My First DIY Subwoofer

So I've decided to build a subwoofer. I'm going to start out modest because from what I've already read you can get into some complex math and electrical issues. I'm sure I'll have a bazillion questions as I get into this but to start I have just a couple.

I've seen people direct DIYers to specific deals on cheap drivers and amps. I looked into these and those deals I found have expired. Anybody know where one might get some decent drivers and amps on sale, b-stock, anything like that? Like I said, I'm going very modest my first round just to get a feel for the process.

I'm not to the stage of buying anything yet since I still have a lot of reading to do, but getting specs on some drivers will help me figure out an enclosure.

Also I have subwoofer DIY guides from Brian Steele, Mike Dzurko and Bill "Collo" Collison. Are these sufficient, are there others I should be looking at? Also any unsolicited advice is welcome.

Thanks,

Matt

Re: My First DIY Subwoofer

Tools - I don't have much in the way of tools but I live in Berkeley where we have a tool-lending library (pretty cool). Other than that I have a friend who rents space in a shop that he doesn't use that much, so I'm hoping I can bum some time off him there. I have moderate carpentry experience and very little electrical. Like I said, lots to read before I actually start this.

Goals - I have a roughly 20'x20' room. I'm looking to get tight, accurate-as-possible bass that doesn't need to shake the house. If it drops off after 30hz I won't cry a river. I want it for music more than anything else.

Budget - I'd like to stay around $500. I'm making a sealed sub just because the math seems much easier. So I'm looking at an enclosure, driver and amp, theoretically. Also one guide suggested making a sort of test enclosure. Make it larger than needed and experiment with stuffing, ports (that you can plug), or reduce volume by putting phone books and the like inside. I thought of making my first go something like this so I don't have to feel bad about it being ugly, then making a nice enclosure later. But if I made the nice enclosure it would hopefully be a nice quality wood that I'd lacquer. Bumming tools and tool use should help the budget somewhat.

Software - I figured I'd use the free WinISD, although i didn't know about the higher learning curve (that's what you deal with for free I suppose).

Parts - Thanks for the list, this is what i was looking for. So is there any reason not to use car audio drivers for home use, since a lot of links are to car audio sites? Are they pretty much the same?

Thanks Robert for the helpful reply,

Matt

Re: My First DIY Subwoofer

Rhythmik audio looks fantastic. I'm going to build their 15" sealed sub with the plans they made for it. Thanks for the link, Robert. That's what I was hoping for.

I think this is going to be the penultimate sub. I'd sort of like to get my feet wet with this first one to get a sense of the process and the math and physics involved (without ending up with a awful sounding sub because I got it wrong) since I've never done anything like this. After I build this first sub I think I'd like to experiment with a different design (other than a straight cube) and with that get into some of the math and physics that would require.

So I think I'm set for now, I'll post again when I'm into it the meat of this project or if I have more questions (which is inevitable).

Thanks again Robert,

Matt

Re: My First DIY Subwoofer

Okay, so I made it for about 10 minutes before I had a ton of questions. So the plans for this 15" sealed sub (link below) are for a down-firing box. But it's a beautiful silver driver and I want to see it thump, so I'm going to make it front-firing. My questions are: 1) Can I just move the driver up to the side of this box while keeping the top and bottom as they were in the original plans (so that the longest part of the box isn't directly behind the driver but above and below it)?, 2) As long as I keep the volume the same, can I move and alter the braces (which I'd have to do)?, and 3) can a driver handle being supported only by its screw-in plate or should I put something for the magnet to rest on?

Also, Brace 3 as shown on page 2 is not at all like Brace 3 as shown on page 7. I won't be using this brace as diagrammed but I thought it odd.

http://www.rythmikaudio.com/download..._DIY_plans.pdf

Thanks,

Matt

Re: My First DIY Subwoofer

Thanks Robert. I've got everything marked up with lines and now I just need to get the mdf to my friend's shop so I can cut it.

Those are some seriously beefy drivers. They look like TC Sounds from the subwoofer-related surfing I've been doing. Looks like rythmik audio took a vacation so I'll have to wait until probably Nov before I get the drivers. But that will give me ample time to make this box.

Re: My First DIY Subwoofer

Actually I emailed Rythmik my question about the Brace in the DIY plans, thinking they'd get back to me in a couple of weeks. Brian at Rythmik already emailed me back (from vacation, I assume) telling me that he realized the mistake in the plans and said he's corrected it but he won't be back until Oct 22 to put the corrected plans up. He also said that they're coming out with some new drivers that will actually be at least $30 cheaper so I should just wait until they get back anyway.

Yeah, it seems like home audio is one of the few remaining holdouts for great small companies doing business in a sort of old fashioned way. Craftsmen I suppose. It's pretty cool.

Anyway, good thing I haven't made any cuts to that mdf yet.

Matt

Re: My First DIY Subwoofer

Nevermind, I think I figured this out.

Re: My First DIY Subwoofer

So I have all the components and the box more or less cut (minus the bracing). I'm buying the polyfill and wondering, do you glue it to the sides of the enclosure or just let it hang out loose in the box?

Thanks

Re: My First DIY Subwoofer

This is for the Rythmik Audio DS12. And I was going to save this for when I finished and posted pics but let me say that Brian over at Rythmik was very helpful. I'd recommend them to anyone who wants an easy DIY sub project.

The SVS drivers that I very much "stole" are for a friend's subwoofer. He's paying for the tools and materials and I get to build another sub; this time I'll buy (I can't remember what it's called) the thing that gives you the specs on drivers and plug the numbers into WinISD for the box configuration. Luckily spousal acceptability isn't an issue for him (since my finishing skills are low). Speaking of those drivers, do you have any suggestions on an amp for them Robert (or anyone else)? Thanks,

Matt

Re: My First DIY Subwoofer

Thanks for those specs Robert. I figured that someone here might know them, I just hadn't gotten to the point of asking yet (since that sub is on the horizon). That'll save me from buying Woofer Tester III.

As soon as I'm finished I'll put some pictures up. I'd have finished by now except that I'm applying to grad school this month and everyone tells me that's more important. Ha, what do they know?!

-matt

Re: My First DIY Subwoofer

Yeah, I'm sure that will be the case. But no worries; I'm just applying now (which is a process in itself) but I plan on finishing the sub in time for my family to visit on Thanksgiving. At least to have it functional, although I'd love to have the veneer on so I don't have to either put it on around the driver and amp or take them off to do so.

Is there a break-in time for a subwoofer? Rythmik says they're not responsible for damage from continuous playing of a test signal. Are there other ways one can blow a new sub (aside from watching Band of Brothers battes at 11).

And, uh, you're a saint for continuing to answer some other sub questions out there btw . Thanks Robert

-matt

Re: My First DIY Subwoofer

Okay, it's done! Well, more or less. I haven't put any veneer or paint on the box b/c I wanted it ready for my visiting family. This didn't end up mattering because my new speakers aren't here yet (where do I post a rant about how mad I am at Legacy Audio/Video in NJ). So here's what I screwed up:

The driver hole is too big on one of the sides. There isn't much clearance between a couple of the screws and the hole. I was routing it out under waning sunlight because I knew that I wouldn't get home before dark to finish it any other day. Do stuff fast and it comes out crappy. Right now I have it so the driver faces upwards to avoid it ripping out or anything but as soon as I can I'm going to make a new face with a new hole.

Besides that the only thing about it is some of the sides don't meet perfectly. There's a little over or underhang (if that's a word). That screws up the veneer job as well. I'm hoping that I can smooth this out with wood-filler but if not then I'll just paint it. There's also a slight gap because the bracing came up a little higher than the edge of the sides. Again, just trying to move too quickly.

It sounds good but I can't really tell with the speakers i have now. They're some sort of old white van speakers from back in the day, apparently, and they pretty much ruin anything that comes out of them. I was only supposed to use them for a couple of days before I got my NHT Classic 3's. That has turned into a frustrating mission with one and now potentially two cancelled orders for these speakers. Really, just give me half a chance to yell about Legacy Audio Video.

Anyway, I'm pretty pleased with my sub. For the first project since junior high shop class I'm pretty happy with it. Thanks a lot for your help Robert. I'm now modeling my next sub with those SVS drivers on WinISD (and learning a lot about that program with an online guide - I remember you saying it has a high learning curve). As soon as I get another go at a proper table saw that project will begin. This time I plan on going slower, paying attention to the little bits and making a sub my future wife would love (it's for me now, not my friend).

So thanks again Robert for all the help

Matt