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That might be a little high. This is the in-room measured response of an 8" down-firing sub I built once, you can see the sharp drop off above 100Hz:
 

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Discussion Starter #3
fusseli said:
That might be a little high. This is the in-room measured response of an 8" down-firing sub I built once, you can see the sharp drop off above 100Hz:
What was the crossover set at on your AV Receiver ?
 

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That would have been either open-ended with no LPF or an LPF very high, e.g. 250Hz. I don't remember which exactly, it was a few years ago.
 

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fusseli said:
That would have been either open-ended with no LPF or an LPF very high, e.g. 250Hz. I don't remember which exactly, it was a few years ago.
Could also be because that particular driver has a natural drop off around that frequency.
 

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The performance of the crossover @ 100Hz will NOT be noticeably affected by orientation of the sub driver.
What you want to accomplish is, first build the sub and then with it (in-place), check for the desired crossover frequency and best performance from the sub AND the mains and then make your needed crossover changes, if any.
The specific circumstances are not described by a static formula. There are way too many variables to be able to say with any surety, exactly how a particular sub driver will perform in a particular sized box, in a particular sized room, with a particular driver orientation, crossed over at a particular Hz, with a particular set of (XYZ) mains, playing @ XdB spl.
WinISD can get you an approximation of what a sub's performance will be in half space but that's not in someone's HT listening area.
 

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I wouldn't run a down firing sub as high. By all means, share some more open ended sweeps of down firing projects. WinISD is an approximation in its best form, it will tell you nothing about a lot of important factors. Any sub may integrate best at different xover points for different mains in different environments. That's a no brainer.

What i posted is an 8" Dayton RS sub, otherwise good a ways higher. I thought it better to post a measurement of a down firing sub and leave it for interpretation. This isn't an easily answered question.
 

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I wouldn't run a down firing sub as high. By all means, share some more open ended sweeps of down firing projects. WinISD is an approximation in its best form, it will tell you nothing about a lot of important factors. Any sub may integrate best at different xover points for different mains in different environments. That's a no brainer.

What i posted is an 8" Dayton RS sub, otherwise good a ways higher. I thought it better to post a measurement of a down firing sub and leave it for interpretation. This isn't an easily answered question.


The reason for the 110hz xcrossover is that i have the small Kef Eggs as LCR.

Just trying to figure out if the Downfiring orientation limits the Cross to lower levels compared to Front firing?
 

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My hunch is yes-- despite the wavelengths around 100 Hz still being pretty long. You might still be able to blend your stuff together just fine. Have you tried yet, how does it sound? Any chance you could take a sweep in REW? Depending on how small your kef eggs are, 110 might be too low anyways.
 
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