Become a Site Supporter and Never see Ads again!

Author Topic: Easy way to set up LD mics for ORTF in the field?  (Read 3586 times)

0 Members and 1 Guest are viewing this topic.

Offline lsd2525

  • Trade Count: (18)
  • Needs to get out more...
  • *****
  • Posts: 3397
  • Gender: Male
  • Eschew obfuscation
Easy way to set up LD mics for ORTF in the field?
« on: September 13, 2016, 08:05:17 PM »
SSIA. I did try searching, didn't come up with much. I need to move away from "guestimates" and try a true pattern. Seems a little harder than lining up small diameter mics. Tips?
Mics: SKM184's; ADK A51s; AT4041; Superlux S502; CK91 active w/homebrew BB; AT853; Naiant X-X; Nak 300's
Recorders: M10; DR-60D; DR-701D

Offline DSatz

  • Site Supporter
  • Trade Count: (35)
  • Needs to get out more...
  • *
  • Posts: 3347
  • Gender: Male
Re: Easy way to set up LD mics for ORTF in the field?
« Reply #1 on: September 13, 2016, 10:20:14 PM »
One reason that you won't find advice like that from knowledgeable sources is that the ORTF technique was worked out with small, single-diaphragm cardioids, and really requires that type of transducer to work well. Large-diaphragm and/or dual-diaphragm microphones have off-axis frequency response characteristics that vary too greatly from their on-axis response.

The large diaphragm causes the high-frequency response to roll off too much as you get away from 0 degrees--while with dual-diaphragm cardioids, the sensitivity at low frequencies conversely fails to roll off as a cardioid should do off axis. This causes high frequencies to be under-represented for sources close to center, while the sense of spaciousness is decreased by the near-mono character of the low-frequency pickup. All in all, not a good deal.

If you must use large- and/or dual-diaphragm microphones for closely-spaced stereo pickup, it's probably better to set them to patterns other than cardioid. Wide cardioid, supercardioid/hypercardioid, figure-8--try them all. One real advantage of this type of microphone, for example, is the low-frequency response available in the higher-directivity pattern settings, which often exceeds what is available with small single-diaphragm capsules. If a Blumlein setup works for you, try that, or perhaps closely-spaced super- or hypercardioids.
« Last Edit: September 13, 2016, 10:28:58 PM by DSatz »
music > microphones > a recorder of some sort

Offline lsd2525

  • Trade Count: (18)
  • Needs to get out more...
  • *****
  • Posts: 3397
  • Gender: Male
  • Eschew obfuscation
Re: Easy way to set up LD mics for ORTF in the field?
« Reply #2 on: September 13, 2016, 10:38:11 PM »
One reason that you won't find advice like that from knowledgeable sources is that the ORTF technique was worked out with small, single-diaphragm cardioids, and really requires that type of transducer to work well. Large-diaphragm and/or dual-diaphragm microphones have off-axis frequency response characteristics that vary too greatly from their on-axis response.

The large diaphragm causes the high-frequency response to roll off too much as you get away from 0 degrees--while with dual-diaphragm cardioids, the sensitivity at low frequencies conversely fails to roll off as a cardioid should do off axis. This causes high frequencies to be under-represented for sources close to center, while the sense of spaciousness is decreased by the near-mono character of the low-frequency pickup. All in all, not a good deal.

If you must use large- and/or dual-diaphragm microphones for closely-spaced stereo pickup, it's probably better to set them to patterns other than cardioid. Wide cardioid, supercardioid/hypercardioid, figure-8--try them all. One real advantage of this type of microphone, for example, is the low-frequency response available in the higher-directivity pattern settings, which often exceeds what is available with small single-diaphragm capsules. If a Blumlein setup works for you, try that, or perhaps closely-spaced super- or hypercardioids.

These are LD fixed cards, so switching around not an option. Taping off a line array about 40' back. Stacks about 30' apart. I know that's not much to go on. What about a 12" spread PAS? I'm grasping here; these are a different beast than the SD's that I've been running outside. 
Mics: SKM184's; ADK A51s; AT4041; Superlux S502; CK91 active w/homebrew BB; AT853; Naiant X-X; Nak 300's
Recorders: M10; DR-60D; DR-701D

Offline DSatz

  • Site Supporter
  • Trade Count: (35)
  • Needs to get out more...
  • *
  • Posts: 3347
  • Gender: Male
Re: Easy way to set up LD mics for ORTF in the field?
« Reply #3 on: September 13, 2016, 11:21:38 PM »
Yes, I think you might do well to consider spacing the microphones farther apart than ORTF--possibly quite a bit more. Keep in mind that at low frequencies, they will behave more like wide cardioids.

But I'll step back now and hope to let you hear from others with more recent experience, because it really has been decades since I recorded with microphones like yours. I do own a pair of Neumann large-diaphragm cardioids that I've used occasionally to good effect, but they're single-diaphragm, and have very accurate cardioid patterns at low frequencies--plus their high-frequency response has a broad plateau rather than the narrower peak that most studio vocal mikes have.

--best regards
« Last Edit: September 14, 2016, 05:20:34 AM by DSatz »
music > microphones > a recorder of some sort

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: Easy way to set up LD mics for ORTF in the field?
« Reply #4 on: September 14, 2016, 11:33:12 AM »
I assume you are talking about using the ADK A-51 pair listed in your signature-line.  I expect that mic is somewhat similar to the ADK TL, yet restricted to the cardioid pattern rather than having the TL's selectable patterns (omni/cardioid/supercard/fig-8).  Although I haven't used the TLs in a few years, I found them relatively well behaved both frequency and pattern-wise for being a LD dual-diaphragm microphone, and there is a long well-known history of those mics producing good sounding recordings for concert tapers here at TS.  However, just as DSatz advises, I primarily gravitated to using them in supercardioid and bi-directional fig-8 pattern configurations, which is where I found them to excel and where they were of the most value to me.

Using cardioid-only LDs in the situation you describe.  I'd suggest PAS with a wide enough spacing to compensate for the limited angle between microphones as mentioned.   "Taping a line array about 40' back. Stacks about 30' apart" implies a PAS angle between microphones of around 40 degrees total.  Consulting the improved PAS table, which suggests appropriate spacings based on the PAS angle between a pair of cardioid microphones, a spacing of more than 64cm is suggested (50deg/64cm is the narrowest-angle/widest-spacing option shown on the table).

In light of that and with a nod to practicality, my advice is to space the microphones as far apart as you are able to achieve, then adjust the angle between mics to something appropriate for that spacing.  That will at least get you as far in the right direction as is practical.  I expect that to work pretty well if you can manage to space them something like 24" apart (60cm) and point the microphones at the outer edges of the hanging PA.  If you were using switchable pattern TLs, I'd suggest the supercardioid or even bi-directional pattern as options to make best use of the limited amount of spacing available, at least in terms of stereo image and ambient pickup.

Here's the simplified PAS table-


And here's a link to the thread discussing it- http://taperssection.com/index.php?topic=167549.0
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 lsd2525

  • Trade Count: (18)
  • Needs to get out more...
  • *****
  • Posts: 3397
  • Gender: Male
  • Eschew obfuscation
Re: Easy way to set up LD mics for ORTF in the field?
« Reply #5 on: September 14, 2016, 09:01:28 PM »
You are correct, they are non-switchable. Thanks for the input; should be a great starting point. Getting a wide spread is no problem. I was just worried about a "hole in the middle"
Mics: SKM184's; ADK A51s; AT4041; Superlux S502; CK91 active w/homebrew BB; AT853; Naiant X-X; Nak 300's
Recorders: M10; DR-60D; DR-701D

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: Easy way to set up LD mics for ORTF in the field?
« Reply #6 on: September 15, 2016, 01:00:16 PM »
Shouldn't have a problem with that as long as you remain within the angle/spacing recommendations of that table.

Also, the unusual* nature of recording a wide-spaced PA from a position out in the audience goes a long way towards preventing a hole in the middle problem.  The sound emanating from the PA is primarily if not totally monophonic, yet is radiated via two widely-spaced speaker arrays located on either side of the stage.  As long as each mic is on-axis and equidistant to the PA speaker on it's side, the monophonic material through the PA will remain correlated and form a solid monophonic center image despite a sometimes ridiculously wide spacing, while the ambient and reverberant sound picked up by the two microphones will be strongly decorellated by the wide spacing.  This is why crazy wide omni splits of 25' or whatever outdoors can work and sound really good without having a perceptual center hole in the middle problem.

*That is, unusual with regards to the "normal world of music recording".  It's obviously a common thing for concert tapers!
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)

 

RSS | Mobile
Page created in 0.053 seconds with 31 queries.
© 2002-2024 Taperssection.com
Powered by SMF