Optimization of seat to seat variance - Page 2 - AVS Forum
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post #31 of 34 Old 09-11-2013, 05:32 PM
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Originally Posted by JonasHansen View Post

I will try the solution you are recommending. It will require that I move all seatings forward though, as I dont have enough space in the back of the room.

What if I place one subwoofer in the back corner of the room? Would this have the same effect as midpoint of back wall? I have individual DSP for each sub.

Corner will work for length mode cancellation though you will likely see the width mode effects get worse. Ideally you would do 2 front 2 back at 25/75% or corners. Pretty foolproof approach to even consistent bass in multi-row home theaters.

If you don't have room for your big subs maybe use some in walls. JL do an awesome in wall. You can frame off that back concrete wall for the in wall sub and then also put extra absorption back there in the other stud bay cavities to improve acoustics. Fabric cover the whole lot and you won't even know there are two subs back there!

Or you could buy Procella's shallow format subs, or DIY some along similar lines.

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post #32 of 34 Old 09-12-2013, 02:36 AM - Thread Starter
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Thanks for your input.

As I see it, I have the following options:

1. Move all seating about 2-2.5 feet forward. This will place the null just between the seatings but my screen will be way to large for the front row then. Its already pretty big for the front row - I can make it smaller though, but I prefer the experience placed as far away from the screen as possible even though the ratio is the same as beeing placed close.

2. Insert aux subs as you mention. I tried a cheap Earthquake inwall, but it didn't say a sound below 30hz, so not usable in my situation. If I should use the Procella subs, then I should get at least the P15? The P10si is a great form factor, but to cancel the mode I assume it has to play that low with authority?

Another solution is just to accept the variance and focus on having the best sound possible at row 2. Tough choice!

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post #33 of 34 Old 09-12-2013, 11:56 AM - Thread Starter
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Just an update... I tried doing some measurements with the Earthquake subwoofer in the rear of the room. All Measurements are with no EQ

The blue graphs are the front subs only measured at row 1 and 2 respectively. The red Graphs are all front subs plus the rear subs in the same two positions. This is an amazing improvement in seat to seat performance! The Earthquake subwoofer rolls off below 40hz, so no improvements there... But if I get/build a subs which fits behind my second row, I think the result could be really good.


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post #34 of 34 Old 09-12-2013, 05:30 PM
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Quote:
Originally Posted by JonasHansen View Post

Thanks for your input.

As I see it, I have the following options:

1. Move all seating about 2-2.5 feet forward. This will place the null just between the seatings but my screen will be way to large for the front row then. Its already pretty big for the front row - I can make it smaller though, but I prefer the experience placed as far away from the screen as possible even though the ratio is the same as beeing placed close.

2. Insert aux subs as you mention. I tried a cheap Earthquake inwall, but it didn't say a sound below 30hz, so not usable in my situation. If I should use the Procella subs, then I should get at least the P15? The P10si is a great form factor, but to cancel the mode I assume it has to play that low with authority?

Another solution is just to accept the variance and focus on having the best sound possible at row 2. Tough choice!

Yes, at least the P15. Remember you will need that rear sub (or subs) to match your fronts in terms of output SPL for mode cancellation to work. Also note that using different subs front and rear can sometimes be unpredictable as most subs have a ton of EQ to make them flat below 50Hz. The EQ causes phase shift and if the phase shift of the front and rear subs is a lot different then mode cancellation may not work. Ideally it's identical subs.

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