competition box

I'm currently trying to build a competition box for a friend of mine. The only material that I have available to build the box is plywood. I have already assembled the box and everything. The sound that is coming out does not sound as good as it did when each 12" was in it's own speaker box. I still have to seal the inside of the box and everything, could this be why it does not sound the way it is supposed to? Also does anyone no of a place where I can find competition box plans? I'm not even sure if it is a competition box.

I just found out that to build a box to sound correct, I have to have the proper measurements and such. I thought that I could just cut pieces and make everything flush and stuff. Does anyone know where I could find the calculation to build this box?

robertn361 wrote:

---

I just found out that to build a box to sound correct, I have to have the proper measurements and such. I thought that I could just cut pieces and make everything flush and stuff. Does anyone know where I could find the calculation to build this box?

---

What subs are you making an enclosure for? So you are trying to make the enclosure for competitions or for a daily driver? There is a big difference in the design and overall sound of the enclosure.

Plywood is not going to be the best material to use. If you want to make a really good enclosure get yourself some 3/4" MDF. It is fairly cheap at around $20-25 for a 4'x8' sheet. It will sound much better then an enclosure made out of plywood will.

whiterob wrote:

---

What subs are you making an enclosure for? So you are trying to make the enclosure for competitions or for a daily driver? There is a big difference in the design and overall sound of the enclosure.

Plywood is not going to be the best material to use. If you want to make a really good enclosure get yourself some 3/4" MDF. It is fairly cheap at around $20-25 for a 4'x8' sheet. It will sound much better then an enclosure made out of plywood will.

---

It will be for a daily driver. I have been told that this type of box is a competition box. It is for 2 12" subs they are two different brands, which I told him it's better to have the same brand of speakers. He has already purchased the plywood, I'm not sure if he would want to go buy MDF.

speaker enclosure design is just not cut/build to fit...it is a science

robertn361 wrote:

---

It will be for a daily driver. I have been told that this type of box is a competition box. It is for 2 12" subs they are two different brands, which I told him it's better to have the same brand of speakers. He has already purchased the plywood, I'm not sure if he would want to go buy MDF.

---

There isn't really anything different about an enclosure made for competition and a regular enclosure. The design is different but basically I'm trying to say that there isn't a certain type of enclosure that is made for competition. When you say you want plans for a competition box there isn't really anything we can give you.

The only difference between an enclosure used in competition and one used for a daily driver is the design of the enclosure. A daily driver will be designed to sound good at a wide range of frequencies. A competition enclosure will likely be made to be very efficient in a small range of frequencies. This will allow you to have a very loud sound in that small range of frequencies. This sound will almost always be bad for regular music. It will be made only to play tones.

There are many things that are not ideal for your friends setup. First, it sounds like your enclosure is just cut and put together without much or any thought of design around the subwoofers you have. Like aznboi said, enclosure building is a science, not something you just put together and expect to sound good.

One more thing your friend has going against him is the fact he is using two seperate subs. This is almost always going to give you bad sound. While it can be loud it will not usually sound good.

The last thing is that you used plywood in the construction. Plywood is not an ideal material by any means. It will greatly reduce the output of your subs and can give you a wierd sound at times. You want an enclosure that doesn't flex and is audibly neutral.


If you want to do this system right there are a couple of suggestions I have. First, only use one sub. You will gain a lot of clarity in your system and could even have a louder system. Having two subs is a 6 db increase at the most (if you double the cone area you gain 3db and if you double the power of your system you gain 3db). So you are not going to hardly notice having one sub over two. One sub in a proper system will sound better/be louder then two subs in an inproper system.

Second, design the enclosure around the specific subwoofer you have. Each sub is going to need a different enclosure. You need to have your enclosure designed to fit your sub in order to reach the optimal performance.

Lastly, tell your friend to buy 3/4" MDF and read the sticky for how to build a proper enclosure. If your friend doesn't want to do this then that is his choice. If you wants a good system and one that will actually sound good then this is what needs to be done.

if he wants things done properly, then he should go and buy the MDF, but its also heavy as hell, im a big guy and i can just barely lug a sheet of this stuff around.

I dont think your box is a "competition" box at all, its just a dual speaker box, probably isobaric loading. I could be wrong, but i dont think there any kind of specific competition boxes.

and as mentioned above, if you want the good sound, then you will build the box properly.

Check the specs on the speakers, it should provide the T/S params. you can use those to design the box and the kind of sound it will produce.

there are a few programs, bassbox pro is nice, winISD also is decent, but isnt my prefered program.

sounds like your "competition box" is a big sealed enclosure...no where near a high output enclosure

-------------
Custom Enclosure Design

aznboi3644 wrote:

---

sounds like your "competition box" is a big sealed enclosure...no where near a high output enclosure

---

Yea after researching and the response from everyone on this forum, I have found out that the guy that told me that the box design was a competition box actually had no idea wth he was talking about. I have one more question:

I had purchased two 12s (600w each) in a box, with a fiberglass front. The box also has 4 holes(ports I'm assuming) I also bought an amp which was a 1000w, I know this is not enough to push the 2 12s to their full capacity. When I first installed the system it sounds great, then one of my friends that works at a audio place said that it didn't sound right. He messed with the amp for a little while and now the system sounds like crap. I have tried the settings on the amp and everything, I just cannot get it to sound the same as it used to. Any ideas on what I can do to fix it or to what he did?
If I need to I will take and post a pic of the box. Thanks for all your help.

this would all work a lot better if we knew what you are working with

-------------
Custom Enclosure Design

Here is the pic that I took recently you can see the four holes on the top of the speaker box, barely but still visible:

thats a ported bandpass box, seemingly dual chamber.

i cant remember, but i THINK its a 2nd order BP box.

as for the amp not driving the 2 subs, that depends on what the subs wattage is. if they are 500W each, then the 1000W amp would drive them just fine.

When you say the system sounds like crap after your friend messed with it, what has changed. Why exactly does it sound like crap now that it didnt before?

Is that a Burger King kid's meal you're sporting there on the shelf?

-------------
VEHICLE: 2002 GMC Sonoma ZR2
Alpine CDA-7940
AudioControl EQT x2
JL Audio 1000/1
JL Audio 10W6 (originals) x3
Kicker ZR120
Kicker ZR460
Polk GXR-6 x4
Polk GXR-4 x2

bigjohnny wrote:

---

thats a ported bandpass box, seemingly dual chamber.

i cant remember, but i THINK its a 2nd order BP box.

as for the amp not driving the 2 subs, that depends on what the subs wattage is. if they are 500W each, then the 1000W amp would drive them just fine.

When you say the system sounds like crap after your friend messed with it, what has changed. Why exactly does it sound like crap now that it didnt before?

---

The subs are 600w each. When I first installed the system the bass and everything sounded good. My friends would tell me that they could hear me a block away. Now you can barely hear the bass or anything unless you are inside the car. The sound seems to be distorted.

Paradigm wrote:

---

Is that a Burger King kid's meal you're sporting there on the shelf?

---

LOL no it's McDonald's I had just picked up McDonald's for my daughters.

you shouldnt have any problems with that amp and those subs (except that they arent the same brand/type)

All you need to do is make sure that you set it up such that when its loud the amp isnt clipping.

the heat caused by distortion will fry a voice coil.

read the sticky for setting your gains and try doing that, it might get your sound back.

bigjohnny wrote:

---

thats a ported bandpass box, seemingly dual chamber.

i cant remember, but i THINK its a 2nd order BP box.

as for the amp not driving the 2 subs, that depends on what the subs wattage is. if they are 500W each, then the 1000W amp would drive them just fine.

When you say the system sounds like crap after your friend messed with it, what has changed. Why exactly does it sound like crap now that it didnt before?

---

Only other way a bandpass wouldn't be ported is if you used a passive radiator.

Also that is a 4th order bandpass...not really "seemingly dual chamber"...a 4th order bandpass must have atleast two chambers.

I guarantee that bandpass sounded like crap as all prefab bandpasses sound like crap.

I'm sure I could get louder and sound better with a single woofer and half the power than that POS bandpass.

Those subs are not 600 watts either.

They look like 12s...good place to start for a loud ported enclosure for them is 2-2.5 cubes each net tuned to however you like your response

-------------
Custom Enclosure Design

aznboi3644 wrote:

---

Only other way a bandpass wouldn't be ported is if you used a passive radiator.

Also that is a 4th order bandpass...not really "seemingly dual chamber"...a 4th order bandpass must have atleast two chambers.

I guarantee that bandpass sounded like crap as all prefab bandpasses sound like crap.

I'm sure I could get louder and sound better with a single woofer and half the power than that POS bandpass.

Those subs are not 600 watts either.

They look like 12s...good place to start for a loud ported enclosure for them is 2-2.5 cubes each net tuned to however you like your response

---

Yes they are 600w each I'm looking at them right now. And yes it is 2 chamber. So how would I make them sound like they use to sound before my friend messed with them? They used to produce clear sound with lots of bass now they do not...

Unhook one of the woofers and see if it makes bass with only one speaker connected.

i am an idiot wrote:

---

Unhook one of the woofers and see if it makes bass with only one speaker connected.

---

It does but it still does not produce a lot of bass like some that i have heard that are of smaller wattage. When I was messing with my amp I disconnected one of the RCA wires from the amp and the sound sounded better than it did with both of them in. Any ideas as to why?

robertn361 wrote:

---

aznboi3644 wrote:

---

Only other way a bandpass wouldn't be ported is if you used a passive radiator.

Also that is a 4th order bandpass...not really "seemingly dual chamber"...a 4th order bandpass must have atleast two chambers.

I guarantee that bandpass sounded like crap as all prefab bandpasses sound like crap.

I'm sure I could get louder and sound better with a single woofer and half the power than that POS bandpass.

Those subs are not 600 watts either.

They look like 12s...good place to start for a loud ported enclosure for them is 2-2.5 cubes each net tuned to however you like your response

---

Yes they are 600w each I'm looking at them right now. And yes it is 2 chamber. So how would I make them sound like they use to sound before my friend messed with them? They used to produce clear sound with lots of bass now they do not...

---

do you believe everything you read??

Those subwoofers would smoke in seconds with a real 600 watts to each of them...any sub that comes in a prefab bandpass is very poor quality...I'd say those subs are 150 watts each.

Also sounds like one was out of phase if you disconnected one of the rcas

-------------
Custom Enclosure Design

aznboi3644 wrote:

---

do you believe everything you read??

Those subwoofers would smoke in seconds with a real 600 watts to each of them...any sub that comes in a prefab bandpass is very poor quality...I'd say those subs are 150 watts each.

Also sounds like one was out of phase if you disconnected one of the rcas

---

Why would they smoke and why would the manufacturer of them put 600w on them and on the package along with the papers for them?

Also how would it get out of phase and is there a way to fix it?

Manufactures overinflate the ratings so people think the more watts the better...and clearly it worked on you. You fell for the big numbers. It's advertising...why else do you think you can buy a "1000 watt" amp for 100 dollars from a cheap flea market company while a real 100-200 amp costs the same???

The subwoofers cannot handle 600 watts....nowhere close. 150 watts at most I'd say.

Phase check the subwoofers with any dc battery...9 volt, car battery....doesn't matter. If both subs move in the same direction than they are in phase with each other...if one moves in and one moves out than you need to rewire either one back in phase with the other.

-------------
Custom Enclosure Design

I remember back in the day when I used to oooh and aaah over Bandpass boxes, like the Qlogics they had setup at bestbuy. I listen to those now and think "why would i want that noise in my car?" I've never heard a properly built bandpass so I dont know what theyre supposed to sound like, but every one I've heard now sounds horrible to me, loud yes, boomy annoying bass, yes, good clean punchy bass, no way.