Is it safe to buy a custom-built subwoofer? - AVS Forum
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post #1 of 9 Old 06-10-2013, 07:35 AM - Thread Starter
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Hello everyone. I'm looking at adding a subwoofer to my system and have been kind of eyeing the Rythmik LV12R. The only thing holding me back is whether this is a good time to spend $600. However, I was poking around on craigslist earlier and I found something kind of interesting--a custom built subwoofer for about $350 (or less).

Keep in mind I know very little about subwoofers---most of you guys have forgotten more than I know smile.gif So I'm just wondering is it fairly safe to buy a custom built subwoofer? If you are using a good amp and a good driver, is that basically all you need? Or is it important on how the box is built, etc.?

Take a look at this and tell me if you think this is worth pursuing: http://phoenix.craigslist.org/nph/ele/3814604998.html

Any advice would be appreciated.

Rich
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post #2 of 9 Old 06-10-2013, 08:32 AM
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A lot of people build their own subs. I don't know the particulars of the sub you're interested in, but 12" is a decent driver size. 350 watts is acceptable and the enclosure looks very big. I don't see anything that would give me a red flag with the sub. If you're interested, listen to it before buying to make sure it actually works and doesn't have any obvious problems.
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post #3 of 9 Old 06-10-2013, 08:36 AM
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Quote:
Originally Posted by rhenschel View Post

Hello everyone. I'm looking at adding a subwoofer to my system and have been kind of eyeing the Rythmik LV12R. The only thing holding me back is whether this is a good time to spend $600. However, I was poking around on craigslist earlier and I found something kind of interesting--a custom built subwoofer for about $350 (or less).

Keep in mind I know very little about subwoofers---most of you guys have forgotten more than I know smile.gif So I'm just wondering is it fairly safe to buy a custom built subwoofer? If you are using a good amp and a good driver, is that basically all you need? Or is it important on how the box is built, etc.?

Take a look at this and tell me if you think this is worth pursuing: http://phoenix.craigslist.org/nph/ele/3814604998.html

Any advice would be appreciated.

Rich

That almost looks like a Rythmik LV12R, with the exception of being sealed and not ported. How big is the room? Rythmik subs are excellent from what I've been reading and hearing from many people. I was actually thinking of buying one, but since I am getting married in 3 months, I can't really spend much $$$. I currently own a Klipsch RW-12D, which I got from newegg.com for $321 shipped. I ordered a 2nd one on Saturday for the same price. I'm very happy with this subwoofer, which is probably the best subwoofer you can get for $300 bucks.

Newegg usually has it on sale for $279.99, which is the lowest I've ever seen it. This past weekend was $299.99, but since I've got to pay taxes it came out to $321 and shipping was free. However, you cannot go wrong with the LV12R. The subwoofer from craiglist appears to be from Rythmik, but I am not 100% sure.

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post #4 of 9 Old 06-10-2013, 09:03 AM
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Looks like a good buy! I would see if you can listen to it before buying.
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post #5 of 9 Old 06-10-2013, 09:50 AM
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it's safe if you do your research. box size and construction definitely matter. he says medium density particleboard, by which i assume he means MDF, which is a very popular material to build speaker enclosures out of. if, on the other hand, if he does actually mean particleboard, it's still acceptable (arguably), but not nearly as good as if it was MDF. he also says its extensively braced, which is a good thing. based on the dimensions he gives, the internal volume should be roughly 2.4 ft^3 gross, which probably leaves about 2.1 - 2.2 once you subtract out the volume of the bracing and the driver. here's how that driver models in a sealed enclosure of that size:



not so hot, in my opinion. with an f3 of 40 hz, it might be alright for music, but it would need some serious eq and/or room gain for ht/movies.

it is a $250 driver though (or at least the current 4 ohm version is). not sure how much that amp went for (it appears to be NLA), but i'd say its a safe bet it was more than $100. plus the enclosure... it's a decent deal based on the parts alone. but as a finished subwoofer, i think i'd pass.

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post #6 of 9 Old 06-10-2013, 10:47 AM
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http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-1114

Weak power handling, decent excursion and sensitivity, premium pricing.

Putting cabinet size aside, there are certianly better values right now.

Comparably specced Bravox sub driver: http://www.parts-express.com/pe/showdetl.cfm?partnumber=269-532 85$
2 cu ft ported box 50$-100$ (varies depending on diy or flat pack)
Bash 300 watt plate amp 120$

That's around 250$-300$ for a brand new box with good quality parts (granted everything is on sale, but there are always sales)

A driver with far more excursion: http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-512

With more excursion a woofer moves more air thus delivering higher spl's all things being equal.

The Peerless xxls in that sub doesn't seem particularly suited to a sealed box (although stuffing will help with that) and the box size is more in line with a ported box for that sub.

If you wanted to take the time to port the box, it may be worthwhile, but 350$ seems a tad steep for a box you would have to modify yourself.
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post #7 of 9 Old 06-10-2013, 11:50 AM
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I emailed the guy a few weeks ago on this same sub - he's selling on ebay for $300, so you probably can negotiate price if you are interested.

The amp is Rythmik, and I asked him what it brings to the table. It's not a servo model amp (and even if so, it's not a servo subwoofer), so it sounds like it's doing the same thing any BASH amp would. Sealed builds should be pretty idiot proof as long as the box isn't too large and it's braced / dampened properly. Do the knock test (knock on the sub at various points and see if it's a "echoey" sound or a solid sound) before you listen to it demoing anything. Maybe you could also remove the amp / woofer for the sake of looking inside and verifying before exchanging money. The sub probably sounds good, but as abs noted, frequency extension may not be low enough for satisfying home theater.

I get a lot more mileage out of buying subs and amps w/o enclosures on craigslist and then building what I need. I'm rocking 2 DIY builds now, and definitely saved money with that approach.
Quote:
Originally Posted by rhenschel View Post

If you are using a good amp and a good driver, is that basically all you need? Or is it important on how the box is built, etc.?

3 things are needed for a good subwoofer. A good amp, a good driver, and a good enclosure (matching may be better term than good here). The enclosure determines how low your sub will play, and poor enclosures or poorly designed enclosures can have ringing, distortion, or other generally bad sound artifacts. There are a lot of subwoofer building primers if you want to look into it, but the general idea is to match all 3 to a happy place. A good enclosure and a good amp would go to waste with a crappy sub driver, and a good amp and sub would be wasted with an enclosure that was poor or not right for it.

Sealed is generally good, and it is a favorite of many in the DIY forum, but it's usually not the best bang for your buck when shooting for loud and low playing subwoofers. Ported usually gets you more for less, but careful design and modelling become a lot more important then as ported can sound really good or really bad depending on design and how well the build is done.

Go big or go home, unless you're already at home. Then you have to go big.
My near 7' tall 18" Xcon Sonotube Subwoofer.
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post #8 of 9 Old 06-10-2013, 02:25 PM - Thread Starter
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Thanks guys!! You have all been very helpful. I especially appreciated the "tech talk" from absolootbs, Mik James and tetsu96!

I don't think I'm up to building my own subwoofer, but I definitely respect those of you who do. It sounds like this might be a "so so" deal, so I might just hold off and try to get the Rythmik LV12R. I was mainly trying to see if this custom-built subwoofer was a smoking good value.

Thanks again.

Rich
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post #9 of 9 Old 06-10-2013, 03:26 PM
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Yeah it certianly needs some work, a port would be a necessity along with a high pass filter to avoid destroying the driver.

Otherwise it would be a good deal up against anything other than current diy deals.
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