Orchestra recording with MK41s

[hagstrom71]

I'm recording some upcoming youth orchestra rehearsals that will be used in short videos about the program.  I'd like to do the best work I can but am also used to working with video where audio gets less setup time, info and support. There are two halls where the rehearsals take place and both have hanging bars I will need to use as I will not be able to use a stand.  There is a larger hall where most of the work will take place and a smaller one where much less recording needs to take place. I will not be able to move the mics from one hall to the other and need to have them both setup ahead of time. I should add that I will not get to hear the Orchestra until after the mics are setup and and will be lucky If I can get the stage hands to lower the bar again and make adjustments.  I certainly will fight for it, but I know I have to be prepared for the least amount of support.

For the larger hall I will use a pair of KM84s in ORTF, and for 2nd hall I have a pair of MK41s that I am not completely sure what setup to use.  I know these are not the ideal capsules for this type of situation, but I need to do the best I can with what I have. I understand that ORTF is meant to be  used with cardioids and not supercardiods. I've read many here mention they use MK41s in a DINa setup, but I know much of this is mainly for concert recordings that involve a PA and not necessarily an Orchestra. I've heard this smaller hall is a very good sounding hall and probably on the drier side. The stereo mic bar hangs near the lip of the stage and only a couple feet behind the conductor.

I've read the Stereo zoom paper a few times and am still taking it in all in. Currently I'm thinking of going with a DINa setup as it sort of makes sense to make the angle 90deg rather than 110deg while using the same 17cm distance. But I wanted to see what others here with Orchestra recording experience think considering the limitations.  It is quite possible I may be the only person who hears any difference in the end with how the audio will be used... but I do enjoy using this as a learning experience.

[celticrogues]

If you have an iPhone (not sure about Android), Neumann makes a really cool app called "Recording Tools".

It provides a graphic representation of how changes in the microphone angle, distance, and polar pattern affect the recording angle.

The app makes it very easy to, for example, start with a known quantity like ORTF and change the polar pattern to supercardioid or hypercardioid, and will then display the appropriate microphone distance and angle to make the pickup area the same as ORTF.

-Mike

[voltronic]

Good to have another kindred spirit here.  I'm a classical recordist who usually records student groups, and I too rarely have a chance to hear them prior to the recording or move the mics after they've been set.   

If you have an iPhone (not sure about Android), Neumann makes a really cool app called "Recording Tools".

It provides a graphic representation of how changes in the microphone angle, distance, and polar pattern affect the recording angle.

The app makes it very easy to, for example, start with a known quantity like ORTF and change the polar pattern to supercardioid or hypercardioid, and will then display the appropriate microphone distance and angle to make the pickup area the same as ORTF.

-Mike

They do have an Android version; I've used it often.  There's also the Sengpeil visualization tool.

Even deeper (but a bit steeper learning curve) is the Schoeps Image Assistant.  I use the browser version, but there is an iOS app as well.  Keep in mind that this app is based on different research so the numbers you will get are slightly different from the above tools.

I think Mike is giving you good advice on starting with ORTF and finding the equivalent with your hypers.  I played around with these tools and in order to get the equivalent SRA to ORTF, it seems your best bet is narrowing the angle to 90 degrees and the distance to 14 cm.  And what do you know - that's DIN-A spacing!  If you kept the mic angle at 110 deg, you'd have to close the distance to about 7 cm, and then you have almost no time difference component with the capsules being so close to coincident that it probably isn't going to sound very ORTF-like.  Probably not great. 

Hypers are really not the greatest choice for this recording situation, but it might be OK.  I'd definitely use them in the smaller hall if push comes to shove.

I strongly encourage you to borrow or rent a pair of good omnis for either or both halls if the acoustics are any good; or put your KM84 ORTF pair in the small hall and the omnis in the large hall.  In the typical orchestra mic position of just behind and high above the conductor, you can get excellent results.  I'd recommend a spacing of 50 cm as a starting point, widening to 60 cm if you are back just a bit farther and I've had success as narrow as 40 cm when I needed a very wide image.  This post has examples of of that narrow spacing for large chorus with orchestra.

[if_then_else]

If you have an iPhone (not sure about Android), Neumann makes a really cool app called "Recording Tools".

It provides a graphic representation of how changes in the microphone angle, distance, and polar pattern affect the recording angle.

The app makes it very easy to, for example, start with a known quantity like ORTF and change the polar pattern to supercardioid or hypercardioid, and will then display the appropriate microphone distance and angle to make the pickup area the same as ORTF.

-Mike

FWIW: There's also the Neoduction tools suite for Android.

https://play.google.com/store/apps/details?id=com.neoduction.tools&hl=en

[opsopcopolis]

I strongly encourage you to borrow or rent a pair of good omnis for either or both halls if the acoustics are any good; or put your KM84 ORTF pair in the small hall and the omnis in the large hall

+1

[hagstrom71]

Thanks for all the suggestions and links to various tools.  I've used the  Sengpiel visualization tool, but never seen the ones by Neumann,  Schoeps or Neoduction.
I like the idea of substituting supercardiod for cardiod and adjusting angles and distance to see the differences in SRA.

I strongly encourage you to borrow or rent a pair of good omnis for either or both halls if the acoustics are any good; or put your KM84 ORTF pair in the small hall and the omnis in the large hall

I've been considering renting another pair of mics or capsules as it obviously makes the most sense to use the proper equipment. There are a few challenges with this at the moment, but I am going to try to make it happen.  If it does I may have to go with another pair of cardioids and an ORTF setup.  I'd love to try a pair of omnis, but the existing bars are very short unfortunately.  I'm also not so sure that the larger hall sounds very good, but it would be very interesting to hear the difference. I wish I had the time to try multiple setups and evaluate but of course this is not an option.

Thanks for all the contributions!

[voltronic]

I strongly encourage you to borrow or rent a pair of good omnis for either or both halls if the acoustics are any good; or put your KM84 ORTF pair in the small hall and the omnis in the large hall

I'd love to try a pair of omnis, but the existing bars are very short unfortunately.  I'm also not so sure that the larger hall sounds very good, but it would be very interesting to hear the difference. I wish I had the time to try multiple setups and evaluate but of course this is not an option.

How short?  I find it hard to believe that if there is a mic bar flown in a hall, that they would bother with one shorter than 60 cm.  And as I said before, 40-60 cm is going to be your sweet spot with a main pair of spaced omnis in this situation.  It's also very quick and easy to attach a longer mic bar to a shorter one using a couple 3/8" bolts and wing nuts.

More omni inspiration, this time from a professional classical recording engineer.  Mic 2 in these samples is a pair of DPA 4006 omnis in exactly the arrangement we're talking about.

[2manyrocks]

How are the acoustics in the larger hall?  If it has greater reverberation time, perhaps use the 41s there? 

[hagstrom71]

How short?  I find it hard to believe that if there is a mic bar flown in a hall, that they would bother with one shorter than 60 cm.

It was surprising to me as well..  the spacing of the mounts in the large hall is only 4" and the handmade bar is about 12" long.
It turns out that anyone who records anything serious brings in their own rigs and gets much more time/support than I'm getting.
Regardless, I've rigged it for ORTF with KM84s as planned as I knew I could do it quickly. With more time I know I could attach another bar
to the existing one and mount omnis.  But I'm doing several different audio jobs for this client and do not have time to experiment at all unfortunately.
If I work at this location again, I will certainly know my options and be able to prepare in advance if I do want to try spaced omnis in the large hall.

I hung the 41s in the small hall and have not heard a single note yet. I have a feeling not much will get recorded in there. 
The hang is so close to the conductor that I would love to try spaced Omni's in there and plan to rent or borrow some in the coming days.

How are the acoustics in the larger hall?  If it has greater reverberation time, perhaps use the 41s there? 

The Larger hall does have a greater reverberation time. Since this hall is getting the majority of the playing time, I felt it would be safest to use the ORTF KM84s in there as the stage and size of Orchestra is much more spread out.

Fortunately it looks like there is another event coming up soon in a totally different environment where I will be able to use stands and rent some mics and not have to deal just with what I have on hand.  At the very least I will get some experience listening to the various stereo setups even if in totally different environments

More omni inspiration, this time from a professional classical recording engineer.  Mic 2 in these samples is a pair of DPA 4006 omnis in exactly the arrangement we're talking about.

The recording you linked sounds amazing and inspires me to consider spaced omni's whenever possible.