I was about to embark on the journey of building my own subwoofer enclosure. The manual for my subs (2 Cerwin Vega 124D4's) says that the box needs to be tuned at 35Hz.... Well I have absolutely no idea what I am supposed to do. How do you tune a box?

 

That means that it needs a ported enclosure. You need modeling software. Or professional assistance.

 

I have been to Vega's excellent web site many times. They have enclosure dimensions/specs for most of the subs, in adobe format. Should take less than a minute to download. Don't enlist professional assistance unless you want to pay a couple hundred $ for less than five minutes of reading.

 

http://www.cerwinvega.com/products/index.html

I think I talked to the techs about these speakers about four years ago. They said although they are designed to work optimally in a vented box, they will also work in a small sealed box. From the t/s parameters it looks like a box between 0.7 cubic ft and 0.8 cubic ft would work. That includes the driver displacement.

 

Jay,
I just read your other thread. Email me if you still have questions. The tuning of the box involves both alterations of the net volume, and port length/diameter. But if you are not an SPL nut the sealed box will work, but if you go too large you will be able to blow the sub. Also, Sony has trouble with accuracy/stability when driveing low impedances. So you may want to find a higher quality amp for those subs.

 

Thanks guys....

The sony amp is just a temporary power unit. I hate the dam* thing. I was planning on getting two audiobahn amps and running one sub on each at 2 ohm (voice coils in parallel).. What do you think? I am actually more inclined towards sealed boxes which is good. Are you sure that the volume is correct? It seems awfully small.

 

I think the tiny box requirement is one reason they don't actively recommend a sealed box. But with Qts of 0.27 and VAS 4.87 cubic ft, the box will have to be small. I would build a small test box and try out a single sub. If it performs the way you want, go ahead and build the full double chamber box or two seperate boxes. Otherwise you will have to go with a 2 cubic ft(net) vented box, per sub. And say "goodby" to your trunk. You could go as large as 1 ft sealed per sub, but you might have to add filler to avoid bottoming out and overextending the voice coil.

For amps you could also get a monoblock with 400-800 watts RMS at 4 ohms. Wire each sub in series and then parallel to the amp. Or, get a large stereo amp with clean output into 2 ohms - not all amps that advertise this ability can do it cleanly.

 

Thanks, I think that I will try to go with a sealed box. I may just go ahead and buy one from www.speakerhole.com They have one that is .88 cubic feet per sub sealed. I listen to my music loud and hard. I am definitely a basshead. Do you think that putting my subs in a sealed box will make them more likely to blow?

 

amazing!

I emailed speakerhole yesterday and asked them if their 3.27 cubic foot per sub slot vented box would work well. They said it would. What do you think jmax? (trunk space is not a concern at all)

 

If you want to blow your brains out, then the ported box would be better- BUT.. with ported boxes, you can blow the subs easier than you can with a sealed box. once you go below a certain frequency, the box can no longer control the movement of the sub, so it'll jsut flop around like there's no box at all.. then kaboom. you blow something up.

best way to get around this is to make sure the amp you buy has a "subsonic" filter on it to keep the really low bass out of the system.

 

Yeah, I wouldn't go larger than the 2.0 cubic ft ported box that Vega recommends. And Matt is right about what happens in a ported box below the tuning frequency. The sub can easily go beyond it's Xmax. But that sub should have a low tuning frequency. I think Fs was 21 Hz?

Having said all that, 1 twelve in a sealed box, with a good amp can rattle your fillings. Two, well you can figure out what two can do.