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I want to build a sub. :)

post #1 of 136
6/20/08 at 12:57pm
Thread Starter 
I've just recently been sucked into the fun that makes up this site, and I've got the itch to make my own sub. I want it big, loud, and fun to listen to while playing Halo or Call of Duty.
I'm going down to my local bookstore to pick up the Loudspeaker Design Cookbook, which I've heard will help a lot in building this.

Other than the fact that I want it to be front-firing and sealed, I don't know anything else about the system... What drivers/amps should I use, how big the box should be for it, etc... So any help at all would be greatly appreciated.
Oh, and my budget for this thing would be around $400, maybe $500.

Thanks in advance
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post #2 of 136
6/20/08 at 1:21pm
Sealed, front firing subs are easy! You build a box, add a brace or two, cut out a hole, mount the sub, and the binding posts and you're done. Finish it off however you like.

As for how big, most drivers within your budget will work well in a box between 2-4ft^3, so one 4'x8' sheet of plywood or MDF is all you'll need.

...oh, and you'll need wood working tools if you don't have any.
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post #3 of 136
6/20/08 at 2:11pm
Don't forget signal processing though - the one final step in sealed sub design. (Ported uses a tuned resonator to adjust the low end; sealed must have the signal manipulated to do the same but overall allows more flexibility for integration with other subs and 'tuning')

You're on the right track with the cookbook. Your project will be proportionally sucessfull to the amount of reading you do IMO.

Start with a driver you like. Better yet, two identical drivers (on same plane you get +6 dB boost across the entire band for the same power level by adding a 2nd driver; this also keeps doubling with more drivers) Jack H still has some 500w amps for cheap... Stick around, you won't go wrong.
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post #4 of 136
6/20/08 at 2:33pm
Quote:
Originally Posted by AlexE View Post

...Better yet, two identical drivers (on same plane you get +6 dB boost across the entire band for the same power level by adding a 2nd driver; this also keeps doubling with more drivers)

Actually, it's +3db for doubling drivers. It's another +3db for doubling power, which is how people get +6db going from one sub to two, because they not only double the drivers, they double the total power.
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post #5 of 136
6/20/08 at 2:44pm
Quote:
Originally Posted by Looneybomber View Post

Actually, it's +3db for doubling drivers. It's another +3db for doubling power, which is how people get +6db going from one sub to two, because they not only double the drivers, they double the total power.

http://www.linkwitzlab.com/faq.htm#Q21

I think we're both right, or at least i knew this, hehe.. d'oh

You double the power (+3dB) but get 4 times the output back (+6dB) so yeah technically not the same power but still a bargain I took when I built mine
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post #6 of 136
6/20/08 at 3:07pm
Thread Starter 
Wow, thanks for the fast replies, both of you!
I'm really new to this whole audio thing, so I'm lost when it comes to choosing a driver I want... Would this one work? http://www.partsexpress.com/pe/showd...number=295-190
Alex, who/what are you talking about when you say Jack H has some amps? I checked the classifieds on this forum, but didn't see any amps from a "Jack H."

As for bracing the inside of the box, I think this looks like a good setup for that:

Credit to Zachary Paisley for the picture. I think I'll be checking his blog a lot for how he did things... His sub came out spectacularly.

Looneybomber, what sort of tools will I need? I've got a table saw, cordless drill, belt sander... Uh... Hammer...
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post #7 of 136
6/20/08 at 3:49pm
Quote:
Originally Posted by Ezcl View Post

Looneybomber, what sort of tools will I need? I've got a table saw, cordless drill, belt sander... Uh... Hammer...

You will want to pick up a Router and possibly a Jasper jig like this to make the holes: http://www.partsexpress.com/pe/showd...number=365-250

If you have a Jig saw and want to save some money then you can skip the router and hole jig. Building subs can be addictive though as I have already built 4 after just planning on making 1. Fun hobby so don't cheap out on the tools as it will save you money in the long run.

Good luck and have fun.
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post #8 of 136
6/20/08 at 5:57pm
Quote:
Originally Posted by Ezcl View Post

Alex, who/what are you talking about when you say Jack H has some amps?

As for bracing the inside of the box, I think this looks like a good setup for that:

Looneybomber, what sort of tools will I need? I've got a table saw, cordless drill, belt sander... Uh... Hammer...

Jack H is the guy with a lot of NHT amps and drivers he's selling. Too bad I forgot his website.

That 2-axis bracing is pretty nice, but also only allows for one woofer, which is great if you're only wanting one!

As MJ points out, an entire enclosure could be build with a drill, jigsaw, and some skill. Create your own strait edges with some scrap wood and build a circle jig for it with some more scrap wood. It's not what tools you have, but how you use them. To make things nice and easy though, a table saw (or circular saw + strait edge) and a router would be awesome, but not needed.
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post #9 of 136
6/20/08 at 5:58pm
Thread Starter 
Thanks for the reply, mj. For a router, would something like the RotoZip work? If so, I don't think I have one, but I can go rummaging around friends' garages for one .

Also, if anyone has an opinion on which drivers they like or which ones should be avoided, let me know! I'm completely in the dark about the good and the bad.
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post #10 of 136
6/20/08 at 6:02pm
Thread Starter 
Okay Looney, thanks. I've got a table saw that I can use, as well as a circular saw. Does the RotoZip look like it'd work for cutting holes?

If I were to use two drivers, would they both go on the front of the enclosure? I'm not too sure how that would work.
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post #11 of 136
6/20/08 at 6:37pm
[quote=Ezcl;14126716] a driver I want... Would this one work? http://www.partsexpress.com/pe/showd...number=295-190

That Dayton driver will work. However it's not Dayton's best driver. Take some more time to acquaint yourself with Dayton's other drivers including the "Titanic" series. They cost more but offer more low frequency performance (loud and low).
There are other speaker makers to consider such as:
Sound Splinter
Fi Car Audio
Creative Sounds
Elemental Designs
Mach 5
JL Audio
and more.
You will be looking for SQ (sound quality) drivers as opposed to SPL sound pressure level-loud onlyl) drivers.
When comparing Thiel Small (TS) parameters look for the lowest Fs, largest XMAX, VAS under 6cu. ft. (that's a box about 22x22x24), large power capability 400 + watts, and others as you get to know what each means.
You're right to be excited about this stuff. If you make the right choices about the driver and amplifier and put those together with the right sized enclosure your sure to attract some attention when you finally get to crank that sucker up! Add to that the fact that you're gonna have hours of pure enjoyment choosing the parts, designing the system, building the enclosure, and finally listening to your creation play better than anything you've probably heard. What more can a DIYer ask?
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post #12 of 136
6/20/08 at 6:42pm
Thread Starter 
Quote:
Originally Posted by LINEARX View Post

What more can a DIYer ask?

Hell yeah! That's exactly what I want to hear The only other thing I've built was a computer, and while that was easier by far, the feeling I got from firing it up the first time was excellent, and I'm looking forward to that again!

Thanks a ton for the help on choosing a driver, LINEARX, I'm continuing to read up on the different measurements and stuff, learning a bit at a time. I should be able to grab that book in a few days also.
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post #13 of 136
6/20/08 at 9:01pm
Thread Starter 
So... Using WinISD for this Dayton Titanic III driver, it tells me the volume I need is around 3ft^3, which I know is wrong, since it says the VAS is 7.7ft^3 on the website.

Oh well, manually changing the volume to 7.79ft^3 gives me a higher response at 10Hz and a bit lower around 100Hz, but that's fine by me. I want the width at 20", the depth to be at 30", so I get 27.03" Height, which is again fine. Altogether not such a huge system... One that should work well with the spaces I have.

Are there any other online resalers I can buy drivers from? Partsexpress has a somewhat limited stock of 15" Drivers...
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post #14 of 136
6/21/08 at 4:17am
http://home.comcast.net/~jhidley/

He has the amps and surplus 10" NHT subwoofers. I bought 4 of them from him and they sound great. 3 of the 11-75s wired in parallel with the 500w amp would be more than enough. I would pick up the eQ.2 from elemental designs for $100 as well. Without box materials your budget will be under $300 including shipping.
If you go this route, don't forget to ask jack to wire the attentuation circuit into the amp for you-i think he charges another $15-well worth it.
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post #15 of 136
6/21/08 at 10:02am
Quote:
Originally Posted by Ezcl View Post

So... Using WinISD for this Dayton Titanic III driver, it tells me the volume I need is around 3ft^3, which I know is wrong, since it says the VAS is 7.7ft^3 on the website.

Your box size does not need to be your VAS size. I tend to be one of the guys that likes a box a tad bigger than what gives a Q of .7, but even 7.7ft is waay bigger than I'd use...maybe for two of them but not one.
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post #16 of 136
6/21/08 at 11:50am
Thread Starter 
Oh, okay Looney, thank you! Saved me a bunch of wood there :P The Qtc for the box of 3.165ft^3 is .71, is that good, or should it be a tad bigger to compensate for the size of the driver and braces?

Thanks very much for that link, mayhem! You're saying I should get three of those 10" drivers for my build? If I did that... What would be the differences in performance between them and the Dayton Titanic III? Would the triple driver system still be able to hit the low frequencies well? I have no doubt it'd be loud enough.

Also, what's that eQ.2 thing for? I see on Jack's site it says I need an LP filter for that amp?

Thank you to all of you who continue to answer my uneducated questions.
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post #17 of 136
6/21/08 at 1:11pm
Quote:
Originally Posted by Ezcl View Post

Oh, okay Looney, thank you! Saved me a bunch of wood there :P The Qtc for the box of 3.165ft^3 is .71, is that good, or should it be a tad bigger to compensate for the size of the driver and braces?

I don't have WinISD here at work to model it, but there are a few thoughts on the subject. What I like to do is figure out roughly how much power I'll need, pick out an amp, then model that driver with that amp and pick an enclosure size that's large enough to use all the excursion, but not too large that i'll have to worry about it bottoming. When you model it, make sure your graph goes all the way to single digits.

Quote:


Also, what's that eQ.2 thing for? I see on Jack's site it says I need an LP filter for that amp?

It's an EQ, LP filter, and subsonic filter all in one. Just know, your A/V reciever has an LFE output which has it's own LP filter.
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post #18 of 136
6/21/08 at 3:17pm
Thread Starter 
A few things there Looney. First, you can model a certain driver with a certain amp in WinISD? How can I figure out what size I need to use all the excursion? And what is 'bottoming'?
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post #19 of 136
6/21/08 at 4:40pm
Fire up WinISD, plug in all the stuff for your woofer, pick a box size, and check out the Max power handling catagory. That should give you a rough idea of how big of an amp to buy. Once you have your amp picked out, plug in the wattage you'll be feeding it in the signal tab. Then select excursion and see what you've got. Play around with it, you'll get it.

Oh, bottoming is where the subwoofer bottoms out which can cause damage! It's typically listed as Xmech or Xlim and will be a higher number than the Xmax.
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post #20 of 136
6/21/08 at 5:22pm
Thread Starter 
I'm sorry... I don't know where I'm supposed to plug the wattage amount in WinISD. I see no 'signal' tab, so...

How do I avoid the woofer bottoming out? That's deeeefinitely not what I want to do.
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post #21 of 136
6/21/08 at 6:12pm
I don't have WinISD on this computer so I'm just going by memory. There's that box that opens up where you can adjust the enclosure size, tuning freq (if ported), qty of drivers, ect... Well towards the top of that box is a tab for signal, which it's default is 1W. Well you can change that to whatever you want.

Wait, I have an old picture of WinISD in my photobucket.


See those boxes on the right? See that tab that says signal? There's where you can change the wattage.
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post #22 of 136
6/21/08 at 6:40pm
Quote:
Originally Posted by mayhem13 View Post

http://home.comcast.net/~jhidley/

He has the amps and surplus 10" NHT subwoofers. I bought 4 of them from him and they sound great. 3 of the 11-75s wired in parallel with the 500w amp would be more than enough. I would pick up the eQ.2 from elemental designs for $100 as well. Without box materials your budget will be under $300 including shipping.
If you go this route, don't forget to ask jack to wire the attentuation circuit into the amp for you-i think he charges another $15-well worth it.

I don't think I needed it for my yamaha; turns out only certain units are 'too weak' - my gain is as low as it goes, just on the cusp of too much.

In other words save the $15, you probably won't need the gain mod. Use the sub you have as a guide... are both levels turned way up or do you have 'headroom'?
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post #23 of 136
6/21/08 at 9:05pm
Thread Starter 
Ah, well there's the problem... I had the .44 version of WinISD, which didn't have that tab. However, I've got two problems with this newer one... I can't look at the box dimensions with this version, and I don't notice any difference in the graph when I change the signal to 1000W from 1W.

Would that amp from that J Hidley guy work, or should I look for a 1000W amp?
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post #24 of 136
6/21/08 at 9:07pm
Quote:
Originally Posted by Ezcl View Post

So... Using WinISD for this Dayton Titanic III driver, it tells me the volume I need is around 3ft^3, which I know is wrong, since it says the VAS is 7.7ft^3 on the website.

No, WinISD had it right. But the important thing you're doing is seeing that there are many ways to implement your own ideas. The 3ft^3 box would turn out excellent in terms of power handling and frequency response but it would benefit from an LT circuit (linkwitz transform) to flatten the response curve below about 60 Hz. You've already noticed by using WinISD that you can change many of the specs and observe the predicted changes. Keep on doing more of that. After studying several different drivers you'll start to recognize which drivers parameters will produce the type of power and frequency response you're looking for.

Oh well, manually changing the volume to 7.79ft^3 gives me a higher response at 10Hz and a bit lower around 100Hz, but that's fine by me. I want the width at 20", the depth to be at 30", so I get 27.03" Height, which is again fine. Altogether not such a huge system... One that should work well with the spaces I have.

Your observations are correct here. A lot of members on here would consider a 7.79ft^3 too big for a sealed box. Depending on your choice of driver, I wouldn't.

Are there any other online resalers I can buy drivers from? Partsexpress has a somewhat limited stock of 15" Drivers...

There is also "Madisound" and "MCM Electronics"
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post #25 of 136
6/21/08 at 11:36pm
Thread Starter 
For some reason I like the idea of a smaller woofer being able to produce massive, high quality sound.
The lines I get from the two different enclosures aren't too far off, but the 3.1ft^3 seems to give a better response at more frequencies, which I like. How much will the eQ.2 raise the response of the lower end? <30Hz?
Here's what I mean:

I want the lower frequencies of the yellow line higher (that means they'll be louder, correct?), will the eQ.2 raise it a significant amount?
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post #26 of 136
6/22/08 at 12:56pm
The surplus 10" NHTs wired parallel (3) will give you a nom. 4ohm load, just right for most sub amps and the amp that Jack is selling. Unibox won't model 3 drivers, only pairs so WinISD will be the way to go. They work very well sealed, i just finished a dual 10" sealedtest box at 60L and it sounds really good.I may reduce it to 52L. I'm building two of these for under MTM mains. Each one will have its own eQ.2 mounted right in the box with the VT-3 amp since the amp has no controls. Now thats 500w, 2 band para eQ for under $200-try and find that in a plate amp !!.
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post #27 of 136
6/22/08 at 1:05pm
Oooops-Unibox will do 3 units, sorry bout that. 3 of the NHT 10s in 10 cubes tuned to 19 hz will give you 110db at 20hz with an F3 of 22hz or so at 500 watts with dual 4" ports 15.6 inches long dual flared. The eQ.2 will help you roll off below that to protect against over excursion below tune. IMO this is essential with ported subs and todays soundtracks. I blew up two of these in my first ported test box with Lord of the Rings-wasn't ready for the ring drop scene and then.......silence. Thank God they're only $20 each LOL
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post #28 of 136
6/22/08 at 2:45pm
Ezcl: How big of a box are you wanting to build? That will determine a lot. You say you want to go "big" but does that mean 6ft or 20ft^3?
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post #29 of 136
6/22/08 at 8:57pm
Thread Starter 
Well, I'm thinking 'big' isn't where I want to be going with this build after all. Heh.

I'm leaning toward either the three 10" NHT's or the single 15" Titanic, since I've already drawn out the plans for the Titanic. I'd like to know how much an amp for the Titanic would cost, and I can't figure out what to look for in an amp. If anyone could help me, that would be awesome. ?
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post #30 of 136
6/23/08 at 2:06am
The eD box should be good for sealed; yes, it will allow you to raise the outout of certain frequencies in the lowest octave, to offset the natural roll-off that the driver has. For amps, see where your cone excursion is at what power levels and buy that. No sense in having a huge amp for a sub that can't move more than 15 mm for instance, unless you want future room to grow. Plate amps are very popular, or you can search for a rack mounted amp. Use fleabay, search engines, and of course the aforementioned sites.
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