Need a DIY Subwoofer Driver advice - 2.5cu ft sealed

[Jack Caldwell]

but still good..

in a small room like yours you'll get plenty of room gain. Try two of these per side: Dayton Audio RS225-8

In a 2.5 cu.ft. box stuffed w. Dacron Polyfill you should get Fb of 42Hz or so, with box Q about 0.67

This type of response, when associated with room gain should give you extended in-room response down to the low 30's or upper 20's. And with the DCX2496 you can knock out much of the room modes.

Is the ceiling 8 ft tall? If so, plan on knocking down the level near 71Hz, the 10ft lateral will give you a big boost around 50Hz and probably need reducing. The room mode from the 17ft length will boost the bass near 33Hz, so you may not need any boost at all to get flat bass down quite low.

However, the advantage of an open baffle woofer would be that the vertical and lateral modes would be much reduced due to not being excited as much.

[john65b]

Whoops, sorry, it is 18 x 14, and just under 8 foot ceiling.

Wow, I am impressed. I haven't really used the DCX for much other than trying slopes and moving crossover points on a two way biamp - not equalization - so this will be interesting...

[Jack Caldwell]

Main modes would be near 31.5Hz (longitudinal), 40.6Hz lateral, and if 8ft ceiling 71Hz vertical

[Jack Caldwell]

Originally Posted by john65b

Whoops, sorry, it is 18 x 14, and just under 8 foot ceiling.

Wow, I am impressed. I haven't really used the DCX for much other than trying slopes and moving crossover points on a two way biamp - not equalization - so this will be interesting...

Yeah, the DCX is quite an amazing unit... and it can be a truly audiophile piece when modded. You owe it to yourself to do it, as the quality of the onboard DAC really deserves a better analog section. It can sound really, really stellar, on a par with any DAC in the under 2K range.

[sreten]

Hi,

FWIW with twin 8" daytons per side and 2.5 cuft a low tuned vented
alignment will give better results than sealed regarding deep bass and
maximum SPL levels, shown is a very fuss free alignment very suited
to room gain that will simply dig deeper than a sealed arrangement.

Eyeopenly different capabilities between 20Hz and 30Hz.

rgds, sreten.

[john65b]

Looking at a pair of NHT 1-11-084-011 8" Woofer...am I kidding myself??

Reve= 5.500 Ohm
Fo= 32.240 Hz
Sd= 21.739m M2
Krm= 1.060m Ohm
Erm= 0.899
Kxm=55.063m H
Exm= 0.521
Vas=63.487 Ltr
Cms= 946.082u M/N
Mmd= 23.916m Kg
Mms= 25.759g
BL= 8.919 TM
Qms= 1.935
Qes= 0.361
Qts= 0.304
No= 0.570%
SPLo= 89.579 dB

[john65b]

Hmm,

Qts of .304 makes an unlikely candidate for a seal box, no?

[Jack Caldwell]

Originally Posted by sreten

Hi,

FWIW with twin 8" daytons per side and 2.5 cuft a low tuned vented
alignment will give better results than sealed regarding deep bass and
maximum SPL levels, shown is a very fuss free alignment very suited
to room gain that will simply dig deeper than a sealed arrangement.

Eyeopenly different capabilities between 20Hz and 30Hz.

rgds, sreten.

That looks like a good option. However, if used without any EQ, the earlier rolloff of the sealed enclosure may mate better with the room. Oft-times a truly extended sub with bass into the low 20's will sound too heavy due to the room modes.

But the beauty of what you're proposing is that with the twin Dayton's one could build the ported version and have the option of running it that way, or to stuff the port to obtain a quasi sealed response, a case of having good cake and eating too.

So yeah, I'd be a proponent of the twin 8's over almost any 10" or 12"

But given that there is some great EQ capability in the DCX2496, I'd like a pair of twin 15's in OB even better...

Yes, there's a usually a tradeoff, losing some of the bass below 40 Hz, but the clarity from 40 to 200 Hz makes it a very appealing option... and when you factor in that in this application the main speakers are di-poles, and that the directionality patterns would match ideally, maybe this would be the better option.

Having done something similar using twin Eminence Alpha 15a's, and (when properly eq'd !!) the bass is really quite astonishing in its quickness, impact and tonality. I would take this option over the sealed or ported or even a really good t-line for sheer musicality and speed, and given that the OP is using Martin-Logans methinks this would be the best match when $$ are a consideration.

[revboden]

Originally Posted by Jack Caldwell

But given that there is some great EQ capability in the DCX2496, I'd like a pair of twin 15's in OB even better...

Yes, there's a usually a tradeoff, losing some of the bass below 40 Hz, but the clarity from 40 to 200 Hz makes it a very appealing option... and when you factor in that in this application the main speakers are di-poles, and that the directionality patterns would match ideally, maybe this would be the better option.

Having done something similar using twin Eminence Alpha 15a's, and (when properly eq'd !!) the bass is really quite astonishing in its quickness, impact and tonality. I would take this option over the sealed or ported or even a really good t-line for sheer musicality and speed, and given that the OP is using Martin-Logans methinks this would be the best match when $$ are a consideration.

+1

[john65b]

Having done something similar using twin Eminence Alpha 15a's, and (when properly eq'd !!) the bass is really quite astonishing in its quickness, impact and tonality. I would take this option over the sealed or ported or even a really good t-line for sheer musicality and speed, and given that the OP is using Martin-Logans methinks this would be the best match when $$ are a consideration.

Um, this could be a totally rediculous question, but does an OB with twin Eminence Alpha 15a's need to be front firing?