Enclosure for a Hemp FR8C

G · 14th January 2008, 03:58 PM

Would this enclosure work for a Hemp FR8C?

http://www.quarter-wave.com/Project0..._Enclosure.pdf

Scottmoose · 14th January 2008, 04:15 PM

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.

G · 14th January 2008, 04:28 PM

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?

Scottmoose · 14th January 2008, 05:35 PM

4in diameter x 2in long.

G · 14th January 2008, 06:05 PM

Quote:

Originally posted by Scottmoose
4in diameter x 2in long.

Thank you Scott.

G · 14th January 2008, 06:16 PM

With the high QT I won't need a BSC circuit I'm assuming.

G · 14th January 2008, 09:02 PM

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.

Scottmoose · 14th January 2008, 09:52 PM

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.

G · 14th January 2008, 10:09 PM

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?

Nanook · 15th January 2008, 04:31 AM

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).

14th January 2008, 03:58 PM	#1
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	Enclosure for a Hemp FR8C Would this enclosure work for a Hemp FR8C? http://www.quarter-wave.com/Project0..._Enclosure.pdf __________________ Gavin

14th January 2008, 06:16 PM	#6
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	With the high QT I won't need a BSC circuit I'm assuming. __________________ Gavin

15th January 2008, 04:31 AM	#10
Nanook diyAudio Member Join Date: Feb 2004 Location: Chinook Country.Alberta	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). __________________ stew ☮ -"A sane man in an insane world appears insane."

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14th January 2008, 04:15 PM	#2
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	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.

14th January 2008, 05:35 PM	#4
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	4in diameter x 2in long.

14th January 2008, 09:52 PM	#8
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	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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