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Dual 15" subwoofer, rcf design?

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Tonskulus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 7:43pm
Originally posted by Hemisphere Hemisphere wrote:

If only 3 of 4 were replaced maybe test to see how the original driver behaves run on it's own.

Problem is that, all 4 are still same type drivers.. which is a bit confusing, as the seller was :D 


I'll add a video soon :)

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Tonskulus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 7:49pm
Short videoclip of this sub in action:




Edited by Tonskulus - 02 November 2017 at 7:52pm
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MarjanM View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 9:39pm
Are you using any high pass filter?

Marjan Milosevic
MM-Acoustics
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2017 at 5:42am
Originally posted by MarjanM MarjanM wrote:

Are you using any high pass filter?


no atm, that particular music I was playing didn't have much content under 40Hz.. but for sure, I can try it with high pass if it makes any difference :)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2017 at 1:30pm
Originally posted by Tonskulus Tonskulus wrote:

Something weird there is, I played these subs a bit "harder", psy trance music having tight bass mostly 40...60Hz. 
Drivers start "flapping" at 500Watts (300W / driver) input. At 300W its clean BOOM BOOM, but 600W makes it sound more like BFLOP BFLOP and sounds like over excursion. Looking at drivers, cones are moving around 10mm.  My 18" RCF subs can take cone movement of >20mm and no flapping problems!

Amplifier is not clipping.. not even close when this happens as there is still some room to increase volume before clipping occurs. Amplifier is Tamp TA1400, 4ohm load / channel. 
Is it possible that L15P540 is not good for this kind of enclosure and goes out of control or what..?  These drivers should take 1kW each according to specs.. 

Well, there's your problem right there.
That model has an Xmax of 6.5mm, so if you can see that the cones are moving well past that, what did you expect it to sound like?
Also, didn't you say earlier that they were tuned to around 50Hz?
If so, putting tracks through them with strong 40Hz content and no HPF is asking for sh1t sound quality in the first place, followed by damaged drivers if you persist.

To expand a little - the stated power rating of a driver has almost nothing to do with how good it sounds or how well it suits a specific box type and tuning frequency - that's what all the other parameters tell you. You can't assume that just because RCF have tested it without damage at 500W (continuous, implying 1000W program), it'll sound good in this box with this type of musical content at that power level.

HTH, 
David.
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Tonskulus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2017 at 2:01pm
Originally posted by DMorison DMorison wrote:

Originally posted by Tonskulus Tonskulus wrote:

Something weird there is, I played these subs a bit "harder", psy trance music having tight bass mostly 40...60Hz. 
Drivers start "flapping" at 500Watts (300W / driver) input. At 300W its clean BOOM BOOM, but 600W makes it sound more like BFLOP BFLOP and sounds like over excursion. Looking at drivers, cones are moving around 10mm.  My 18" RCF subs can take cone movement of >20mm and no flapping problems!

Amplifier is not clipping.. not even close when this happens as there is still some room to increase volume before clipping occurs. Amplifier is Tamp TA1400, 4ohm load / channel. 
Is it possible that L15P540 is not good for this kind of enclosure and goes out of control or what..?  These drivers should take 1kW each according to specs.. 

Well, there's your problem right there.
That model has an Xmax of 6.5mm, so if you can see that the cones are moving well past that, what did you expect it to sound like?
Also, didn't you say earlier that they were tuned to around 50Hz?
If so, putting tracks through them with strong 40Hz content and no HPF is asking for sh1t sound quality in the first place, followed by damaged drivers if you persist.

To expand a little - the stated power rating of a driver has almost nothing to do with how good it sounds or how well it suits a specific box type and tuning frequency - that's what all the other parameters tell you. You can't assume that just because RCF have tested it without damage at 500W (continuous, implying 1000W program), it'll sound good in this box with this type of musical content at that power level.

HTH, 
David.

Yes, but as I said I can drive those 18" rcf's well beyond their xmax limits no problem (mechanical limit is 50mm). Clean and loud!

Anyway, it sounds like these 15" drivers are reaching their mechanical excursion limits which makes it sound "flobby" even tho thats not the case, spec sheet says limit is 36mm.  As you said, these are indeed not designed much under 40Hz frequencies and that might be a problem. 
I need to try these w/ highpass filter.




Edited by Tonskulus - 03 November 2017 at 2:08pm
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Tonskulus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 12 December 2017 at 4:32pm
I just loaded this sub with old Cerwinvega 15" drivers and flapping is much much worse!  Some 50Watts / driver and things go horribly wrong.
 
Is it possible that manifold makes cone loading asymmetrical somehow? Something really weird there is.. 


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