Become a Site Supporter and Never see Ads again!

Author Topic: Shotgun mic test in a poor room  (Read 3674 times)

0 Members and 1 Guest are viewing this topic.

Offline bombdiggity

  • Trade Count: (11)
  • Needs to get out more...
  • *****
  • Posts: 2234
Re: Shotgun mic test in a poor room
« Reply #15 on: October 02, 2015, 03:36:50 PM »
I'm calling this one the "Gutbucket array". Pretty much as described above in Gutbucket's post, a pair of supercards, at 60cm with a 40 degree angle and an MKH805 in the middle.
Edit: Found the actual angle of the supers in my notes.

I kinda like that.  I preferred the super when it was just one or the other... 

As noted if you can mix them without significant cancellation issues it may give a little more dimension to the result than one or the other on their own.  Some of the added dimension/warmth may be that this is now a "stereo" result vs. the mono in the prior samples though. 


« Last Edit: October 02, 2015, 03:38:31 PM by bombdiggity »
Gear:
Audio:
Schoeps MK4V
Nak CM-100/CM-300 w/ CP-1's or CP-4's
SP-CMC-25
>
Oade C mod R-44  OR
Tinybox > Sony PCM-M10 (formerly Roland R-05) 
Video: Varied, with various outboard mics depending on the situation

Offline Gutbucket

  • record > listen > revise technique
  • Trade Count: (13)
  • Needs to get out more...
  • *****
  • Posts: 12398
  • Gender: Male
Re: Shotgun mic test in a poor room
« Reply #16 on: October 02, 2015, 05:25:57 PM »
Not sure if anyone cares, but this is a good opportunity for me to further the explanation of my line of thinking about "stereo" in this way, and in particular these kinds of less-than-typical microphone configurations which spring from that line of thinking, designed with the intent of optimizing for the aspects of a recording which are most important and I want, given the constraints we are required to work around.  In other words- thinking more in terms of "Direct/Reverberant", "Front/Back", "Middle/Sides", and how some stereo requirements change by frequency range, rather than thinking in terms of "Left/Right".

Imagine we're recording outside, say in an amphitheater.  There is a PA, and we can setup pretty much were we'd like, but no SBD access, no on-stage access, and I'm going to record from a single location out in the audience.  My two channel starting point for that is a pair of spaced omnis, say 3' apart.  From there I add a center directional mic which directly addresses the two primary problems I hear with spaced omnis: It provides a far greater overall forward bias and "presence" (Front/Back, Direct/Reverberant stuff) because it is pointed so as to reduce pickup of everything but what is directly in front, and also provides a strong, solid center which allows for an even more optimal spacing of the omnis without getting a hole-in-the-middle.  To my ear that greatly improves upon the spaced omnis alone- sort of like teamwork, the addition of the forward facing center directional mic allows the omnis "do what they do best" and provides the ability of adjusting for the optimal balance between the omnis and center after I get home, which is a huge advantage.

I'm completely happy with those recordings, yet in search of sharper stereo imaging (which is important to me, but further down the hierarchical list of what is most important) I add the pair of supercardioids.  I space them ~2' or so apart and point them directly to the sides, forming a three-mic array with the center directional mic.  I choose that arrangement because I want to maximize the level differences between the signals of those three directional mics, while still keeping them in a viable stereo configuration.  That 180 degrees supercardioid angle is going to produce the greatest channel separation possible for sounds arriving from angles which approximately line up with the left and right speakers on playback.  The null angle of each supercardioid pattern points approximately 45 degrees off center to the opposite side, which more-or-less lines up with the opposite playback speaker as well as more-or-less with the opposite PA speaker in the venue (opposite edge of the SRA in Stereo Zoom terms).  Not exactly, but close enough.  Sound arriving from that direction will appear in the signals from near-side supercardioid and the center mic, but will be minimized as much as possible in the supercardioid channel on the opposite side.  (Farther off-axis than that, say fully to one side or the other, the inverse-polarity back lobe of the opposite supercard comes into play somewhat, introducing some anti-phase information in the channel opposite the sound source which is probably useful as well).

I retain the wide omnis, which are my fall-back starting point anyway.  As omnis, they compensate for the reduced low-frequency response of the supercards, and their wide spacing provides excellent stereo bass which a more narrow microphone spacing does not.  They also contribute to an open and "airy" stereo ambience and sense of space.  I now have 5 mics in the array, arranged to work optimally together, in a way which minimizes potential conflicts between them when their signals are mixed together, and provides even greater flexibility when I'm mixing to 2-channel stereo.

In a surround playback environment, the channels stay discrete instead of being mixed, but are still level balanced to taste afterwards for best effect.  The supercards are routed directly to the Left/Right speaker channels, and the center mic routed to the Center speaker channel.  The omnis get routed to the Surround channels (possibly with their bottom octaves mixed into the front Left/Right speaker channels to take full advantage of their deep stereo bass contribution).

Moving into a less ideal recording situation, say much further back or in a more reverberant space, I'd start pointing the Left/Right supercardioids more forward while increasing their spacing to compensate for the narrowing angle between them.  That's going to reduce the optimal channel separation somewhat, but increase the forward pick-up bias of the array and reduce sensitivity to reverb and ambience from the sides and back.  That's a trade off I'm happy to make because if I can't have both, I value getting a good direct/reverberant balance far more than super-sharp imaging.

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

  • record > listen > revise technique
  • Trade Count: (13)
  • Needs to get out more...
  • *****
  • Posts: 12398
  • Gender: Male
Re: Shotgun mic test in a poor room
« Reply #17 on: January 10, 2018, 09:31:59 AM »
Hi Christine,

Old thread I know, but I came across it searching for something else the other day and realized I forgot to suggest a microphone technique which I think would be most appropriate to the this particular recording situation.  I'd let that slip in all the discussion about interference-tube microphones and 3-microphone arrays using them.

Anyway, if I was recording in this situation from that position in the back of the room I'd try first boundary mounted omnis spaced on the back wall.  This is an ideal situation for that technique.  The recording position is nearly at the back wall, the back wall is large and flat and the room is reverberant and somewhat boxy.  Boundary-mounting will increase the direct/reverberant ratio as much as possible from back there while greatly improving the apparent clarity, eliminating pickup of 1st reflections off the back wall entirely.  I think it could work quite nicely for this application.

You can try it by simply placing a pair of spaced omnis very close to the wall, perhaps even gaff-taped directly to the wall.  You might still record the shotgun to a third channel, which may or may not be useful or needed.  As stated previously, the other two mics should help bury the off-axis response irregularities of the shotgun used alone.  If you have three omnis, I'd try boundary mounting all three in a line across the back wall facing the band.
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 connloyalist

  • Trade Count: (0)
  • Taperssection Regular
  • **
  • Posts: 78
  • Gender: Female
Re: Shotgun mic test in a poor room
« Reply #18 on: January 10, 2018, 12:10:09 PM »
Hi Gutbucket,

Thank you for the suggestion! Yes, I think I have three omni's. Or more accurately, two pairs of different omni's. Strange question perhaps, but would the omni's be facing into the wall, creating a boundary mic effect, or into the room with the cable at the rear against the wall?

Can you suggest boundary mics that are appropriate to music recording (as opposed to speech as many appear to be) and don't cost an arm and a leg?

Regards, Christine

Offline Gutbucket

  • record > listen > revise technique
  • Trade Count: (13)
  • Needs to get out more...
  • *****
  • Posts: 12398
  • Gender: Male
Re: Shotgun mic test in a poor room
« Reply #19 on: January 10, 2018, 01:24:09 PM »
If you're okay with to attaching them directly to the wall with adhesive-tape, I'd point them toward the ceiling.  I think that should work well and at least be a good test.  Try whatever small diaphragm omnis you have on hand, but avoid electronically switched large-diaphram mics which have an omni-pattern.

If using mic stands you might point them directly at the wall, perpendicular and very close to it, like just a few millimeters away.  If you can monitor while setting up and hear any weird high frequency resonances with that arrangement you might play with angling them upwards somewhat so the diaphragm face will have a sightly varying distance from the wall across it's diameter. That should spread out any resonances occurring between the diaphragm and wall.

Ideally the mics would be mounted into the wall itself, with the capsule diaphragms flush with the wall surface, which obviously isn't practical as you'd have to modify the wall.  The old Crown PZMs have their capsule facing into a boundary-plate, and the Crown PZM guideline booklet talked about how closely they positioned the capsule to the boundary plate so that the boundary effect works cleanly up into the ultrasonic frequency range.  It goes on to talk about how the diameter of a typical mic body is big enough to cause the very high frequency response to suffer from reflection interaction at the points of the diaphragm furthest from the boundary when the diaphragm is perpendicular to the surface, but I'm remain to be convinced that really matters very much in terms of real world taper arrangements.  If it does its only affecting the very highest frequencies.

When I've done this I've used miniature DPA 4060 or 4061 omnis, and have both taped them directly to the wall facing up (easy to do since they are so small and light), and have used the intended DPA boundary-mount accessory for them, which is a little round rubber disk into which the microphone is inserted from the back.  The front has a little opening to the diaphragm and the surface of the disk sort of smoothly tapers so as to blend into the wall surface with no defractive edges.   Both methods worked well and the results seem to me about the same honestly, but these are very small microphones to begin with.  I use and highly recommend the 4060 omni (more sensitive) or 4061 omni (less sensitive), but they aren't inexpensive (not crazy expensive, but around $900 a pair new, probably $400-500 used).  Fortunately decent performing small omnis are easier to get right at lower cost than small directional mics.  Some around TS really like the Countryman B3, which is the same size and about half the cost last I checked.  The TS mic builders all offer inexpensive small omnis which will probably work well for this.  Any of these tiny lavalier-sized mics you can very easily tape to the wall.

I've never used either the Crown PZMs or the inexpensive RadioShack version which were popular years ago so I can't comment on them, but they are specifically intended for this kind of thing. Opinions I've read seem to vary widely.  More manufacturers make a dedicated boundary mic these days such as Audio Technica and others, but personally I lean towards small multipurpose omnis I can use for other situations as well.  Also many of those are intended for setting on a stage floor or conference table- and so are heavy, weighted, and/or armored against being stepped on.  Those types would be more difficult to mount on the vertical wall.

Its a great technique that really works well in situations when other things don't, but a somewhat special case thing which doesn't come up enough for me to have dedicated mics for doing it.
« Last Edit: January 10, 2018, 03:02:58 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 illconditioned

  • Trade Count: (7)
  • Needs to get out more...
  • *****
  • Posts: 2649
Re: Shotgun mic test in a poor room
« Reply #20 on: January 10, 2018, 02:08:32 PM »
I've made some recordings with a pair of shotgun mics,
Spaced about 20-30cm, pointing almost straight ahead, at the back of the room.
I am using in a narrow room where I am trying to avoid reflections from the walls.
Not sure how good this method is, but I like the results to far.
I'm also considering this type of setup for permanent installed setup where I want the mics well away from the front of the room.

So far I've used various mics, including:
AKG C747 (very short shotgun, almost a hyper cardioid in practice)
Beyerdynamic CK706 (short shotgun)

I'm waiting on a pair of AKG CK8 next for my continued experiments (and continued gear acquisition!!).

 Richard

Please DO NOT mail me with tech questions.  I will try to answer in the forums when I get a chance.  Thanks.

Sample recordings at: http://www.soundmann.com.

Offline EmRR

  • Trade Count: (2)
  • Taperssection Regular
  • **
  • Posts: 121
    • ElectroMagnetic Radiation Recorders
Re: Shotgun mic test in a poor room
« Reply #21 on: January 10, 2018, 10:34:43 PM »
My only comment on shotguns is a bit of a tangent, I use them occasionally in recording studios, specifically to get the distant sound of an electric guitar amp, as part of an overall multi-mic blend of the total event.  The advantages have outweighed any negative consequences of using them within a small room with close reflections, FWIW.  Adding to it, many times a close mic on an electric amp sounds too clean, and nothing like the sound that congeals at listening distance, and the sound at distance as heard by a MICROPHONE sounds nothing like the way our ears reinterpret it.  I would not be afraid to experiment with a shotgun or two in a poor room, the balance may weigh in favor, but of course, throw up as many options as you can record! 

Offline Moke

  • Trade Count: (2)
  • Needs to get out more...
  • *****
  • Posts: 3625
  • m0k3 - √!n¥¬ 633|<
Re: Shotgun mic test in a poor room
« Reply #22 on: January 11, 2018, 09:36:24 AM »
Here is a pretty decent boundary layer capture, done with DPA4060 pair, spaced ~6', and taped tight to the hard wall face of the theater balcony. Very much of a mid-room recordng.
https://archive.org/details/pso2017-03-19.pso017-03-19_dpa4060-ble_1644flac
https://archive.org/details/pso2017-03-19.pso201-03-19_dpa4060-ble-balcony_flac2448


Shotguns,....
Lets say that I prefer a more musical mic for music, and a more news gathering tool for news gathering.
Sent From My Craftsman Garage Door Opener

 

RSS | Mobile
Page created in 0.172 seconds with 31 queries.
© 2002-2018 Taperssection.com
Powered by SMF