Gear / Technical Help > Microphones & Setup
Wide cardioid/subcardioid spacing and angle
Gutbucket:
Attached is the latest Improved PAS write up. To make it easier to use, the useful part is now presented as a list of mic setup diagrams arranged by PAS angle, rather than the former table of figures. The other change is that in addition to standard 2-mic Improved PAS it's now extended to also include 3-position PAS - for the use of 3 mics with single mic in the center, or 4 if using a coincident X/Y or M/S pair in the center (those two mics share the same center position). If only interested in standard 2-mic PAS for subcards, just ignore ignore the 3-position stuff. I've been meaning to start a new thread on this, just haven't made the time.
The 2-mic PAS part is based on the same data as the older table version, originally derived using the Sengiepelaudio.com on-line calculator tool that aaronj linked in his post above. So you'll get the same answer if referring to the older Improved PAS table, the new PAS diagrams, or the online Sengiepel tool. The 3-mic PAS part of it is based on data from the online Schoeps Image Assistant tool which is capable of handling both 2 and 3 mic-position configurations. The 2-channel solutions derived from it are very close to those from the Sengiepel tool but are based on a more extended data set. It also provides additional information and control options (some of which are a bit hard to find, burred in the menu). However, Image Assistant is less straightforward for most folks to use than the Sengiepel tool. Additionally, I used a slightly different way of determining the appropriate offset between the PAS and SRA angles, some details of which are mentioned in the write up, and which I plan to discuss in the future thread in more detail.
Gutbucket:
I totally agree with morst when he says "Gotta admit I like to go with a setup I'm confident in... Experimentation is important, but on the day of the show I just wanna nail it."
In that regard I consider the improved PAS stuff relevant for taping from out in the audience. Taping on-stage or at stage-lip is a different deal. Improved PAS still works in those situations, but very different approaches can also work and may work better. The acoustic situation there is quite different and makes for additional options when up close.
--- Quote from: C.Clark on April 17, 2024, 04:05:17 PM ---I also find that the closer I get to the PA, in smaller venues, the more likely I am to run PAS. Hope that helps!
--- End quote ---
This is very interesting to me, please tell me more. A primary intent of Improved PAS is to make the most of the very typical less-than-ideal taper situation of recording from farther away.
goodcooker:
Farther away from the source I tend to do more separation and less angle and up front or onstage the opposite - more angle and less separation.
Some examples
15 feet from the band unamplified jazz small listening room- https://archive.org/details/JVidacovich2019-06-25.MBHOka300.flac - DINa 17 cm 90 angle
Back of the floor medium venue 1000 cap loud blues rock - https://archive.org/details/tabbenoit2021-06-12.flac24.mbhoka300 30 cm 75 angle
At FOH 50ft from stage small venue ~400 cap loud blues rock - https://archive.org/details/rrfb2023-08-12.cm3.portico.mr1/rrfb2023-08-12mr1t07.flac 25 cm PAS
Big outdoor festival at FOH enclosure 150 ft from stage reggae - https://archive.org/details/matis2018-06-02.MBHOka300.flac/matis2018-06-02t07.flac 25 cm PAS - IIRC I tightened up my usual wider outdoor spread since there was little room to be had so small footprint and high wind
DuctTaper42:
Greatly appreciate all the feedback so far, has been enlightening and as I could've guessed... it varies. My initial inclination was a bit of a mid-point between AB and near-coincident, angled arrays, something like a 2-3' spaced PAS so nice to see I wasn't tooooo far off the opinions of others.
--- Quote from: C.Clark on April 17, 2024, 04:05:17 PM ---The more bass, the less angle I use.
--- End quote ---
I'd also be interested in further detail on these comments. When there's more bass do you not want the mics pointed directly at the source in attempt to attenuate it some to prevent the bass from overpowering the other frequencies? With the CM4s specifically, it appears that the lower frequencies have the least amount of rear rejection so I could see wanting to maximize what attenuation it does have while still making sure the sound is relatively on-axis.
--- Quote from: C.Clark on April 17, 2024, 04:05:17 PM ---I also find that the closer I get to the PA, in smaller venues, the more likely I am to run PAS. Hope that helps!
--- End quote ---
Is this in order to ensure the max sensitivity is facing the source rather than stage/crowd noise? and by "closer to the PA" do you mean strictly closer to the stage or lateral moves as well if you're not able to set up in the center?
--- Quote from: morst on April 17, 2024, 04:59:42 PM ---So now I usually run Neumann KM143 wide cards on stage, split wider than 6' if possible, aimed at snare drum for a regular rock band setup with center drummer.
--- End quote ---
Aimed at the snare as in angled inward? So that each mic is picking up it's respective side of the audio while keeping the drummer centered between the two as it was in reality?
I appreciate the other comments as well, I'll spend some time checking out the links, tools, and tapes when I can so I can get a sense of the differences between circumstances and resulting tapes.
Thanks all
rocksuitcase:
--- Quote --- it appears that the lower frequencies have the least amount of rear rejection
--- End quote ---
Acoustically, frequencies below approximately100 Hz are too lengthy to be "localized" to one side or the other using most microphones no matter the configuration. e.g. a 40 Hz wave is 1/4 length at about 40 feet, so to pick up the full wavelength you need to be 160 feet away. However, most recording principles use mic distances less than that. Of course live music is not white nor pink noise so it behaves a bit less "uniformly".
In summary, human hearing does not perceive separation between Left and Right at frequencies below approximately 100 Hz.
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