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Discussion Starter #1 (Edited)
Here's a quick look into my first subwoofer project, which I finished a few months ago.

Reasons for upgrade:

I used to own a REL Q150E, and although it provided plenty of very clean and tight bass, it couldn't keep up with some of the more bass-heavy action movie scenes, so I decided to bite the bullet and build a sub that could satisfy me for at least a few years.


Why the Rythmik Audio DS1500 kit?

As a newbie I was looking for an easier way to go, so the first criteria for the driver/amplifier was that it could have been ordered as a kit. Especially when the shipping costs to Finland easily double the price of the driver. Also with all the good reviews and Brian's good customer service the decision was easy.


Enclosure:

For this project I wanted to go flat out and build the biggest thing that would fit into my listening room(which also doubles up as my bedroom and workroom). After some measurements I come up with a 8cu.ft box enclosure tuned to 19hz with 3 3" vents(flared at both ends). I know that it might be a little overkill for my 1200cu.ft(35m^2) room, but at least I won't run out of headroom. :hsd: The box was built out of 1" MDF with double thick front and rear walls and was braced with 16 braces, 4 running along each axle, so the the box is very sturdy. The finish is semi-glossy matte black with clear lacquer coat.


Building:

(Sorry, no build pics)

As I didn't have the skill, tools or courage to build the box myself I took my drawings into a local woodworking shop. The building took almost half an year, instead of the promised 3 weeks, but I couldn't be happier with the result.

End result:

I'm really happy with the subwoofer, and it really can shake the house down if needed, but at higher levels there is some port chuffing. I'm planning to swap the 3" vents to 4" ones. The length won't be a problem, but the flares might be. Cutting bigger holes in the enclosure would be a very major pain, so I thought as I have access to a really nice lathe, I could cut my current flares so that they would accept a 4" port. Well they wouldn't be as much flares as mounts for the vents, so I'm asking you shacksters, which is better: 3" heavily flared or 4" with almost no flaring on the outside?



Some photos:
















//Edit: MikeP: Are the pictures better now?
 

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Discussion Starter #5
Yeah, the 3 4" ports would have to be very long, but I think I can fit them in. Because of the lower braces designed to support 3" ports the 4" ones would have to be mounted in a ever so slight angle. If I get past those problems, I think the rest won't be so hard.
 

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Discussion Starter #6
Took some measurements a while ago, the sub seems to perform very well :)

FR-graph:

Driver = purple
Port = blue



How can I approximate the output of the port and driver? The sub is in a corner and I really wouldn't want move it around a lot (250 lbs. sub with a ton of stuff on top), so no open field measurements :( As you can see there is a rumble filter at 20hz and another filter at 14hz with Q of 1,07 (3db lift before rolloff IIRC). Actually I'm not using that 20/14hz filter combo anymore, it caused over-excursion ar subsonic frequencies, where the driver unloads. Now I'm using 20/20hz combo, which means the FR is ruler flat to about 22hz and rolls off sharply after 20hz.
 
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