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5:1 setup in small theatre


iDan

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Hi all,

Looking for some advice on putting together a 5:1 in our studio theatre for an 'immersive' event. Surround isn't something I've been required to deal with before and, while I have a basic understanding of required speaker placement in relation to the performance and audience areas, as well as how to route channels to said speaker positions in the desk (in this case, an old DM3200 with surround capability), I'm not sure how we get from a physical stereo LR out from the desk, to the speakers themselves.

I'm imagining there exists a piece of kit similar to a crossover, that takes the stereo out mix and splits it into a 5 way pan (according to how channels are bussed/panned in the desk), and then sends this off to the various amps associated with the speaker sets?

Or am I barking up the wrong tree? 

TIA

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I’m not clear what you want to achieve. Surround ‘5’ is 5 different sound mixes not stereo spread across 5 speakers. For 5 different mixes you would probably use 5 mix busses on your mixer and mix each source into those to achieve the surround effect you want. For example the centre channel may be dialogue heavy and the front left/right pair might emulate a stereo mix of supporting music. The surround rears would be ambience effects.

That wouldn’t be trivial to manage if you were intending to do it live in real time. 
 

Can elaborate more on what you want to achieve, what sound sources you intend to mix and what mixer you have?

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You need a source and a specifically designed amp or decoder and amps for the 5.1 stream.  Lots of amps around, but not cheap.

Then consider - you set the thing up so that sitting in the middle of the room it sounds great.  However, most of the audience are not sitting in that sweet spot.  Don't expect miracles.

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Multichannel sound in theatre tends to be source specific routing rather than surround panning - though setups like Soundscape and PanLab are starting to change that.

Typically, if we want a sound to sound like it is coming from somewhere we put a speaker there and route that sound through it (often called 'spot effect' speakers). We might also 'blend' a little into our main arrays to assist with coverage. If we want a sound to sound like it is coming from a wide area of space, we'd route it to a spread array of speakers (or break that soundscape down into components and route each component to a speaker). Speakers onstage are often far more significant than in the auditorium, as we usually want to place sound effects alongside the action, which is usually on stage.

In a small theatre I'd usually be looking for a strong main L/R array, a centre cluster with some headroom, options for speakers onstage, and then maybe some rear surrounds - acknowledging that not all seats will get the same result from them.

My L/C/R might be on a L/C/R bus, then my spot effects on direct outs, auxes, or busses - depending if I'm only routing QLab to them or if I need to route a mic or reverb return to them.

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I too am a little unclear about the initial question, but the first thing I would want to know is what format the source material is being supplied in and what physical audio outputs that will appear on. So is it, for example, SPDIF (optical or coax) or embedded in an HDMI signal or 6 discrete analogue channels. Once you know that, you can then decide whether your desk already has the appropriate input(s) or whether you need some kind of decoder/de-embedder between the playback device and the desk.

The other common misconception is about the LFE output. This is not a sub-woofer feed. It is interned to be used for low frequency effects only. However, if your 5 'full frequency' channels do not have the capacity for reproducing the required bass response, the LFE speaker can 'double up' as a sub-woofer; this is achieved by high pass filtering the feeds to the 5 'full frequency' channels whilst simultaneously combining the 5 'pre-filter' outputs, feeding those through a low-pass filter and mixing this signal with the LFE channel. In other words, a bit of clever routing/speaker management may be required here.

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This one never ceases to amaze me.

I worked for a company whose main work was video conferencing and presentation rooms. There was, unfortunately, usually a consultant involved and far too often spec'd a 5.1 system, in those days it was commonly Pioneer or Panasonic. The loudspeakers were rarely used and eventually dumped. The main audio source was the mono from the  conferencing system and I recall a certain amount of 'fudging' to get anything coming out of the rear system and stopping the unwanted bass bin spoiling the clarity.

In the bigger companies the presentation rooms could seat hundreds and the spec'd system was simply not up to the job and invariably fed from a failrly basic mixer (without 6 channel capability on a fader).

So moving on 20 years and desks with SPDIF and HDMI inputs is very different for a job I helped set-up a couple of years back, albeit stupid 1KW anplifiers per 7.2 channel for a theatre with 400 seats. We spent ages setting the 9 EQ's to a centre mounted meter which only about 10 people benefited from.

Edited by sunray
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Thanks for the responses. To give a bit more context, this is a training theatre and the sound designer for the show is a student, who is using the project to explore and try out something more elaborate than the typical L/R output. The event in question is a musical so she wants to send her tracks (no live band in this instance) through the venue's existing PA, making use of the current FOH and foldback setup, then add a central speaker for vocals, and two small actives as rear fill for the audience, to which a blended soundscape will be routed. It will not be a professional or in any way 'ideal' setup, but rather a first step towards live surround mixing. Based on the trends emerging from the comments above, it seems the best option is to route audio where required via aux's, buses or directs rather than attempt to employ a true 5:1 system where it isn't really applicable. 

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47 minutes ago, iDan said:

......it seems the best option is to route audio where required via aux's, buses or directs.....

Definitely the way to go. Not the ideal desk for this application - one with lots of groups would make life easier.

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For that scenario I'd absolutely be routing using discrete busses/auxes, and indeed currently have a tracked musical in tech on a similar setup (L/C/R, Subs, Fills, Delays, L/R Surrounds, 4 ch of foldback) on a Digico SD10.

A LCR bus might be nice for your vocals and tracks main output, then I'd probably use auxes for onstage and the rears.

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