I plan on upgrading the box that are on may subs now, to my own custom design. I have a few questions about it.

1) Do I have to have two chanbers for my subs? One for each sub? Would that sound better then just one chanber for both subs?

2) What materials make the best box, for sound quality?

--The subs are 2 12' Kicker CompVR's

------------------
91 RS Camaro
3.1L
Cat Back System, K&N filter,modified air box, Fastchip Stage 2, 160 thermo, Rapidfires and Bosch Wires 5 Air Horns
Stereo: Clarion Deck, 2 12' Kicker CompVR's, IX702

ICQ: 65384740

My Car ( no stereo pics yet)

 

If you use two chambers, you get a more tight, punchy bass. If you combine the chambers into one, then your bass gets boomier. The larger, one chamber box, acts like it has a bigger speaker, because of the fact that you have two whatever, (10s,12s) pushing into the same area.

If you are modifying an original box, and it was made with quality materials, use MDF. (Medium Density Fiberboard) If it was a cheaper box, just use particle board. Particle board is alot cheaper.

No matter what you use, make sure that you buid it to specs. Build it to the right air space that the speaker needs. If you don't, then it won't sound good what so ever.

------------------
'82 Firebird, dead stock, 9 bolt disc rear, over 200,000 miles and still going strong, more to come...
http://www.spinfrenzy.com/stingerssx...easures.html#4

 

I'm almost afraid to do it, but I'm disagreeing with Stinger. Whether or not you use a common chamber makes absolutely no difference as long as airspace stays consistant. If the subs need 1 cubic foot per sub, then whether you use 2 one-foot chambers or a single 2 cubic foot chamber will not differ. The only interraction that the sub has with the enclosure is the pressure created by the sealed airspace. If you have 1 sub in one chamber, you get X amount of pressure behind the sub. If you double the airspace, and double the piston area (the speaker), you still get X amount of pressure. I generally build my boxes with separate chambers for the sake of rigidity and just incase somebody decides to run their subs in stereo instead of mono.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

 

Now jim, are we going to start this again?


What I was saying is that comparing a single sub, in an enclosure, to two subs, in a single enclosure, acts like one larger speaker. Because of the fact that there is more cone area being driven into the airspace. When using two seperate enclosures, you are just haveing two subs, in two boxes. I'm not saying that one way is louder, just one hits harder, and the other booms more. I've experimented with this many times.

 

The box that I am going to make will be a brand new one. The one I have now was custom made, but for ****s and giggles I want to make my own.

How thick should the MDF/particle board be?

 

do a single box with a divider in the middle.

stinger and jim, lets all be friends...

and the reason i say use the divider is just incase. if stinger is right (not saying he is or isn't) than that extra boom may annoy you. a kick drum should sound like a kick not a boom. and but one thing that i can vouch for is to use the correct space. some subs it isnt too critical, but just incase you buy a sub that is, you want it to be right the first time.

only use MDF. my experience with particle board is you get a "tinny" sound because it dosent flex enough. the box actually has to compress and expand with the soundwave to get correct sound.

what else it there?

[edit]
I remeber what else there was. you can also use Fiberglass. its a pain in the **** to lay the cloth, (done it on my vette) but you can go way more custom. is harder to shape a piece of wood and keep it rigid than fiberglass. it can be done, but it wont come out as good as the fiberglass.

and a question for everyone... everyone bltches about how much boxes weigh... so has anyone tried making a box out of carbon fiber? it seems like a good idea to me, but i havent really worked with it.
------------------
1985 WS6 Trans AM
T-tops
bone stock sloth of an engine LG4
T-5 tranny. thank god, i couldnt stand an LG4 auto.
Plans for an LT-1 or LT-4,
dual flowmaster exaust,
& a pounding stereo.
mods right now include a radar detector.

[This message has been edited by 85ws6TA (edited February 25, 2001).]

 

Not to drag this one out, but there is a down side to using a single large chamber...we all know that you wouldn't even think of running subs in stereo, but even in mono the two subs can work against each other if they are in the same airspace.

Not every sub is 100% the same. Even the same model of the same brand is going to be different from speaker to speaker. If you don't believe me, take your trusty Ohm meter and play around with how the resistance varies from one to the next when you start moving around the cone. Now if you get two speakers that don't move exactly 100% the same when given a signal, you will effectively be loosing output due to the speakers working aginst each other.

You will see what I mean if you take two subs in the same enclosure and push in on one...the other will move out. What you are seeing is wasted energy and efficency if one moves slightly faster than the other when you apply signal.

Now whether or not there is an audible difference...each person may have opinions one way or the other. Depends on too many other factors regarding the design of the box. I personally prefer divided, but that's because I would like to eliminate any potential problems before they even begin.

L8rs

Carl
CarAudio Resources
http://www.caraudioresources.net

 

Forgot to reply to the second part of the question...

As far as material. The popular choice is either 1/2" or 3/4" MDF depending on the enclosure size. Alternatives would be fiberglass or marine grade birch (pricey) or a host of other exotic woods. Look at what some of the high end home speaker manufacturers use. Anything goes really. Though I wouldn't use plywood or particle board. Each has it's own host of problems.

By far MDF is the material of choice though.

Carl

 

I have noticed more distortion in a single enclosure, and I would perfer two seperate enclosures. Even when ported, the woofers work against each other. That's what helps give the boomier sound. But 85ws6ta, jim and I like to bug each other. Although our opinions differ on ocasion, we still both own third-gens, so we're all family. I guess we're like brothers or something. Anyway, you're right about the kick drum. We are all trying to create an acurate sound right? Some "ricers" want to rumble everything in site, although it sounds better, and cleaner if you've got more of a punching sound.

 

Hrmm, I didnt' even notice the comment about the box "flexing" to get correct sound. I'm gonna have to disagree here.

I have not been able to stress enough how important bracing is to prevent a box from flexing. When an enclosure flexes you are loosing output and affecting the sound of the system. A quality enclosure should have ZERO flex in the box.

Unfortunately I don't have much time to get into deep explinations now, but drop over to CarSound.com and ask Matt in the install forum. I'm sure he's got more than enough ammo to explain all this.

Carl

[This message has been edited by GndPrx (edited February 26, 2001).]

 

Thanks for all the info, by the way I took some new pics of the car along w/ the stereo, should be on here in a week!

 

Personally, I prefer a divided box. That way if for some reason one of your subs gets messed up, you still have the right airspace for your good woofer. If one sub stops working, you end up with one sub operating in an enclosure twice as large as it was designed for.

------------------
82 Camaro:
350, Erson cam, ported heads, Crane Hi-6 ignition, Accel supercoil, Comp Cams 1.6:1 rocker arms, Turbo 350 tranny with 2500 stall.

 

well i dont have a degree in box making and im defineatly not a pro, but i have read in many places that in a sealed enclosure, the box must flex somewhat or it will #1 not sound as good, and #2 Blow up after a couple years. thats way too much stress to try and put on glue, liquid nails, or screws. but.... in a ported design, Zero flex is better because it will then push more air out of the port blah blah more SPL. but like i say, this is out of stuff ive read, and some areshole could have been stating his opinion as a fact. makes sense to me tho

------------------
1985 WS6 Trans AM
T-tops
bone stock sloth of an engine LG4
T-5 tranny. thank god, i couldnt stand an LG4 auto.
Plans for an LT-1 or LT-4,
dual flowmaster exaust,
& a pounding stereo.
mods right now include a radar detector.

 

You absolutely, under NO conditions want a box that flexes. You want a box that's as rigid as possible. A weak box that flexes is going to substantially reduce your SPL and is going to cause a huge reduction in sound quality and could cause damage to your subs. A 3/4" MDF box that's glued and screwed every 3" will NEVER split or come apart if it's built properly.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

 

A sub is generally not going to generate more than about 5psi at max inside the box and even at that, only during full excursion.

Let's use this as an example. Take a 10" sub with an average of 80sq in of cone area. 80sq in x 5psi = 400lbs of force. (thanks to MPipes from the Carsound.com forums for this example) How many subs do you know of that have a cone that can withstand 400lbs of force on it?

If a box can not stand up to 5psi, then something is wrong with the construction. A good quality wood glue on MDF with straight cuts and good joints will hold up to about anything you can give it. Most of the time the wood will break before the glue gives way. Screws are used mainly as a means of clamping the wood together until it drys.

Flexing takes away from the output of the speaker as Jim stated.

Carl