# Should i use this 21" sub in my HE system?



## StabMe (Nov 17, 2011)

Hi

I am planning my HE system and slowly buying components. The system will include ES fullbodies, Beyma 8G40 in ported enclosures and i haven't still decided on a sub.

Some time ago i bought B&C 21SW152 on a whim and never used, so i thought maybe it would be a good candidate for a subwoofer in my new system.

Here are the specs:











I modeled in WinISD. Below are the graphs showing the SPL response with 700W applied. 










*Yellow *graph shows the response in 60 liters sealed box (2,119 ft^3). That is about the volume i am going to get if i build the box in a spare tire well. *Purple* graph shows the response of a vented box with tuning frequency at 32Hz. Both sims have cabin gain applied by the means of Linkqitz transform i estimated for my SUV (f0=56Hz, fp=15Hz, both Qs at 0,707), lowpass filter at 80Hz and a highpass filter at 80Hz. 

Thinner *orange *and *blue *lines show the response of vented and sealed boxes respectively without the cabin gain.

*Gray *line is JL Audio 12W6V2 in a vented enclosure tuned at 22Hz. Included for comparison.

Do you guys think i will be satisfied with this speaker? I used JL Audio 12W6V2 in my previous install in a vented enclosure tuned at 22Hz and it played really low. I liked the character of its sound and the low notes it was able to play. But i think it lacked in 50-80Hz region. And i want this one from B&C to cover the full range from 25 to 80Hz and do that with authority. 

Am i on the right track?


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## Eric Stevens (Dec 29, 2007)

With 3 times the static displacement of the JL it will have more output everywhere. B&C build a good product and I think this will do the job very well.


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## StabMe (Nov 17, 2011)

Thanks for chiming in, Eric.

Do you think the suboptimal box volume i can provide for this driver won't be as huge limiting factor?


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## Eric Stevens (Dec 29, 2007)

The transfer function of the two systems will be drastically different with the larger system having far more LF increase due to transfer function. If the enclosure lacks the lowest octave you can always vent the rear wave outside the vehcile for a IB system.

Not sure how the modelling in WinISD looks compared to the real world but unless you have a subsonic I guarantee your bottom end will not roll off as depicted is may be at most down 6 dB at 10Hz from 20 and problably less. I use LEAP and it doesnt model like the graph you have in your post.

If you are after SQ type of bass even with high levels with a deep extended botom end I am prety confident it will achieve what you are after and especially if IB.


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## Lycancatt (Apr 11, 2010)

I think either the sealed or ported would do you just fine, I'd lean towards the ported because I tend to like the sound of vented better, but the sealed box would be solid too since you have so much cone area.


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## StabMe (Nov 17, 2011)

Well, i guess i will try sealed, then ported and then try IB as a last resort. But something is telling me that i will be satisfied even with sealed.

Thanks!


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## Elgrosso (Jun 15, 2013)

So how did it work after few months?


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## T3mpest (Dec 25, 2005)

Wish I had seen this sooner, I'm hardly on here anymore. I used this subwoofer for about 6 months in my Cadillac SRX. In a trunk install you might be able to do well with a sealed box it.

To really hit 25-80hz with authority, if you have the space I'd shoot for about 5.5-6 cubic feet tuned at about 30-32hz. (depends a bit on your cabin gain and space limits) These do like quite a bit of port area, in a trunk I'd suggest an aero port to save space and port length while minimizing port compression. Probably still need at least a 8 inch aero even on 700 watts.


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## StabMe (Nov 17, 2011)

Well, thanks for chiming in.

The woofer and the rest of the stuff for the install is already stashed and waiting their time. I will be taking the car to the shop in May, i think. I will be constrained by the spare tire well anyway, so it will most probably be a sealed box. The sub is so big and powerfull, i really hope it will provide enough SPL.



T3mpest said:


> Wish I had seen this sooner, I'm hardly on here anymore. I used this subwoofer for about 6 months in my Cadillac SRX. In a trunk install you might be able to do well with a sealed box it.
> 
> To really hit 25-80hz with authority, if you have the space I'd shoot for about 5.5-6 cubic feet tuned at about 30-32hz. (depends a bit on your cabin gain and space limits) These do like quite a bit of port area, in a trunk I'd suggest an aero port to save space and port length while minimizing port compression. Probably still need at least a 8 inch aero even on 700 watts.


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