Hello royalswin and Dennis.
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Originally posted by Dennis Erskine
Pablo has done a good job on his spreadsheet; however, there are no perfect dimensions for a home theater...just more optimal and less optimal. (In fact, if you'd follow the advice of such a speadsheet, you'll find the 'perfect' room (from a modal perspective) is one with almost infinite dimensions.)
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I have been offering this spreadsheet as a tool for sometime now, as Dennis points out. Once I started mentioning that an optimal dimension set was already derived from it there have been much more interest. I like this, as it improves the odds for someone to build a room based on this work. Hence the use of the word "perfect". I can cop out and say that it is perfect because, AFAIK, the default dimension set can't be improved ;-)
I believe that, for reasons explained in the ReadMe doc, the default dimension set derived from the SS is optimal. It is not based on ratios but on an specific dimension set.
Would love to be proved wrong. Would love for others to develop a better dimension set. This is not an ego trip, but yes, I'm proud of what I've done so far and would love to go forward.
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Second, such examination of modal properties work only for perfectly rectangular bounded spaces (with 0 sound transmission). If you have a perfectly retangular room, you will have problems far more annoying than room modes. None of these speadsheets will accommodate rooms with raised platforms, stages, bulkheads, sofit, columns, steps, seats (yup, putting your seats in your theater changes modal characteristics), splayed walls, etc. |
Yes, the dimension set is just an starting point. This is mentioned in the Read Me file that is sent with the SS.
Finite element analysis for developing more complex rooms is way out of the purpose of this work. The intent from the beginning was to develop a smallish, simple and cheap room.
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Third, no speadsheet can predict the amplitude of any given resonance frequency; hence, you could be chasing problems that don't need a fix.. |
It's just an starting point. Transmission is an important part of the room design. It is the main way to get rid of very-low-frequency resonances, whatever the neighbors think about it.
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Fourth, IMHO, the best way to design a theater is from the inside out. Accommodate seating, design elements, picture/screen/projector elements, egress, speaker placement, speaker type, and then place the walls... |
Here I disagree. Please note that I have not any experience building home theathers while Dennis is a full-time designer and builder perhaps. But conceptually it is clear to me that if you are going to have resonances in any case, the dimensions that provide the less damage are to be selected at the very beginning. Unless of course there are other considerations that can't be bypassed.
Whatever you do from then on for getting the best sound would be more effective if the bare room faults are lesser.
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Fifth (and my bigger complaint with these speadsheets) is they place an undo emphasis on one aspect of acoustic room design at the expense of other, equally, if not far more important considerations in the design process. |
Again, idimensions are just an starting point, perhaps the most basic one. But must be the right ones from the beginning.
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And, sixth, this is not directed toward Pablo ... he expects my lecture will accompany his posts. Such a review is an interesting exercise in any design process and does not fall into the category of vodoo acoustics (like being able to tune more than one position in a theater without averaging). |
LOL. Will keep pushing the SS here. I hope to continue getting valuable input from you and from all members. My dream is to develop a public-domain full design that can be built cheaply.
Will post the ReadMe file (long) later. It provides more info on where does this work comes from and its use as a tool.
Best regards.