Hey guys,

I recently got my hand on two subs and an amp. However, I only want to put the one sub in the Matrix, but I am not sure if I can do it with the amp I have. I tried doing research but I don't understand audio all that well, so I hope someone can join in.

Specs on the subwoofer:

Infinity Reference 1230 W

- 12" 4-ohm subwoofer
- Polypropylene cone with rubber surround
- Deep-draw I-beam basket
- 70-ounce magnet structure
- Recommended power range: 50-300 watts RMS (1,200 watts peak power)
- Frequency response: 23-400 Hz
- Sensitivity: 90 dB
- Top mount depth: 6-1/4"
- Sealed box volume: 1.25 cu. ft.
- Ported box volume: 2.00 cu. ft.

Specs on the amp

Memphis PR 1.500

- 500 Watts X 1 RMS @ 1 Ohm
- 300 Watts X 1 RMS @ 2 Ohms
- 150 Watts X 1 RMS 4 Ohms
- 1000 Watts Max Power
- Power Reference PR Series Class D Monoblock Car Amplifier
- Wired bass remote optional
- Bass Boost: 0-18 dB at 45 Hz
- Variable low-pass filter: 50-350 Hz
- Subsonic Filter: 20-50 Hz
- CEA-2006 compliant amplifier
- 1 Pair Preamp Outputs
- Sensitivity: 90 dB
- Frequency response: 10-400 Hz
- Dimensions: 12.6"L x 10"W x 2.3"H

I am overly confused with the RMS and Ohms, as I have no clue how they work. I was hoping someone could clear things up. What I am getting from all this info is that the amp has too much power? for the subwoofer. I plan on putting the subwoofer in a ported box if that helps. Thanks!

Im no expert but I know a little bit about audio and electronics...

A short and simplified answer:

"Ohms" is the speaker internal resistance or "impedance", most speakers are 8 or 4 ohms. Lower
ohms equal more current in the system at equal voltage. Power or watts = volts x current.

To get lower omhs you need to connect multiple speakers together in paralelle. If you connect
2 x 4ohms speakers together in paralelle, you get 2 ohms (the amp "sees" 2 ohms) and more
amps are "sucked" from the amplifier thus more power!

http://www.harmony-central.com/articles/ti...aker_impedance/

RMS watts or RMS power is the average power the amp is designed to drive. The Peak watts
is for brief spikes in music power witch is not a good way to rate an amplifier or a speaker.

So your subs ar 4 omhs and capable of 300W RMS each (600W total), your amp can output 300W RMS in 2ohms.
(2 subs connected in paralelle) You are good, your amp won't damage your speaker, the amp will clip
before your speakers reach there electrical or mecanical limits!

As for the box, a sealed box is more compact, can handle more power and has a flatter response curve
(low notes have relatively the same volume) and is more "universal".

A ported box, has lower frequency "boost" from the port but must be matched with the speeker (box
size and port tuning frequency) to sound very good. With a universal ported box it's pretty hit and miss!
It may sound ok or it may sound boomy (some frequency are alot louder than others).

If you listen to hip hop or techno music, a ported box will shake the car from low frequency. If you
prefer rock or punk, a sealed box will have a better and cleaner punch to it!

2 x 12" subs in a ported box is going to be pretty big (4 cu ft plus the bracing, basket and port volume...)
do you really need that power and that big of a box in the trunk? 2 x 12" in a sealed box would be
better I think, half the size, powerfull and good quality bass!

that should work for you... that amp may SLIGHTLY over power the sub but it will work fine

Thanks for the fast response! I was hoping to only run a single sub, not both. I was just going to keep the other sub for my girlfriends Civic when we have the extra cash. That's why I was worried about the amp being too powerful for just the one sub. This amp was running both subs in a ported box for about 3 years, and my brother just gave them to me. With both subs in a ported box, it is wayyyyy to big for my little hatch haha.

I had two 10' subs in a ported box in the Matrix a while back, but it didn't sound good at all. Hopefully the 12' single sub set-up will sound better. I was going to go ported because I listen to music with a lot of bass (rap), but if a sealed box will still give out a decent amount of boom I am definitely willing to go that route, especially if it saves me space. So if my amp is capable of putting out 500 RMS @ 1ohm, then with one of my subs having 4 ohms and capable of handling 300 RMS, does that mean everything will be golden for a single sub with this amp??

And also, I am trying to figure out what wires I need (gauge and brand), what would you suggest?

Oops didnt see this response. So if my amp is slightly over powering the sub, what precautions should I take when playing loud music?

dont play it TOO loud... the amp has a saftey feature which will turn off the amp when it peaks out... if u ever have the music cut out at lets say vol. 25 then dont play it near that lol i know my amps cut out at 30/50 i usually only play it at max 25... and when im just enjoyin the music i play it at like 5... anything over 10 gets ridiculous with hair vibrating and stuff lol

btw it also depends on the song when your amp cuts out.... which size wiring are u planing on using?

OVER-power? I don't know how you came to that conclusion with those specs, but it is most definitely powering a single sub at half of its potential.
You want to compare the RMS wattage at a specific impedance (ohms) as that is the continuous power that can be accurately measured and compared, whereas the maximum wattage is inconsistent between manufactures and is sometimes made up. From the specs you show, the sub is a single voice coil that is @ 4 ohms, and it can handle from 50-300 watts RMS. And that amp shows that it gives out 150 watts RMS @ 4 ohms. I typically don't recommend powering a sub lower that 2/3 it's potential. I mean it will work, but I believe that it better to have the maximum potential and lower the output if you don't want all of it than to not have the output you want and try to crank it up to try to get the output you want. And cranking up the amp has its own set of problems.
Long story short, it should work with no problems, except for possible installer/user errors.

^2 ur right lol i mis-read the specs and mixed the peak values with the rms values...

Thanks for the help guys. Like I said, I don't know much about RMS and Ohms and all that stuff. So I'm getting that I should be fine with this set up. If not don't crank it up! As for wiring, what do you guys recommend? I am not sure what to get as in gauge and brand. Same with the sub box, does it matter what brand it is?

i like my wiring to be by stinger... for your setup i think 4ga. should be sufficient... but get a whole wiring kit that includes an inline fuse and everything... as for the sub box get something that is close or exact to the spec's of that sub... the correct amount of cubic volume of air will result in the optimum sound... if your going to go buy a pre-made box i'd recommend BassWorks

I was planning to get the whole amp wiring kit, which includes the fuse and everything. Is there a spacific site or something I can order it from for a good price? eBay? Crutchfield?

And that's perfect, so far every sub set-up has been in a bassworx box, and I was planning on getting one, but wanted to hear some suggestions. Thanks!

If you wire the system yourself, don't forget to run the power and remote wire on one side of the car, under
the plastic cover on the floor, and the RCA signal wires on the other side to avoid interference between
power and signal.

Yeah I have read up on that. I didn't do that on my other car. Definitely will this time. Also, another problem I had when I installed the system was the corrosion I kept getting on the positive battery terminal. I was wondering if there was something I could do to prevent that?

for the wiring kit i'd say a local car audio store... or if worse comes to worst go to future shop or best buy

Thanks for all the help guys. I think I know what I am going to get. future shop can give me a deal right now if I buy both the box and the amp wiring kit from them, which is a Bassworx sealed box and Stinger 4ga wiring kit. However, reading up on some specs, the box is only 1 cu. ft. where my sub calls for 1.25 cu. ft.

Do you guys think this box will still be okay? It is the Bassworx CS12 box, and I like it because it is compact and has a nice look to it, and it is not all that expensive. I am going to look for better prices at other stores, but they are willing to give me 50% off of the amp wiring kit if I buy both at the same time.

It should be fine, but does the speakers ask for 1.25 cubit feet on a ported or a sealed box? If you wanted to you can just put some polyfill into the box. Polyfill will make a subwoofer perform as if it were in a larger enclosure by slowing sound waves as they pass through the polyfill. The physical internal volume of the subwoofer box remains the same, yet the effective internal volume changes when polyfill is added.

1cu ft box is ok for a 10" sub, too small for a 12"...! If you do it you will loose some low frequencies,
Get a 1.25 to 1.5 cu ft box or a 2 cu ft ported box with the recommended tuned port size and lenght
matching your sub specs...

Sometimes, the 1 cu ft box are not really 1 cu ft... you have to substract the volume of the woofer basket
(part inside the box) to get the "real" volume.

That's what I was reading online. Can you buy the polyfill from any audio store? How much should I put in?




Ah there is no way? The Future Shop here is very limited to the boxes they have and can get, and there is nothing for car audio in North Bay I thought that you had some leeway from the factory specs on the sub, but I guess I didn't think of variation in the real volume of the box. I was going to go ported but I don't need anything crazy loud, just something with more bump then I have now, plus when I had my two 10' subs in a ported box, I had almost no trunk space left!

You can get the same polyfill from a fabric store. It would be cheaper even though its the same kind of stuff. You shouldn't need too much, but from what I understand, for 1 cu/ft 1 lb of polyfil should increase the effective volume by 1/3. I would avoid fiberglass based polfil since it's messy to work with.

It really all depends on the manufactures specifications on what would the best volume would be to use with that particular sub. You really cannot generalize volume to the diameter of the sub, because different subs have different displacement and excursion.

Thanks everyone for the help! Sorry to be such a pain, I am still learning! I will probably have all the material needed but the latest Wednesday next week, so when there is a mild enough day out I will be outside installing everything. I will take some pictures and maybe even a video!

For his Infinity 12" sub the specified sealed enclosure volume is 1.25 cu ft.... (of free air volume)

Don't go lower!!! 1.25 is already pretty small for a sub enclosure...

Ahh!! I don't know what to do now! It seems like Bassworx doesn't have too much more for a sealed 12' enclosure unless you pay out of the butt. What other brands of boxes are good? perhaps maybe one I can order online that is not too expensive? Here in the North Bay and Sudbury area there is not too many audio stores.

Build your own!


Look here for some tips:

http://mobile.jlaudio.com/support_pages.php?page_id=164

If you dont have lots of tools, you can get the wood (3/4" MDF) cut at your
local hardware store, they have very good and precise table saws.

It's a cool little project to do, and you learn more about sub enclosure
at the same time!

Defiantly wish I could! I have no power tools/supplies/experience, and I live in a basement apartment for school! However, I am willing to pay someone to build me one! as long as its good quality and not a ridicules price, and you don't live too far!

Like I said, get the wood cut at your hardware store....

You need a drill, a jig saw, wood glue, screws.

Wait... you have a 09 Matrix XR, two 12" sub, an amp but dont have
tools...!!!

Haha yeah. Well I have basic socket sets but nothing more. I also don't have experience with building boxes. And I got the subs, boxes, and amp off my brother! School is too expensive too or else I would have more power tools

Actually reading up on building the box, it doesn't seem all that bad. Have you had experience with building your own box?

If you are wanting a box inexpensive that will do fine for that woofer and still thump look at this.

http://www.parts-express.com/pe/showdetl.c...tnumber=260-630

The port would be tuned to 50Hz and will give you a lot more spl out than for a 2ft^3 box.

Also, if you want to custom build a box that fits the back angle of the seat the would be cut at a 21 deg angle.

Yes, I built 3 subwoofer enclosure so far. I dont have one in the trix yet... The last one I built was for a 10" Orion XTR10
Subwoofer. It was a ported 1.25 cu ft box if I remember well, it was very similar to the one on the link in the previous
post... (rectangular port) I built the box very carefully with advice found on th JL Audio web site. It sounded very
good, I sold the kit with my last car...

Building a simple rectangular sealed (no ports) enclosure is pretty easy...

Thanks! I was looking at that site, the only thing I am worried about is hidden shipping costs to Canada. Have you had experience with shipping to Canada? because that is a good price for sure!



Thanks! I was actually wondering what the angle was if I do decide to build my own box.






Wow that's sweet. How long does it take on average? Would I be able to do it in one weekend with the proper tools? My grandfather has a bunch of wood tools I can use, but because of school I would would only be able to do it on weekends. I would definitely go with a sealed box, especially for my first box!

If you have the tool it shouldn't take more than a couple of hours.

its fine. run it. the speaker will get 150W @ 4ohm.

Well the March break is approaching, and I decided to build the box! I used this site to calculate measurements http://www.the12volt.com/caraudio/boxcalcs.asp , and I found the following:

Width: 15inches
Height: 14inches
Depth: 15inches
Thickness: 3/4 inches (I ASSUME this is the standard)
Total interior volume: 1.31836

Would this be okay? Now I do want to make the back of the box the same angle of my back seat, but I am not sure how to mess with the measurements to do that. Would someone be able to help me out?

sure. i'll help you out.

final interior volume will be 1.31836 <-- Please confirm this is the final volume you want. Once i make the box you wont be able to change it.

the backplane of the backseat is angled at 16 degrees, i just checked it.

what's the diameter of the cutout. can you post a link the woofer(s) you're gonna use? i dont want to miss anything.

also, you want to use banana connector terminal cups or just regular crappy push-in ones. if you're gonna run 2 speakers how are you gonna wire them, where do you want the cup(s) on the side(s) or the back?

Hey thanks for helping me out, I really appreciate it. Here is the link for my sub:
http://www.crutchfield.com/S-77J2BbNMO3d/p...ence-1230w.html

I just want to use one, and the sub calls for 1.25cu. ft. in a sealed box. I'm not sure how to get that measurement exactly. It doesn't matter to me where I put the terminals, I just want them on the back. I will probably be putting the amp on the top of the box if that helps. The angle of the 2009 Matrix back seat is 16 degrees? this is where I have no clue how to make those measurements. Thanks a lot!!

note: 16deg off vertical, not off the trunk floor.

MATERIAL THICKNESS:0.750" (19mm) thick MDF.
WIDTH: 16.000"
HEIGHT: 14.000"
DEPTH (bottom of box): 15.500"
DEPTH (top of box): 11.486"
INTERNAL VOL.: 1.254753CU FT.

You can give this to a box builder and he will know what to do.

Thanks! so with this angle, would I be able to put the sub box up against the back seat and it will sit flush? I will be building the box, I just wasn't sure how to get the volume correct. So I should be able to get the MDF wood at the local Home Hardware in that thinness? And I am guessing the hole for the sub is smaller than 12' so you can properly mount it?

-yes you can put it against the backseat. it will be hellaflush.
-yes, there are different grades of MDF but in this case it dont matter just get the stuff at the depot.
-the hole for the sub is based on the instruction manual for the sub you posted a link to.

I'm sorry to say do you know anything about car stereos you never put a woofer against a back seat without any room for movement. Even freeair/infinite baffles require movement for the speaker to move. If you restrict the movement of the woofer you will cause damn to the woofer.

Recommendation for this woofer if to rear fire the woofer toward the back hatch do to the time delay in the box delay.

You can do either design but I recommend that if this is your first time building a speaker box to do a simple one. For more loadness on the deeper notes you can port it.

Perfect, thanks a lot! I will be taking pictures during the whole process to show you exactly how I have done it.



I'm not sure exactly what you are trying to say, but what I am getting out of it was that you think I want to point my sub towards the rear of the seat, but that is NOT what I want to do. I want the BACK of the sub box to sit flush against the back of the seat, with the sub itself pointing towards the rear hatch.

Please, id love to see that.


just ignore that guy's post. he did not read the thread, did not express himself clearly, did not interpret my drawing correctly and the 'sub box' he posted does not add up to 1.25 cu ft. interior volume. do your thing, you're pretty much set up to go. If you need any specific measurements for the box let me know and i will break it out into parts to help you get it squared away.

Usually with class D amps and for Subs, that doesnt really wont make that big a difference. The only time that really starts to matter is when you run A/B amps and are powering door speakers or tweeters. Due to that fact that your playing vocals and things on the higher end of the noise spectrum. Just my 2cents

Well I have all of the material, so I should be starting the build tomorrow! One problem though, the terminal cup I ended up buying I'm not too happy with now. It is the spring loaded press and release ones. It just seems really cheap to me and a bad connector piece. So with that said, would it be terrible to just drill a small hole and run the wires from the sub to the amp like that? Obviously i would load it with silicon to make sure it is air tight, I just haven't seen anyone do it this way before. I am not too concerned about the looks of it because it will be out the back of the box which will be against the seat.

Also, if it is okay to run the wires like that, would it be a bad idea to run them out the top of the sub box? I want to do this because I am more than likely mounting my amp on-top of the box, so this way it will be a shorter distance to run the wire on the outside of the box.

Thanks!

So long as you seal it well you should be ok to run your wire through the box itself. It's not as convenient if for some reason you have to remove the box.
I usually don't recommend mounting the amp to the box, because all the vibrations directly from the subs movements have the ability to break the solder joints of the components on the circuit boards within the amp. Some members (including myself) have mounted their amps underneath the front seats. There are others who have mounted their amps within the spare tire compartment. It also go in line of convenience if you have to move the box, and makes for a cleaner and more reliable install mounting the amps in a stationary position off of the box. I would only mount an amp on the box if no other viable option was available.