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Acoustic screen behind mic against a wall? Condenser Microphones
Old 3rd October 2018
  #1
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Acoustic screen behind mic against a wall?

The title might be a bit cryptic, but here is the situation.

Early November we will have a concert with a somewhat different setup from usual. The room is a box, 15m x 12m and about 5.5m high. As currently planned the band (community wind band) will be sitting against one of the short walls with a large projection screen above. At the other end against the other short wall will be the audience in three tiers (floor, 30cm, 60cm). A large projector ("beamer") will be hanging roughly above the audience from the ceiling (securely, I hope).

I have been trying to figure out how best to record this.

1) Hanging mics above the band from the ceiling might be possible, but would probably require more XLR cable than available. As well as be logistically a bit complicated.

2) Hanging mics above the audience is easier logistically, but that would put the mics close to the beamer. Those things are noisy and have air currents around them with cooling fans and all that, so not ideal. I intend to do a mid/side with the side being one of my AT4081 ribbons, so....

In both cases of a hanging mic the fact that my preferred mid mic is a T12 powered Sennheiser. The Tüchel cabling and necessary adapters would complicate a hanging arrangement further.

3) Putting a stand somewhere directly behind the conductor would probably have people tripping over it, and the mics and mic stand would probably cast a shadow on the screen.

4) Mic stand in the middle of the band (I have done that with some success in the past) would probably be safe, but again it would cast a shadow on the screen.

5) A mic stand at the rear of the room, against the rear wall. That would probably put the stand on top of the top tier (60cm high), requiring very good shock mounts. My Rycote would be tested to the limit. Also, placing a mic with its back against a wall is not a good idea on account of reflections. The mid mic will probably end up being an MKH416 which might have a rear lobe.

Here is the question: In situation 5, would placing one of the acoustic screens used behind a singer's mic behind my mid/side combination alleviate the rear wall issues? Important factor would of course be to ensure that the side panels don't get in the way of the side mic. I am considering this one:

TM-AR1 | OVERVIEW | TASCAM

Not that expensive and collapsible. Not sure if the side panels can be hinged outward to be flatter so as to not block the side mic. It probably isn't designed to do that, but when did that ever stop us, right?

Regards, Christine
Old 3rd October 2018
  #2
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Perhaps a less compromised stand position might be a pair of stands, either side of the conductor with either wide cardioids, cardioids or Omni depending on how live the room is with band and audience present

. In effect they would be in the middle of each half of the band, or in the typical outrigger position if you were running a Decca Tree. What you might expect would be lack of centre of band coverage, and you might overcome this with a boom arm on each stand bringing the mics closer to the centre, actually a wide AB array.

It's not ideal, but if you have control over height, width spacing and mic pattern you should be able to minimise the compromises ? Of course the mics should avoid casting a shadow between projector and screen. Cardioid type patterns should minimise audience noise and rear wall reflections, but may be too close to the front row of players...so experiment with height and rotate the boom arms to help.

Your option 5 may give the best overall blend of the band, but at the distance and height necessary (even with screen behind) you may find the recording lacks presence and focus and sounds a bit too 'roomy'.
Old 3rd October 2018
  #3
Gear Addict
 

Thanks for your thoughts, I hadn't considered the dual stands as you described them. I will give that some thought. At the moment I can't quite visualize how high I will be able to raise the stands before interfering with the picture.

Option 5 is basically a variation of what I have been doing in the recent past. I agree that with a standard cardioid it sounds too distant and roomy. But in my experience using a Sennheiser MKH416 (or MKH816 in an extreme case) as the mid mic makes a big difference.

There will be a dress rehearsal a week before, so I will have a little time to experiment and adapt.

Regards, Christine
Old 3rd October 2018
  #4
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Quote:
Originally Posted by connloyalist View Post
Thanks for your thoughts, I hadn't considered the dual stands as you described them. I will give that some thought. At the moment I can't quite visualize how high I will be able to raise the stands before interfering with the picture.

Option 5 is basically a variation of what I have been doing in the recent past. I agree that with a standard cardioid it sounds too distant and roomy. But in my experience using a Sennheiser MKH416 (or MKH816 in an extreme case) as the mid mic makes a big difference.

There will be a dress rehearsal a week before, so I will have a little time to experiment and adapt.

Regards, Christine
The main reason for recommending the dual stands plus boom arms is to get the mics/stands out of the projector's beam...hopefully they can be adjusted to be just outside the left and right right frame edges of the projected image.

Your supercardioid Sennheiser's could well make M/S workable at the rear wall distance, particularly if it's worked before.

You may even want to swing the boom arms backward (toward the audience) and then angle the mics downward, which would get you a little more distance from the front row of players. Hopefully one or more of these methods will prove viable in your dress rehearsal !

Edit: here's a 'backwards leaning MS pair' pic from Rolo 46 (Roger) to give an idea of what could work for a pair of outrigger-type mic stands, either side of the conductor
Attached Thumbnails
Acoustic screen behind mic against a wall?-rolo-46-ms-pic.jpg  

Last edited by studer58; 3rd October 2018 at 02:46 PM.. Reason: add photo
Old 3rd October 2018
  #5
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Thomas W. Bethe's Avatar
I recorded the Canton Symphony Orchestra who were using three screens above the orchestra and three projectors in the audience for one of their concerts. I used two pairs of microphone (X-Y setup XY Stereo) in positions they would not cast shadows on the screens. Worked well. FWIW
Old 5th October 2018
  #6
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Simmosonic's Avatar
 

Quote:
Originally Posted by connloyalist View Post
Here is the question: In situation 5, would placing one of the acoustic screens used behind a singer's mic behind my mid/side combination alleviate the rear wall issues? Important factor would of course be to ensure that the side panels don't get in the way of the side mic.
In answer to your question, I’m assuming it would work within the range of frequencies the screen is designed to block.

If you had the right mics at your disposal, a pair of forward facing bidirectionals (Faulkner style) would be your best bet for situation 5. In fact, Tony Faulkner describes that same approach when recording in a very reverberant environment - a pair of forward facing bidirectionals with baffles behind them. You can read about in my interview with him, here:

Stereo Masterclass

If I got your dimensions right, it means you would be recording a community wind ensemble that is placed at one end of a 15m long room, with your mics at the other end. The total distance won’t be 15m due to the depth of the ensemble, but it’s safe to say you’re looking at a distance of at least 12m, which is a long way. If you want to pursue that approach you might even want to consider shotgun mics with baffles behind/beside them. If I’ve got it right, the room would be 12m wide and about 5.5m high, so reflections off the side walls and ceiling might be a problem - another reason for going very directional...

Also worth noting that if you’re above/behind the audience you’re going to get a lot of audience noise - phones taking pics, people shuffling in their seats, children who don’t understand the need to be quiet, even just normal breathing - that may be louder at the microphones than the wind ensemble. And finally, projectors are rarely silent; most have a fan or similar for keeping them cool and that’s going to be making a hum in the room’s reverberation while also being directly in the path from the mics to the musicians, and closer to the mics than the musicians. Possibly can be filtered or removed with Rx.

I would consider this approach as a last resort. It has many practical benefits, but I’m not sure you’d leave with anything better than a document of the event for the musicians’ reference. Also, any coincident pair at that distance is going to capture a very mono sound image, and no amount of MS widening is going to change that. You might be better off with two bidirectionals or shotguns, with baffles behind each of them, and space them as required to get some semblance of stereo...
Old 5th October 2018
  #7
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Quote:
Originally Posted by Simmosonic View Post
In answer to your question, I’m assuming it would work within the range of frequencies the screen is designed to block.

If you had the right mics at your disposal, a pair of forward facing bidirectionals (Faulkner style) would be your best bet for situation 5. In fact, Tony Faulkner describes that same approach when recording in a very reverberant environment - a pair of forward facing bidirectionals with baffles behind them. You can read about in my interview with him, here:

Stereo Masterclass

If I got your dimensions right, it means you would be recording a community wind ensemble that is placed at one end of a 15m long room, with your mics at the other end. The total distance won’t be 15m due to the depth of the ensemble, but it’s safe to say you’re looking at a distance of at least 12m, which is a long way. If you want to pursue that approach you might even want to consider shotgun mics with baffles behind/beside them. If I’ve got it right, the room would be 12m wide and about 5.5m high, so reflections off the side walls and ceiling might be a problem - another reason for going very directional...

Also worth noting that if you’re above/behind the audience you’re going to get a lot of audience noise - phones taking pics, people shuffling in their seats, children who don’t understand the need to be quiet, even just normal breathing - that may be louder at the microphones than the wind ensemble. And finally, projectors are rarely silent; most have a fan or similar for keeping them cool and that’s going to be making a hum in the room’s reverberation while also being directly in the path from the mics to the musicians, and closer to the mics than the musicians. Possibly can be filtered or removed with Rx.

I would consider this approach as a last resort. It has many practical benefits, but I’m not sure you’d leave with anything better than a document of the event for the musicians’ reference. Also, any coincident pair at that distance is going to capture a very mono sound image, and no amount of MS widening is going to change that. You might be better off with two bidirectionals or shotguns, with baffles behind each of them, and space them as required to get some semblance of stereo...
Good points. I do own two Sennheiser MKH816's and also a pair of AT4081 ribbons. I have experimented with that in the past. It works decently well. The AT4081's work better close up (or as a mid mic). The 816, as I think is common with long shotgun mics, has some off-axis coloration. Most recently I have been using a Sennheiser MKH416 with AT4081 in a mid-side configuration from about 7 to 8 meters away with very decent results.

Since it looks like we will be doing a rehearsal with mostly the same setup a week before hand I could set up a whole bunch of mics and see which combo works best. My Zoom F8 has 8 channels so plenty of space.

In my usual configuration I am also behind the audience. Height and directionality solves that. But in this case that will put me closer to the projector.

And yes, staying as far away from the projector is important. I do use RX4 if required, but prefer to avoid needing it.

Regards, Christine
Old 5th October 2018
  #8
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Tony Faulkner explains the genesis of his 4 mic phased array, in this video, from 32:20 to 33:25....but before he placed them on a single bar.

What he explains is somewhat the same as I'm proposing...with the mic spacing contingent on avoiding the projected image left/right side frames...and omitting the omni mics.

YouTube

Maybe CM3 or similar cardioid/sub-cardioids would work ok at the spacing necessary ? Also, probably avoiding the angling altogether and point them directly to the mid or back rows of the band (depending on stand height)
Old 6th October 2018
  #9
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Simmosonic's Avatar
 

Quote:
Originally Posted by connloyalist View Post
Since it looks like we will be doing a rehearsal with mostly the same setup a week before hand I could set up a whole bunch of mics and see which combo works best. My Zoom F8 has 8 channels so plenty of space.
That’s going to be very helpful!
Old 6th October 2018
  #10
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jnorman's Avatar
Studer and Tom both have good suggestions. I would probably do a curtain array of 3 wide cardioids.
Old 10th October 2018
  #11
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Christine, maybe a 'mic bridge support' like avillalta has pictured in posting #6 here could help to get your mics out of the way of the projector: Concert in church - but no centre mics....

Or, maybe it would put the horizontal bar directly in the path of the projection beam....only you can know the answer to that.... but it presents an alternative method to those already offered here (and gets your mics away from the projector noise )
Old 3 weeks ago
  #12
Gear Addict
 

Reopening my own thread... As it turns out before the dress rehearsal a scaffold will be set up where the band will be to hang some lights on an "I-beam" directly above the band. I should be able to clamp a small stereo bar to that I beam while the scaffold is up. Or more to the point: I will prepare it on the ground and let someone else climb up to hang it, under my instruction. From that point I shouldn't need more than 10 ~ 15 meters of XLR cable (twice), which I have. I can set my recorder up out of the way against a wall behind the trombones.

Can you please check my math?

The space is 12 meters wide, the band will be using most of that. The beam is 5.10 meters above the floor. Assuming the instruments (the sound sources) are about 1 meter above the floor, that means the band covers about 112 degree field field of view from where the mics will be.

Using Williams that means two cardioid mics at 60 degrees and 25cm will do the trick. Alternatively 90 degrees at 16 cm or 46 degrees at 30cm.

Or would it be better to hang two mics straight down from their XLR cables. That would require a spacing of 62cm (I am using a Neumann app on my phone to figure this out).

I would prefer using the stereo bar because I feel it can be attached to the beam more securely. I have a clamp for such a purpose and we can attach an extra cable to it and the beam in case the clamp fails. If I were to suspend the mics from the XLR cables I would be relying solely on the XLR connector to prevent anyone underneath from being injured by a falling mic.

Regards, Christine
Old 3 weeks ago
  #13
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Hi Christine,

So the I beam is directly above where the conductor would be standing (if it were a symphony string orchestra) ? How wide is the ensemble, compared to its length (imagine you have a helicopter view of the band, from above ?)

Are you now thinking of omni mics, wide cardioids...something else ?

If the dimensions of the band are square like, or wider across the front than deep, you might also consider 3 equal spaced mics, hung from above by their XLR cables ...omnis would be best. Just like the old Mercury Living Presence or RCA Living Stereo from the 1960's

Hanging by xlr's is not bad, just make sure the xlr connector makes a secure click adhesion to the mic, pull on it strongly...and then wrap some gaffa around the connection with the mic (making sure when you squeeze the tape around, that you don't compress and release the spring button !)

A few more options there !

A wind band throws sound forward and upward differently than a string orchestra....you don't want to get too high in the air/ above the band with your mics (especially as your room is quite boxy sounding)....as the brass especially are quite forward-projecting. Is there percussion at the rear ? Any scope for spot miking of those, either from above, or with stands ?
Old 3 weeks ago
  #14
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Wyllys's Avatar
 

"From that point I shouldn't need more than 10 ~ 15 meters of XLR cable (twice)..."

I've seldom been happier than the day I first switched over to single 2-channel cables. With both genders of 5 pin XLR>3 pin XLR x 2, I can send or receive as needed and cut clutter and setup time in half...or better. One of the best investments you can make.

Also consider using right-angle XLR's at the mics to relieve stress and increase directional stability.
Old 3 weeks ago
  #15
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Quote:
Originally Posted by Wyllys View Post
"From that point I shouldn't need more than 10 ~ 15 meters of XLR cable (twice)..."

I've seldom been happier than the day I first switched over to single 2-channel cables. With both genders of 5 pin XLR>3 pin XLR x 2, I can send or receive as needed and cut clutter and setup time in half...or better. One of the best investments you can make.
A good idea Star quad cabling can work very well for this purpose.
Old 3 weeks ago
  #16
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To answer the question as to how large the band is: during this concert we will be about 10 meters wide and 4 meters deep. Percussion across the entire rear. The I beam is just in front of the conductor, over the top of the band. So I would be recording straight down from a front/back perspective.

I can't easily use my Sennheiser MKH406's (the best cards I have) since they are T powered which is too complicated under the circumstances. So I will be using my Advanced Audio CM1084's. I have omni, wide and cardioid caps for them.

The acoustics of the place is poor in a horizontal plane. Vertically it might actually be better, since the ceiling is a type of acoustic, perforated metal type. I have set my mic stand up in the center of the band a few times and the results were pretty good. But I have no idea how this is going to sound.

I am planning on using the CM1084's with the cardioid caps to eliminate as much horizontal acoustic "stuff" as possible.

Regards, Christine
Old 3 weeks ago
  #17
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Quote:
Originally Posted by connloyalist View Post
To answer the question as to how large the band is: during this concert we will be about 10 meters wide and 4 meters deep. Percussion across the entire rear. The I beam is just in front of the conductor, over the top of cthe band. So I would be recording straight down from a front/back perspective.

I can't easily use my Sennheiser MKH406's (the best cards I have) since they are T powered which is too complicated under the circumstances. So I will be using my Advanced Audio CM1084's. I have omni, wide and cardioid caps for them.

The acoustics of the place is poor in a horizontal plane. Vertically it might actually be better, since the ceiling is a type of acoustic, perforated metal type. I have set my mic stand up in the center of the band a few times and the results were pretty good. But I have no idea how this is going to sound.

I am planning on using the CM1084's with the cardioid caps to eliminate as much horizontal acoustic "stuff" as possible.

Regards, Christine
Given your band's substantial width to depth ratio, I'd even more incline towards 3 equi-spaced hanging down mics ....even if you don't have 3 identical mics. Consider a centre Omni to give an overall 1950's 'mono radio' glue, plus outer cardioids to give ensemble width and detail.

If it was a great room I'd suggest 3 omnis but not in this case....3 cardioids will tighten up things nicely, and you can afford to go higher up to the ceiling. Your time to experiment would be limited...however if you mounted 3 rope pulleys on the I-beam, you could simply raise or lower each mic as required.

The 4 m depth means that percussion won't lose detail with spot mics. You might still prefer a near coincident or XY pair, but 3 mics is a viable alternative....if you have sufficient cable length ?

To give more centre width, you could go with central ORTF/XY with outer cardioid flanks all hanging down....but that involves even more cables ! However 10 m is very wide, and without the wider flank mics the outer edges could become fuzzy and lacking in the detail that the centre will have ?

Last edited by studer58; 3 weeks ago at 12:40 AM..
Old 2 weeks ago
  #18
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For the curious, I recorded the dress rehearsal last Saturday. This was with the Williams array, two cardioids 25cm 60 degree angle. Above the band, straight down from a front to back perspective. Roughly a meter or so in front of the conductor.

I can upload a sample later (I am at the office now), but to my ears the stereo image is very good and the acoustics are amazingly dry. So dry that I think it needs some reverb to make it nicer to listen to. But this dry is excellent for purposes of hearing errors in the band's performance (of which there are many).

Interesting how a different angle can make so much difference; in the past in this same space I was always fighting bad acoustics.

The conductor made what I thought was a very nice compliment: with headphones on it sounds like you are there. I must say that when I was doing a quick listen back test on the spot on Saturday I had to check that I was listening to the recording and not someone talking in the room.

Regards, Christine
Old 2 weeks ago
  #19
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jimjazzdad's Avatar
Quote:
Originally Posted by connloyalist View Post
Interesting how a different angle can make so much difference; in the past in this same space I was always fighting bad acoustics.
Congratulations on finally finding a solution for a good mic position in your room; I know that you have been fighting that battle for a long time.
Old 2 weeks ago
  #20
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Simmosonic's Avatar
 

Quote:
Originally Posted by connloyalist View Post
The conductor made what I thought was a very nice compliment: with headphones on it sounds like you are there.
Excellent! Seems like you found a decent solution. I’m keen to hear it if you’re allowed to share it...
Old 2 weeks ago
  #21
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Here is the first 1:30 of a piece called "Nina Rota Film Music". Nothing done to it except normalize it to -1 dB and take it down from 88KHz 24 bit to 48KHz 24 bit. I left 5 seconds before the music starts so you can hear the inevitable compressor from the skating rink next door and the ventilation.

For your mental picture:
Band in a semi circle around conductor. Furthest left trombones, with in front of them trumpets (me on 3rd trumpet here). Near left flugelhorns (replace clarinets in a Dutch "Fanfare" style band). At the 11:00 o' clock position French horns. To the conductor's right hand is supposed to be the soprano saxophone who was taking her bass trombone husband to the doctor to get his head bandaged (he had closed the trunk/boot of his car just a little too quickly). Conductor's 14:00 o'clock position alto saxophones. At the 13:00 position behind alto's baritone and tenor saxes. Far right baritones and euphoniums (strictly speaking all euphs) and right hand corner two bass tuba's.

All the percussion spread out in a line at the back from left to right. The drum set was on the right hand side. If you hear a harp, it is an electric piano on the far right.

And of course, no accounting for the quality of the band.

Regards, Christine
Attached Files

Nina Rota for GS.mp3 (3.69 MB, 129 views)


Last edited by connloyalist; 2 weeks ago at 06:33 PM.. Reason: Typo
Old 1 week ago
  #22
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Simmosonic's Avatar
 

Quote:
Originally Posted by connloyalist View Post
Here is the first 1:30 of a piece called "Nina Rota Film Music".
A very acceptable outcome under the circumstances. Snatching victory from the jaws of defeat! Good one!!
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