Ideas for triangle shaped DIY corner sub - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 12 Old 03-22-2020, 09:19 PM - Thread Starter
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Ideas for triangle shaped DIY corner sub

I am building out the rear corner of my brick walled dedicated theatre room with framed MDF and would like to use the resulting cavity as a subwoofer.
See drawing for plan and front view.
I was planning on just boxing in the area directly above the AV rack and using that as the enclosure in a LLT sub design but then I though maybe the size or shape of the available area ay be more conducive to a different design - horn, sealed, IB (or close to ?) etc.

I already have the driver (15" Clarion PXW1552 car sub - not ideal but its all I have / can afford) for a LLT design and it works best with around 650litres volume. The square area directly above the AV rack is almost exactly 650l.
If you include the triangle area behind (and still above) the rack as well it becomes 800l.
If you include the entire volume available behind the wall (excluding the rack volume) it is 1780l

I will also be building a matching one in the other rear corner. And I have another 2 matching drivers which I was going to use for 2 more subs in the front of the room, although they can't go in the corners unfortunately. Would be open to using 2 drivers in each rear corner if that would make it better. I already have 5 'subs' (I use quotes because they only go down to 30hz) being driven from the 5 main speakers output and in the corresponding locations, and a nice 15" sub that goes down to 20hz in the front of the room if any of that makes a difference.

Open to any ideas and input - unless I don't agree with it of course

Also looking for pointer on how to actually build it too
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post #2 of 12 Old 03-24-2020, 06:23 PM
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Without providing the T/S parameters, it's hard to tell if it's worth doing it at all. Car sub drivers are very hit and miss in a home environment. If you've already modelled it, posting that would also be a help in giving advice.


Anyway, for all the volumes you've given, you're going to need to add a hell of a lot of bracing to stop those large wall panels dancing along with the driver. Or put two in each corner and have them drive into a manifold with the drivers mounted dual opposed.

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post #3 of 12 Old 03-24-2020, 10:26 PM - Thread Starter
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Quote:
Originally Posted by A9X-308 View Post
Without providing the T/S parameters, it's hard to tell if it's worth doing it at all. Car sub drivers are very hit and miss in a home environment. If you've already modelled it, posting that would also be a help in giving advice.


Anyway, for all the volumes you've given, you're going to need to add a hell of a lot of bracing to stop those large wall panels dancing along with the driver. Or put two in each corner and have them drive into a manifold with the drivers mounted dual opposed.

I was initially just wondering if there was an obvious option for the size/shape/location I have available.

I have modelled the driver - it works very well as a LLT with between 650l and 800l volume which is either the area directly above the AV rack or that area plus the little triangle bit directly in the corner. It might come down to which one is better and or easier to build. Also it allows me to build 2 identical enclosures for the front of the room so I guess I ave answered my own question

I did also try IB but I don't think the driver is suitable.

I like your thoughts on the opposing drivers in a manifold - but not having much luck finding info on that design unless it is IB - any pointers ?

And see attached for TS parms.


Cheers
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Last edited by niterida; 03-25-2020 at 02:16 AM.
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post #4 of 12 Old 03-29-2020, 03:39 PM
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Quote:
Originally Posted by niterida View Post
I like your thoughts on the opposing drivers in a manifold - but not having much luck finding info on that design unless it is IB - any pointers ?
The first pic is an OB, but is included to show the driver arrangement; just enclose it like you would with a normal enclosure. Pic 2 is a completed ported unit.


Manifold opening are to the room should be Sd x 2 or more and the manifold depth should be as short as possible as that determines the HF rolloff. Push/pull, like both of these are is best to reduce motor/suspension non linearities as muxh as possible.
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post #5 of 12 Old 03-29-2020, 07:51 PM - Thread Starter
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Quote:
Originally Posted by A9X-308 View Post
The first pic is an OB, but is included to show the driver arrangement; just enclose it like you would with a normal enclosure. Pic 2 is a completed ported unit.


Manifold opening are to the room should be Sd x 2 or more and the manifold depth should be as short as possible as that determines the HF rolloff. Push/pull, like both of these are is best to reduce motor/suspension non linearities as muxh as possible.
Had a slight change of plan - the AV rack is going back to the front of the room and the sub will go across the entire face of the triangle at floor level.
Will this sub design work with a triangular shaped enclosure and if so will it outperform my LLT design (modelling down to 15hz) ??
Is there anywhere I can model the push/pull design and work out enclosure shape/size ?
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post #6 of 12 Old 03-30-2020, 03:11 PM
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Quote:
Originally Posted by niterida View Post
Will this sub design work with a triangular shaped enclosure
Yes.
Quote:
Originally Posted by niterida View Post
and if so will it outperform my LLT design (modelling down to 15hz) ??
You may get a bit of increase in the bottom end as it's closer to driving into 1/4 space than it would be a long way up the wall.

Quote:
Originally Posted by niterida View Post
Is there anywhere I can model the push/pull design and work out enclosure shape/size ?
Any sim program will do it. it's the same as two drivers mounted to a baffle. You just need to add the volume of the manifold to the total enclosure volume required.

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post #7 of 12 Old 03-30-2020, 03:32 PM
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Quote:
Originally Posted by niterida View Post
I already have the driver...And I have another 2 matching drivers...already have 5 'subs'...and a nice 15" sub
Um, wow. That is a lot of stuff, somehow not seeming all optimum.
- So there are five "30 Hz" subs what underneath the 5 speakers? What model?
- And a "20 Hz" sub somewhere else? What model? How did you determine if it's really in a good spot?
- AND you have 3 of the Clarion 15"?
- Now you're thinking to build in the two corners, but without built-in rack?
- Is there any kind of room correction sorting all this out? What is implementing the lowpass and highpass crossovers, and what frequencies are they set to?
It seems like you should already have a ton of bass, I question if you really need more subwoofers or optimize/modify what you have already. (i.e. maybe the 30 Hz can be stuffed or ports extended to go lower, as they should have a lot of mutual gain with 5.

About the sub you state that's all you have/can afford. Think about it, that's a bit silly! You're talking about a massive project, do it right. If those drivers work great, great. If not save up, don't do something huge and suboptimum.

I've always wondered about some kind of corner horn, especially if I had enough drivers to feed it from an 8 foot tall vertical array (get 3 more of those Clarion! ). That would be best as a separate thread, here and at https://www.diyaudio.com/forums/subwoofers/ specifying (A) what can I do with these Clarion and also (B) what would you advise with the proposed enclosure space, and what driver
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post #8 of 12 Old 03-30-2020, 03:49 PM
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I helped a friend design & build some triangle subwoofers. I attached some pictures.

The top 2/3 of each box we left unfinished (no paint). He used white craft glue to attach a patterned fabric. He only glued around the two sides vertically and the fabric stretched and held pretty well. The advantage of doing this is that you can choose any fabric and even change it out very easily.

Acoustically, they sounded great. They were different than the Simplexx 15" box design by Bill Fitz Maurice. I helped another friend build some of those and we installed the same 15" subwoofers.
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post #9 of 12 Old 03-31-2020, 04:05 AM - Thread Starter
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Quote:
Originally Posted by A9X-308 View Post
Yes.
You may get a bit of increase in the bottom end as it's closer to driving into 1/4 space than it would be a long way up the wall.

Any sim program will do it. it's the same as two drivers mounted to a baffle. You just need to add the volume of the manifold to the total enclosure volume required.
OK my limited knowledge and WinISD is showing that I need 1500l to make 2 drivers work which I don't really want to do.
And with my limited knowledge and ability I think it best to stick to a simple ported design.
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post #10 of 12 Old 03-31-2020, 04:21 AM - Thread Starter
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Quote:
Originally Posted by head_unit View Post
Um, wow. That is a lot of stuff, somehow not seeming all optimum.
- So there are five "30 Hz" subs what underneath the 5 speakers? What model?
- And a "20 Hz" sub somewhere else? What model? How did you determine if it's really in a good spot?
- AND you have 3 of the Clarion 15"?
- Now you're thinking to build in the two corners, but without built-in rack?
- Is there any kind of room correction sorting all this out? What is implementing the lowpass and highpass crossovers, and what frequencies are they set to?
It seems like you should already have a ton of bass, I question if you really need more subwoofers or optimize/modify what you have already. (i.e. maybe the 30 Hz can be stuffed or ports extended to go lower, as they should have a lot of mutual gain with 5.

About the sub you state that's all you have/can afford. Think about it, that's a bit silly! You're talking about a massive project, do it right. If those drivers work great, great. If not save up, don't do something huge and suboptimum.

I've always wondered about some kind of corner horn, especially if I had enough drivers to feed it from an 8 foot tall vertical array (get 3 more of those Clarion! ). That would be best as a separate thread, here and at https://www.diyaudio.com/forums/subwoofers/ specifying (A) what can I do with these Clarion and also (B) what would you advise with the proposed enclosure space, and what driver

Lots of reasons why I am doing what I am doing - cost being the main one.
Living in a remote area without access to anything else is another.
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post #11 of 12 Old 03-31-2020, 10:49 PM - Thread Starter
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So I have weighed up all my options and going with the attached design with absorption above the subs.
Also attached modelling of my driver in this enclosure.
It was the best compromise between, cost, ease of build, cost, performance, cost, aesthetics and cost
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post #12 of 12 Old 04-01-2020, 06:50 AM
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Quote:
Originally Posted by J Macker View Post
I helped a friend design & build some triangle subwoofers. I attached some pictures.

The top 2/3 of each box we left unfinished (no paint). He used white craft glue to attach a patterned fabric. He only glued around the two sides vertically and the fabric stretched and held pretty well. The advantage of doing this is that you can choose any fabric and even change it out very easily.

Acoustically, they sounded great. They were different than the Simplexx 15" box design by Bill Fitz Maurice. I helped another friend build some of those and we installed the same 15" subwoofers.
That's actually very cool

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Audio: 5.2.4 Marantz SR7011- (LCR) QSC 2180 - (Surrounds) (4) BIC FH6-LCR- (Atmos) (4) Dayton Audio B652 6-1/2-Inch- (Subs)2 23ishcuft ported HS24s 14-15Hz tune - 2 Devastator Minis B&C21ds115 - 4 PA460 in ported cabs 40Hz tune- FP20000Q- 2 Sanway FP10000Q- Crown XLS1500- . To be continued...
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