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

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corell View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote corell Quote  Post ReplyReply Direct Link To This Post Posted: 30 September 2017 at 6:40am
With the first horn segment having about 30 liters and a decreasing cross sectional area, your design goes into the bandpasshorn direction, which also explains the good 2pi response. Cone area DOES matter a lot for these types of enclosures! What i said is only valid for true FLH with very little air cavity infront of the cone.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote logsquared1 Quote  Post ReplyReply Direct Link To This Post Posted: 30 September 2017 at 9:28pm
Originally posted by corell corell wrote:

With the first horn segment having about 30 liters and a decreasing cross sectional area, your design goes into the bandpasshorn direction, which also explains the good 2pi response. Cone area DOES matter a lot for these types of enclosures! What i said is only valid for true FLH with very little air cavity infront of the cone.

I do think the volume in front is having a bandpass effect.  The rear volume of the woofer occupies this space too.  And the magnet sits in the "neck" area.  I subtracted the area of the magnet from the "neck" cross section  (S2).    The shape of the woofer plays into the first segment actual shape and expansion.  Not sure how to model it in hornresp.  Should that area be considered a throat chamber or a neg expansion like I have it?  The prototype measures very close to the sim.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SouthwestCNC Quote  Post ReplyReply Direct Link To This Post Posted: 01 October 2017 at 1:30pm
With the negative expansion, would i be right in thinking the first fold will be over 90 degrees? Increasing the band pass effect. Is there a way of estimating this effect as hornresp doesn't seem to.

Sorry for hijacking thread, hope it's relevant otherwise I'm just learning of the back of your project.

Edited by SouthwestCNC - 01 October 2017 at 1:37pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2017 at 11:45am
Negative expansion is from the magnet facing forward horn. Keep in mind there is no Vtc in sim. Basicly edge between large S1 and Vtc can be very fuzzy depending on design.
There was topic on diyaudio with this pic;

about bending horns but it seems the image is no longer there cause of photobucket.

Edited by gen0me - 03 October 2017 at 11:50am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SouthwestCNC Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2017 at 12:03pm
Originally posted by gen0me gen0me wrote:

Negative expansion is from the magnet facing forward horn. Keep in mind there is no Vtc in sim. Basicly edge between large S1 and Vtc can be very fuzzy depending on design.
There was topic on diyaudio with this pic;

about bending horns but it seems the image is no longer there cause of photobucket.


I would have thought that if the first segment surpasses the width of the driver it would be better modelled as a OD s1 over front chamber.

Its the effects of the angle of the fold itself on the response that interests me i.e when its over 90degrees. Laying flat for hornresp doesn't give you the bandpass effect from tighter angles, Or is this effect minimal?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2017 at 5:53pm
Its the same story between OD and Nd.
You need to find this topic. There were measurements there if they haven't disappeared. Should clear your doubts.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ricci Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2017 at 9:00pm
I just posted a bunch of data from testing with a 21DS115-4 driver. The cabinet is not intended for a typical "pro" reinforcement application. That testing and sealed cab testing will be done next spring, but this does give some concrete information into the drivers performance. 21SW152-4 was done in multiple cabs years back and is also floating around.
 
 
If you aren't familiar with navigating DB if you click on most of the titles or names they are links to more information. There are currently 4 measurements sets with notes for the 21DS115-4. There is a lot of information there.
 
100V into the 21DS115-4 could be dangerous to the driver thermally over the long term with high duty cycle.


Edited by Ricci - 13 October 2017 at 9:01pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote logsquared1 Quote  Post ReplyReply Direct Link To This Post Posted: 17 October 2017 at 12:49am
Originally posted by Ricci Ricci wrote:

I just posted a bunch of data from testing with a 21DS115-4 driver. The cabinet is not intended for a typical "pro" reinforcement application. That testing and sealed cab testing will be done next spring, but this does give some concrete information into the drivers performance. 21SW152-4 was done in multiple cabs years back and is also floating around.
 
 
If you aren't familiar with navigating DB if you click on most of the titles or names they are links to more information. There are currently 4 measurements sets with notes for the 21DS115-4. There is a lot of information there.
 
100V into the 21DS115-4 could be dangerous to the driver thermally over the long term with high duty cycle.

ThanksThumbs Up  That's what i was looking for.  I can't really do full power long term tests in my shop due to neighbors.  

You put some time into those measurements!  

How long are the sine sweeps for the "long term" power measurements?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ricci Quote  Post ReplyReply Direct Link To This Post Posted: 19 October 2017 at 5:48pm
Originally posted by logsquared1 logsquared1 wrote:

ThanksThumbs Up  That's what i was looking for. 

How long are the sine sweeps for the "long term" power measurements?
 
The sine sweeps are ascending covering the range of 2Hz - 240Hz (240Hz needed for measurement resolution to 120Hz.) Duration is roughly 22 seconds. It is brutal at the higher voltages.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2017 at 4:10pm
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. :-)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ReubGold Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2017 at 4:49pm
Still think there is too much reliance on SP,  regarding simming with HR, versus real life measurements.

For the OP, to achieve 50-150hz, simple solution would be 1850 Horn with V18-1000s, and  Staiper  ES18.

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 ReubGold Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2017 at 4:50pm
Any thing that involves bridging 9001, should really ring alarm bells.
If he turns me into a zombie, first person I'm coming after is you.
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