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Xmax Being Exceeded WinISD

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SteveAATW View Drop Down
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    Posted: 12 May 2009 at 6:47pm
I mentioned this in this thread but thought I'd post it in here in case it gets missed:

http://www.speakerplans.com/forum/fane-18xb-600w-advertised-as-800w_topic26685.html

I'm simming a reflex box. 250L, tuned to 35Hz. Every driver but the Turbomax goes way over XMax in the 45-60Hz and <30Hz regions when full power is applied (ie whatever the max AES rating of the driver is). The lower region I'd expect but the higher region not so much so. Only way to get it back into acceptable realms is to pull the the power down to anywhere from 1/2 - 2/3 Max.

Is this because WinISD feeds continous power or is it just some anamoly of simulation which can be ignored in reality?

I think I'm going to go with the turbomax anyway so it doesn't really matter just wondered whats going on. PD186 and Fane 18XB both do it and from what I read they're propped as being pretty decent reflex sub drivers.
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jonminns View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonminns Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2009 at 8:03pm
I just use the standard isd which doesn't have the xmax simming on, i can never get the new one to accept driver parameters

Never had any issues, i just prototype with cheap mdf

Jon
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mobiele eenheid View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2009 at 8:18pm
A reflex, 250 liters tuned to 35 Hz is pretty big for most 18" drivers, especially for a driver with such Qts and Vas. A reflex, 150-180 liter tuned to 35 Hz would increase your power handling. Furthermore WinISD Pro indeed assumes a worst case scenario, music is ussually more dynamical then the signal used for simming, except some special bass tracks with continues sine waves in 'em. If the powerdip is unusual large it can however tell you that you might be expecting to much from a particular driver. 
 
Quote  i can never get the new one to accept driver parameters
If you're having problems with inputting new drivers into WinISD Pro, you can read the sticky in the Newby-section. It suggests a way of inputting parameters and leaving some blank, so that the calculated parameter doesn't disagree with the parameters you typed. IIRC the auto parameter calculating can also be turned off.
 
Best regards Johan


Edited by mobiele eenheid - 12 May 2009 at 8:19pm
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jethrocker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jethrocker Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2009 at 8:44pm
Originally posted by mobiele eenheid mobiele eenheid wrote:

Quote  i can never get the new one to accept driver parameters
If you're having problems with inputting new drivers into WinISD Pro, you can read the sticky in the Newby-section. It suggests a way of inputting parameters and leaving some blank, so that the calculated parameter doesn't disagree with the parameters you typed. IIRC the auto parameter calculating can also be turned off.
 


I have had similar problems, even when inputting minimal parameters following the recommended sequence. I suspect the problem comes from manafacturers rounding figures to nearest decimal point, causing small anomalies.  i didn't know you coulñd turn off the auto calculation, but will have a look as I'd almost given up trying to enter new drivers after the majority of times they fail to save.
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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2009 at 10:05pm
It must be WinISD. I stopped using it close to 10 years ago because it tends to get its calculations wrong.




Best Regards,
Elliot Thompson
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Glenn View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Glenn Quote  Post ReplyReply Direct Link To This Post Posted: 13 May 2009 at 2:16pm
As mentioned above, the excess excursion is due to too large of cab and/or too low tuning frequency.
 
Not good for PA, if you are using it for low power in home theatre fine.
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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 13 May 2009 at 5:04pm

I think you are looking at the graphs differently than what it states.

It shows the linear xmax is exceeded in the mid-late 20's at 600 watts. My eighteens sit in bigger chambers than 8 cubic feet and, will handle 1000 watts with no issues.

We also need to keep in mind exceeding the xmech will cause damage to the driver. Not, the xmax. The Fane 18 XB and Precision Devices 18 PD 186 are very old drivers and, are 600 watts long-term despite what marketing will promote.

Best Regards,


Edited by Elliot Thompson - 13 May 2009 at 5:05pm
Elliot Thompson
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