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DYI Sub for Built In Shelving system?

post #1 of 13
5/30/11 at 1:30pm
Thread Starter 

I am in the process of building a new home.  In the living room we will have built in shelving system.  The original idea was to put the sub in the lower shelves behind cabinet door with acoustic treatment.  Clearly not ideal but there is wife factor. 

 

The problem i am running into is that the space is only 19.5" D x 25"H x21"W, depth being the main problem.  I was searching for subs which would meet these dimensions when I started reading threads re: DYI.  SO the question is would DYI sub be a good solution for my space problems?  How hard are they to design and build if I don't use some of the plans already done?

 

The room itself is no treat either. it is 18x 22 with open back to kitchen and 18' ceiling. So i am also needing some help in deciding what size sub I should be looking at.

 

Thanks

CraigH

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post #2 of 13
5/30/11 at 2:53pm

You can squeeze a 4 cubic foot enclosure into that space.  I suggest a Dayton (Parts Express) RS 15" HF sub with an O Audio 500w BASH amp.  The main limitation is your budget though.  If it is high enough, I have a different set of suggestions but the total cost will be close to $1,000.  On the other hand it will have twice the output of the Dayton.

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post #3 of 13
5/30/11 at 3:32pm
Thread Starter 

Well I was contemplating the SVS SB13-plus, which would knock me back $1500ish so if I can be south of $1000 it would be found money. The only concern I have about dropping $1k is that because this will be my first DYI attempt, i am a little nervous about the $ as there is a real possibility I will screw it up.

 

Also, any ideas on where to find plans on the box t fit that size.

 

Thanks

Craig

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post #4 of 13
5/30/11 at 6:27pm

http://www.danmarx.org/audioinnovation/tc3000.html

 

Make yours a little shallower and a little taller to keep the internal volume the same.  Instead of the plate amp, use a Behringer EP-4000 and Behringer Feedback Destroyer (more power and more features than that plate at the same price).  It will easily fill your large listening room with bass.  If you have to mount the amp in the room, budget $12 more for a quiet fan swap.

 

If you can build a box, you can build a sub.  If you don't want the complexity of a 10 band parametric EQ, you can substitute a Tempest X2 - http://www.diycable.com/main/product_info.php?cPath=24&products_id=652 and use a Behringer EP-2000 amp.  Almost the same output but a little cheaper and easier to install.

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post #5 of 13
5/31/11 at 1:10pm

My living room is very similar - open to the second story and kitchen on one end.  The 15" Dayton I built is PLENTY of sub to fill the room, lol.  (And most other rooms in the house, to be honest).  Follow Robert's advice, and you will be pleased as punch :)

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post #6 of 13
6/1/11 at 7:02pm
Thread Starter 

Can I make the sub 3.5 cubic foot?  Also any good references re: how to.  I get the build a box, but looking at avsforum and other sites, it looks quite a bit of work in the bracing and also insulation etc.  Does it matter how the box is braces and where the insulation is placed?

 

Thanks for your help.

 

Craig

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post #7 of 13
6/2/11 at 5:43am

 

Quote:
Can I make the sub 3.5 cubic foot?

100L is 3.5 cubic feet.

 

Quote:
Also any good references re: how to.  I get the build a box, but looking at avsforum and other sites, it looks quite a bit of work in the bracing and also insulation etc.

The link to the Dan Marx site is the "how to".  It is a great example of construction methods and how to brace.  And bracing is easy - cut the brace to the appropriate size and then cut a circle in it.  Polyfil is even easier - just buy two $2.50 pillows from Wal-Mart and stuff them in.

 

 

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post #8 of 13
6/5/11 at 10:28am

bracing is necessary in order to make the box a none box in order to prevent waves to be effective from parallel walls.

you must prevent a situation that lead to a double wave or zero wave from two that comes at each other...

i hope that I am clear.

you can take a look here as another example of barcing

 http://www.subwoofer-building.com/ go to step 9 for example

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post #9 of 13
6/5/11 at 12:16pm

 

Quote:
i hope that I am clear.

It's not that you are not clear, you are not correct.  For subs, the waves are much longer than the size of the enclosure so the shape of the enclosure or reflected waves cancelling each other is nothing to worry about.  To find the length of sound waves, go here - http://www.sengpielaudio.com/calculator-waves.htm .  For example, an 80hz wave is slightly over 14 feet long. 

 

Bracing is there to keep the walls from flexing and coloring the sound.

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post #10 of 13
6/5/11 at 12:50pm
Thread Starter 

Is it fair to say that volume is king in building the box rather than shape?  My box will actually be a rectangle, taller rather than deep. 

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post #11 of 13
6/5/11 at 3:48pm

Enclosure volume is everything.  Shape means nothing.  Look at SVS and their cylinder vs box subs.  Same performance out of vastly different shapes.

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post #12 of 13
6/6/11 at 10:05am

why do you think shape means nothing?

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post #13 of 13
6/6/11 at 11:39am

If you are going to use a sub crossed over at 80hz, then shape only matters if one dimension of your sub is longer than 14 feet (the length of an 80hz wave). 

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