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Author Topic: Let's talk about variable acoustics systems  (Read 13717 times)

Stefan Maerz

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Re: Let's talk about variable acoustics systems
« Reply #10 on: February 10, 2014, 01:52:45 PM »

Thanks for the Explanation Tom. Your comments agrees with what I've learned about reinforcement design.

"Electronic enhancement" is new to me -- could someone explain how this is done? I work at a venue that has Variable acoustics in the form of drapes. I've heard stuff about Meyer's technology, just never understood it.
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Tom Young

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Re: Let's talk about variable acoustics systems
« Reply #11 on: February 10, 2014, 03:49:03 PM »

Thanks for the Explanation Tom. Your comments agrees with what I've learned about reinforcement design.

"Electronic enhancement" is new to me -- could someone explain how this is done? I work at a venue that has Variable acoustics in the form of drapes. I've heard stuff about Meyer's technology, just never understood it.

I'll take a crack at it.

Many of the principals, or goals, of enhancement systems (and the components used) are completely counter to what we do for sound reinforcement and recording. Think about what reverberation is: a huge number of reflections that arrive from all directions, at all sorts of levels and at all sorts of differing arrival times. These reflections differ spectrally, as well, due to air losses and other absorption effects. Early reflections (which are closer to discrete echoes, not reverberation) are also required for the performers as well as the audience.

You install very high quality microphones, usually suspended, above the stage or platform. One of the goals is to NOT highlight any specific sources, so omnidirectional mic's are employed. Plus they must not be seen, so they are (ideally) pretty high up. These are fed into mic preamps and then into the DSP. Within the DSP the signals are routed to many outputs and these are delayed based on where the speakers are located. These DSP channels are gain-set and also equalized and may be phase-manipulated or fed through digital reverb (depending on the system). The outputs feed power amplifiers which feed fullrange loudspeakers and subwoofers.

The fullrange loudspeakers are not necessarily aimed directly towards specific seating areas and some (as many as half) are aimed away from the audience and into architectural elements (ceiling, walls, decorative surfaces) to create (real) reflections. Although the speaker elements may be located in out of the way positions (to hide them) the system needs to be symmetrical so that each side of the space sounds the same and set up so that the front to back sound behaves naturally. The fullrange loudspeakers are not required to be directional nor is it desirable to have pristine performance such as flat amplitude response, perfect phase response, etc. In many cases, the enhancement system and specifically the loudspeakers, must be hidden. So they are usually quite small (usually bookshelf speaker size or even smaller). Subwoofers are used to extend the LF response, but fewer are required. Although these systems are seldom really loud, they must be able to handle the dynamic range (peaks) of the sources, if only for fractions of a second.

Disclaimer: I can guarantee you that I will be corrected by a representative of one of these technologies. I have described what goes on fairly well but (largely because I very seldom work with them) I tend to forget some important little detail or difference in technique.

Commissioning one of these systems takes lots of time and a pretty thorough knowledge of natural acoustics and the enhancement system. In some ways, the people who commission these systems have more control over the various parameters of the sound field than the acousticians who design a performance space do.

LARES has some great papers:  http://www.lares-lexicon.com/welcome.html

go to Library, then Scientific Papers and read Griesinger's "Improving Room Acoustics through time-variant synthetic reverberation"

Meyer Sound has a brochure on their Constellation system: www.meyersound.com

a cool video about a Constellation system installed for changing the background noise levels in a restaurant is here: http://www.youtube.com/watch?v=f-QFK-IpkM8

Yamaha info is here:  http://www.yamahaproaudio.com/global/en/products/afc/

SIAP is here: http://www.siap.nl/en/
« Last Edit: February 10, 2014, 03:57:01 PM by Tom Young »
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Ville Kauhanen

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Re: Let's talk about variable acoustics systems
« Reply #12 on: February 10, 2014, 04:27:55 PM »


Are there any white papers that I need to read up on on the concept in general (i.e. non manufacturer specific)?

I have somewhat limited experience with the electronic variable acoustics systems available but I'm interested in these and would like to participate on the discussion. I’ve only heard Meyer Sound Constellation and Yamaha AFC3 in real use. To my experience and information Meyer Sound Constellation is by far the best of the complete systems available. It is also the most expensive (of course depending a lot on the room and system configuration). The quality and success comes due to several things. To me one the keys to their success is that they work really hard on the design and they will just not sell a system to a room that is not acoustically suitable for the system. They would like to be involved in the design of the room acoustics as soon as possible since they don't like to participate matches they can't win. The room must be acoustically suitable for the system for them to start a design for Constellation system. Also their hardware (COMPLETE signal chain) is really high quality.

Other systems in my experience can work fairly well for one specific purpose in a room if the goal is clear and it is achievable with the room/system combination. What I like in Constellation is that from all the systems available it is easiest to use as a "acoustic enhancer" just to add some reverberation to make the room more suitable for some specific program material AND you can use it as a creative tool to create unnatural (but very realistic/good sounding) effect like acoustic sensations for specific parts of program material.

Although written by Ron Bakker the Systems Marketing Manager of Yamaha Commercial Audio Europe this document is the best single presentation I've seen on this whole subject in general:

http://download.yamaha.com/api/asset/file/?language=en&site=countrysite-master.prod.wsys.yamaha.com&asset_id=58479

I've met Ron and seen his presentation a couple of times about the Yamaha AFC3 system. I've heard the AFC3 system in demo and in real use. It is clear after seeing Ron's presentation and hearing and seeing the system that Yamaha has done a lot of research on the subject. This paper is basically about the AFC3 but there are some very good explanations regarding the systems and how they roughly work. I say roughly since the use of DSP is the key parameter in all the systems available and that is very complexed and large subject itself.

One interesting piece of information about these systems in general can be seen on the FIGURE 5. on the document that lists all the professional products on this market from 1955 to this day. Almost even more interesting information is the number of systems installed by each manufacturer. This is the small number on the left of the brand name. This document states that there would be 28 V-RAS/Constellation systems installed. OFCOURSE this document is prepared by Yamaha but I personally believe that while these numbers might not be EXACT numbers they give an idea about the market shares between the systems available. And it also tells that there are not so many systems in use globally.

Yamaha released the current version of their AFC system in 2012 and while the AFC 1 and 2 were only available in Japan and US they now work hard in bringing the AFC3 available in Europe as well.


I personally think these systems are the future. Not sure how far though. Before these kind of systems can become more common acoustics design of performance rooms need to come as important part of (re-)construction projects as strength calculations and the colour of the flooring/carpet.

-v
« Last Edit: February 10, 2014, 06:26:50 PM by Ville Kauhanen »
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Ville Kauhanen

Justice C. Bigler

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Re: Let's talk about variable acoustics systems
« Reply #13 on: February 10, 2014, 05:06:18 PM »

To add another question to the discussion...

How suitable are these kinds of systems for existing rooms that may or may not already have acoustical problems with the hard and soft surfaces?

If one were to go through the trouble of doing a complete retrofit of the absorption, diffusion, and reflective surfaces in the room would it make an electronic enhancement system more or less suitable to address the issues in the room? And if so, would I be correct in assuming that both the hard and soft surfaces should be designed along side the electronic system?

When I was speaking with the Meyer Training Rep in April, he did mention that they are installing a lot of the Constellation systems in rooms that were built in the mid 70's. In fact he correctly assumed that our building was built in the mid 70's before I even told him.
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Ville Kauhanen

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Re: Let's talk about variable acoustics systems
« Reply #14 on: February 10, 2014, 05:51:03 PM »


How suitable are these kinds of systems for existing rooms that may or may not already have acoustical problems with the hard and soft surfaces?

If one were to go through the trouble of doing a complete retrofit of the absorption, diffusion, and reflective surfaces in the room would it make an electronic enhancement system more or less suitable to address the issues in the room? And if so, would I be correct in assuming that both the hard and soft surfaces should be designed along side the electronic system?

For me personally these systems are best when the starting point is a room that is acoustically very dry and where the RT management is designed in the acoustic design also to the subwoofer frequency range. This means more complexed structures and more complexed acoustic design. To have full benefit of a system like this the room would need to have no problems in acoustics from sound reinforcement point of view.

Also these kind of systems are best (in my opinion) when used to enhance acoustic performance in acoustically great (but "too" dry) room and not together with sound reinforcement. Although IF the system is designed to be used together with sound reinforcement it can be really good addition. The problems typically are the relative positions of PA loudspeakers and the acoustic enhancement system mics. I have seen good systems (Constellation) where there are different recallable setups/programs where mics in front of the PA are muted and some other adjustments that make the systems work together better. The use of PA of course colours the reverberation differently also in the stage mics (if the design has these) but anyway the systems CAN work together if designed and programmed properly.

Like I said in my earlier post I think Meyer is doing a good job on the Constellation designs. My feeling is based on real installations I've been able to follow from a distance and heard the end result. I believe that they can tell you quite quickly if they think Constellation is right solution for you and the room if you can give good description of the room and your goals.
« Last Edit: February 10, 2014, 06:22:10 PM by Ville Kauhanen »
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Ville Kauhanen

Ivan Beaver

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Re: Let's talk about variable acoustics systems
« Reply #15 on: February 10, 2014, 05:52:15 PM »

To add another question to the discussion...

How suitable are these kinds of systems for existing rooms that may or may not already have acoustical problems with the hard and soft surfaces?

If one were to go through the trouble of doing a complete retrofit of the absorption, diffusion, and reflective surfaces in the room would it make an electronic enhancement system more or less suitable to address the issues in the room? And if so, would I be correct in assuming that both the hard and soft surfaces should be designed along side the electronic system?

When I was speaking with the Meyer Training Rep in April, he did mention that they are installing a lot of the Constellation systems in rooms that were built in the mid 70's. In fact he correctly assumed that our building was built in the mid 70's before I even told him.
If the room already has "acoustic issues" then the enhancement system can do nothing about that.

THe best rooms are pretty dead.  You can always liven them up-but you cannot kill reflections-reverberation etc.

You have to have a good room to start with.
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Tom Young

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Re: Let's talk about variable acoustics systems
« Reply #16 on: February 10, 2014, 05:58:13 PM »

To add another question to the discussion...

How suitable are these kinds of systems for existing rooms that may or may not already have acoustical problems with the hard and soft surfaces?

If one were to go through the trouble of doing a complete retrofit of the absorption, diffusion, and reflective surfaces in the room would it make an electronic enhancement system more or less suitable to address the issues in the room? And if so, would I be correct in assuming that both the hard and soft surfaces should be designed along side the electronic system?

You need to incorporate both. As others have said, a dry or dead space is where you want to start with an enhancement system. You may be best served by an acoustic consultant who is skilled at the natural acoustics part and can work with the enhancement system folks to ensure that one does not conflict with the other. I can recommend a few (see PM) 
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Tom Young
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Justice C. Bigler

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Re: Let's talk about variable acoustics systems
« Reply #17 on: February 10, 2014, 06:04:15 PM »

Another quick question.

When you turn the electronic systems on, is there, or do you notice an increase in the base SPL of the room? Or is it so small that you don't notice it? I'm thinking about long term exposure to higher averages of SPL and ear fatigue over long tech rehearsal periods.
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Justice C. Bigler
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Tom Young

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Re: Let's talk about variable acoustics systems
« Reply #18 on: February 10, 2014, 07:29:00 PM »

Another quick question.

When you turn the electronic systems on, is there, or do you notice an increase in the base SPL of the room? Or is it so small that you don't notice it? I'm thinking about long term exposure to higher averages of SPL and ear fatigue over long tech rehearsal periods.

Yes, the overall/base SPL of the enhanced sound will be louder. Probably in the 3-6dB range. This may be adjustable to some degree, but there are several factors which limit the gain of the system. First, in natural acoustics what you hear is both the source (timing-wise and its dryness) and the ambient/reverberant energy, most of which arrives after the initial source. So too much "room gain" will sound artificial. The other factor is gain-before-feedback.
« Last Edit: February 10, 2014, 07:36:43 PM by Tom Young »
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Justice C. Bigler

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Re: Let's talk about variable acoustics systems
« Reply #19 on: February 10, 2014, 08:33:05 PM »

LARES is connected with Lexicon and Harman somehow? Or is that just an oddity in their domain name? I don't see LARES listed on the Harman home page.
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Justice C. Bigler
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Re: Let's talk about variable acoustics systems
« Reply #19 on: February 10, 2014, 08:33:05 PM »


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