. 

An arrangement which I think would work much better than Blumlien for tapers from further back, which I've thought about and mentioned here before but have never tried, is a near-spaced pair of 8's using an inclusive angle of less than a 90 degrees - increasing spacing to compensate for less inclusive angle as it is made smaller.  In that case the configuration actually does begin to achieve increased side-rejection as a pair as the inclusive angle is made smaller.  Combined with what you note about apparent direct clarity I think that could work really well Pointed At Stacks from further back.
« Last Edit: April 07, 2021, 09:18:58 AM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline kuba e

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #65 on: April 07, 2021, 08:01:39 AM »
Thanks to Gutbucket and Rocksuitcase for clarification. I read it too, but I didn't understand it, so I skipped it. It's a good thing you corrected it.

Thanks for your ideas about recording with fig.8. It's a good inspiration to think about. E.g. that fig.8 is the narrowest classic pattern, although it is not visible at first glance from the graphics. I understand that rear lobes are a disadvantage in many cases. If I think correctly about it, pair of fig.8 could be used wherever we use omni as the main pair. The bleed from the rear lobes will not be harmful in these cases. And compared to other patterns, a pair of fig 8 will create a nice stereo image for sounds from the back and an interesting stereo image for the sides with the opposite phase.
« Last Edit: April 07, 2021, 10:34:23 AM by kuba e »

Offline Gutbucket

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #66 on: April 07, 2021, 11:17:18 AM »
I don't consider rear lobes disadvantageous necessarily, they are simply a part of what makes first order patterns what they are, and can be advantageous depending on how they are used.   I find a solitary fig-8 tends to sound a bit more open than many super/hypercardioids, and suspect the rear lobe pickup may responsible for that, maybe its generally better off-axis response behavior.  The main things I consider disadvantageous with 8's are their greater susceptibility to handling and wind noise, and their inherent dipole roll-off that reduces sensitivity at low frequencies.

If I think correctly about it, pair of fig.8 could be used wherever we use omni as the main pair.
Sure, in terms of a stereo pair any pattern can be substituted in place of a pair of spaced omnis, as it's the spacing not the pattern that is the basis upon which a wide-spaced configuration works.  The opposite is not true - a pair of omnis will not produce stereo if arranged in a coincident array.  However, often omnis are chosen because they have extended low frequency sensitivity in comparison to other patterns (they have no dipole roll-off, fig-8 has the most, and patterns in between have varying amounts). In this way they are the opposite of fig-8, and a pair of 8's would not make a suitable substitute.

For some applications it would certainly be useful to have a pattern the shape of just the front lobe alone.  Such a thing is actually possible with higher-order patterns, around 3rd order or so you get a pickup pattern that begins to approach something like that.  There are a few higher order microphones are now available, but they tend to be complex, costly, require a lot of recording channels and processing, and may produce audible artifacts that make some of them less than suitable for music recording.  There are a few threads discussing them.  Coresound's OctoMic is a 2nd order ambisonic microphone which requires 8 channels. The music samples I've heard recorded with it sound very good.  It it able to produce tighter patterns, but not something quite as tight as just the front-lobe of a 1st order fig-8.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline kuba e

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #67 on: April 07, 2021, 05:35:26 PM »
I thought of using omni and fig. 8 with respect to acoustics. Several times I made nice recordings with a pair of omni. It was always when the acoustic in the room was great. When the acoustic is worse, the hypercardiod or cardiod works better for me. I just guess that where a great recording with an omni comes out, there may be a nice recording with fig. 8. I don't know how fig.8 behaves in a bad acoustic space. I thought that due to the back lobe, it is not a suitable microphone for these cases, just as the omni is not suitable for it. But this can only be a misconception. I havn't hear the recording with near spaced fig.8 and I have heard only few with blumlein.

Yes, higher order patterns are very interesting. It is a pity that so far it is difficult to record so many channels. But that will change in the future. I could immediately compare it with a few clicks on the computer, as the pair of fig.8 and eg the pair of cardiod sounds. A few recordings would be enough and I could play with it all year.
« Last Edit: April 08, 2021, 06:33:30 AM by kuba e »

Offline Gutbucket

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #68 on: April 07, 2021, 06:50:46 PM »
Depends on what makes the room bad.

A hypercardioid is the least sensitive pattern to reverberant sound arriving from all directions on average in comparison to its sensitivity on-axis, so that often makes it the best choice in an overly reverberant or otherwise bad room.  Check out the table below.  That particular attribute is the degree of ambient sound sensitivity

Notice that a cardioid and a figure-8 have the same distance factor and degree of ambient sound sensitivity.  They both pick up the same amount of diffuse reverberance in compared to sound arriving on-axis, yet pickup direct arriving sound from angles other than on-axis differently. 

If the problem is not so much too much diffuse reverberance, but something like a specific slap-echo off close sidewalls, or a noisy bar or trashcan left or right of the recording position, you can reduce senstivity in that direction if you can arrange things such that the bad reflections or specific problematic sound sources are somewhere around the direction of the angle of maximum rejection, while the PA or other source of interest remains more or less on-axis. So a figure 8 could work well if those things line up, as long as there is relatively benign reverb and ambiance coming from behind the recording position. Also the increased dipole rolloff a fig-8 increases the built-in high-pass filter effect, but of course that's baked-in and may be better applied later if at all.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline illconditioned

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #69 on: April 07, 2021, 07:23:16 PM »
I thought of using omni and fig. 8 with respect to acoustics. Several times I made nice recordings with a pair of omni. It was always when the acoustic in the room was great. When the acoustic is worse, the hypercardiod or cardiod works better for me. I just guess that where a great recording with an omni comes out, there may be a nice recording with fig. 8. I don't know how fig.8 behaves in a bad acoustic space. I thought that due to the back lobe, it is not a suitable microphone for these cases, just as the omni is not suitable for it. But this can only be a misconception. I didn't hear the recording with near spaced fig.8 and I heard only few with blumlein.

Yes, higher order patterns are very interesting. It is a pity that so far it is difficult to record so many channels. But that will change in the future. I could immediately compare it with a few clicks on the computer, as the pair of fig.8 and eg the pair of cardiod sounds. A few recordings would be enough and I could play with it all year.
I really like Blumlein, especially with a stereo ribbon mic.
It gives simultaneously input from all directions (sum of L+R = omni) and it still gives a spatial image.True, you have front/back ambiguity, but if you want the whole room, this is perfect.

Please DO NOT mail me with tech questions.  I will try to answer in the forums when I get a chance.  Thanks.

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #70 on: April 07, 2021, 07:25:07 PM »
> Notice that a cardioid and a figure-8 have the same distance factor and degree of ambient sound sensitivity.  They both pick up the same amount of diffuse reverberance in compared to sound arriving on-axis, yet pickup direct arriving sound from angles other than on-axis differently.

And in situations where there's significant direct sound in front of the mike(s), direction of incidence is related to diffuseness and time of arrival. Sound arriving from farther off-axis will be more diffuse, and will arrive later than direct sound. Thus if the room is generally good-sounding, you can trade some of your pickup angle for a more spacious sound.

A smaller pickup angle also means (paradoxically for some people, but crucially) a wider stereo image in playback. Excessively wide pickup angles lead to mono-sounding recordings, a situation made much worse by the use of dual-diaphragm cardioids, since their pattern widens out in the bass, right where difference information between the channels is the most needed but the hardest to get in coincident or closely-spaced setups.
« Last Edit: April 07, 2021, 07:27:54 PM by DSatz »
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Offline kuba e

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #71 on: April 08, 2021, 07:06:59 AM »
Thank you all for the explanation. It's very kind of you. It's getting clear to me. It helped me better imagine. I can only write a small detail, the sum of two coincident fig. 8 is new fig.8. But I understand that Illcoditioned didn't mean to make mono from blumlein.
« Last Edit: April 08, 2021, 07:09:17 AM by kuba e »

Offline Gutbucket

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #72 on: April 08, 2021, 09:35:58 AM »
^ And that is the essence of conversion between Left/Right and Mid/Side.  A Blumlien pair presents the most straight-forward example of this.  Sum the Left and Right fig-8 channels of a Blumlein pair and the result is equivalent of a single forward-facing fig-8 pattern, which is the Mid channel.  Differentially sum them (subtract them, by inverting polarity on one of them before summing) and the result is the equivalent of a single sideways-facing fig-8, which is the side channel.

If the angle between the two coincident fig-8 microphones is other than 90-degrees, conversion to Mid/Side will produce the same virtual forward and side-facing fig-8 patterns, but there will then be a level difference between them that corresponds with that change in angle.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline rocksuitcase

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #73 on: April 08, 2021, 10:09:17 AM »
OK, quickly blowing by the theory, which is well stated in this thread, in the field experience jibes with what is being said by dsatz and gutbucket. We ran the AKG c422 several times at "bi-directional" 110 degrees from about 40 feet from stacks in a large arena. very non stereo "mono" sounding. Typically back then (mid 1980's) we ran them at 90 degrees. We have run that mic and kindms' 426 at 60 degrees, almost a PAS for large venue PA's, MUCH better channel separation.
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Offline BonoBeats

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Re: Binaural Recording (latest thinking from tapers?)
« Reply #74 on: April 21, 2021, 11:24:28 AM »
Hi

I did search before posting (but didn't find anything recent that addressed my questions).

1. Binaural recording - where do you stand?  Often use?  Sometimes use?  Niche offering?  Just for kicks?  Waste of time (why?)

2. Gear.  I'm put off by low-end products (I don't want to use my iPhone).  If I'm going to do this I want a 3.5mm connector.  I don't want to spend $$$s (no heads!).  Is there a sweet spot currently in the market?  I'm a quiet, ambient recordist (not a rock taper).

3. What's the difference between 'binaural' and simply positioning a good pair of mics in or near your ears?  Little difference?  Big difference (if so, why?)?

Many thanks in advance.

Regards,

Rob

It's a bit of a niche as far as live concert recording, but I think generally more accepted for your purposes.

Sound Professionals recently added these in-ears to their inventory. I can't speak for the sound quality (yet), but the high sensitivity and low noise seem ideal for more ambient material.

https://www.soundprofessionals.com/cgi-bin/gold/item/MS-TFB-2-MKII

And keep in mind, dummy heads don't have to be expensive. I'm all in for a dummy head and silicone molded ears for about $40 (ears are still en route).
« Last Edit: April 21, 2021, 02:24:34 PM by BonoBeats »
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