well, in obtained a few subwoofers for a great price and now i want to ultilize my xB for ultimate SPL


i have a single 12" Volfenhag ZX-4812 (the large 45lb subs) and i wanted to know if anyone has measurements for a sub box that fits ontop of the spare tire cover between the rear shock mounts.

i had an idea for 2 more, making a total of three 12" woofers, but being a guy, i never measure so does anyone have pics of custom enclosures

even better, does anyone have a write-up on how to build a custom enclosure???

 

Well, first off, what is the recommended size cabinet for the sub? Sealed or ported? Are you looking for a basic rectangle, or something more complex?

There are lots of pics of custom enclosures within this forum.

So far as a write up goes;
Do you have any experience with basic carpentry? Have you ever worked with fiberglass?

 

its recommened at 1.5cu ft sealed and prob. near 2 or so ported


whats the benefit between a rectangular and a triangular box??

 

EDIT : bought four 10" Rockford Fosgates


recommened in about 1 cu foot each

 

Is your goal Competition SPL or just "as LOUD as possible!!!"? There's a BIG difference.
What are the specifics (model number) for the woofers and what kind of wattage are you intending on applying?
What amplification?

 

I have a set of JL 8w7's. I took their reccommended sealed enclosure dimensions and calculated internal volume w/ the subwoofer from them. I am in the middle of doing custom fiberglass, so to correctly size it I will be doing the following.

1) Mask off and lay fiberglass for the back wall and floor of your box, go bigger than what you think you will need.

2) build a square box out of cardboard to your internal dimensions.

3) Line the box with a plastic bag and fill it with packing peanuts

4) Lay the peanut bag in the enclosure box.

5) put the speaker ring on top of the bag and secure in place with hot glue and wood supports

6) Stretch fleece over the ring and hot glue to the back side of the box

7) Resin. Once the resin hardens cut out the speaker hole and remove the bag of peanuts, the enclosure will be the correct volume.

Fill and paint, good to go.

You can use the peanut bag trick to lay out your box if it is not a regular shape. I wouldn't go ported unless port length and volume are specified, it tunes the box to a specific frequency so if done incorrectly, you could "mistune" it and it will sound bad.

 

the subs are the simple Stage One 10" single voice coil


i heard two of these exact woofers at BestBuy in a sealed box and they rattled all the way accross the store to the registers.

they RMS at 150 and peak at 300

small stats for a simple sub, but i'm sure a quantity of four should even it out.


Incredibly, they require under a cubic foot of airspace sealed, somewhere near .80 Cu feet.

 

You're talking about this one, right?
Here's the data sheet (TS Parameters).
This setup is going to perform considerably louder in a vented enclosure compared to performance in a sealed setup, but the box would have to be considerably larger.
Sealed, the woofer will work well in a .6 cubic foot enclosure, but requires 1.4 cubic feet of air space for a vented setup. This is per woofer, so a 4 10" vented setup would require almost 6 cubic feet of air space. If you are willing to lose the spare tire and cubby, you can build an enclosure for the 10s, but it will take up quite a bit of your rear storage space.
There are other alternatives that offer a smaller enclosure, such as isobaric loads, but they will not perform as efficiently as the vented setup.

 

chambered, i figured i'll use a full 1 cu feet sealed


if i can build a box to fix within the 40" between the shock mounts, and then extend off a little, i can give each woofer a little more than a cu foot

 

If you are going to go sealed, then I wouldn't build the box much bigger than .6 to .7 cubic feet internal volume for each 10. If the box is considerably larger, you will dramatically cut down on the woofer's ability to handle power. It will also make the bass seem "muddy" sounding and will not have as much tight punch as a 10 should have.
If you are willing to lose the spare and cubby, you could build the base, sides, and dividers of the enclosure from 3/4" MDF, filling up the spare tire/storage area and build up from there. you could easily divide the area into quarters for the 4 10s.
Position some smoothed MDF rings for the 10s, suspended by wooden dowels (any break-away material that will offer enough rigidity to support the rings under some stress will do), placing each one over its appropriate section of the enclosure. I usually glue my dowels into place and just snap them in half and pull them out later.
Stretch fleece over the enclosure to get the desired shape, stapling the fleece down to the sides and dividers.
Liberally coat the fleece with fiberglass resin/hardener, mixed appropriately. You will need to apply plenty of resin in order for the fleece to adequately soak it all up. It is also a good idea to apply as much as possible from the inside as well. The fleece will act like a sponge, so don't be too worried about using too much resin. The harder you can make the fleece layer, the better.
Once the fleece is hardened and thick enough, you can seal the seams of the enclosure with silicone, liquid nails, caulk, etc., ...whatever sealant you choose. You can also snap out the dowels that were used to support the rings during the build. They will not be necessary anymore and will only take up enclosure volume.
In order to make the fiberglass look nice, you will need to sand and fill the surface to get it smooth. This is really important if you intend on painting the finished product.

 

Is it the P1S410? it reccommends .5-.85 ft cu. That's probably net, so you'll want to add in around .05 cu ft for the volume the speaker will displace when inserted in the box. Optimal will probably the middle of the spec (.67+.5 = .72 ft cu) per sub as UV7 says. It differs depending on the speaker, my 8w7 needs .875 net internal sealed, .9377 counting the volume the speaker will take up.

Here's the tutorial I used for glassing, it hjas lots of pics and illustrates the method UV7 outlined.

http://www.ajquick.com/cars/tutorials/fiberglass.php

 

it is the P1S410

i kinda wanted to keep the spare tire and cubby. If possible, i wanna make this enclosure removable.


fiberglass seems difficult, i've never built a fiberglass box before.

 

I'm doing my first fiberglass box as well, only learn by doing. For the larger ones, it ain't cheap due to the large ammount of resin needed at $30 a gallon. MDF is cheaper and works well, but you lose space due to wall thickness and not conforming to the car side exactly. Good luck with the project.

 

thanks, will post pics when finished

 

Fiberglassing can get expensive and does take quite a bit more time than basic MDF, but it REALLY looks trick when it's done right. As Vettereddie said, it is a skill that can only be learned by practice. Everyone that has worked with 'glass develops their own little tips and tricks based on what works well for them and what doesn't. If you've got some spare time, an open garage (you'll be high as a kite from the fumes if you do this in an enclosed space!), and enjoy building things, then grab some fleece and a can of resin/hardener and give it a shot. Start with a small project and work up to the larger ones. It gets much easier as you do it, and your skills will only be limited by your imagination.
As for this enclosure, you can build the setup to be removable, but it is going to be somewhat heavy. Your best bet would be to build the enclosure out of 3/4" MDF and make sure it is sealed up tight before you put it to use.
If you angle the woofers up toward the rear gate glass, you will get a little deflection effect, bringing the bass forward in the vehicle.
Have you thought of what amplifier you are going to run the 10s with? Also, keep in mind, if you wire the 10s so that all the positives are connected and all the negatives are connected, you will be running the 10s at a 1 ohm impedance, which will be too low for many amplifiers and may cause others to produce too much power for the 10s. Remember, as you cut impedance (resistance) in half, the amplifier will theoretically double its power output. Be careful what amp you pick and how you wire the setup.
Good luck with the build. Snap some pics when you're finished.

 

thanks again for all the support

i was thinking of either running a single 4-channel that has 150x4 channels or two 2-channel amps running at the same wattage.


these subs are at 4ohms already, so a direct non-bridged channel hook up would give the cleanest sound, i dont really wanna over power these right away.


does anyone know if subs need a break-in??

also, what hurts subwoofers more --> lower wattage, or over-powering???

 

You will most likely do MORE damage by under-powering the subs. Gain control plays such a huge part in properly setting up a stereo system. Most people tend to keep cranking the gain until they get it to their chosen loudness. Often, this is beyond the point of distortion for the woofer, which will dramatically shorten the woofer's life span if subjected to prolonged use at a distorted signal.
I would recommend wiring the subs in series-parallel to a mono or bridged amplifier. 4 4-ohm woofers wired series-parallel will give a 4 ohm impedance at the amplifier. Find a nice, solid mono amp that puts out 250-300 RMS @ 4 ohms and you will be MORE than satisfied. Keep the gains at a low, clean level and you should have a setup that plays clean, low, and loud, and that will last a long time.
http://www.bcae1.com/spkrmlti.htm
Scroll down the page a little until you see the Series-Parallel diagram. This is an excellent representation of 4 woofers in a series-parallel wiring scheme.

 

so, basicly, i should get four mono block 200watt amps?

simple & cheap!!!

 

Under-powering won't hurt the subs, but by using an amp that is underpowered with the gain all the way up may hurt the amp, the output waveform may start clipping and you'll be sending out squareish pulses instead of a sine wave. This makes the FET operate at a peak amplitude longer, creating more heat and eventually leading to thermal overload and failure. I did this on a real old POS amp, it actually blew the FET into about five chunks. Four mono 200 RMS or a single 800 RMS, just make sure that it is RMS at 4 ohms, a lot of amps vary power by the load, i.e. 400 RMS @ 4 ohm but 700 RMS @ 2, etc. Even though the subwoofer RMS is 150, I go a bit above on the amps because most manufacturers rate them at 14.4 V. In a vehicle, they are probably only getting about 12.8 so, if they use an unregulated supply, the power output is decreased when used in your car.

One more reason I went with JL amps, they are constant power output from 1.5-4 Ohm and 11 - 14.4 V DC, so it's 500 RMS regardless of speaker configuration, I wish more manufacturers would use regulated power supplies. They are a little complicated to tune though, it's a nine step process that uses a volt meter and a resonant frequency zero gain sine wave, I use a 60 Hz mp3 burned onto a cd.

 

Oleson,
One mono-block amp will be enough to power all 4 10s. Buying 4 amplifiers would be a waste of money and current.
Output is less effected by the number of woofers and more effected by the overall impedance. Since Series-Parallel wiring yields 4 ohms at the amplifier, the overall impedance would be the same for all 4 woofers wired together in series-parallel as it would be if the amplifier were running only one of the woofers.
I know it sounds strange, but it does work this way.

Vettereddie,
JL's "Slash Series" amplifiers are VERY powerful. IMHO, they are some of the best amplifiers on the market today. Those amplifiers regulate their power output so that it is not dependent upon the impedance or voltage (within reason). Unfortunately, these amplifiers ARE current-hungry and will eat up a charging system and battery in no time.
JL's "A Series" amplifiers, while not as powerful, are much more forgiving when it comes to the vehicle's charging system. The xB doesn't host the most powerful charging setup in the world, so anyone using a stock setup (i.e. stock alternator, battery) should be very mindful of how much current they occupy. Enough current loss can cause damage to very important electrical components within the xB which could become VERY expensive to correct.