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Ambience recording with a Frankensteined surround tree


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I'm frankensteining together a surround tree with a Mid-Side front and an almost-ORTF (ORTF with hypercardioids) rear.  I'm using it for ambience recordings for what will ultimately become a 5.1 theatre mix for an indie film.  The sound designer is more than happy to accept any form of multi-channel ... he was pleasantly surprised and very enthusiastic when I told him I was capable of doing this setup.

I've done next to no 5.0 recording, but I know a little bit in theory.  I know what I'm doing doesn't really fit into standard practice, but I also know there's close to a dozen varieties of mic configurations that get used, so I'm assuming there's some room to play.  I'm doing this with the mics that I have (i.e. hypercardioids and shotguns), not the mics I want, so I'm sure that will affect things as well.  There's no way this would pass muster for music recording, but I think for ambience it should work well enough.

My mid-side is Sennheiser:  MKH30 with either a MKH50 or MKH60 in the middle.  The ORTF is a pair of Neumann KM150s.

I'm looking for opinions on a couple things:

1. What's a good front-rear distance between the Mid-Side and ORTF pairs?  I typically see 45-60 cm, but I don't think Mid-Side front & ORTF is a particularly common pairing (probably for a reason, but, again, I'm using what I have).

2. Suggestions for the Mid mic:  MKH60 or MKH50?  My assumption is that MKH50 will be more natural, and will probably be my first choice, but is there any merit to using the MKH60 to provide a more distinct centre channel?  Would that be useful in a theatre mix?  I'm not planning to record any particular subject, just ambience, so I'm imaging all the MKH60 will do is create phase imprecision ... but then the whole setup is pretty janky.

3. Any reason to consider X-Y instead of ORTF for the rear?  I'm not sure if I should be worrying about mono-compatibility for all channels (and I'm assuming the non-coincidence between front and rear will be more serious than the 17cm between the rear pair.

4. I don't imagine the Sennheiser / Neumann split will match very well (the Sennheisers are quite dark, and the Neumanns are spicy and bright).  Any suggestions for how to mitigate this?  Or should I just leave it for post?

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If you're using hypercardioids consider the nulls: that 180 deg is actually a pickup, but there's a null either side of this. Consider this (along with distance) when positioning (designing your tree) and you may be able to heighten definition (minimise crosstalk) over the surround pickup area. What I'm trying to say is that difference between front and rear, or specifically between L-C and Rs and C-R and Ls, may be more important than thinking of the stereo pattern of the rear.

 

And I would start my thinking with omni, or sub-cardioid, for C ... so are you really stuck between the choice of 50 or 60?

 

And all that said, if it were for me, I'd probably flip the recordings around, so I had the 'ortf' at the front and the ms at the back ... so maybe sit down again with the post guy, outline the possibilities (mics, channels, windproofing) and decide from there.

 

Nothing beats an IRT cross btw for simplicity and usability when it comes to ambience, so if you had a second MKH 50 I'd consider foregoing the MS and go that route.

 

Jez

 

 

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Thanks!  My mic locker is pretty limited, so yes, I'm stuck with hypercardioids everywhere.  I'm eyeing some AK40 capsules for the Neumanns so I at least have cardioids to count on in the future, but I won't have those for this gig.  It's a learning gig for me, and post is grateful for whatever I send back ... they weren't expecting anything other than mono or at most stereo tracks.

I think you are right about swapping the direction ... I like the directional tracking of ORTF better than MS, but unfortunately, then my centre channel (mid) ends up facing backwards, and I'd have to add a mic to the middle (and then widen the side mics into a more conventional tree?).

I'm just dipping my toes into surround, so this is what I've got for now ... thanks for widening my horizons!  I'll have to get a second MKH50 try an IRT cross at some point!  I'm basically just using what I have as a way to learn a bit more about it and hopefully I'm more informed next time.

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9 hours ago, The Documentary Sound Guy said:

I think you are right about swapping the direction ... I like the directional tracking of ORTF better than MS, but unfortunately, then my centre channel (mid) ends up facing backwards, and I'd have to add a mic to the middle (and then widen the side mics into a more conventional tree?).
 

 

Frankly the C channel for ambience often isn't even a 'plus' and a good strong LR with LsRs would be gladly taken by post (particularly if the C in question is highly directional and of 'irrelevant' information).

 

9 hours ago, The Documentary Sound Guy said:

I'm just dipping my toes into surround, so this is what I've got for now ... thanks for widening my horizons!  I'll have to get a second MKH50 try an IRT cross at some point!  I'm basically just using what I have as a way to learn a bit more about it and hopefully I'm more informed next time.

 

Yep I get that, I just thought it might be the case you had a second MKH50 so suggested that.

 

 

I'm not a great fan of MS for film (big theatre LCR+ combinations) but concur it might sit better in broadcast and documentary roles. That said, if the 5 mics are what you have and nothing more, and assuming you can record 5+ channels, I would consider a Bride of Frankenstein rig comprising Matthais' MSM and a frontal 'ORTF-ish' L-R; with the Neumanns up front for Left and Right, the MKH50 facing forward and the 60 backward in the MSM (the rear being less important a component for definition thus the least critical mic). And then they have the option of using (frontally) the MSM rig either as a M-S (LCR) decode or just the raw MKH50 as a Centre (and of course the rear M-S will be there for them as well).

HOWEVER - this would be messy to receive as a sound editor / rerecordist IF it wasn't absolutely explained what it was, and why (= available mics etc) so ABSOLUTELY MAKE SURE to talk such an option with Post before you go ahead. (If I, as editor/mixer, received such tracks unannounced, unexplained, I would probably figure the LR were useful and ignore the rest!) Also, I'd set it up and have a try out first: any Frankenstein setup, Bride, Son or Meets Abbott and Costello, can end up being so unwieldy that in the field and in different conditions (and certainly 'on set') they may prove an ultimate headache.

 

J

 

 

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8 hours ago, Matthias Richter said:

another option would be double MS


Double MS is actually my preference.  That would massively simplify things.  But I can't fit the third mic in my zeppelin with any sort of coincidence, and I don't think close is good enough for MS matrixing.  Eventually, I hope to build a permanent DMS rig for this kind of thing, but it will mean switching to less chunky mics.
 

 

5 hours ago, The Immoral Mr Teas said:

Frankly the C channel for ambience often isn't even a 'plus' and a good strong LR with LsRs would be gladly taken by post (particularly if the C in question is highly directional and of 'irrelevant' information).


This is good to know, and it makes good sense to me.  I think in the future I will aim for 4ch ambience rather than 5, either with DMS or two back-to-back pairs.  I think I kind of knew this in the back of my head because I know the centre channel is mainly used for dialogue, but my inexperience in post and ambience recording convinced me I needed to record a separate centre.

At this point my shoot is happening today, so I'm committed to the frankenmic that I cobbled together last night.  No time for configuration changes at this point, but I'll be able to experiment with putting the ORTF forward.  I'd imagine it will be a flawed experiment, but at least I can give the editor a front and a back pair, and they can ignore the centre channel or lack thereof.

Thanks for all the suggestions ... I wish I had more time to incorporate them all.  I've learned lots already.

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Well, that was an interesting experiment.  I probably won't do it that way again, but it was interesting.
 

I was plagued by issues that weren't to do with the mic configuration ... My Neumanns are susceptible to RF interference, and I had an unshielded 10" jumper cable on one that made it that much worse.
 

Then, the bar I was using to mount the array had holes in it and started turning into a flute in the wind.  And my wind protection wasn't really adequate overall (especially for the ORTF pair).
 

Add in a location that didn't justify a 360° recording, and it was a disappointing day overall.
 

I don't think I'll use hypercardioids again ... the rear lobe really muddies things.  And I think I even prefer my shotgun as centre channel in Mid-Side, and I didn't think Mid-Side and ORTF complemented each other very well.  I like Mid-Side for the convenience, and I might build a double-Mid-Side rig for lightweight surround recording in the future, but it's clearly not the best choice.
 

So ... learned a lot.

One last question:  Is there any good way to monitor a surround setup using headphones?  How do people monitor this in the field?  I had front, rear and a stereo mixdown as headphone presets, but I didn't feel I got a good sense of what I was doing.  Maybe that just comes with experience.

 

 

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I recall two recent movies from the cinema where the surround sound truly had a real effect for me:

Killers Of The Flower Moon:
https://www.mixonline.com/sfp/inside-the-sound-of-killers-of-the-flower-moon
Here, I liked everything.

Furiosa: A Mad Max Saga:
https://enhanced.media/blog/2024/6/24/the-sound-design-of-furiosa-a-mad-max-saga
Here, I really liked the engine sounds- they made a strong impression on me. Well done!

Of course, there are other movies, but not all are memorable, especially if the effects aren't special.

You should also have an appropriate room for playback - how else would you check it?

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I have done a lot of DMS surround recording and often really like the results. It’s especially suited for interior ambience and close micing like moving trains etc. I recently got the chance to do a steam locomotive which was really fun!

For nature ambiences i usually find coincident techniques to be too close together.  The whole surround image ends up small and doesn’t feel very immersive. Wider spaced techniques have more feeling imo. A double ORTF or similar in a single rig creates a nice large envelope without having a hole in the center. You can add a spot mic for the center for locations that have a distinct feature like a stream in the foreground.  Also great for passby’s like motor sports. 
I’ve also been really happy with spaced omni’s for forest recordings. Even 5 DPA 4060 can get a great, wide, and immersive recording. And it makes wind pro easy since each mic can have its own zeplin / fur. 
 

For monitoring i listen to pairs. F stereo, R stereo, spot check. Doing a lot of ambisonics work i played with doing surround mix downs with hrtf’s to try and replicate the surround monitoring and it never worked for me.  Listened to the pairs translated the best and helped me identify any issues that came up. 
 

One thing I’ve found is the left right relationship is very important, but the front back relationship is much less so. So i see no problem having different mics on the surrounds.   Of course your experience could end up very different than mine, and the environment you are in could change everything. 

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All that tracks with my experience.  I was doing mainly exterior ambience with no obvious directionality, and I think I would have been better served with 2x ORTF, or perhaps the IRT cross for what I was doing.

I'm very keen to set a double MS setup going, because I think that would be most practical for me to carry with me on regular shoots.  What mics / wind protection were you using?  I wish I could find a rig that would accommodate my all my MKH mics, because heavy as they are, they are quiet and bulletproof.  I might have to consider jumping to the 8000 series now that the 8030 exists.

I've also heard a DMS setup for a guitar-playing singer-songwriter type setup, and I absolutely loved what that sounded like.

 

Interesting thought about using lavs as spaced omnis.  I hadn't thought about that for ambience, though I've considered doing it for music / choral.  The downside for me is I don't have the capability to run them all hardwired, and I'm using Zax wireless, which makes me hesitate to use them for music because I lose the half octave above 16K at the top.  It probably doesn't matter for casual usage, but I'd prefer not to be in that situation for professional recordings.

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Your experience trying to get clean wide-angle or surround ambiances while doing production sound on an indie movie is pretty much how it always went for me.  The locations were almost never suitable for this kind of recording at any time of day, and certainly not when the rest of the crew was there.  For this to really work there has to be some sort of buy-in and support from production (and post, if they have been hired while you are still shooting).    There are some useful ambiances and sfx you might could get after the rest of the crew has left a location, but on a union job your extra work has to follow the contracted work rules and hours.  On non-union indies I spent a lot of free time trying to get extra sound after hours but would have to admit that we often weren't very successful.  If there are specific requests from post then you can take those to production and get yourself on the official shooting schedule.  Doing this will get you AD Dept support and maybe even grip assistance as well.  That's the best way to do it and get what post actually wants.

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Yeah, that's pretty much exactly my experience.  The best luck I've had was on a documentary in a remote location, and we were able to designate "ambience recording" time slotted in whenever camera was shooting B-Roll.  We would coordinate to be close but far enough away that I couldn't hear them (>1 km most of the time), and I had several blocks lasting an hour or more to find interesting ambiences.

This past weekend, I was hired as "swing" crew to help out when camera needed me, and the rest of the time I was able to move around the location independently and find what I needed.  I had the better part of a day and a half to myself.  I didn't get everything we wanted because we were filming in a resort town and the more "pristine" ambiences that we wanted simply didn't exist.  But we definitely got a decent amount of usable recordings.  I'm very curious to find out how much post ends up using.

In both cases, I had support and a rough wish list from post.  I'd say less than 10% of my clients are organized enough (or well funded enough) to take advantage of it, but I'm getting better at making clear how and when it can be done.

I've also managed to get some very unique ambience recordings on an arctic documentary where I was able to record away from camp a little bit.  That one was difficult because I required a guide to escort me for safety when I was out of visual range of camp (and when I was in visual range, I could hear the camp).

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For narrative I keep a Schoeps DMS rig in a Cinella Pianissimo. Cmc4 for the center, ccm8 side, ccm4 for the rear, recorded on a mixpre6. It sounds killer and is really flexible. I mostly end up using it for pfx work, cars etc. I try to identify the vehicles that play a character in the script, or have a unique sound that will be hard to design from stock libraries, and then coordinate with production to get half an hour with a driver to get as much as i can.  Most of the time i don’t bother trying to get ambience, it’s almost impossible to get far enough away to get a clean bed when recording 360.    That being said I’ve done a couple shows in the woods and have been able to run the mic out on a tripod and drop it in between setups and get some really good stuff. A recent project we spent 5 weeks in the forest filming and i was really happy with some of the ambience i got. It comes out on Netflix later this year, I’m really excited to hear how it came together. 

17 hours ago, The Documentary Sound Guy said:

  What mics / wind protection were you using?  

 

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