Very low budget sub. - Page 5 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #41 of 54 Old 02-01-07, 04:26 PM Thread Starter
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Re: Very low budget sub.

Hm, What about a 5 ft^3 with a 22hz port? Still lots of overexcursion?
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post #42 of 54 Old 02-01-07, 04:32 PM Thread Starter
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Re: Very low budget sub.

What would that vent do exactly? If sealed is what I have to do to get down to the lower 20's without exploding, that's fine I guess.
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post #43 of 54 Old 02-01-07, 04:35 PM
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Re: Very low budget sub.

Here's the best I can do so far: 3 PRs, 144g in washers on each, 100L box.
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post #44 of 54 Old 02-01-07, 04:41 PM
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Re: Very low budget sub.

Please note that I am by no means an expert here - maybe someone else can pipe up with an idea. I have built a sub that had a similar class driver that has the same excursion pattern at about 23 Hz. It sounds fine as long as I don't feed it movies with real real low bass.

I'm just concerned about your desire to go lower then 27Hz and stay "very low budget".

Also, if anything else, this would make a decent sealed sub in a 1.8 cubic foot box.
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post #45 of 54 Old 02-01-07, 04:51 PM
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Re: Very low budget sub.

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What would that vent do exactly? If sealed is what I have to do to get down to the lower 20's without exploding, that's fine I guess.
I have heard that an aperiodic vent will give a sealed sub a bit more low end extension, but no one seems to know how to model them except with trial and error. I also doubt it would get you to the low 20's.
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post #46 of 54 Old 02-01-07, 05:11 PM
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Re: Very low budget sub.

I am a moron. I was getting too hung up on the F3 and ignoring all the other stuff. Here is a 4.2 cubic foot box with three PR's with 300 grams on each (closer to what you calculated in post #34). It looks pretty good across the board and should get you close to 20Hz.

Let this be a lesson in not chasing one metric!

Last edited by BoomieMCT; 02-01-07 at 09:35 PM.
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post #47 of 54 Old 02-01-07, 05:18 PM Thread Starter
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Re: Very low budget sub.

What happens when only two are used?







** Edit: Could you model a 16*16*36 (= 4.23 ft^3 ) sealed? I can't get WinISD working for the life of me.

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post #48 of 54 Old 02-01-07, 09:37 PM
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Re: Very low budget sub.

Just two would be like a higher tune. For the 4.2 cubic foot box it looks like the attached. A 6 cubic foot box is earlier. A sealed box of the same size looks like a sealed box with an F3 of 55 Hz (see post 44).
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post #49 of 54 Old 02-02-07, 12:48 PM Thread Starter
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Re: Very low budget sub.

No, I meant just a 4.23 sealed set up, with out any of the PR's just to see the response vs. excursion.
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post #50 of 54 Old 02-02-07, 12:59 PM
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Re: Very low budget sub.

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No, I meant just a 4.23 sealed set up, with out any of the PR's just to see the response vs. excursion.
Yeah, post #44 above has that plot. It is in a larger box but they look almost identical. Where the dark line crosses the red line is where the driver has overexcursion. As you can see it is always well within the mechanical limits.

Try not to get too hung up on the excursion graphs. Remember that these graphs are assuming you are getting the full 200 watt signal at each frequency. Also, the xmax is the maximum linear response - you have some more excursion past that before you start damaging things.
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