Building a box for one sub, but eventually for 2.

[Blacksheep Josh]

Subwoofer that's being delivered tomorrow courtesy of credit card reward points:
http://www.crutchfield.com/S-n8sWYeFiuFM/p_2067C12VR4/Kicker-CompVR-07CVR124.html

Box I'm wanting to use for a design:

I'm wondering if I can build the box, install just 1 subwoofer, and then eventually add in the second when I receive it. I believe I can, because the Crutchfield sight states for a sealed box:
sealed box volume: 1.0-4.6 cu. ft.

If I build a 3.0-4.0 box, install one sub, then add another in a few months, it shoudl sound decent, and then good correct? If you have suggestions they are appreciated, but know I am very intent on building the box above except with Kicker on the window, I'm not going to build anything else.

BTW: I realize the circle in the middle is most likely a port, but I won't be using that. Just going with a simple sealed box with a window.

 

[aznboi3644]

those "recommended" enclosure sizes are just random numbers thrown out. If you want to use one now and add one later I would design the enclosure with separate chambers

 

[Blacksheep Josh]

But wouldn't that up the chance for an "echoing" problem?

 

[Blacksheep Josh]

I'm wondering if I can build the entire box... and build almost like a divider that when I install the second subwoofer I just remove it.. almost like those fish dividers for fish tanks... just unscrew it up the back, slide it out the front, and then reinstall the front with the window like I had been talking about.

 

[toypaseo]

I would just build an optimum box for the single sub, and then build one later for the pair.

It has been a long time since I built an enclosure, but back then, I bought bare MDF shelving pieces that had one rounded edge, which was cut off later. I had enough to make a smaller sealed enclosure for a 10" sub, for way under $10.

 

[Fabbed4d88]

Yea, build 2 seperate boxes then connect them at a later date with an amp rack or something......

 

[BigBoom]

if it's any reputable company, than those "recommended" numbers are NOT thrown out. extensive testing is done on each speaker to test the specs like fs, qts, xmax, etc. so they would obviously test output in different types of boxes. i know the companies i've dealt with dont throw numbers out.

being a sealed box it wouldnt hurt to build one big one, then throw in the other sub when you get it. just as long as you seal the open sub hole. besides adding in another sub, the output wont be the same. but as long as both volumes are within specifications you should be ok. any reason why you're going sealed over ported? you'll get more output with a ported box. unless you're looking more for SQ than SPL

 

[Blacksheep Josh]

any reason why you're going sealed over ported? you'll get more output with a ported box. unless you're looking more for SQ than SPL

I'm more concerned with sound quality. I listen to music ranging from a bunch of different rap artists to quick kick drumming metal groups. I was debating about 10" vs. 12" and decided to go with the 12's just to have more Kick. Both CVR's will eventually be powered to the max wiht 400rms watts going to each, so I'm not worried about volume

I've had a bandpass box before and it was just TO loud. I like having bass, but I like the way sealed boxes sound, just clean and efficient. Plus I'm building it myself and it's just easier.

Thanks for the comment about the larger box and sealed sub hole, I was just going to cut out the second hole yet and when I get the second speaker THEN cut it out.

 

[Beastb15]

if it's any reputable company, than those "recommended" numbers are NOT thrown out. extensive testing is done on each speaker to test the specs like fs, qts, xmax, etc. so they would obviously test output in different types of boxes. i know the companies i've dealt with dont throw numbers out.

I was just about to post this.

But ya, those numbers are far from just "thrown out" there. These subs are designed and tested a lot. Those numbers are an acceptable range based on the thiele-small parameters and real-world testing. With a range like 1-4.6 cf, odds are you won't like every enclosure you could possibly make...but if you stray from that range there isn't a very good chance of you liking it.

Now then...

You will be just fine with building a large box for 1 sub and adding another eventually. However, unless you like low/sloppy/boomy bass, you may find your results are undesireable until you add the second sub.

Hope this helps

 

[aznboi3644]

"recommended" enclosure volumes are just basically random numbers...between 1.5-6 cu ft is wayyy too general.

They do not account for what the user wants and the application at hand....I never go by them.

Alpine is a reputable brand yet they have crappy "recommended enclosures"

 

[Blacksheep Josh]

Now this might be a stupid question... but I'm not positive so please bear with me a little bit longer.

Basically, tell me what I need to do:
http://www.crutchfield.com/p_575700S/Rockford-Fosgate-Punch-700S.html?tp=14

That's the amp I have now. Can I hook up each channel to a different voice coil? Unless there's a problem I don't see why I can't... I have a 12" Kicker CVR with Dual Voice Coils, each voice coil being 4ohm.

Can I do this? If not... can I hook up just one of the outputs at a 2OHM load? So I'd have the left side playing but not the right side?

 

[Beastb15]

Now this might be a stupid question... but I'm not positive so please bear with me a little bit longer.

Basically, tell me what I need to do:
http://www.crutchfield.com/p_575700S/Rockford-Fosgate-Punch-700S.html?tp=14

That's the amp I have now. Can I hook up each channel to a different voice coil? Unless there's a problem I don't see why I can't... I have a 12" Kicker CVR with Dual Voice Coils, each voice coil being 4ohm.

Can I do this? If not... can I hook up just one of the outputs at a 2OHM load? So I'd have the left side playing but not the right side?

You would want to wire each sub to separate channels, with the voices wired in parallel.

(2) 4 ohm voice coils wired in parallel will give each channel a 2 ohm load.

EDIT: You can wire it this way whether you have 1 sub or 2 (if thats the question you were trying to ask)

EDIT #2: You will want to follow the following wiring diagram.....

 

[Blacksheep Josh]

I understand all of that...

I ended up talking to someone on Crutchfield's Live Online Tech Support and they answered my question.

I'm wiring one channel, to one voice coil. So both channels will be hooked up to their own voice coil on the same subwoofer. The crutchfield tech support told me it'd be fine. So that's what I'm going to go with. Thanks though

 

[BigBoom]

it's late so maybe i'm not understanding right, but before you asked if you could run one coil. you're still not going to do that right? i know you talked to crutchfield...but the way that last post sounds is each channel will just be wired to one coil. i just wanna make sure...cuz both coils should be wired to one channel

 

[Blacksheep Josh]

That's correct. 1 channel to 1 coil on the subwoofer. They said it'd be fine. Everything is within specs.

 

[Wagonized]

I say you should still go ported. You just build a sealed box and cut an extra round hole and buy a 4" aeroport. Tape it together to the desired length for your tuning, drop it into the box and screw into place...viola ported box. Your results will be far more desireable than a sealed box. You just need to have someone put 10 minutes into designing the ported enclosure so it will sound good while playing all music.

As for putting a window in the box....Id honestly focus more on the audio portion of the box. Getting good results that way rather than making it look good.

But if you insisted on doing a window..i made the one pictured above out of 3/4" plexi which isnt cheap but is damn strong. Then put in a divider in the center to block your other speaker hole and port.

If you were better at building boxes an even better solution would be a 4th order bandpass with the sealed chambers being individually chambered. So you could run one sub in it normally then the only difference when you add the 2nd woofer is the box will be less efficient because the ported chamber is now half the size. But if you were dropping your load on your amp down anyway with the 2nd woofer your additional power would compensate for the loss in efficiency. Then your window would actually show an interesting box inside aswell.

 

[DMacLennan14]

I understand all of that...

I ended up talking to someone on Crutchfield's Live Online Tech Support and they answered my question.

I'm wiring one channel, to one voice coil. So both channels will be hooked up to their own voice coil on the same subwoofer. The crutchfield tech support told me it'd be fine. So that's what I'm going to go with. Thanks though

you are better off bridging the amp and hooking up both coils to one channel. what will happen when you are playing music that is in stereo that is only coming from one channel? the coils will be working against eachother, which isnt the most efficient way for a sub to work. this is what i have learned over the years of doing installations, but if i am wrong, someone feel free to correct me.

 

[sjr033]

you are better off bridging the amp and hooking up both coils to one channel. what will happen when you are playing music that is in stereo that is only coming from one channel? the coils will be working against eachother, which isnt the most efficient way for a sub to work. this is what i have learned over the years of doing installations, but if i am wrong, someone feel free to correct me.

You are right, that the same signal needs to be going to each of the voice coils. This can be done by bridging the amp or spliting a mono signal on the input side of the amp. But yes, make sure that both voice coils get the same signal, not a stereo signal.

If you do bridge the amp with 1 sub, make sure that you wire the voice coils in series. So that you don't over load the amp.

 

[Blacksheep Josh]

That's just it though... if I do bridge the amp so that 2 channels become one channel, such as using a positive from the L side and the negative from the R side, it'll be 700 watts RMS, my amp is an 800 watt max. It's simply to much.

What if I used a splitter then before the amp? Use the Left side RCA signal, split it so the amp receives the same signal for both L and R channels, and wire each channel to it's own voice coil? It'll still be playing the SAME thing on one subwoofer... not working against each other at all...

 

[Blacksheep Josh]

Sorry for the crappy picture.... but this is what I mean... Splitting one RCA channel into two inputs for teh amp, so the amp is getting the same signal, and outputting the same signal in both channels into the voice coils... Make sense?