Help Designing Subs to Match Current Subs - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 5 Old 06-19-2019, 08:34 AM - Thread Starter
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Help Designing Subs to Match Current Subs

I just finished up my theater design with Nyal Mellor at Acoustic Frontiers, who I can't say enough good things about. Due to space limitations, we decided to build the rear subs into the riser in the back corners. We were limited to 15" drivers since we only had so much depth inside the 12" riser. The final product ended up being 2 15" drivers wired in series in each corner and those will be wired in parallel to connect to one channel of the sub amp. The plan is to do the same in the front and integrate them in a source-sink. He designed the boxes for the risers, but where I need help is for the front sub boxes. With the source sink method, the subs need to be identical: same driver, same internal and port volume. Since the space behind the screen is slightly different than underneath the riser, I was hoping someone could help me design a box that would match the specs of the rear subs but would better fit in the space. I attached some of the specs for the sub designs.

The space between the back of the wall and the screen is about 28" and there is about 45" from the riser to the bottom of the HTM12s that I will be using for the LCR. The speakers are about 50" apart center to center and there is about 18" between the center of the right speaker and the wall. That is the limiting factor due to the cutout on that space, obviously much more space on the other side but want to keep it symmetrical.

I plan to use the Behringer NX6000D to drive the subs.

I understand the basics of this stuff, but the actual design is way over my head and I would really appreciate it if someone could lend some assistance.

Thanks in advance.
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File Type: pdf Subs.pdf (491.3 KB, 12 views)
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post #2 of 5 Old 06-19-2019, 08:51 AM
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Making ported boxes a desired shape and size is not too difficult. The easiest question would be how big can the boxes be or what are the ideal dimensions? Resizing a Marty sub is pretty easy - https://www.avsforum.com/forum/155-d...alculator.html There is still math that needs to be done in WinISD for checking the length of the port for a tune, for slot ports like a Marty use 85% of the value. What drivers are you thinking of using? Is the goal deep bass for watching movies or do you also desire the chest pounding sensation for music and gunshots?

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post #3 of 5 Old 06-19-2019, 11:37 AM - Thread Starter
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Quote:
Originally Posted by Red Five View Post
Making ported boxes a desired shape and size is not too difficult. The easiest question would be how big can the boxes be or what are the ideal dimensions? Resizing a Marty sub is pretty easy - https://www.avsforum.com/forum/155-d...alculator.html There is still math that needs to be done in WinISD for checking the length of the port for a tune, for slot ports like a Marty use 85% of the value. What drivers are you thinking of using? Is the goal deep bass for watching movies or do you also desire the chest pounding sensation for music and gunshots?
Thanks for the response. The room will be 100% for movies, so no music.

The driver is the Dayton Audio RSS360HO-4 15". All the details of the driver and riser sub boxes are on the file I attached in the first post. Each pair of subs in each location is acting as 1 sub.

As far as the size, I am limited to the same internal volume as the riser subs (5 cu ft including the 0.3 cu ft driver). The boxes need to be tuned (as best as possible) identical to the riser boxes since we will be using them in a source sink (attached more detail on that). Ideally, the 4 boxes would fit underneath the R and L speakers (2 on each side).
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File Type: pdf Source Sink.pdf (201.6 KB, 8 views)
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post #4 of 5 Old 06-19-2019, 12:10 PM
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Use https://www.the12volt.com/caraudio/boxcalcs.asp to play with dimensions that work for you to get to a 5.3ft^3 box, just a bit larger to account for bracing.

Looks like the riser subs utilize round ports, use the same in the new boxes, keeping proximity to boundaries (bottom, wall, back, etc) the same. Same volume, driver and ports should net same tune.
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post #5 of 5 Old 06-20-2019, 10:21 AM - Thread Starter
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Thanks for that site, it was very helpful.

I came up with a box of 20"Wx28"Hx18"D which gives me an internal volume of 4.68 cubic feet. The rear subs are 4.71 cubic feet. I'm assuming that should be close enough?

Will I need any bracing in the box?

I will continue the round ports like in the rear subs. Due to the port length, I will have to bend them at least once. Any tips on where to find long sweeping 90 degree ports? Could I just use PVC?
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