Stereo setup: LCR's C a must or useless?

[Fred Salles]

Hi, More and more colleagues sound recordists are using LCR stereo setup nowadays for wide ambient wild recordings, and many post-prod sound editor and re-mixer say that without the C they feel an "hole" in the middle.

Being an ORTF setup (LR) long time fanatic I often argue that it depends how you choose to record the space you want to hear.

I have tried it several times but always ended up listening to LR only as -mixed in a LR hearphone- wide spaces sound mushier. I found the C useful for proximity stereo recordings but for wide ambient I do not see the point. I know it is still an ongoing debate.

What are your opinion on it, location sound or post-prod sound friends?

[The Immoral Mr Teas]

Neither a must nor useless for me Fred - or rather I'm inclined to agree somewhat with your comment,

"I found the C useful for proximity stereo recordings" and am sympathetic to,

"but for wide ambient I do not see the point".

 

I agree wholeheartedly with,

"it depends how you choose to record the space you want to hear" (or rather; how you wish to hear the space you need to record).

 

I have recorded much specific multichannel FX for features and there are certainly many instances I have gone for LCR when I'm trying to give a realistic and high clarity acoustic image particularly when fitting or matching to picture. My general preference and starting point would be spaced omnis for this sort of thing.

 

For multichannel ambiences I would (following your reasoning) often plot a simple 4.0 quad against setting up some kind of 5.0 or 5.1 rig, although in some situations the C of a 5 point recording could be beneficial or even necessary if there is some strong frontal information to convey. (Again, I like spaced omnis but have a lot of time for crossed cardioids - an IRT Cross - for general 4.0 multichannel ambiences). Often one is asked specifically for 5 channel, sometimes I was asked just to cover particular sounds and ambiences ('sounds' very often being mono).

 

We have got used to thinking of stereo as a 2 channel thing, largely because of music which, when played reproduced rather than live, would more often than not be played in a relatively small space. Film theatres, at least in the glory days, were grand auditoria. Stereo records were (/are) a particular (rather ingenious) medium and as a result gave rise to many other previously mono media such as radio and television moving from one to two channels. When stereo film sound was in its infancy however experiments were done from the very beginning on different numbers of channels for auditory perspective and localisation (eg Steinberg, Snow and Fletcher all at Bell Labs, and others elsewhere) and it was generally agreed that 3 channels were noticeably better than 2 but after that improvements to perception dropped rapidly. So 2 channel reproduction (or recording) never had a look in for the large screen when stereo (and its high cost) was eventually embraced: of course (... and a while after Fantasia and its multichannel system designed for presentation of the music rather than dialogue driven narrative ... ) by the 1950s film stereo went hand in hand with super wide screens too to compete for audiences (so more channels sometimes across the front as well as rear and side).

 

So its probably best to remember, despite the usefulness and quality of results of various 2 channel recording techniques, that they were generally born out of recording angles designed for 2 channel music reproduction.

 

Jez

 

[Fred Salles]

Thanks Jez.

Anyone else recommending recording stereo ambient with LCR setup rather than LR classic ORTF ?

 

Btw what cable do you use? I have been doing some research and have not found yet a proper cable with 3 pairs and a suitable ext. diameter.

 

[Sebi]

I think or sort of learned that most stereo recording techniques that come from the music recording such as ORTF, MS, small AB, etc... have the disadvantage of requiring a listener in a sweet spot. Since only a small amount of seats in cinemas are actually in this sweet spot, these ambiences can fall apart very quickly and the listener will locate it towards the direction of the nearest speaker. Same with music that is just played LR in a theatre setup.

So yeah, I think the center channel can make sense to focus the sounds more towards the screen and blend the ambience with the dialogue. Another approach might be a spaced pair with a rather large distance between the mics to de-correlate the LR signals. It's not the prettiest stereo-image for headphones or a proper speaker-setup but it helps to widen the "sweet-area" of the listener in theatres.

Unfortunately a spaced pair is not as handy for field recordings as a ORTF or MS in a single blimp...

[The Immoral Mr Teas]

5 hours ago, Fred Salles said:

 

Btw what cable do you use? I have been doing some research and have not found yet a proper cable with 3 pairs and a suitable ext. diameter.

 

 

I have no 3 channel cables, Fred (aside from a handful of stray ends I did nothing with). Virtually all my cabling is Mogami 5ish mm quad. I have a couple or so 5pin leads, the main (nicest) being a Schoeps original. I was fairly interested at Ambient's stereo curled cable - I have a couple of Ambient poles - but am in no immediate hurry to fork out the cash for something I don't need (as an editor who sometimes records effects).

 

Though I'd be interested in any results of tests on different multichannel cables for the future ... thinner 2-4 channel and/or thicker 4-8 channel - for flexibility, handling noise, ease of soldering, interference rejection etc

 

(though probably separately in Equipment, Discussion or DIY rather than here?)

 

Best, Jez

 

[Fred Salles]

On 5/29/2023 at 5:37 PM, The Immoral Mr Teas said:

 

(though probably separately in Equipment, Discussion or DIY rather than here?)

 

Best, Jez

 

Good idea, I post it there now.

 

On 5/29/2023 at 3:34 PM, Sebi said:

I think or sort of learned that most stereo recording techniques that come from the music recording such as ORTF, MS, small AB, etc... have the disadvantage of requiring a listener in a sweet spot. Since only a small amount of seats in cinemas are actually in this sweet spot, these ambiences can fall apart very quickly and the listener will locate it towards the direction of the nearest speaker.

True, but that is why we have learned to record ambient sound that bring space but do not have significant event. Significant I mean that serve the narration or just would attract attention. We record these as mono wild or fx for post to put in the space as required. For exemple for wide ambient  of Wind blowing in a forest it does not matter where you are seated if the Left and right are well balanced. 

Also we record ambient that do not necessarily require sweet spot and if there are small events they must have no problem being played to the audience seated closest to the speaker (ex. A dog barking very far away).

In fact, any sound even mono being sent in a specific speaker will be perceived differently depending on where the listener is seated. So maybe actually (thinking out loud now) the sweet spot issue applies anyway for any setup. I mean re-recording mixers rarely work too far from their sweet spot do they?

[Rick Reineke]

How about a three or four-channel snake cable. I have an old 3-channel snake that is about 6 or 7mm diameter. It is not super flexible though. I will look at the model # when I can.

[Fred Salles]

Hello, after some research and reading I came up with more questions rather than conclusions:

 

1- I see now why I am never happy with the results of recording with an LCR portable setup, like the Cinela Albert Tri, the only one available afaik: the mikes are way too close to each other to make a proper LCR without phase issues. Adding a center mike to a ORTF setup is actually a non sense in term of phase correlation. Cinela themselves acknowledge or rather warn on their page that it is not an LCR setup per se but an ORTF with an extra center mike... https://www.cinela.fr/gammes-de-produits/albert-windshields/albert-windshield-for-ccm-ortf-xy-tri/

All test and reviews I could find agree that the L&R mike should be 80 cm apart from each others or a minimum of 35 cm with an angle of 160°, with the center mike being placed a bit forward, not aligned with L&R. Anyway that calls for some tests that I have not done yet. In any case nothing practical on set seems to be possible.

 

2- It seems a post-production solution from a LR recording is actually more suitable, with a software that create a usable center channel without phase correlation. Apparently very few soft/plugin are capable of that and not just a basic M/S process that always brings crazy spacial issues. So far I found only Waves Center and this one, AOM Stereo Imager D :  https://aom-factory.jp/products/stereo-imager-d/

The latest has good reviews on forums. Any of you post-prod guru friends are using it or tried it? Just your thoughts would be welcome as well 😉

 

[Rick Reineke]

Check out the Sound Redux Auto Align which is specifically for phase issues. Imager plug-ins are more for widening and/or creating a spacial stereo effect than a repair tool. The imager tool can be used to collapse a stereo field, but that would make an out-of-phase issue even worse.

FWIW, iZotope has an free 'Imager'  plug-in which is similar to the above mentioned. It is also included in most versions of  iZ's 'Ozone'.