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B&C 21DS115


Ricci

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  • 3 months later...

Hi all, i am looking for two smallish sealed subs for music and movies. Ideally 18 cubes but could push that a little bit. I have shortlisted the 15ds115 4 ohm but whenever i try to calculate sealed volume on winisd it keeps comming up with a very tiny box that doesnt look right for a qtc of .7. Has anyone made a sealed 15ds115 and if so how large was it and would you recommend it. Thanks

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You can completely ignore the winisd recommendations. In fact you should also ignore qtc for the most part. IMHO. I never use it for design work anymore. 

Start with a size that is practical to build such as a 17" or 18" cube and use that calculated volume for modeling. Use the model to determine an appropriate amount of power to use. Don't worry if the excursion below 20Hz seems to go beyond Xmax at low power. It will due to a very low qtc alignment. The DS series drivers are almost impossible to bottom out and it takes WAY more power than winisd will show to push the driver beyond 20mm excursion. The driver does not respond linearly to power increases beyond Xmax and a little past 20mm one way even huge increases in power will not push it further. It is effectively done at 25mm no matter how much power is dumped in. 

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Just now, Ricci said:

You can completely ignore the winisd recommendations. In fact you should also ignore qtc for the most part. IMHO. I never use it for design work anymore. Extremely efficient drivers result in impossibly small box sizes for nominal qtc values. 

Start with a size that is practical to build such as a 17" or 18" cube and use that calculated volume for modeling. Use the model to determine an appropriate amount of power to use. Don't worry if the excursion below 20Hz seems to go beyond Xmax at low power. It will due to a very low qtc alignment. The DS series drivers are almost impossible to bottom out and it takes WAY more power than winisd will show to push the driver beyond 20mm excursion. The driver does not respond linearly to power increases beyond Xmax and a little past 20mm one way even huge increases in power will not push it further. It is effectively done at 25mm no matter how much power is dumped in. 

 

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Thanks Ricci, I really appreciate your input.  Yeah I have no faith in the output I am getting from winisd but 45l, which seems tiny, seems to top out the extension.  The smaller the better for me (17cube is perfect) but if its wrong I am worries about the transient response if its too small.  On the flip side I am also worried about damaging the drivers.   I already have an inuke 6000 to drive 2 of them but it doesn't have a limiter  (eq via minidsp). According to winisd the power for xmax drops off pretty fast below 22.    I could get 8ohms to be safe but then I'll be missing out on output.

Unfortunately I am size restricted by how big I can go with the subs as its not a dedicated room otherwise I would just get 2 BMS 18N862 which are pretty much the same price (or even the 18DS).  The location for the second sub just cant accommodate anything bigger than an 18 cube . I would however like to go for the best quality drivers I can to deliver the clean bass as is practically possible and plenty of output above 40 to add some slam when needed.    I had considered the Alpine swr 15 and Datyons 15 HO which are cheaper (and easy to model!) but I do like the idea of pa type subs.

 

  

 

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