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PostPosted: 04 Nov 2018, 12:05 
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First time on this forum! thanks for having me. Question: has anyone used a coaxial driver in a backloaded horn enclosure. I think it would have to have a low Qts.?? Backloaded horn enclosure like the Fostex FE206En? thanks


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PostPosted: 06 Nov 2018, 22:04 
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Hi and welcome to the forum. Yes, they would require a lowish Qts for that horn enclosure. What coaxial driver did you have in mind?

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PostPosted: 07 Nov 2018, 06:44 
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Yes, the coaxial driver would be the Beyma 8" 8CX300Nd/N available at US Speaker, Qts of .27, thanks


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PostPosted: 07 Nov 2018, 15:20 
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The Qts of that driver seems close enough. With the FE206E/FE206En, the published Qts is 0.19 and of the drivers I measured, I would get a Qts of under 0.24, so reasonably close considering air pressure, humidity and temperature can affect this reading significantly.

Another point is that for the FE206E/FE206En, the Fs is published as 39Hz and my measurements confirm that frequency. What I will tell you however, is that in this horn enclosure, with the FE206E driver, there is a steep bass rolloff below 50Hz.

One concern with the Beyma 8" 8CX300Nd/N would be that the published Fs is 61 Hz, which is about 20 Hz higher than the FE206 with the concern being perhaps even less bass output.

Another item to consider is the driver Xmax. With the FE206E, the excursion is less than 1 mm. With the Beyma 8" 8CX300Nd/N, the Xmax is 6 mm, so many times more and I'm not sure if that is too much to function properly for a rear loaded horn enclosure. Too much excursion may affect how accurate and tight the bass is, in particular at higher SPL.

So it looks like I only really added questions and concerns rather than answers. Sorry.

With that Beyma driver, perhaps a double bass reflex enclosure would work better. But with a Fs of 61Hz, a speaker system with that driver may require some LF reinforcement, which is consistent with how these drivers would be typically used in proaudio applications.

Hope this helps,
Gio

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PostPosted: 07 Nov 2018, 17:16 
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Thanks so much for your info! It does help, Steve


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