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Senior Shackster , Platinum Supporter
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I have a little project!!

My friend has a 12" Boston G5 dual 4 ohm sub and I want to build a box for it, so my question is how big the box need to be and if a ported box is better for this driver and what size port do I need and what tuning frequency, the amp he wants is the Behringer A500 Reference, 500 watts @ 8 ohm bridge, his room is about 12x14x8, this is the sub..
http://bostonacoustics.com/manuals/G5_GTR_Man.pdf

Thanks!!!:T:T



I like this one :gah::gah:
 

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You could always use the recommended enclosure size and vent size listed on your linked pdf file.

I had troubles when I plugged the T/S numbers into WinISD -- I could never get a Vent Length -- it always said "Too short". Maybe using UniBox would give you better results.

JCD
 

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hey rodney, its me

ive measured some and i dont really want a huge box, def no more than 4cubes net, and less would be even better

with the behringer am i going to need to get a RCA subsonic filter?

and what will be the best placement for sub and port

sub down port foward/back
sub down port down
sub foward port foward
sub foward port down


and this is my 1st decent HT sub setup, htib sucks

maybe i should just throw one of my BTL 18s in there...

edit:
where would the best place be for the sub to go

the gray one is where it is now because its aslong as the rca was that came with it, Xs are where it could go, where would have the best place for it

Shot at 2007-08-09

would the dresser mess it up in the back corner

have to forgive me here, dont know too much about home audio, and i dont need something amazing ar sub 20hz, im not into all out HT yet, jsut want something to fill the low end out better
 

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Limited to 4 cubes, I'd use a 4" diameter port that is 9" long and a 2nd order highpass at ~20hz, which you will NEED. Far from a bottom troller, but with a commercial 12" subwoofer driver, you could do a lot worse. I'd go driver forward with the port facing up.
A 9 inch long port would tune it to 26hz. Won't the woofer unload below the tuning frequency considering this is a HT sub? I'd suggest a 15 inch long port which would tune the box to 21hz. That would give the driver much more protection. He would still get 107db at 20hz with 315 watts. Your thoughts Steve?
 

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Would using a plate amp be an option? It seems like it would be easier to protect the driver using a built-into-the amp highpass section instead of having to find other ways to add a highpass to the pro amp?

I know rythmik offers some options as far as including a highpass in his amps..but then again that'll be nowhere near 500 watts @ 8ohms output...

Too bad the A500 doesn't have highpass filters built in.
 

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Mike said:
A 9 inch long port would tune it to 26hz. Won't the woofer unload below the tuning frequency considering this is a HT sub? I'd suggest a 15 inch long port which would tune the box to 21hz. That would give the driver much more protection. He would still get 107db at 20hz with 315 watts. Your thoughts Steve?
Though the generally accepted mindset says differently, drivers don't just instantly bottom immediately below tuning in ported enclosures. In my opinion, the 26hz tuning gives him the best FR with plenty of headroom in the usable range - this driver clearly isn't going to win any displacement awards, so I designed to keep it optimized over a range in which it can perform quite well. The ~20hz highpass should keep it pretty safe with 500 watts.
 

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If you drop to 3 cubes and maintain the 26hz tune, the FR looks pretty poor (barely flat to 30hz) and the port grows to ~13.75" in length, which might be hard to implement properly in such a small box. I'd raise the tune to 28hz to keep the FR flat in the usable range, making the port ~11.5" long and probably requiring the highpass to be moved up ~22hz.

I really would stay at 4 effective cubes if at all possible - that design won't do anything subsonic for you, but it gets you closer to being a real subwoofer.
 
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