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Old 14th January 2008, 04:58 PM   #1
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Default Enclosure for a Hemp FR8C

Would this enclosure work for a Hemp FR8C?

http://www.quarter-wave.com/Project0..._Enclosure.pdf
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Old 14th January 2008, 05:15 PM   #2
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Not particularly well. Doesn't have sufficient volume for the driver to get LF gain up to a useful level. Increase the CSA to 198in^2 up from 104.5in^2 & you'll be flat to the high 30Hz zones.
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Old 14th January 2008, 05:28 PM   #3
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Quote:
Originally posted by Scottmoose
Not particularly well. Doesn't have sufficient volume for the driver to get LF gain up to a useful level. Increase the CSA to 198in^2 up from 104.5in^2 & you'll be flat to the high 30Hz zones.
I could do 10" x 20" x42" cabinets. I have the room. What length would you make the port tube off the top of your head?
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Old 14th January 2008, 06:35 PM   #4
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4in diameter x 2in long.
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Old 14th January 2008, 07:05 PM   #5
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Quote:
Originally posted by Scottmoose
4in diameter x 2in long.
Thank you Scott.
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Old 14th January 2008, 07:16 PM   #6
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With the high QT I won't need a BSC circuit I'm assuming.
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Old 14th January 2008, 10:02 PM   #7
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Quote:
Originally posted by Scottmoose
Not particularly well. Doesn't have sufficient volume for the driver to get LF gain up to a useful level. Increase the CSA to 198in^2 up from 104.5in^2 & you'll be flat to the high 30Hz zones.
Have you modeled these dimensions using the TS parameters for a FR8C Scott or is this a best guess? Just curious.
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Old 14th January 2008, 10:52 PM   #8
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Not a guess, the dimensions are my own calculation -I quickly checked in MathCAD to confirm.

Baffle-step is unrelated to driver Q. It's to counter the transition from 2pi to 4pi radiation space & the resultant SPL drop-off at the listening position below this point. With as wide a baffle as you can manage, you should be able to push it down a reasonable way, to a point where room-gain will take over, or for positioning near a rear-wall. The FR8C does have a reputation for being a touch bright, so a notch-filter & zobel (similar principle, different reason) might help to tame it. Depends on your taste & the room.
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Old 14th January 2008, 11:09 PM   #9
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Quote:
Originally posted by Scottmoose
Not a guess, the dimensions are my own calculation -I quickly checked in MathCAD to confirm.

Baffle-step is unrelated to driver Q. It's to counter the transition from 2pi to 4pi radiation space & the resultant SPL drop-off at the listening position below this point. With as wide a baffle as you can manage, you should be able to push it down a reasonable way, to a point where room-gain will take over, or for positioning near a rear-wall. The FR8C does have a reputation for being a touch bright, so a notch-filter & zobel (similar principle, different reason) might help to tame it. Depends on your taste & the room.
Thanks for the reply Scott. So just to double check I should use a CSA of 198^2, a height of 42", measured on the inside of the enclosure and just use the normal center for the speaker and port as shown on Martins diagram with a port length of 2" correct?
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Old 15th January 2008, 05:31 AM   #10
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Default an alternative enclosure...

Check out the Demetri w/ baffle step

easy to build, and works well (I've been listening to them for a month now and really enjoy them).
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