First dedicated HT sub, clamshell isobaric, ported

toenail · 28th April 2003, 11:27 PM

I finally got around to fabbing up a temporary version of a dedicated HT sub this past weekend. Despite it's ungainly appearance it performs pretty well. I used an old 2.5ft^3 box that used to reside in the back of my RX-7 housing two twelves. Since I was testing a clamshell design I had to seal off one of the old 12" cutouts with a piece of plywood cut to size. Wiring is parallel, out of phase. Technically winisd calls for a 3.66ft^3 for optimum low end response from the Jl Audio 12W 0's, but the frequency response difference is negligible.

This was my first experiment with isobaric or compound woofer configurations and I'm very happy with the results. I don't own an SPL meter just yet but I do own several test cd's, one of which has 0db test tones from 10 to 98hz. By the ear I would call response very flat. I'm impressed with the effect of low 20's hz in my living room. Quite a kick.

I don't often hear of people using these configurations for HT subs. I guess others just have more space than I do.

toenail · 28th April 2003, 11:34 PM

frequency response

toenail · 28th April 2003, 11:35 PM

phase

toenail · 28th April 2003, 11:36 PM

group delay

navin · 29th April 2003, 06:18 AM

photo of system would be nice

toenail · 29th April 2003, 09:39 AM

Unfortunately no digital camera yet. I have to wait until film is developed. Picture a combination of blue and black automotive carpeting mixed with raw plywood and the basket of one speaker protruding into the room. Handsome. There's a ton of sawdust stuck in the carpeting for good measure. I'll post pics as soon as I have them developed.

28th April 2003, 11:27 PM	#1
toenail diyAudio Member Join Date: Mar 2003 Location: Cranston, RI	First dedicated HT sub, clamshell isobaric, ported I finally got around to fabbing up a temporary version of a dedicated HT sub this past weekend. Despite it's ungainly appearance it performs pretty well. I used an old 2.5ft^3 box that used to reside in the back of my RX-7 housing two twelves. Since I was testing a clamshell design I had to seal off one of the old 12" cutouts with a piece of plywood cut to size. Wiring is parallel, out of phase. Technically winisd calls for a 3.66ft^3 for optimum low end response from the Jl Audio 12W 0's, but the frequency response difference is negligible. This was my first experiment with isobaric or compound woofer configurations and I'm very happy with the results. I don't own an SPL meter just yet but I do own several test cd's, one of which has 0db test tones from 10 to 98hz. By the ear I would call response very flat. I'm impressed with the effect of low 20's hz in my living room. Quite a kick. I don't often hear of people using these configurations for HT subs. I guess others just have more space than I do.

29th April 2003, 06:18 AM	#5
navin diyAudio Member Join Date: Jan 2002 Location: Mumbai (Bombay), India	photo of system would be nice __________________ ...still looking for the holy grail.

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29th April 2003, 09:39 AM	#6
toenail diyAudio Member Join Date: Mar 2003 Location: Cranston, RI	Unfortunately no digital camera yet. I have to wait until film is developed. Picture a combination of blue and black automotive carpeting mixed with raw plywood and the basket of one speaker protruding into the room. Handsome. There's a ton of sawdust stuck in the carpeting for good measure. I'll post pics as soon as I have them developed.

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