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

 

It is very demanding. The reason it is done like this is an effort to produce an accelerated heat buildup. I don't have time or the area for a whole other setup for much longer thermal compression testing over many hours with pink noise. This type of thing is already done with AES testing anyway. Also it will change drastically depending on the enclosure used and signal applied. This type is more abusive over the short term but not as abusive as applying a sine wave at a worst case frequency. At tuning for a vented cab for instance. Most drivers seem to bounce back from being driven to 3-4dB of thermal compression once or twice. I'm not sure that would be the case if heated that much many times. Of course I've burnt up some drivers and also broken some mechanically with this type of test. Using that type of signal also pushes the speaker extremely hard at all of its weak points in the sub bandwidth so it reveals a lot of warts, distortion and other bad distortions or sonic issues. Often driver excursion becomes a limiting factor right at about the time the driver is running into serious thermal issues. Whichever one throws up a flag becomes the limit for that test type.

 

The available wattage calculated from the maximum RMS voltage capability of the amplifier.   Roughly .707 X the Rail voltage.  Or the "continuous program" rating used by most woofer manufacturers.

Hey. Digging old corpses I guess...

 

In B&C, they say they put more wire into the magnetic gap with 21DS115, for motor strength. I still cannot wrap my head around how they did it. The math doesn´t work here (Resistance, wire diameter and length) for me. Looks like it is not possible with Aluminium. Yet they did it somehow.

That is not the topic though.

 

The more I think about it, the more it seems to me that the Al coil must be beefy one. Significantly greater wire diameter and volume than with Copper. And thicker coil body too, obviously. That might mean good things for cooling capabilities, couldn´t it? Greater coil area and volume/heat capacity. And the weight is also there. Mms of 21DS115 is greater than with 21SW115.

 

The 21SW152 doesn´t have much more coil area than 21DS115, and that is not counting for split coil of 21SW152. It might be, that the coil area of 21DS115 is the same as 21SW152, despite significant difference in the coil diameter. That would certainly make Ricci´s tests slightly less "unbelievable".

 

 

In time, these drivers BOTH rose and dropped in my evaluations. In my usage, it is not enough coil, and 2000+ model is very needed, in order to work its purpose. On the other hand, for peaks, with these kinds of Bl, in 21" size it starts to show "that scary" bass, and it is able to blur my vision when I turn my back to it. So it is not that bad. 

In the meantime,many thongs moved and changed. I have tested many more speakers, Celestion TSQ2460 arrived yesterday, and soon I am deploying a review platform.