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| Re: starting construction on bass horn ? [message #16624 is a reply to message #16623] |
Sat, 26 June 2004 11:18   |
Mike.e
Messages: 471
Registered: May 2009
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Illuminati (1st Degree) |
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oh
2240?
Xmax is a peak measurement,(if i remember right) and if you have a driver with 10mm xmax,with 20mm xmech, an 18MM mdf spacer should do the trick.if your sending it to its 20mm xmech then it will hit obviously,but thats what the xmech is-where the driver gets physically damaged.Purely arbitrary numbers there btw,i dont know the specs on that woofer. you could always do 2 spacers..ofcourse that would increase the Front chamber volume.
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| Re: starting construction on bass horn ? [message #16626 is a reply to message #16625] |
Sat, 26 June 2004 14:14 |
Bill Fitzmaurice
Messages: 335
Registered: May 2009
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Grand Master |
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The front chamber would be the volume of the air space between the cone and the baffle if there is no other separate compartment. The front chamber size in combination with the throat size affects LP filtering and Fs alteration. Xmax is a one way measurement but it is only considering the voice coil overhang, not potential excursion. Some manufacturers list the destructive Xmax, which is when the coil hits the backplate, and that's the depth you'd use for the spacer,inclusive of the driver gasket. If you can't find the destructive XMax then go with twice the regular XMax to be safe.
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| Re: voice coil overhang and Xmax [message #16627 is a reply to message #16626] |
Sun, 27 June 2004 07:32 |
wunhuanglo
Messages: 912
Registered: May 2009
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Illuminati (2nd Degree) |
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I thought I once understood (and now clearly don't) that Xmax represented the one-way excursion limit to keep the gap filled with voice coil. With that understanding it was clear to me that, with an overhung coil, Xmax is equal to the overhang. But what isn't clear is why the same doesn't apply to an underhung coil. Wouldn't Xmax the the excursion limit at which the first (or last) turn of voice coil just started to peek out of the gap?
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| Re: starting construction on bass horn ? [message #16637 is a reply to message #16626] |
Mon, 28 June 2004 05:27 |
John Sheerin
Messages: 8
Registered: May 2009
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Esquire |
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Just another point to consider - the mechanical limit can be other things besides the voice coil crashing on the back plate: spider crashing on the top plate
voice coil former coming out of the top of the gap
suspension getting torn up John
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| Re: starting construction on bass horn ? [message #16639 is a reply to message #16637] |
Mon, 28 June 2004 07:38 |
Mike.e
Messages: 471
Registered: May 2009
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Illuminati (1st Degree) |
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spider crashing on the top plate
voice coil former coming out of the top of the gap
suspension getting torn upCan certain geometries be chosen,as to avoid some of the above?
Somewhere i saw a site,it mightve been LDSG ,and they showed in depth magnetic circuit analysis and physical excursion limits etc,discussing the pros and cons of each.
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