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[Mac Kerr]

I don't know what you're trying to say with the list. There is nothing in that list particularly relevant to designing a sound installation. What is important in the design is to meet a specification of function. The mics don't matter, the CD player doesn't matter, even the console barely matters. What matters is understanding the use the system will be put to, and guaranteeing a certain level of performance. Compared to the cost of installing wire, and designing and installing and optimizing a proper speaker system, the other items are spare change. They can also be added at any time, the speakers and wire cannot.

The proposal returned by the bidder should describe how their system will fulfill the functional spec, and should be backed up by documentation. After completion, at acceptance, where they demonstrate that the spec has been met, they should also turn over full documentation, including "as built" drawings.

Mac

[Ivan Beaver]

Totally agreed.  Anybody can spec a mic or a console, but designing a good sounding system that has proper coverage is a whole different issue.

Here is a shot of before and after of a job we finished rehanging and realigning a customers system and did not sell them any gear, just reused their existing stuff.  The different traces are different positions around the room.  The yellow one is FOH.

[Mac Kerr]

I really like the way everything from about 2k and up varied around the room. Man, did they pay someone for that? it looks like you brought it together pretty well. Care to mention what you had to do?

Mac

[Nathan Walker]

Ok, so from all of this I assume that a good vendor will be able to get similar frequency response at all seating areas and be able to measure it with a device rather than by ear alone.

[Tom Young]

"Ok, so from all of this I assume that a good vendor will be able to get similar frequency response at all seating areas and be able to measure it with a device rather than by ear alone."

That's it, but still is a bit too simplified.

A good contractor will be able to measure and then correct the frequency response so that it is similar in response at all seats. This may include tweaking the aiming of some of the devices and then applying delay, gain adjustments and precision equalization to make the system response smooth and natural sounding.  This process may also include identifying acoustics effects (problems) and applying treatment.

In most cases, the designer of the loudspeaker system gets the loudspeaker positions and aiming right and also spots acoustic problems ahead of time (and recommends or provides appropriate treatment). Measurement confirms these but sometimes shows anomalies that the design process missed (modeling software is a work in  progress). Measurement also displays the interaction between loudspeakers and the interaction between the loudspeakers and the room that are impossible to accurately predict or model. Finally; measurement shows you whether the correction you have applied has worked. Important note: this is complicated stuff and sometimes what we first think will fix something does not, so we go back and rethink what we can do.

Another important note: it matters not whether you have a budget ldspkr system or a top shelf system - they both will exhibit interaction problems and need to be measured and then optimized.

This is not a process that goes like clockwork.  Sometimes you run into a problem that there is no easy answer to. But you have to have the tools, experience and determination to stick with it until you reach an acceptable point. Sometimes it takes an extra day.

And it doesn't stop when you play a CD and everyone (including you) goes: "Wow !!" You need to then do sound checks, coach/instruct the band and sound crew and measure/optimize key (sometimes problematic) microphones such as the pastors lav or headset. Here, too, whether you have an E6 headset mic or you have a cheaper model..... any mic used in this manner needs to be optimized without changing the overall system performance.

The important thing is that the contractor (or consultant when they carry this ball) is capable of handing over a system with no blemishes that will effect how the system performs.

[Tony Mah]

Nathan,

You got it all wrong. Anyone can stick up a microphone in a church and use an equalizer with some software and make the graph look flat at one seat on the floor. A good contractor will be able to show you before you buy how the speakers they choose will give a similar response at most seats. A program like LARA can do this and is very inexpensive.

In a prebuilt room your size (250) this should not take more than a few hours and will be quite accurate. It only gets complicated whne the room gets large and is not built yet.

contractor come on site and:
1. Measures the floor and seating surface area
2. measures reverb time
3. asks where the speakers are allowed and not allowed to go
4. asks about present and future style of worship music.
5. Gets a feel for the amount of money the client wants to spend, from a basic clean system ie. passive 2-way, shure 58, no subs, to something that would make everyone coming in on Sunday to say wow.

Should be able to produce coverage plots in a few hours and a quote in less than a day. Will provide calibration service as part of the package.

A red flag would be if the contractor used room modeling software and goes overboard and draws too much detail like doors and windows. With a prebuilt room, only the floor plan is needed! The walls don't matter because the reverb time is known and you can actually go inside the room and listen for problems like echos.

Tony

[Brad Weber]

Tony Mah wrote on Fri, 15 December 2006 08:40

A red flag would be if the contractor used room modeling software and goes overboard and draws too much detail like doors and windows. With a prebuilt room, only the floor plan is needed! The walls don't matter because the reverb time is known and you can actually go inside the room and listen for problems like echos.

Had me agreeing with you pretty well up to here.  When you can get data for an existing room that is definitely the preferred way to go.  However, you typically measure a lot more than reverb time, such as gathering multiple Impulse Responses that you can later analyze for many acoustic descriptors and characteristics.  And one of the primary reasons for making these measurements can be to use that data to tweak a model in order to provide a more accurate result, which takes the model being complete and sufficiently detailed.

The last thing one would want to do is measure high reverb times and/or hear echoes and then go and model the system based only on direct coverage of the seating area with no room acoustical environment included.  This situation would be precisely where I would want to most carefully model the room and get the model results to match what was found to actually exist before modeling the sound system.

Modeling direct coverage only for speakers in a more a complex acoustical environment (such as in a any enclosed space) does not give an accurate picture of what can be expected.  Why do this if you have actual data that can be used to more accurately model the acoustical environment?  A quick model of just the seating area(s) can certainly be used for some initial modeling to verify that good coverage is even possible, but it would not show that good coverage and good intelligibility, clarity, etc. could actually be expected as that requires considering the acoustical environment of the space.

[Nathan Walker]

Heh, do they have college courses for all this? I just realized how little I actually know about sound systems.

Do any of you live in Missouri?

[Ivan Beaver]

Here is a really poor photo of the center cluster before redoing.  I tried using the nighttime setting, but it moved a bit The camera was at the rear seating.  Notice how far down it is pointed.  It was aimed about 1/3rd or less back into the sanc.

The seating is all on the floor.  Notice how the side loudspeakers on the cluster point to the walls.  There were also 2 exploded cabinets on the sides.  The cabinets were all Renkus Heinz.  The centers trap 40's and the sides TRX151's.

We took two of the main loudspeakers off of the cluster and moved the cluster closer to the ceiling.  We then pointed it towards the rear of the room and added one of the side loudspeakers as a downfill.  The other side loudspeaker was moved to the rear of the room to act as a delay.  The extreme rear seats narrowed from the widest part of the room, so it was fine for coverage.

They also had 2 120* loudspeakers for the choir that were "arrayed" at about a 25* angle.  We busted them apart and moved both of them so as to give 2 different choir monitors for 2 different locations.

The other 2 mains were moved to the sides and positioned so as to add to the main coverage pattern.  The origional setup had the side loudspeakers too far off to the sides so as to pull localization to the sides.

We had to pull extra send lines as the DSP (Media Matrix) was located at FOH.  I wiped the DSP as that was faster than trying to "clean it up".  I rewired the amp rack so as to fit the new DSP settings.  We pulled the extra speaker wires as needed.

We did sell them an Aviom system, but that doesn't count as selling them gear for the PA.  We started on Mon. morning and were finished Tues. afternoon, including the Aviom install.

The part in the DSP that I liked best was using a stereo eq with mono controls with the inputs being the highs and lows of the biamped mains.  How does that work? Not very well at least.

The design and install was by one of the largest sellers and installers of church sound system in the US.

After talking to the church the contractor never actually sent anybody to do alignment.  They just kept sending programs up for the customer to load into the DSP.  Alignment by customer opinion I guess.

The install was 6 years ago and the gear was fine GL4000-48 FOH, Media matrix, QSC/crown amps, Renkus loudspeakers etc.  It was just how it was used that was the problem.  They have not had a service with it yet, but this weekend is their Christmas drama.  We will find out next week, but comments from rehersals are very good.

I enjoy doing this type of work as pushes us to make the best of what is available on the fly.  This time we reused all the existing equipment, but often times we actually give gear back to the customer because too many loudspeakers were installed.

[Ivan Beaver]

We had a consultant once that had me build the model for his own church. He was going to do the loudspeaker design. He didn't like the actual building of the model.

When I got to the church and looked at the loudspeaker placement(as per consultant specs) I noticed that there was no way the aiming was going to cover the room.

When I asked him why he speced them at the aiming he did, he said that he had ramped up the reverb time to almost 3 times what it actually was and was modeling for greatest intelligability.  Why, the RT60 in the room was not that bad.  

We aimed the loudspeakers the way I wanted and all was fine.  I asked him a couple of months later how it was and he said that he had not had a chance to "tweek" it yet, but everybody was happy.  

Models are just like everything else, a tool, and how you use it and how much you understand about it, determines what you will actually get out of it.  My honest opinion is that some people spend waaayyyy too much time inside the model and not enough time in the real world.

I use both methods, just mapping the seating plane for coverage and full models.  It depends on what the customer is willing to spend and what I need out of the model.  Depending on the complexity of the model (as you know), it can take a week or more to build it and get data out of it.  That gets expensive.

The real question is like so many other things in audio-What are you here to do?  What do you want out of the model?

Just like in measurement, I could spend weeks gathering data, but is that really necessary for what it takes to fix "the problem".   Maybe, maybe not, It depends.

I do not believe in over engineering (design time or equipment)(to an extent) or anything else that does not bring the customer any real value for their money.  Stewardship is what we are all about, and that does not mean cheap, just not excess.

Sorry to rant, it has gotten to be a habit    

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