Room Mode Calculator and Converter - Page 3 - Home Theater Forum and Systems - HomeTheaterShack.com

Old 10-25-07, 12:33 AM
olddrum1
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Re: Room Mode Calculator and Converter

I hate to say this but I am in the same boat as Vader. I at one time in my career worked with climate control systems balancing out rooms that were held to tight tolerances. I see many things that might be similar but also I see things that would oh so complicate a simple spread sheet such as this. How would a ceiling fan with five rotating hard surfaced blades effect the accoustics of a room? Does moving the furniture in a room have equal ramifications? Does this spread sheet tell where the ideal speaker placement would be? What does it do?

Old 10-25-07, 08:53 AM
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brucek

Join Date: Apr 2006
Posts: 7,514
Re: Room Mode Calculator and Converter

Quote:
Does this spread sheet tell where the ideal speaker placement would be? What does it do?
The various calculators available are simply a starting point to show the ideal modes, given three room dimensions. After that it's all about measuring and trial and error...

brucek
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Old 11-08-07, 07:59 AM
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Doug Plumb

Join Date: Mar 2007
Location: Toronto Ontario
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Re: Room Mode Calculator and Converter

Calculating room modes is a waste of effort because your room is never quite square and never quite the exact measurement that you input. In addition to this the actual response varies with a measurement mic location. Higher order modes are strongly affected by room shape.

The results of these excercises have no practical value. Measurement is the only option when assessing room behaviour. Properly averaged measurements show dominant mode behaviour very clearly.

They can be useful for designing a room but favourable dimension ratios have already been found. The best rule is to build as big as possible, for mid/HF reasons as well as bass response.

Doug Plumb
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Old 11-09-07, 04:53 PM
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Ahmed

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Re: Room Mode Calculator and Converter

Quote:
Doug Plumb wrote: View Post
Calculating room modes is a waste of effort because your room is never quite square and never quite the exact measurement that you input. In addition to this the actual response varies with a measurement mic location. Higher order modes are strongly affected by room shape.

The results of these excercises have no practical value. Measurement is the only option when assessing room behaviour. Properly averaged measurements show dominant mode behaviour very clearly.
Doug, I have to disagree with you....sorry
Waste of effort??? No, it is quite the contrary. Normally, what is in my opinion a correct and, what is an effort and time saving procedure is to simulate room response at LP first with one of the great programs like Room Respose Calculator by Yavuz Aksan. Then tweeking or slight subs position change is made through measurements.
When you're having small subs it is OK not to give such a theoretical response any importance..but when you're having 200 Lb+ subs, that's another story.
In my case, my room is almost a perfect rectangle, but if it weren't, it would be harder but still not a waist of effort though as one can know at least some of the modes.

Look at my room theoretical subs response graph vs practical measurements....Can you see any similaritires?
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Last edited by Blaser; 11-11-07 at 01:42 PM.
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Old 11-12-07, 06:56 PM
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Naut

Join Date: Apr 2006
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Re: Room Mode Calculator and Converter

Quote:
blaser wrote: View Post
Can you see any similaritires?
Yup. Cool!

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Old 11-12-07, 07:25 PM
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Doug Plumb

Join Date: Mar 2007
Location: Toronto Ontario
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Re: Room Mode Calculator and Converter

It depends on what you mean by similarities - you always have to verify a simulation with a measurement. Those two are many dB off - the dip is predicted but not exactly in frequency.

Doug Plumb
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Old 11-13-07, 06:52 AM
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brucek

Join Date: Apr 2006
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Re: Room Mode Calculator and Converter

blaser says:
Quote:
Look at my room theoretical subs response graph vs practical measurements....Can you see any similaritires?
Yeah, interesting. The peaks and dips appear to line up, and if the vertical scale was the same they'd be quite close. It's nice that the measurement verified the simulation.

There are always lots of influences in a room that will change the actual meaurement, but if you've got a rectangular room, there's a good chance the resonance calculators will give some decent indications where the modes are and whether they'll line up or not. Certainly useful in finding the optimum room shape for home theatres or listening rooms if you happen to be building one.

brucek
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Old 11-13-07, 07:12 AM
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Ahmed

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Re: Room Mode Calculator and Converter

You're correct Doug. A similation will not tell you everything very accurately, but it gives only an idea. BTW, I am sure I could get closer to practical measurements by increasing the no. of reflection (as my room has brick walls) that I have quite ignored.

Here is another SIMULATION which made me decide not to chose the nearfield arrangement in the same room because I like a steep house curve.
I know there will be a dip around 30 Hz, but measurements might show that dip propably more or less enphasised with a propable slight change in frequency. But the concept is still the same...There will be a Dip with this configuration at a frequency low enough to be unpractical for a house curve without overstressing amps/drivers...

This is what I beleive to be the real intention of such room calculator programs.
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ASME AI
Yamaha RX-V2500, Wharfedale Diamond 9.6 Fronts, Wharfedale Diamond CM Center, Diamond DFS Surround and rear, Behringer FBQ 2496, Dual RL-P18s 625L LLTs, Dual TA-2400 Pro (2 * 2000 W Amp), Samsung HD870 DVD player, Carada BW 16:9 106" screen, Epson TW-2000, 60 Gb PS3
Important HT proverbs:
- "you can never have too big a screen" (talking about still pictures)

Projector selection basics
Epson TW 2000 review
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Old 11-13-07, 07:15 AM
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Ahmed

Join Date: Aug 2006
Location: Cairo-Egypt
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Re: Room Mode Calculator and Converter

Quote:
brucek wrote: View Post
Certainly useful in finding the optimum room shape for home theatres or listening rooms if you happen to be building one.
brucek
DEFINITELY! I wish I knew this before constructing my House

ASME AI
Yamaha RX-V2500, Wharfedale Diamond 9.6 Fronts, Wharfedale Diamond CM Center, Diamond DFS Surround and rear, Behringer FBQ 2496, Dual RL-P18s 625L LLTs, Dual TA-2400 Pro (2 * 2000 W Amp), Samsung HD870 DVD player, Carada BW 16:9 106" screen, Epson TW-2000, 60 Gb PS3
Important HT proverbs:
- "you can never have too big a screen" (talking about still pictures)

Projector selection basics
Epson TW 2000 review
Blaser is offline
Old 05-10-08, 11:12 PM
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Eric Desart

Join Date: Jul 2007
Location: Antwerp/Belgium
Posts: 3
Re: Room Mode Calculator and Converter

Quote:
franman wrote: View Post
The bonello criteria is based on Axial mode distribution but we look at Oblique and Tangential modes as well, as they do help "fill in" the areas above the fundamental for each dimension in small rooms. Hope this makes sense....
Just a small comment, since I accidentally stumbled upon this post by Googling.
My idea is not to discuss this but to correct something.
The Bonello criteria are based on all modes not on the Axials alone. Hence taking the tangential and oblique modes into account is integrated in Bonello's approach/calculation method.

Just info.

Best regards
Eric
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