DIY Subwoofer Help (Amplifier & Crossover)

C

cbraver

Audioholic Chief
In high school I built a subwoofer enclosure out of cherry wood. It's a beautiful piece, but I simply ran out of money after I finished the enclosure. Now I have some extra money and I want to finish it up this summer, when college gets out. It's made for a 12" subwoofer, although it has been too long for me to remember to exact dimensions (I can measure when I get home, I'm at school until next week). I think it's about a 15" by 15" interior, so 1.56ft^2 volume box. Not 100% sure on that though, and I know it is important. It's been too long to remember what driver I was designing it for.
I obviously need to figure out the exact box dimensions before I can finalize a driver for it, but any off the wall recommendations?

I also need a seperate amplifier and some sort of method for a crossover. I don't want to use a plate amp, I'd rather use a seperate. I realize that probably will raise my costs. I was going to use a Crown XLS202 bridged, but there isn't a crossover. The Dayton subwoofer amp is too expensive.

My budget for finishing the sub (I need a driver, an amp, a crossover, box fill, and whatever else I'll need) is going to be about 300.00 USD. I guess 400 if I really need to. I've been putting a lot of money into investments and such, so I don't have a lot of cash laying around. I'll thank myself when I retire though (I'm only 22, haha, never too soon to plan! The retiring baby boomers with no money in the bank scared me into planning ahead!).

Any help would be appreciated. I'm going to measure next week when I get home to find the interior dimensions. I'm very excited about this project, but I need to be careful not to go crazy and spend too much money. I want it to be a subwoofer that I keep though.

Thanks guys!

-Chad
 
WmAx

WmAx

Audioholic Samurai
In high school I built a subwoofer enclosure out of cherry wood. It's a beautiful piece, but I simply ran out of money after I finished the enclosure. Now I have some extra money and I want to finish it up this summer, when college gets out. It's made for a 12" subwoofer, although it has been too long for me to remember to exact dimensions (I can measure when I get home, I'm at school until next week). I think it's about a 15" by 15" interior, so 1.56ft^2 volume box. Not 100% sure on that though, and I know it is important. It's been too long to remember what driver I was designing it for.
I obviously need to figure out the exact box dimensions before I can finalize a driver for it, but any off the wall recommendations?
Because of the rediculously small volume, this is going to involve compromise. You will lose low end SPL and gain distortion using this small sealed cabinet for a 12" woofer. However, if you choose a driver with an excellent motor and high linearity, you can still get some good performance. For this volume, an Infinity Kappa Perfect 12VQ would work very well. Because they are all clearanced, you can find them pretty cheap($150-$170 each range). Using the mid-Q motor insert, it will be about -2 at 40hz, and -4 by 30Hz in a 1.5 ft^3 box. You can use an EQ boost near the lower end to give more extension, but you will quickly run out of dynamic headroom when doing this. You can not expect but so much in a small closed box.

I also need a seperate amplifier and some sort of method for a crossover. I don't want to use a plate amp, I'd rather use a seperate. I realize that probably will raise my costs. I was going to use a Crown XLS202 bridged, but there isn't a crossover. The Dayton subwoofer amp is too expensive.
Crown XLS amps are over-priced and under-built. I recommend Behringer EP2500 - it is made far better - and an Ep2500 has has far more power available than an XLS202D - for close to the same price. For a low cost crossover to integrate your mains with the sub, you can go with the Behringer CX2310; low cost, but great quality parts used inside.



My budget for finishing the sub (I need a driver, an amp, a crossover, box fill, and whatever else I'll need) is going to be about 300.00 USD. I guess 400 if I really need to. I've been putting a lot of money into investments and such, so I don't have a lot of cash laying around. I'll thank myself when I retire though (I'm only 22, haha, never too soon to plan! The retiring baby boomers with no money in the bank scared me into planning ahead!).
How did you intend to buy a Crown XLS202D and still have money left for a crossover and driver? If you PM me, I'll tell you how to get an EP2500 for about $270 shipped from a reputable online dealer. If you need to keep strict budget, a plate amp may be the only feasible option here.

-Chris
 
WmAx

WmAx

Audioholic Samurai
Since I've posted this, I've been searching around Part's Express. It looks like to stay within 300 dollars I'll need to go with a plate amplifier.

I was thinking something like this:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-804

with this driver:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-444
The Kappa Perfect unit I recommended will perform better in the volume, and has a larger linear range of movement, which is very important for a small sealed box application such as this.

The plate amp you linked is not powerful enough for this application if you ever intend an using any compensation EQ to boost LF to a more flat response. If you use it without EQ, however, it will be okay. But it will definitely clip before you approach the limits of the Kappa Perfect driver.

-Chris
 
WmAx

WmAx

Audioholic Samurai
Kappa Perfect 12VQ

techronics.com/index.cfm?fuseaction=product.display&product_id=812&aff=45847

-Chris
 
C

cbraver

Audioholic Chief
I never thought of using a car subwoofer driver, what a great idea. I actually have that Infinity Kappa Perfect in my truck powered by a Kicker 600.1 in a sealed box.



Those are great subs!

I can get JL Audio subs at wholesale cost though (from work), is there a JL Audio subwoofer you'd recommend? That might allow me to use the Behringer seperates if I can get a good driver cheap enough.
 
WmAx

WmAx

Audioholic Samurai
I never thought of using a car subwoofer driver, what a great idea. I actually have that Infinity Kappa Perfect in my truck powered by a Kicker 600.1 in a sealed box.



Those are great subs!

I can get JL Audio subs at wholesale cost though (from work), is there a JL Audio subwoofer you'd recommend? That might allow me to use the Behringer seperates if I can get a good driver cheap enough.
Sorry. I just don't know of their is a JL driver of equal quality available at the same price. The W6 JLs seem to be good distortion performance - but you need to model the 12" and see if it has a favorable response in that sealed box volume. I assume your dealer cost is very low if it can allow for that driver under the price of the clerance priced Kappa Perfect unit.

-Chris
 
C

cbraver

Audioholic Chief
I'm pretty set on seperates now, rather than a plate amp. For the simple reason of expandability. The crossover I could use where ever, forever... and a rack mount amplifier can always power something. If I get a plate amp, it'll only be good for that sub. So, I'll be going over my budget, but probably save myself amplifier costs in the future when I finally build my home theater.

I'm gunna go with the Behringer CX2310 crossover for sure, that's a steal right there.

I still would prefer the Crown XLS202 amplifier though, it's just my preference. 600watts should be plenty, no? It's also 234 dollars from BHphotovideo (after the rebate). Which is still closer to my budget, even though I'm already going to be over it... now I'm at 324USD after rebate with the crossover and amp. Not sure what I can get a W6 for, but it might be cheaper than the Infinity Kappa Perfect. Those Infinity's are tough to beat though. I've abused that thing SO BAD I'm surprised it hasn't blown yet. They are built to withstand hurricanes or something.
 
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WmAx

WmAx

Audioholic Samurai
I still would prefer the Crown XLS202 amplifier though, it's just my preference. 600watts should be plenty, no? It's also 234 dollars from BHphotovideo (after the rebate).
It's just not nearly the build quality, nor can it handle 4 ohm bridged mono loads ;it's not really rated for it. Every single aspect of build quality and design of the EP2500 is superior. I have a couple of XLS202D amps and an EP2500 - so I have inspected both first hand. The XLS202D is a fine amp; it has no audible noise from the outputs(though there is a fan that makes noise) and it probably measures exactly as Crown specifies. But why pay about the same and get a lesser amplifier? Especially for sub use?

. Not sure what I can get a W6 for, but it might be cheaper than the Infinity Kappa Perfect. Those Infinity's are tough to beat though. I've abused that thing SO BAD I'm surprised it hasn't blown yet. They are built to withstand hurricanes or something.
The real thing bout the Kappa Perfect *.1 and VQs is, they are designed to remain at very low distortion at high mechanical movement. Strictly a sound quality device. That's why I favor them.

-Chris
 
C

cbraver

Audioholic Chief
I see your point, it's just that 30 dollars here and 30 dollars there adds up pretty fast.

I know underpowering is more likely to blow a speaker than overpowering, but would the EP2500 be overpowering to the point where I'll always have the gain knobs turned way down to prevent over-excursion of the driver? I mean, the Kicker 600.1 I have powering my Kappa Perfect now already can drive it to the limits of cone excursion... would the EP2500 be pure overkill? Overkill is better than, um, "underkill" (?? haha), but I don't want to spend money I don't need to. If the Crown 202 can do it, It'll keep me closer to my original budget. See what I mean?
 
annunaki

annunaki

Moderator
The JL Audio 12W6v2 would be a nice option for you in that enclosure. The 12W3v3 and 12W3v2 would also work in that volume. Be sure to use about 1-1/2 to 2lbs of poly-fil stuffing as well. The poly-fil will help to lower the F3 on the system as it will help make the enclosure "seem" larger.
 
C

cbraver

Audioholic Chief
The JL Audio 12W6v2 would be a nice option for you in that enclosure. The 12W3v3 and 12W3v2 would also work in that volume. Be sure to use about 1-1/2 to 2lbs of poly-fil stuffing as well. The poly-fil will help to lower the F3 on the system as it will help make the enclosure "seem" larger.

Great, I'll find my price on those. I'll also stuff the box.

The box is pretty well sealed, but I need to make it air tight. I was thinking of using fiberglass and epoxy resin to make it air tight... is there something else I could use? What do DIY speaker builders use to seal their boxes well?
 
Hi Ho

Hi Ho

Audioholic Samurai
The box is pretty well sealed, but I need to make it air tight. I was thinking of using fiberglass and epoxy resin to make it air tight... is there something else I could use? What do DIY speaker builders use to seal their boxes well?
How was the box assembled? I build speaker and sub boxes with MDF using biscuit joints and polyurethane glue. A bead of glue around all joints expands and fills any gaps. If you used a method that did not seal the seams then I don't see why a fiberglass/epoxy resin wouldn't do the trick.
 
WmAx

WmAx

Audioholic Samurai
The JL Audio 12W6v2 would be a nice option for you in that enclosure. The 12W3v3 and 12W3v2 would also work in that volume. Be sure to use about 1-1/2 to 2lbs of poly-fil stuffing as well. The poly-fil will help to lower the F3 on the system as it will help make the enclosure "seem" larger.
You think a 12W3 can match the linearity of the Kappa Perfect drivers? Measurement confirms that a sealed Kappa Perfect 12.1 has lower distortion than the servo-controlled Velodyne DD12, and nearly matches the DD15 on all issues.

-Chris
 
WmAx

WmAx

Audioholic Samurai
I see your point, it's just that 30 dollars here and 30 dollars there adds up pretty fast.

I know underpowering is more likely to blow a speaker than overpowering, but would the EP2500 be overpowering to the point where I'll always have the gain knobs turned way down to prevent over-excursion of the driver? I mean, the Kicker 600.1 I have powering my Kappa Perfect now already can drive it to the limits of cone excursion... would the EP2500 be pure overkill? Overkill is better than, um, "underkill" (?? haha), but I don't want to spend money I don't need to. If the Crown 202 can do it, It'll keep me closer to my original budget. See what I mean?
If it makes you so nervous, you can use just one channel of the EP2500 for now. That will provide 650 watts into 4 ohms. BTW, you can't run the XLS202D at 4 ohms bridged. It was not intended to run this low constantly.

-Chris
 
WmAx

WmAx

Audioholic Samurai
Great, I'll find my price on those. I'll also stuff the box.

The box is pretty well sealed, but I need to make it air tight. I was thinking of using fiberglass and epoxy resin to make it air tight... is there something else I could use? What do DIY speaker builders use to seal their boxes well?
I use acrylic-latex outdoor/indoor caulk to ensure a perfect seal. Easy clenan up/water soluble.

-Chris
 
C

cbraver

Audioholic Chief
How was the box assembled? I build speaker and sub boxes with MDF using biscuit joints and polyurethane glue. A bead of glue around all joints expands and fills any gaps. If you used a method that did not seal the seams then I don't see why a fiberglass/epoxy resin wouldn't do the trick.
Biscuit joints for sure and polyurethane glue or something similar (It's been a while since I built the box). I still don't think it is completely air-tight, though. I'll probably fiberglass the edges just to be sure, or use acrylic-latex caulk like WmAx recommended.

When I'm ready to mount the driver, I'll test the box by applying a vacuum and watch a gauge to see if there are any leaks.

If it makes you so nervous, you can use just one channel of the EP2500 for now. That will provide 650 watts into 4 ohms. BTW, you can't run the XLS202D at 4 ohms bridged. It was not intended to run this low constantly.

-Chris
Point taken. I have a pretty good idea of what I want now... but I need to make measurements of that box next week and then see my prices on JL Audio drivers. If the JL Audio stuff isn't much cheaper, I'll get the Kappa Perfect. Then I'll make a final amp determination. I would think a W6 would be better than a Kappa Perfect though, you certainly hear about them more often. W3s are popular also. Probably all of them wouldn't be a bad choice, it comes down to making the best choice.
 
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C

cbraver

Audioholic Chief
You think a 12W3 can match the linearity of the Kappa Perfect drivers? Measurement confirms that a sealed Kappa Perfect 12.1 has lower distortion than the servo-controlled Velodyne DD12, and nearly matches the DD15 on all issues.

-Chris
May I see where ever you measured/read that? I'm not calling you a liar, but, that's pretty surprising.
 
C

cbraver

Audioholic Chief
Wow. I'll probably go with a Kappa Perfect regardless, then. That's impressive.

Probably still won't sound as good as a DD12 because of my enclosure, but, we can only strive. ;) Maybe if this setup works out alright I'll build another box and specifically build it for the Kappa Perfect 12.1 driver.
 

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