B&C 21SW152 and 21DS115 long term power handling

Been toying myself with 21/18/15 sims in flh. The slightly lower response from the 21 seems like its not really much of a gain compared with a 15" where there is potential for a smaller chamber and a longer horn and with it lower response and spl gain.

I think that's a mechanical issue not electrical.

logsquared1 wrote: turbo7 wrote: You dont need that much cone area for 50-150hz, you will not really achieve more output and you would probably get a better sound with a 15". The price difference should also be quite significant Simulations are saying otherwise.  Also, I A/B tested my prototype against 3 X HD215's eq'ed to match as closely as i could get.  The hd's are loaded with EV DL15X's (EBP = 140).  The single 21 had no less "punch" than the 6 X 15's.  Sound quality was very good.  Obviously the the 6 15's were louder but not by much.  And the 21 when not eq'ed went at least 10 cycles lower.   Crashpc wrote: Sure. But finding 15" with so much power and cone excursion for mildly unloaded horn is very hard. But 18DS115 should be better for that task. I do agree that 21" for 50Hz horn sounds like something is not right. The 21" could even not move enaugh and burn the coil edges soon. The 18DS115 looks like a nice woofer.  However, the 21 is a much more efficient driver.  I should have mentioned I plan on using the box as a general purpose sub down to 40 cycles for non EDM gigs.  The extra surface area should be helpful here.  Good point on the possible thermal problems if the cone is not moving enough.  That kind of goes back to my original post..... What long term power are people putting to these things? Elliot Thompson wrote: logsquared1 wrote: MarjanM wrote: They can certainly take tons of power, but, how long they will last, it is a different question. Pushing lot more then 2KW per driver will for sure start exhibiting power compression and you wont get much louder from that point even if you push 4KW to them. One of the reasons I am so excited about the newer amp is the ability to have large voltage swings and limit the average power to keep driver heating down.  Should give more confidence when running hard.   . You can still damage the driver by creating an offset which will lead to the voice coil rubbing against the magnetic plate. Best Regards,   Not sure I follow. Anyone have any real world experience with the 21DS???

A single 21 is equivalent spl to six 15s and can generate the same kick? Is that right????

JonB67 wrote: A single 21 is equivalent spl to six 15s and can generate the same kick? Is that right????

corell wrote: again, cone area is worth very little in a front loaded horn. yes, a 21" will have lower excursion than a 15" in the same enclosure (while having about the same sensitivity), but if your Front loaded horn is excursion limited (and not thermal/power limited) you dont have a good horn design. As southwest cnc stated, just build a longer horn with more compression for the 15" (compared to the planned 21" cab) and you will have more SPL and lower response for a given input power in an enclosure about the same size. this is not valid for BPH though.

logsquared1 wrote: corell wrote: again, cone area is worth very little in a front loaded horn. yes, a 21" will have lower excursion than a 15" in the same enclosure (while having about the same sensitivity), but if your Front loaded horn is excursion limited (and not thermal/power limited) you dont have a good horn design. As southwest cnc stated, just build a longer horn with more compression for the 15" (compared to the planned 21" cab) and you will have more SPL and lower response for a given input power in an enclosure about the same size. this is not valid for BPH though. I would like to sim this.  What are some modern drivers I should look at?  I tried b c sw115-4.  I can get similar response to 21ds with a horn as you describe.  However, it shows a bit less sensitivity ~2db and 3-4db less max spl.

Hey logsquared,

i simmed an example for you:

Both are FLH with identical horn mouth size and netto volume, both have a compression ratio of 1:2,5 and both are fitted with modern high power high motor force drivers. I designed them for a 50Hz cutoff (see the excursion graph) and went for an almost identical frequency response 50-120 Hz while keeping the last 2 horn segments identical (note that the 15" response could be further optimized around the 100Hz range with different horn shape). I added 7cm on the 15" version to make it 510 liters aswell, but it hardly changes response.

As you can see, both will take 1500w well within its excursion limits. The 21" has a higher thermal power handling on specs but i wouldnt advise to power any closed backchamber enclosure (Like FLH) with significantly more juice, as they will get warm! Also, 200w give or take are barely noticeble from 1500w on or off (<0,5dB).

Please also note that the 15" horn mouth could be made smaller with small impact while the 21" would "suffer" more from it. This could be for this exact sim only, so i wont generalize here.

Hope this makes sense to you :)




Edited by corell - 29 September 2017 at 11:02pm