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Old 31st October 2008, 02:55 AM   #1
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Default Is this a good beginner project?

http://www.vikash.info/audio/xls10/

I have to replace the sub amp with another model, the one he specifies is not available in NA. Would I need one that has a plastic cover over the internals?

Thanks, Brendan
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Old 31st October 2008, 07:23 AM   #2
simon5 is offline simon5  Canada
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If you have average to good woodworking skills, yes, this is a good beginner project. If you are unsure about your woodworking skills, a sealed design would be easier.

You could swap the amplifier for another one, no problems. No need for a plastic cover, just check if the amplifier is fully sealed and correct the design for the amplifier size differences.

Some plate amplifiers without rear covers are fully sealed, some are not. It's really important that you have no air leaks at all, since this is a passive radiator design.
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Old 31st October 2008, 11:20 AM   #3
MaVo is offline MaVo  Germany
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The only thing which would be even easier is a closed box, i.e. the same thing just without the passive radiator. A PR box is in its essence like a bassreflex, so you get a few dB more output around the low cutoff but need a highpass filter, because below a certain frequency the excursion gets very high. Closed boxes are more error insensitive and have a slightly better sound quality, but less maximum spl.
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Old 31st October 2008, 07:35 PM   #4
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Quote:
Originally posted by simon5
If you have average to good woodworking skills, yes, this is a good beginner project. If you are unsure about your woodworking skills, a sealed design would be easier.

You could swap the amplifier for another one, no problems. No need for a plastic cover, just check if the amplifier is fully sealed and correct the design for the amplifier size differences.

Some plate amplifiers without rear covers are fully sealed, some are not. It's really important that you have no air leaks at all, since this is a passive radiator design.
Otherwise I'd hear the air fart at high excursion right? My woodworking is fairly good, just need to get acquainted with a plunge router and a circle jig. Would it be a big difference if I doubled the thickness of the walls (from 3/4" to 1 1/2")?
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Old 31st October 2008, 07:57 PM   #5
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A sealed design with the XLS10 is a more difficult project IMO as you need equalisation to get a decent bass response.

I personally don't believe you will gain anything using thicker wood for the walls only, the cabinet is already heavily braced.
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Old 1st November 2008, 07:35 AM   #6
simon5 is offline simon5  Canada
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Quote:
Originally posted by cyberspyder
Otherwise I'd hear the air fart at high excursion right? My woodworking is fairly good, just need to get acquainted with a plunge router and a circle jig. Would it be a big difference if I doubled the thickness of the walls (from 3/4" to 1 1/2")?
Any air leak will introduce lots of unwanted noise and huge loudness loss. It also mess with the enclosure volume, the enclosure looks larger to the driver so the tuning point is messed up. Even if the leak looks like negligeable, it's not.

It needs to be totally fully perfectly sealed. You can achieve it with caulking inside the enclosure. After the box was fully built and glued, I personally achieved a perfect joint by using excess wood glue, until I got a perfect inner joint on all the inside. (Yes, I'm crazy)

For sealing the amplifier and the driver, you can use some double sided adhesive weatherstripping, or some caulking. Some drivers and amplifiers already come with a strip of foam, that when screwed down, it seals itself.

As richie00boy said, doubling the walls won't help you much. The box will only be much heavier and also it will be a bit bigger. If you want to countersink the driver on the other hand, you could double up the baffle. Countersinking ain't that useful for subwoofers, unless you like the aesthetics of it.

If you have good woodworking skills, go for it. I built my first subwoofer with a basic jigsaw, a drill, a table saw, sand paper and patience. With a circle jig and a router, it will be easy for you.

Good luck !
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Old 1st November 2008, 03:32 PM   #7
GM is offline GM  United States
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Hmm, even with a very low Vas by PR standards, I wonder how well a down firing PR will work over time sag wise, especially if exercised regularly with pipe organ and/or HT LFE.

GM
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Old 1st November 2008, 05:01 PM   #8
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That's what I'd worry about.
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Old 2nd November 2008, 06:08 AM   #9
simon5 is offline simon5  Canada
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I agree with GM and Cal Weldon, I should have checked the design completely hehe.

Interesting design. I don't think it's a good choice. I'd at least put the driver downfiring and the passive frontfiring... Or even better, use dual passive side firing with the driver front firing.
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Old 2nd November 2008, 02:48 PM   #10
GM is offline GM  United States
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OK, yesterday I was just 'thinking out loud' when I posted my concern, but I found it hard to believe one of our moderators wouldn't do a performance update to such a meticulous presentation if it didn't work well, so out of curiosity I used Adire's downward sag math to calc/confirm it and found that the published 'Cms' is listed as mm/N for both driver and PR, but is in m/N.

Corrected to mm/N:

830452 = ~0.69 mm = ~5.52% sag
830841 = ~1.99 mm = ~9.05%

Adire recommends < 5%, so if you accept their math and I didn't screw up (a real possibility, so someone please double check it), then the driver may/may not be OK in a down firing app depending on how hard it's likely to be driven, but the PR is a no-no if driven hard. Regardless, I asked Vikash to give his thoughts/real world experience since IMO this is the final arbiter of what's acceptable.

GM
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