Which would you choose?

cogitech · 21st December 2012, 09:36 PM

If you were limited to choosing between the following subwoofer scenarios, which would you choose, and why?

Assume that the crossover will be set at around 65-75Hz

Same size enclosure, one is closed, one is 4th order bandpass.

Thanks in advance for your opinions/advice.

cogitech · 22nd December 2012, 06:00 AM

Nobody?

Ummmm...

planet10 · 22nd December 2012, 06:06 AM

Quote:

Originally Posted by cogitech

Nobody?

Fridays are always slow. And the Friday before xmas...

I'd pick the yellow one.

1/ match room gain better
2/ less group delay
3/(my own metric). 1st derivative of the FR does not cross zero more than once.

dave

bobodioulasso · 22nd December 2012, 06:17 AM

I would choose the closed box for it's regular roll off.
Active linkwitz transform could make it go lower. Depending on x max.
Bandpass is peaky. Difficult to deal with.

cogitech · 22nd December 2012, 06:38 AM

Thanks guys!

ßart West-VL. · 22nd December 2012, 08:12 AM

Watch the curve of the group delay and cone excursion too, or better yet, post them here.

head_unit · 29th December 2012, 04:39 PM

Um.

I'd choose to port the box with a low tuning (under-tuned), for more SPL but still a smooth rolloff.

I don't think the bandpass gains you much here. This simulation is crude, but let's pretend it is perfect. In the bass, the bandpass gains 4 dB sensitivity. But at 100Hz it is down 4 dB, needing more power. Apples and oranges, but the bandpass is not always more sensitive is the basic point.

The excursion should be much less for the bandpass, but a ported design can get a lot of that as well. Bandpass designs are really really easy to become a peaky, boomy mess, especially when actually trying to build a real enclosure, which often doesn't have enough room for big enough ports due to the complexity.

What the heck box size are you using? And what driver? And did you buy the driver already?

Try running a simulation with a 25 Hz and 30 Hz port. And publish the excursion and group delay curves if possible.

21st December 2012, 09:36 PM	#1
cogitech diyAudio Member Join Date: Jan 2011 Location: Kamloops, BC	Which would you choose? If you were limited to choosing between the following subwoofer scenarios, which would you choose, and why? Assume that the crossover will be set at around 65-75Hz Same size enclosure, one is closed, one is 4th order bandpass. Thanks in advance for your opinions/advice.

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22nd December 2012, 06:00 AM	#2
cogitech diyAudio Member Join Date: Jan 2011 Location: Kamloops, BC	Nobody? Ummmm...

22nd December 2012, 06:17 AM	#4
bobodioulasso diyAudio Member Join Date: May 2008	I would choose the closed box for it's regular roll off. Active linkwitz transform could make it go lower. Depending on x max. Bandpass is peaky. Difficult to deal with.

22nd December 2012, 06:38 AM	#5
cogitech diyAudio Member Join Date: Jan 2011 Location: Kamloops, BC	Thanks guys!

29th December 2012, 04:39 PM	#7
head_unit diyAudio Member Join Date: Feb 2004 Location: Los Angeles	Um. I'd choose to port the box with a low tuning (under-tuned), for more SPL but still a smooth rolloff. I don't think the bandpass gains you much here. This simulation is crude, but let's pretend it is perfect. In the bass, the bandpass gains 4 dB sensitivity. But at 100Hz it is down 4 dB, needing more power. Apples and oranges, but the bandpass is not always more sensitive is the basic point. The excursion should be much less for the bandpass, but a ported design can get a lot of that as well. Bandpass designs are really really easy to become a peaky, boomy mess, especially when actually trying to build a real enclosure, which often doesn't have enough room for big enough ports due to the complexity. What the heck box size are you using? And what driver? And did you buy the driver already? Try running a simulation with a 25 Hz and 30 Hz port. And publish the excursion and group delay curves if possible.