DIY Subwoofer... DRIVER! - Home Theater Forum and Systems -

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post #1 of 17 Old 04-18-10, 01:00 AM Thread Starter
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Location: San Diego, California
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DIY Subwoofer... DRIVER!

Yes. I plan on building a driver from scratch. I don't expect a lot out of it... I just expect it to be better than my VR3's : ).

It's been done before and very well:

If you have a good sub hooked up to your computer, you can tell that the sub he built has amazing SQ.

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So, I have a basic design already. The one on the left is the one I'm going with, other than the one on the right (the one on the right looks like a Fi driver) because the flimsy connections from the basket to the rim are a bit too weak. Also, the one on the left uses up much less foam board. Here's a more detailed and accurate rendering of what I'm aiming for:
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So this is a build log for a project that I may never finish due to lack of supplies... but I'll try it anyway. I have a very cheesy test coil ready, but I'll replace when I get some decent coil wire. The surrounds will be made of duct tape. And if I run into any problems that you guys might be able to answer, I'll also ask them here. I'm off the get the measurements and cut out the pieces!
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post #2 of 17 Old 04-18-10, 04:24 PM Thread Starter
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Smile Re: DIY Subwoofer... DRIVER!

I have pics of the half way done driver... once I get the magnet wire, then things will really get going!

Here's the general size of the sub... next to my VR3 12's (I've never held an 18" sub in person... I cannot even imagine what a Fi BTL is like in person!)
DIY Subwoofer... DRIVER!-18-inch.jpg

I profile of the sub...
DIY Subwoofer... DRIVER!-18-inch-2.jpg

The magnet will sit in the center of the backplate on a foam core...
DIY Subwoofer... DRIVER!-18-inch-3.jpg so...
DIY Subwoofer... DRIVER!-here-.jpg

...and yes, I did leave some room to make a spider : ).
DIY Subwoofer... DRIVER!-magnet.jpg

Here's a very nice picture of the neo magnet ($3.10 each + shipping for 2! (but the shipping was more than the magnets combined)). I put a penny just like how they do for the pictures on the neo magnet selling websites : ).
DIY Subwoofer... DRIVER!-magnet-2.jpg

And here's a really nice profile of the subwoofer!
DIY Subwoofer... DRIVER!-nice-pic-tha-sub.jpg

And, here's an example of the quality of my craftsmanship!
DIY Subwoofer... DRIVER!-nicely-focused.jpg

I can't wait until I get the magnet wire (which will be a long time from now)! There's not much more I can do until I wind the coil... but until then, let's discuss issues, what kind of wire I should get, any possible improvements I can do at this point... this is a serious project. It's inevitable that delays of months will hit but, please, I want to hear your opinions and thoughts about this project! Thanks in advance!
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post #3 of 17 Old 04-18-10, 04:43 PM
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Re: DIY Subwoofer... DRIVER!

The frame is foam? What will the cone be?
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post #4 of 17 Old 04-18-10, 06:40 PM Thread Starter
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Re: DIY Subwoofer... DRIVER!

The frame is made of foam, poster board foam you find at the Dollar Tree, and the cone will be made of the same. The foam has a layer of paper over it glued to the front and back of it, so, there's virtually no loss of sound output because it's not very sound absorbent at all (just as absorbing as paper or wood). The voice coil former will be made of an aluminum soda can cut into a tube, and the wire will... I'm not sure where I'll get the wire. But the spider will be made of rubber bands and duct tape (I have a design in mind), and the surrounds will also be made of duct tape.

Anyone know of any electronic devices to extract a good coil of wire from? I tried a CRT, but they wire was in many separate strands, and I don't have any speakers that are damaged enough to want me to extract the coil. What else is there?
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post #5 of 17 Old 04-18-10, 06:54 PM
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Re: DIY Subwoofer... DRIVER!

Are you just building a prototype or is that actually going to be the driver?
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post #6 of 17 Old 04-19-10, 06:56 PM
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Re: DIY Subwoofer... DRIVER!

Is this serious or tongue in cheek? I'm hoping the latter.
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post #7 of 17 Old 04-20-10, 05:10 PM Thread Starter
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Re: DIY Subwoofer... DRIVER!

@bambino: Uhh, sorta prototype-ish. I was going for an actual driver, but, the coil (actually much stronger than I thought it would be) heats up FAR to easily (it takes about 5 minutes to smell coil @ about 5 mm of excursion). It's also starting to melt the duct tape I used to attach it to the former.


BTW I finished the sub : )

Here's the magically melting coil...
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Yes, I know it looks pathetic.
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And the surrounds are very tacky but they're the least of the sub's issues.
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I got the wire from an old CRT...from an old portable karaoke machine, . I put the coil on the former and made the coil itself a few months ago. The former of the coil is paper, but, the paper is better at taking the heat than the duct tape.

I can get it to move about 1 cm @ 15 hz, and at 30 Hz it's really noisy and I don't want to push it beyond 5 mm (the coil has loose strands scraping against the rest of the coil... I tried to fix it with the best of my ability).

So, it doesn't move much without mayhem in the coil, and it gets hot. There's no way it'll make a legitimate subwoofer, at least by normal 18" driver standards. So yeah, it's still a prototype.


@SteveCallas: It was more towards the former at first but it began to move towards the latter as I moved through the project and began to realize the mediocrity of my craftsmanship on this project. I'll make a better one once I get a good amount of wire.
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post #8 of 17 Old 04-20-10, 06:20 PM
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Re: DIY Subwoofer... DRIVER!

That gives a new meaning to the term paper cone.
What did you make the spider out of?


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post #9 of 17 Old 04-20-10, 08:07 PM
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Re: DIY Subwoofer... DRIVER!

You might want to try a tire tube of the right diameter for a surround. Cut it in half and glue it on.
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post #10 of 17 Old 04-20-10, 08:45 PM Thread Starter
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Re: DIY Subwoofer... DRIVER!

Actually the surround is very effective... if I could push the speaker a little more than I would, because there's a lot of headroom for excursion (probably over an inch, maybe an inch and a half). But I have never smelled so much coil! I cranked it up just a bit more than what I have been playing it at, and the leads touched each other and I saw a small flash, although the speaker showed no signs of stopping. Even though it shows no signs of burning coil I can SMELL IT. I can still touch the coil (it's really hot though), but it smells absolutely blown when I turn it up.

@Matt: The spider is made of (asymmetrical) rubber bands like so:
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@Mike: Really, the duct tape is fine (I spent a lot of work on it!)... I'll save that for when I make the improved subwoofer with a better coil : ).
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