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Author Topic: Improved PAS setups - better imaging with higher direct-sound/reverberant ratio  (Read 14834 times)

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Offline fobstl

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Wow Gut, this new chart is awesome. Thanks for taking the time to put it together! I look forward to trying the PAS method moving forward.

Offline Gutbucket

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Hey, I hope it helps!

A few comments on the previous revised table which I removed, and the new one-
The only thing the older table included which the new one does not was a choice between four different Stereo Recording Angles (SRA's) for each PAS angle.  The four choices provided were SRA = PAS angle -10°, SRA = PAS angle , SRA = PAS angle +10°, and SRA = PAS angle +20°.   Solving for each of these was acknowledgement of what I see as the primary subjective variable of the Improved PAS method and of the Stereo Zoom itself (as mentioned by Michael Williams in the paper)- "What is the most appropriate SRA?). I originally included the four choices so that after using Improved PAS a number of times and trying those different variations, folks could home in on their prefered PAS SRA.  My thinking being that after a while we may be able to come to a consensus on which is most prefered.  But taping isn't some rigorous methodical scientific study and that's just not realistic.

So for this table I just solved for SRA = PAS angle +10° (approximately, with a tolerance of ~ +/- 1°) for all entries.  This is what Williams suggests as probably most appropriate for orchestra sources, is what I suspect is close to optimal for PA taper recording, is sort of the intent behind pointing-just-outside-of-stacks (although generally not what that really does, which is partly the reason for doing all this), and was the suggested starting point in the old table represented by the highlighted row entries.

A few implications of SRA = PAS angle +10° are-
The microphone spacing for any given PAS angle are slightly narrower than they would be for SRA = PAS angle.  Improved PAS tends to suggest spacings much wider than tapers generally use for traditional PAS, so a slight reduction in suggested setup spacing is probably a good thing in a practical sense.  It's difficult enough setting up wider spacings to begin with, and I suspect the spacings Improved PAS suggests may seem overly wide to many tapers simply because they differ from the traditional norm.  In defense of the wider spacings, I'll stay that most common near-spaced setups (ORTF, DIN, DINa, NOS) etc fall within a range close to what the SZ suggests, and by extension what the Improved PAS method suggests.  What is difficult for some tapers to accept is the basic implication that narrower angles between microphones require wider microphone spacings to compensate, or rather the extent to which that relationship pushes the configuration wider rapidly as the angle grows smaller.

Another interesting implication can be seen by looking at the fig-8 column.  Note that "Standard Blumlein" (fig-8's @ 90° / 0 cm) isn't represented there.  Instead, the coincident fig-8 arrangement occurs at PAS angle = 80°  (and this tends to correlate with my own experience running Blumlein from an audience perspective).  Narrower PAS angles between microphones begin to push the fig-8 microphones further apart, but less so than any other pattern. Since many tapers are constrained to using relatively narrow mic bars, either by the equipment they have on hand or by setup constraints, it may be advantageous to consider using figure-8s in Improved PAS.  Not only do fig-8's tend to sound "natural" (somewhat in a similar way to omnis, not falling into what I sometimes call the "cardioid compromise"), they include a "built-in low-cut" as a result of their bi-directionality which will be appropriate for many indoor AUD situations.  Break out your old LD's which have a switchable 8 position and give it a try.

Back to the SRA = PAS angle +10° thing- Anyone using this table and wishing to experiment further and tweak the method, can do the following (quoting myself from one of the earlier explanatory posts in the thread)-

Tweak it to your liking if you want- Play it back and listen.  If you prefer a more narrow-image presentation with the on-stage and PA sound more tightly grouped in the middle between the speakers, use a slightly narrower microphone spacing next time (which corresponds to a wider SRA squeezing more between the speakers on playback).  If you’d prefer a wider-image presentation, use a wider microphone spacing the next time (narrower SRA stretching things out to the width between speakers).  Once you determine your personal preference you can use this table as a guide to get close then bump the spacing one way or the other as you like.

If you end up doing that a few times and find a consistent preference for modifying the suggested spacing in a particular direction, please let me know.
« Last Edit: December 07, 2018, 02:48:37 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline Gutbucket

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Oops, brain fart.  Minor detail but perhaps, but will revise the chart and repost it, removing the ORTF reference.  The non-highlighted box is not close to ORTF (110º / 17cm).. I somehow saw 7cm, thought ORTF and added that last-minute.

[Edit- corrected table now posted.  Apologies to the 18 of you who already viewed/downloaded since last night]
« Last Edit: Yesterday at 01:56:46 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline Gutbucket

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Noah, Stereo Zoom data isn't available for the Schoeps mk22 "open cardioid" pattern specifically.  Yet since it's pattern falls somewhere between cardioid and subcardioid, so should the optimal spacing for a pair of them in PAS.  So with regards to applying the Improved PAS technique to your mk22's, you can at least use the new table to determine the appropriate range of spacings, fine-tuning from there by ear.
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<<

Offline noahbickart

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Noah, Stereo Zoom data isn't available for the Schoeps mk22 "open cardioid" pattern specifically.  Yet since it's pattern falls somewhere between cardioid and subcardioid, so should the optimal spacing for a pair of them in PAS.  So with regards to applying the Improved PAS technique to your mk22's, you can at least use the new table to determine the appropriate range of spacings, fine-tuning from there by ear.


Thanks so much. If only schoeps made a mk22v capsule, my 50cm Bar would be perfect.
Recording:
Capsules: Schoeps mk41v (x2), mk4v (x2), mk22 (x2), mk3 (x2), mk21 & mk8
Cables: 2x nbob KCY, 1 pair nbob actives, Darktrain 2 and 4 channel KCY extensions:
Preamps:    Schoeps VMS 02iub, Naiant Littlebox, Naiant IPA, Sound Devices Mixpre6
Recorders: Sound Devices Mixpre6, Sony PCM m10

Home Playback: Mytek DSD 192> McIntosh MC162> Eminent Tech LFT-16; Musical Fidelity xCan v2> Hifiman HE-4XX / Beyerdynamic DT880

Office Playback: Grace m903> AKG k701 / Hifiman HE-400

Offline Gutbucket

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I *always* run a pair of mk22 no matter what.

Do you have a standard way of positioning them? I just got a pair of Neumann KM143's, their Wide Cardioid condensers, and have only used them a few times, and all but once, on stage. Very interested in practical experience with the Hypocardioid (!) pattern!!

I try to use the PAS theory with them. I've found that a 35cm spread at 70 degrees tends to work well from the OTS at MSG. FOB, I've used them with a NOS setup with good results. Onstage I've used them at 21cm and 110 degrees.

Basically apply the stereophonic zoom, knowing that you'll always want a little wider spacing than regular cardioids.

I just checked the figures Noah states above against those suggested in new table.  Indeed, the values fall pretty much in line with either the cardioid or subcardioid range.  Might want to try a touch more space between them next time at MSG if easily doable.

Edit- Noah, I just remembered you are using a dedicated-width bar, so probably not easily doable without a new bar.
« Last Edit: December 07, 2018, 03:04:49 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

 

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