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Discussion Starter #1
I have a rather large build thread that is designed by Dennis and have some questions specifically for you DIYers.


The room has a baffle wall that will house 10-21 inch speakers for the majority of the bass. The financial situation wont allow me to buy the drivers and amps needed for these extra modal subs, but I am and will build the boxes into the columns for the future.


Dennis proposed putting subs spaced out into 3 of my columns but I'm going to prewire/build for 4. The way I'm thinking is that 2 will be on one amp with only the need to adjust phase/delay equally/together as they will be on the rear wall at aprox 1/4 width distances. The other two will be in columns on the side walls. One in the left column in front of the first row of seating and one in the right column in front of the third row of seating. So these will require a bit more attention with adjustments. I'll worry about the need for adjustments later.


Right now I just want some opinions as to what size and brand of speaker I should use for these subs. The columns will allow for 12" subs of up to three in each location. I want to approach this with the method of building the enclosures to limit excursion as the ULFs will never match the baffle wall any way. I've looked at TC sounds but just dont know if they would be worth it for this application, and I dont really understand the difference in the LMS-ultra, LMS-r, and axis enough to justify the cost between them for something like I'm planning. Cost is an issue but not one of great concern if its worth it.


So, anywhere from 1 cubic foot to 4-5 cubic foot for each column is doable. And anything from a single 10 to 3 twelves in each column is doable. Power doesnt really concern me at all but would like for these to all be sealed unless someone can REALLY convince me vented/ported will blend in with the rest of the system. That reminds me, all other speakers will be JTR 8's. Triple eights LCR and single eights for surrounds.


Any and all thoughts welcome.
 

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Quote:
Originally Posted by audiovideoholic
The room has a baffle wall that will house 10-21 inch speakers for the majority of the bass.
Could you elaborate on THIS a bit first?
 

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It's early and I've not had much coffee, but are you talking about doing something like a double bass array where you have subs in the front and in the rear, with the ones in the rear out of phase...but with more subs in columns along the side walls?


Right now I am processing six sub channels in my head?
 

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Why not 8 21" subs instead of 10? The $$$ saved might give you enough to get 4 other smaller subs to place around the room. The difference of going from 8 to 10 subs is pretty much meaningless.
 

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Discussion Starter #5
Quote:
Originally Posted by penngray
Why not 8 21" subs instead of 10? The $$$ saved might give you enough to get 4 other smaller subs to place around the room. The difference of going from 8 to 10 subs is pretty much meaningless.
Because I already have the subs. well, I have the mals for the horns and have already paid Mark at mach 5 for the other 8 that he is building.
 

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Discussion Starter #6
Quote:
Originally Posted by Looneybomber
It's early and I've not had much coffee, but are you talking about doing something like a double bass array where you have subs in the front and in the rear, with the ones in the rear out of phase...but with more subs in columns along the side walls?


Right now I am processing six sub channels in my head?
There will be a baffle wall that houses 2 mal x 21 FLHs hooked to the L and R channels. Then there will be 8 mach5 21s that will either be super small sealed or IB. All the subs I have at the momment will be on the front baffle wall. When Dennis designed my theater he knew what my plans were as far as subs on the baffle wall but thought that was total overkill. So, he strategically placed subs around the room that met his design programming goals.


That leaves me with the opportunity to plan for subs in these locations. I just dont know how many I should plan for since they will obviously never produce as much bass/spl as the wall. These are strictly going to be used to smooth out the modal response. It may not even be a good plan. Thats why I am asking you guys.


Here is the side layout



Here is where the two in the rear will be. The center two columns.
 

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Discussion Starter #7
Quote:
Originally Posted by mayhem13
Could you elaborate on THIS a bit first?
2 Malx 21FLHs on the L and R channels, and 8 mach 5 subs will be either super small sealed (limit over excursion) or IB (waiting on TS params).
 

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I think you are going to have the bass covered in that room. What is the knee on the Malx horns? And what are the dimensions?


Honestly, you don't need much for those rear subs. I assume you are using those for smoothing purposes, right? I would suggest bandpass enclosures with a passive radiator instead of a port. You are correct, you will only need those to produce a fraction of the overall SPL. Not only because they are closer but because they are really only used to smooth the response and not add significant SPL. It is not to to their proximity. When your primary subs are producing 115db, these might put out 85-95db.


The reason I suggest bandpass boxes is because they provide an acoustic low pass effect which filters harmonic distortion. This is important for subs that are closer to you and in odd locations such as your columns. It helps ensure that you won't be able to localize these subs.


These also only need to operate over a limited range. I would guess 25-120hz in your room. Since your room is rather large this is likely the range that you want to smooth.


There are many designs that can do this. One that I've modeled which looks good is an AE TD12H in 1.4cu ft with a .3cu ft front chamber and a Dayton NS310PR passive radiator. With 400w and a 20hz highpass, it will do 103db +/- 1db from 25hz-150hz. It will do better than that in your columns because it will be in 1/4 space and my model is in 1/2 space. You are taking an already very low distortion driver and reducing it even further by using it in a bandpass.


This is close to what Geddes does. One on each side would do you just fine. In fact, just one on one side would probably give you the results you want.
 

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Discussion Starter #9

Quote:
Originally Posted by coctostan /forum/post/20906592


I think you are going to have the bass covered in that room. What is the knee on the Malx horns? And what are the dimensions?


Honestly, you don't need much for those rear subs. I assume you are using those for smoothing purposes, right? I would suggest bandpass enclosures with a passive radiator instead of a port. You are correct, you will only need those to produce a fraction of the overall SPL. Not only because they are closer but because they are really only used to smooth the response and not add significant SPL. It is not to to their proximity. When your primary subs are producing 115db, these might put out 85-95db.


The reason I suggest bandpass boxes is because they provide an acoustic low pass effect which filters harmonic distortion. This is important for subs that are closer to you and in odd locations such as your columns. It helps ensure that you won't be able to localize these subs.


These also only need to operate over a limited range. I would guess 25-120hz in your room. Since your room is rather large this is likely the range that you want to smooth.


There are many designs that can do this. One that I've modeled which looks good is an AE TD12H in 1.4cu ft with a .3cu ft front chamber and a Dayton NS310PR passive radiator. With 400w and a 20hz highpass, it will do 103db +/- 1db from 25hz-150hz. It will do better than that in your columns because it will be in 1/4 space and my model is in 1/2 space. You are taking an already very low distortion driver and reducing it even further by using it in a bandpass.


This is close to what Geddes does. One on each side would do you just fine. In fact, just one on one side would probably give you the results you want.

There is a build thread for the malx horns here http://avsforum.com/avs-vb/showthread.php?t=1329711


They are rather large about 7'4"x4'x2' (HxDxW).


I dont really know much about the design you provided. The columns will leave interior dimensions of 14.5"Wx14.5"Dx40"H.
 
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