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

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gen0me View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2017 at 5:55pm
Strange that you dont heat them long term. You could measure impedance before and during/just after the test and outside temperature.
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Ricci View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ricci Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2017 at 6:21pm
Originally posted by Crashpc Crashpc wrote:

Wow, that is really brutal! In light of knowing that thermal capacity of the coil usually only allows for precious SECONDS of overloading before it burns in hell, and in light of knowledge that you do some "few period sweeps", I thought we´re talking roughly about 4-8 seconds of torture.
This one is not just mind blowing, but coil blowing, and the speaker still holds its own. Bravo! for B&C speakers! And thank you for very good and high strain tests, risking your own money for all of us. :-)
 
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.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote logsquared1 Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2017 at 9:04pm
Originally posted by ReubGold ReubGold wrote:

Any thing that involves bridging 9001, should really ring alarm bells.

Don't be scaredLOL  Pedal to the metalBig smile

Seriously though,  If your not putting at least 4Kw peak RMS to a 21SW152 you might as well get a cheaper woofer.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 21 October 2017 at 6:19am
Well, if I rather listen to "square wave music", 2500 seems to be okay. :-D
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sirius Sounds Quote  Post ReplyReply Direct Link To This Post Posted: 21 October 2017 at 10:59pm
What's 4kW peak rms? Is it peak or rms?! I was planning on putting about 2k7 rms and i think thats about 4k peak for my amp.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote logsquared1 Quote  Post ReplyReply Direct Link To This Post Posted: 21 October 2017 at 11:55pm
Originally posted by Sirius Sounds Sirius Sounds wrote:

What's 4kW peak rms?

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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ReubGold Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2017 at 11:12am
Originally posted by logsquared1 logsquared1 wrote:

Originally posted by ReubGold ReubGold wrote:

Any thing that involves bridging 9001, should really ring alarm bells.

Don't be scaredLOL  Pedal to the metalBig smile

Seriously though,  If your not putting at least 4Kw peak RMS to a 21SW152 you might as well get a cheaper woofer.



If you have sufficient mains supply, would think 2x 4 ohm drivers per channel of 9001, each cab with it's own pair of 4mm2 conductors, should do the job, for reasonably sensitive drivers.
If he turns me into a zombie, first person I'm coming after is you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 28 January 2019 at 1:34pm
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".
 
 
Nikon and Canon people should not be married to each other. Why did you let this happen?
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