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Author Topic: New speakers for a semi-circular auditorium  (Read 11918 times)

Chrysander 'C.R.' Young

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Re: New speakers for a semi-circular auditorium
« Reply #20 on: February 04, 2016, 09:53:18 AM »

Don,

Where are you and your church located?  Some folks here, myself included, might be willing to visit and give you some ideas or advice in the spirit of grace and service.  Kudos to you for having an open mind, a willingness to serve your congregation, and thick skin - the latter is VERY important around here.  :)

In the meantime, read this:

http://audiosystemsgroup.com/3Times.pdf
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Don DeJong

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Re: New speakers for a semi-circular auditorium
« Reply #21 on: February 04, 2016, 06:21:50 PM »

C.R.,

We're in Durham, NC.  First of all, though, I'd like to do as much learning as I can in this process, learning how to do things like measuring RT60, etc.  If I go through the whole process I'll understand any advice given more completely, I'll be able to explain why we need the equipment we do, and I may be able to help someone else down the line.  If you more experienced folks can keep pointing me in the right direction I may be able to see the decision I (we) need to make pretty clearly.

It appears from things I've read so far that RT60 measurements are a good place to start as far as acoustic measurements.  My ears tell me that the room is acoustically dead, but I want to get a better idea of how dead.  I'll start with something like this:  https://www.youtube.com/watch?v=HFIXPjp0fgc  While I'm sure it's not the precise kind of measurement an acoustical pro would make, it's something I can do with readily available equipment.  If I work at it long enough, I think I'll get close enough.  If my testing gives me consistent readings in the .5 sec range, for instance, I won't worry too much about reverberation.  It's never been a problem in that room as far as intelligibility, but if I expect to understand the process, I need go through it.

I don't have access to fancy dedicated equipment, but I didn't have fancy tools at the beginning of my carpentry career, either.  By working very carefully with what I had, I was able to get excellent results.  My tool collection has expanded exponentially since then, and it's a lot easier to get good results, but I still have to work carefully, paying attention to all the details.  And I still adapt some of my tools to do more than they were ever intended to do, when it just doesn't make sense to invest in a specialized tool I'll use only once or twice.

I'm a lot more encouraged today about the prospects of figuring out this puzzle, thanks to some very understanding forum members.  Thanks.
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Scott Carneval

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Re: New speakers for a semi-circular auditorium
« Reply #22 on: February 04, 2016, 06:49:39 PM »

Don,

I've been following this thread since the beginning, but it seemed like you were already getting great advice so I never bothered to chime in. I'm in Raleigh, probably 30 minutes from you, and we're currently working on a project in Durham on 9th street, so I'm sure I could stop by and give you some advice.

Shoot me an email at scarneval (at) avantsi.com and we can set something up for one day next week.

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Ivan Beaver

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Re: New speakers for a semi-circular auditorium
« Reply #23 on: February 04, 2016, 09:18:02 PM »

If the RT60 is anywhere near the .5Sec range, I would not worry about trying to get exact.  It is not worrying about.

The thing I would be more concerned with would be any nasty reflections that might exist.

If you have any- you might want to treat those.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Irvin Pribadi

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Re: New speakers for a semi-circular auditorium
« Reply #24 on: February 05, 2016, 11:23:17 PM »

Don,
If you're really in for measurements, there is quite a simple setup for that.
The vid you linked was good for RT-60, but RT60 doesn't tell the whole story.

Search for Room EQ Wizard (REW). It is a freeware that is very professionally made specifically for audio analysis; no need for balloons or guns anymore!
Then you need a calibrated measurement mic and a mic pre-amp to PC device. I chose a Dayton EMM-6 mic (with s/n specific calib file) with a MicMate USB mic adapter. Total cost was around $110.

Doing measurement runs you can see how sound varies by frequency, location and time within the room.
One function called "waterfall" shows the audio decay across the swept frequency range for each frequency step.
This easily show any nasty room resonance frequencies and IMO is 100x better than a single RT60 figure.

If you do go down this route, what I do as part of my routine is take multiple measurements across the whole seating area, then overlay each measured FR graph on top of each other. You can then see how the speaker and room interact with each at different location which better equips you on how to improve the situation.
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Don DeJong

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Re: New speakers for a semi-circular auditorium
« Reply #25 on: February 06, 2016, 11:29:06 AM »

Irvin,

Thanks for the tips on measurement.  This is exactly the kind of thing interests me.  I just like doing technical things like this.  I've been talking to Scott C. about a site visit to help us size up our needs, but I love geeky stuff like making these measurements.  I've learned the hard way that hard facts are usually more reliable than intuition.
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Irvin Pribadi

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Re: New speakers for a semi-circular auditorium
« Reply #26 on: February 06, 2016, 10:26:41 PM »

Don,
Awesome, you and I are alike in this regard.
But as many others here will point out, don't get hung up on the #s .. if it sounds good, it is good; and vice versa regardless of what the measurements may say :)
Reason being is that our measurements many times are incomplete, skewed or simply incapable of representing the human perception of sound and music.
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TrevorCrowe

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Re: New speakers for a semi-circular auditorium
« Reply #27 on: February 07, 2016, 07:11:29 AM »

I use REW with a MiniDSP Umic, and calibration file. I agree that even with this, the human ear is still right. REW is great for finding glaring peaks or dips, but don't try to perfectly flatten the response. A lesson in futility!
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Don DeJong

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Re: New speakers for a semi-circular auditorium
« Reply #28 on: February 07, 2016, 10:57:13 PM »

Trevor,

I checked out the miniDSP site, it looks like they have some powerful yet affordable tools.  Thanks for the ideas.  More research to do, but ain't it fun?
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Don DeJong

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Re: New speakers for a semi-circular auditorium
« Reply #29 on: February 11, 2016, 08:09:00 AM »

In the words of Sergeant Preston of the Yukon (for those of you who are old enough to remember that), "It looks like this case is closed."  Scott C. visited our building Wednesday afternoon with a newly developed speaker that (literally) sounds like it will cover the odd-shaped room very uniformly, well, two of them will cover the room, he just had one with him.  We had a great discussion about different gear that we might want to use with those speakers.  Of course, we still have to raise some money to buy them, but I think that's just a matter of time.  If I'm allowed to talk about brand and model I can try to explain how it will work, but I don't want to appear to be advertising where that isn't supposed to happen.  And Scott could explain it better than I could.

Thanks to all of you for a lively discussion and great advice, I look forward to thinking of another question to ask.  It's even possible that I could contribute to an answer to somebody else's question, who knows.

DD
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ProSoundWeb Community

Re: New speakers for a semi-circular auditorium
« Reply #29 on: February 11, 2016, 08:09:00 AM »


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