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Gear / Technical Help => Microphones & Setup => Topic started by: deadheadcorey on March 26, 2014, 03:31:30 PM

Title: PAS/POoS
Post by: deadheadcorey on March 26, 2014, 03:31:30 PM
just wanted to get a feel about this mic config from people and their opinions of it.
Title: Re: PAS vs POS
Post by: dnsacks on March 26, 2014, 04:12:51 PM
i'm familiar with PAS (Point At Stack), but what's POS?
Title: Re: PAS vs POS
Post by: Chuck on March 26, 2014, 04:13:20 PM
I use PAS (Pointed At Stacks) regularly in crappy sounding rooms. IS POS (Pointed at Outside of Stacks)? If so, I consider that the same as PAS. I mainly use hyper-cardioid mics with these configurations.
Title: Re: PAS vs POS
Post by: deadheadcorey on March 26, 2014, 04:16:15 PM
i'm familiar with PAS (Point At Stack), but what's POS?

pointed outside of stacks.

ive seen it in some lineages with other tapers before
Title: Re: PAS vs POS
Post by: Gutbucket on March 26, 2014, 05:06:01 PM
Point At Stacks -verses- Piece Of Shit?  I'd go PAS every time.

Maybe POS = Point Outside Stacks?  If so..

I think of PAS/POS is a configuration based on simplicity, practicality and ease of setup.    All of which are valuable things, and oftentimes the most important things. I don’t think I need to say anything about the simplicity and ease of setup.

In terms of practicality, it points the most well behaved and most sensitive region of the microphone's pickup pattern more or less directly at the primary sound sources, and the least well behaved and least sensitive regions away from them and towards the non-direct room sound (and much of the direct crowd noise).  For those reasons it makes pretty good sense at the individual microphone level for the situations in which most around here find themselves recording.  In tech-speak it maximizes the direct to reverberant pickup ratio for that particular recoring position.  In taper-speak a higher ratio there is more SBD-like, a lower one more back of room AUD-like.

However, if PAS happens to provide a recording with good stereo aspects, that’s entirely by chance determined by the geometry of the particular situation and the width of the mic-bar, but certainly not by design.  In fact, most of the time PAS will not be an optimal setup for the stereo qualities of a recording, even if each mic individually is positioned more or less optimally in regards to those other things. But stereo quality is a high-level nicety, which needs to be built upon a strong foundation of that other stuff before it can shine.  It’s more important to get the other stuff right first.

The primary problem is that for any near-spaced stereo recording configuration, the optimal angle between microphones is directly tied to the spacing between the microphones.  Change one and you need to change the other as well.  PAS only specifies the angle between microphones and doesn’t say anything about their spacing.  Notice that most other common near-spaced configurations specify both the angle between the microphones and a specific spacing between them (ORTF, DIN, DINa, NOS, etc)

PAS can work based on same theoretical basis of those other configurations for making recordings with good stereo qualities if the correct mic spacing is determined once you know the mic angle needed to point at (or outside of) the stacks. Usually the mics need to be spaced much wider apart than they are.

I posted a quick reference chart a few years ago with suggested spacings for various PAS angles using cardioid pattern microphones.  It’s based on the Stereo Zoom tables which describe a way of trading mic angle against mic spacing for more consistent and predictable stereo qualities.  It may be useful to some and I’ll link it here if I can find it.  The problem with using it is no longer simple and easy to setup- you point the mics at the stacks, then you need to figure out what that angle is, consult the little table, and have a simple enough way of adjusting the mic spacing to suit.  Those two things present the same if not more hassle than using the standard configurations.  However, in combination with supercardioids it does let you maximize the direct to reverberant ratio from that particular recording position while also getting good stereo qualities.. and that's the real value of it I think.

The practical take away is this-  If you setup PAS, you’ll probably have a rather minimal angle between microphones and will need more spacing between them for good stereo.  As a point of reference, DIN is 90 degrees and 20cm apart (about 8”), if PAS puts the mics at less of an angle than that, you’ll need more spacing between them (a lot more as the angle decreases significantly).  If you are constrained by the length of your mic bar, then pointing outside of the stacks is a good idea because it makes the angle slightly wider, which requires less spacing, but still keeps the mics on-axis for all practical purposes, which maximizes direct/reverberant pickup ratio from that position.
Title: Re: PAS vs POS
Post by: Gutbucket on March 26, 2014, 05:38:51 PM
Improved PAS reference table for cardioids, based on the DIN (90 degrees, 20cm) configuration-

(http://taperssection.com/index.php?action=dlattach;topic=153112.0;attach=105743;image)

Here's the thread from a few years ago discussing it- http://taperssection.com/index.php?topic=153112.msg1938190#msg1938190 (http://taperssection.com/index.php?topic=153112.msg1938190#msg1938190)

Since it effectively takes PAS and shifts it's usefulness from ease and simplicity of setup for less experienced tapers to maximizing direct/room pickup ratio for more experineced tapers recording in less than ideal situations, it should really be re-calculated specifying supercardioids rather than cardioids, and perhaps showing a few spacings for each angle to provide both aditional spacing flexibility when that's limited and the ability to adjust the resulting playback width to suit the tastes of the taper.
Title: Re: PAS vs POS
Post by: Chuck on March 26, 2014, 05:50:36 PM
As always you are a wealth of information Gutbucket.

My experience matches with your information. I usually use my hyper-cardioid mics in PAS/POS situations. I spread the mics more than my typical DIN configuration to get that bit of air that would be missing with a smaller spread and more narrow angle.
Title: Re: PAS vs POS
Post by: cashandkerouac on March 26, 2014, 06:08:26 PM
i've had very good results using AKG ck8 capsules spaced 2-3 feet apart at a 50-60 degree angle (PAS).  when listening to recordings with very directional mics my ears prefer the results gained from a wide spacing with mics PAS rather than using a wide angle with less spacing between the mics.  in most cases the sound coming through the left and right stacks is mono anyway, so using a traditional stereo mic orientation with shotguns has diminished value (in my opinion). 

with a less directional mic (i.e. cardioid) i think that traditional stereo mic orientation has greater benefit... not so much from the perspective of creating a more accurate stereo image (because the sound coming through the stacks is still mono), but rather from the perspective of creating a wider and fuller sound stage.   
Title: Re: PAS vs POS
Post by: Gutbucket on March 26, 2014, 06:33:27 PM
Crediblity and enjoyment beats accuracy everytime for music recording in my way of thinking.  Accuracy is a loosing battle of measurement that can never be won, most don't care for it anyway (even if they think they do), and most original recording situations were less than ideal to begin with and benefit from non-accurate improvements.  Credibility and enjoyment are artistic goals and what listeners really care about.

I usually prefer the results from configs with space between the microphones too. 

However, I'll make an exception for X/Y with hyper(or super)cardioids and a wide enough angle.  For a coincident configuration I like that.  It's nearly as sweet as Blumlein crossed 8s, but has enough forward bias directionallity to be far more useful nearly everywhere and sounds better.   But it requires an angle between mics of something like 100-120 degrees which makes more or less impossible to use for PAS.
Title: Re: PAS/POoS
Post by: BlingFree on March 27, 2014, 10:01:28 AM
I approve of the "POS" and support the PIS as well... pointed INSIDE the stacks  8)

..yes I'm put that in my source descriptions and I get a giggle out of it every time :)
Title: Re: PAS/POoS
Post by: beeco on April 01, 2014, 07:12:10 PM
There's some "credibility and enjoyment" right there, dude.  Especially the enjoyment. 

Man, I love this place.  And, I even learn cool stuff on a regular basis, too!   Thanks Gutbucket, for the illumination (and the handy reference table)!

I approve of the "POS" and support the PIS as well... pointed INSIDE the stacks  8)

..yes I'm put that in my source descriptions and I get a giggle out of it every time :)
Title: Re: PAS/POoS
Post by: Gutbucket on April 03, 2014, 10:18:27 PM
Started a new thread with both the simple PAS table posted above and a new revised and extended table with more options and information for the advanced taper using PAS as a tool for difficult rooms- PAS table (printable) - maximise direct/reverberant pickup & retain good imaging (http://taperssection.com/index.php?topic=167549.msg2087409#msg2087409)

Didn't want the new table buried in other threads, figured it deserves a new one.  Check it out and let me know what you think.