Become a Site Supporter and Never see Ads again!

Author Topic: Omnis arranged at 180 degrees  (Read 2948 times)

0 Members and 1 Guest are viewing this topic.

Offline jagraham

  • Trade Count: (20)
  • Needs to get out more...
  • *****
  • Posts: 2996
  • Gender: Male
Omnis arranged at 180 degrees
« on: January 28, 2018, 06:39:49 PM »
Anyone tape much with omnis arranged at 180 degrees? A taping friend suggested it a while back and I've tried it at a couple shows, one at the board and one up front 5' back from the stack, and I think they came out pretty good. This setup isn't something I see too frequently so I was curious what others on the TS thought of the method, and if you had any specific suggestions I would love to hear them. Seems like a good option for stack taping, and I haven't tried onstage yet but I'd imagine it would work well.

https://archive.org/details/spafford2017-11-07.cm300s.cp2s.16bit
Mics: Nak CM-300s, Nak CM-100s, CP-1s, CP-2s, AT-853s(Cards, Hypers, Omnis) CA-14s(Cards, Omnis)
Pres: CA STC-9200, CA-UBB
Recorders: Tascam DR-70D, DR-2D, Edirol R-09

ISO: 1 Teac ME-120, CP-3 Caps, AT-853 Subcard Caps

Offline Hypnocracy

  • Site Supporter
  • Trade Count: (46)
  • Needs to get out more...
  • *
  • Posts: 2011
  • Hypnocratic Missionary
    • Hypno on teh LMA
Re: Omnis arranged at 180 degrees
« Reply #1 on: January 28, 2018, 08:08:58 PM »
This works for Large Diameter microphones...and has been called the "Healy Pattern" because he had two LD's mounted in front of him at the SNB back in the Grateful Dead days...The Polar pattern of a large Omni is not directional at the Lower frequency's but is directional at higher frequency's (somewhat at mids and more so the higher you go).

If you are using Small Diameter or Pinpoint Omni you would be better off spacing them 36" apart for a stereo image. These microphones are much less directional across the whole spectrum.
_____________
hypno on teh Archive

This must be heaven -- 'cause here's where the rainbow ends
If this ain't the real thing, then it's close enough to pretend

Offline aaronji

  • Site Supporter
  • Trade Count: (9)
  • Needs to get out more...
  • *
  • Posts: 3861
Re: Omnis arranged at 180 degrees
« Reply #2 on: January 30, 2018, 08:11:10 AM »
^ Even SDC omnis get fairly directional at higher frequencies.  I find that the 180 degree angle audibly impacts the image and is particularly useful when you can't space them as far as you might like for time-of-arrival differences.

Offline Gutbucket

  • record > listen > revise technique
  • Trade Count: (15)
  • Needs to get out more...
  • *****
  • Posts: 15698
  • Gender: Male
  • "Better to love music than respect it" ~Stravinsky
Re: Omnis arranged at 180 degrees
« Reply #3 on: January 30, 2018, 11:45:38 AM »
It's an ambient sound recording technique, that is to say it will sound natural and pickup the sound from all around as heard from that location, which is probably why Healy used it (not spaced very widely) in his Ultramatrix mixes for audience and hall pickup, and apparently onstage as well for a while to feed the band's in-ear monitors when they first started using them. 

The 180 degree angle introduces some level differences between channels at high frequencies.  How how low into the treble range that goes is determined by the size of the diaphragm and/or microphone housing.  As Aaron mentions, that can be a useful technique for tapers when they aren't otherwise able to space a pair of SDC omnis as wide as they might otherwise prefer.  Likewise, it can be helpful when using another microphone or pair of microphones in the center between spaced omnis with the intend of mixing them together, by way of creating a bit more signal difference to help reduce phase interaction, at least within that small frequency range.

Conceptually this is sort of like a very tiny Jecklin Disk which is only effective at the highest frequencies.  You can lower the frequency above which the level difference becomes apparent by placing a baffle between the omnis.  The larger the mic housing, the larger the baffle, the lower the corner frequency where this directionality begins to occur.

LDCs behave somewhat oddly and less predictably. A true pressure-omni LDC would exhibit such directionality to slightly lower frequency based on its larger housing (exhibiting more directionality up top) yet those are rare.  Most LDC omnis are electrically switched opposing diaphragm mics and will exhibit this high-frequency directionality in both the forward and aft directions, producing a sort of ragged figure-8 pickup pattern in their uppermost range.
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 goodcooker

  • Trade Count: (43)
  • Needs to get out more...
  • *****
  • Posts: 4638
  • Gender: Male
  • goes to 11
Re: Omnis arranged at 180 degrees
« Reply #4 on: January 30, 2018, 12:18:31 PM »

I did this technique several times with my SP C4 omnis outdoors at festivals where I felt like experimenting. I spaced them around 12 inches apart and 180 degrees. I found that closer was better and the playback sounded much better on headphones than on speakers (same thing I've discovered with HRTF). Oddly enough I didn't feel the need to apply the mid and high EQ curve that I usually added to my outdoor omni recordings. Even though theoretically SDC omnis are more directional at high frequencies and I had the mics facing away from the sound source the recordings turned out surprisingly bright and clear.
Line Audio CM3/OM1 || MBHO KA500 hyper>PFA|| ADK A51 type IV || AKG C522XY
Oade Warm Mod and Presence+ Mod UA5s || Aerco MP2(needs help) || Neve Portico 5012 || Apogee MMP
SD Mixpre6 || Oade Concert Mod DR100mkii

pocket sized - CA11 cards > SP SB10 > Sony PCM A10

http://www.archive.org/bookmarks/goodcooker

"Are you the Zman?" - fan at Panic 10-08-10 Kansas City
"I don't know who left this perfectly good inflatable wook doll here, but if I'm blowing her up, I'm keeping her." -  hoppedup

Offline yug du nord

  • ...til things never seen seem familiar…
  • Trade Count: (56)
  • Needs to get out more...
  • *****
  • Posts: 5533
  • made with natural flavor
Re: Omnis arranged at 180 degrees
« Reply #5 on: January 30, 2018, 01:28:27 PM »
I think that the "Healy Method" is technically a pair of omni's spaced 17cm and angled at 180* (horizontal to sound source).
It's been a while, but I've done it a handful of times in the past with good results IMO.
Experimenting with omni's is pretty interesting!
.....got a blank space where my mind should be.....

Offline Limit35

  • Trade Count: (4)
  • Taperssection Member
  • ***
  • Posts: 337
Re: Omnis arranged at 180 degrees
« Reply #6 on: January 31, 2018, 12:07:17 AM »
I've stealthed small omnis 180*/90* off axis approximately 8" apart a few times, it was convenient and stealthy. I liked the sound, but it obviously wasn't the best use for the mics, ver. 1 Naiant X-Xs sound good 1.3 m or greater in my opinion where they get a good spaciousness and bass punch. When I run one meter or greater I always have the omnis 180*/90* off axis due to my setup. Since they are small it is easy to mount that way, the old Naiant omnis I mount forward or up because they need SDC style clips. I have never noticed a difference in angle. The CP-2 omni caps I have seem pretty directional for some reason. I have never tried 180*/90* off axis with those yet, it may be interesting with a card center now that I think about it.

Offline DSatz

  • Site Supporter
  • Trade Count: (35)
  • Needs to get out more...
  • *
  • Posts: 3347
  • Gender: Male
Re: Omnis arranged at 180 degrees
« Reply #7 on: January 31, 2018, 10:33:44 AM »
When I was first learning to record, the usual recipe for setting up a pair of omni microphones was to take the full stage width, then place the mikes at the 1/3 and 2/3 points along the front of it. That often meant that the mikes would be 10 feet apart or more. That creates a stereo image with a "hole in the middle" and "swimmy" localization in general. People might put up with those problems, or not perceive them; not everyone cares very much about localization.

Meanwhile over in Europe, the typical usage of omnis was quite different: They were often placed with anywhere from one meter to half a meter between the mikes. Any Americans who saw a setup like that might assume that there would be no "stereo separation" in the resulting recording, but such was not the case.

The thing is, if distance between your two omnis is only a few inches or less, the resulting recording will be essentially mono in the bass. And that means that you're missing one of the main pleasures that an "A/B" recording can offer, which is spaciousness. It comes mainly from low-frequency energy that isn't strongly "correlated" (highly similar from moment to moment) between the two channels. You will be able to localize to a surprising extent, especially if you listen through headphones, but the feeling of immersion in a live space will be absent.

Nowadays there are much better options available: small, single-diaphragm condenser microphones with patterns between omni and cardioid, and very smooth all-around response. These microphones can make beautiful, spacious stereo recordings (like omnis) with stable stereo imaging (like directional microphones) in a way that is simply not possible with omnis or ordinary directional microphones--and they can do this with spacings even less than the typical "small A/B" approach. These are still mostly higher-end microphones (Schoeps, Neumann, Microtech Gefell) but I think in time there will be good-sounding, lower-cost alternatives as well.

P.S.: If you absolutely must use a pair of omnis in this way, consider getting sphere attachments for them, which will emphasize their midrange directivity. See for example http://schoeps.de/en/products/ka40 (please visit the "graphics" page to see the effect).
« Last Edit: February 07, 2018, 09:38:04 AM by DSatz »
music > microphones > a recorder of some sort

 

RSS | Mobile
Page created in 0.209 seconds with 36 queries.
© 2002-2024 Taperssection.com
Powered by SMF