Just curious to see what you guys think of using a bandpass box for a subwoofer outside of car audio. After messing around with WinISD, i figured out a design for a 6th order bandpass that is almost flat from 30 to 75 Hz, which would be prefect for music use, and is significantly more efficient than a ported box with similar frequency response (at least for my woofer). Are there any downsides to using a 6th order bandpass enclosure, like reduced sound quality or anything like that?

I don't know of anyone who has tried this, so any opinions would be appreciated and just let me know if knowing the box or woofer specs would help

only down side is a huge box. just make sure you have proper filters on the sub ssf and lowpass otherwise you can bottom the sub out very easy.

the enclosure doesn't start dropping off ( at 24dB an octave) until 30 Hz, that should be allright for music, right? I don't have an ssf, although i'm pretty sure i could build one, but i won't bother if it won't really be helping.

So no noticeable effects on SQ, assuming there is enough port area?

Home theater audio usually plays far below 30hz for movies..

Home theater audio usually plays far below 30hz for movies..

I was thinking the same thing. Usually people build sealed boxes or really low tuned boxes (like 15-20 hz).

6th order vented tend to have pretty bad group delay.... One reason why Bose subwoofers sound so horrible...

It would (could) be very, very loud though...

You could use some FMODS, or even a passive high pass filter if bottoming out really became a problem...

I have built a few 6th order BP boxes for home audio, I like 4th order better.... I copied that stupid Bose bazooka 12" sub, it sounded like ass but was loud...

home theater is normaly tuned lower as others have already stated.... IB, sealed, ported down around 20 are common for custom builds

most low end pre-fab home subs (that I've seen) are tuned around 30 though

This will be used primarily for music, it will be in my dorm room at college. I would be willing to keep the volume lower, or turn the sub down, for movies if it will work better for music. Will it start bottoming out as soon as it hits that 24dB slope, or will it be safe until the output level drops significantly, like 3 dB or something

The sub I have (elemental designs 11kV.2) wont cut it in a sealed box, and don't think will be able to do an infinite baffle set up. So it is either ported or bandpass, and I couldn't get the response I wanted out of a 4th order.

And group delay, is that an actual time delay for the sound or a weakened transient response or something else?

It is the difference in time the different frequencies get produced (arrive) by the alignment, the more group delay you have, the worse things sound. Some people would call this transient response, it technically isn't, but you could describe it that way....

Group delay tends to be worse right above and around tuning, so thats two strikes against a 6th order right off the bat....

Is there a way to minimize delay, like enclosure placement, volume, tuning, port area, etc? Or if i got the tuning frequencies outside of the range that I want the woofer to reproduce (ie tune to say 25 and 90 Hz to reproduce from 30-75 Hz), would that help?

If not, would the sound quality drop be worth a 4-5 dB increase in efficiency over a ported enclosure?

Is there a way to minimize delay, like enclosure placement, volume, tuning, port area, etc? Or if i got the tuning frequencies outside of the range that I want the woofer to reproduce (ie tune to say 25 and 90 Hz to reproduce from 30-75 Hz), would that help?

If not, would the sound quality drop be worth a 4-5 dB increase in efficiency over a ported enclosure?

There isn't much you can do about the group delay. Does your program show it? If it does, see how bad it is and if you can manipulate it much with tuning variations...

If you look, you'll probably have 2 huge spikes in group delay at the lower and higher tuning points, with a trough (of still high group delay) in the middle.... The lower end tuning will probably have more group delay, but it isn't as audible down there. Where it gets annoying is 40Hz on up... Near the upper end of your pass band (drums, bass guitar, and such) you may get the results of muddy or sloppy sounding bass...

I was using WinISD beta, which doesn't have it, at least not that I'm aware of. I'm gonna see if i can find the alpha version, which should have more stuff (maybe group delay). If i can find it, what are acceptable numbers for group delay?

If there is really no way around this, and 6th orders are just gonna sound bad, then i will just go ported and lose the efficiency. 325 watts on a 10" should still be enough for my dorm room, I just think it would be really cool, and it would offer more protection for the woofer since it would be completely surrounded

WinISD actually does have group delay, i just never paid attention to it before. the delay is 8ms at best, it's pretty bad at the upper tuning and atrocious at the lower tuning, over 20 ms at 30 Hz and it skyrockets up from there. Although the ported box also has significant delay at the low end, but not nearly as extreme

Just for the information. I run 100W max to my 10" sub, sealed, in my dorm room and lots of things start to shake and rattle. Most of the time I'm running about 50 on music.

Depending on your budget i would have alook at this...

I know its not DIY but i decided to buy one becasue for this little i doubt you can make better, the cost of a 10 driver amp etc etc will be more and besides for dorm use with music as a priority i think it should be perfect, i would like to see a better DIY Music sub for $230

http://www.zzounds.com/item--BEHB2092A and another review (although bad) can be found here http://www.tcmagazine.com/articles.php?act...1&pagenum=1 you get quiet a lot for your money to, it weighs 73lbs and is 24.4x12.8x22.9 with two 8 inch drivers. The amplifier is way over rated but i figure even if its only 100watts RMS considering the options it has it is still very good value for money

I am going to write a detailed review of mine here in the next week or so...

Edited January 26, 200916 yr by Samuel

Depending on your budget i would have alook at this...

I know its not DIY but i decided to buy one becasue for this little i doubt you can make better, the cost of a 10 driver amp etc etc will be more and besides for dorm use with music as a priority i think it should be perfect, i would like to see a better DIY Music sub for $230

http://www.zzounds.com/item--BEHB2092A and another review (although bad) can be found here http://www.tcmagazine.com/articles.php?act...1&pagenum=1 you get quiet a lot for your money to, it weighs 73lbs and is 24.4x12.8x22.9 with two 8 inch drivers. The amplifier is way over rated but i figure even if its only 100watts RMS considering the options it has it is still very good value for money

I am going to write a detailed review of mine here in the next week or so...

Thanks for the suggestion, but the whole thing ended up costing me like 150 or less, since I already had the amp. It ended up in a 2 ft^3 box tuned to 27 Hz. Sounds great and gets loud enough, but I might just try the bandpass for kicks