I've had a lot of different stereo setups in a lot of different cars... but I've never had just one sub in my setup. People tell me all the time that a single sub can sound as good as two, but it doesn't seem possible to me. If you were going to set up a single sub system would you stick with a 12" or would you go to a bigger one like a 15? I'm going to be driving this off of a Alpine MRV-F450 amp that runs 4 ohms on the sub channel and is not stable at 2... so I need a single voice coil 4 ohm.

Also... I'm more concerned about quality of sound, not so much on decibels.

 

There are rules of thumb about this. I believe it is double the subs you get an increase of 6db. If you double the power you increase output by 6db. This is with the same speaker. You can also port your speaker to increase output by about 6db.

The options are limitless... the size speaker will change its frequency response, but the enclosure is most important for determining that.

Most high quality speakers are dual ohm voice coils now.

This is all FYI, doesn't really answer your question because you need to give specifics about if you want SQ, one loud frequency, what enclosure you want etc etc.

Brian

 

Sound quality > all

 

dude i have one jl audio 12 it rocks, i had 2 in there but i neede a lil trunk space, i like the one better. get a good set of components to put up front and in the back, it will rock. the box that hides in the back, subthump, is perfect for the jl u wont be dissapointed. its all i needed but then agian im not entering any contests for my sound equipment. or if you have to have more speakers u can make 8's fit in the back and have you 12 in the trunk, its all about sound quality and clearity to me. and u have to find the right box size and power u put to the speaker.

 

Why would you run a sub with a 4ch amp? Sell the amp, and get one that is stable so you can run a dvc sub. You are limiting yourself so much by going this route. As for a good SQ sub -> IDQ, Oz matrix elite, JL w6v2, eD Ov2 just to name a few. Many people out there say the bigger the better, but I feel that a 15" takes up way too much room.

And just to clarify, if you double the power, you will see an increase of 3dbs, not six.

edit: here is a great amp stable to 1ohm for $159 http://www.ikesound.com/product-product_id/2307

 

It is a 5 channel amp, 50x4 and 200x1 for subs. I have it already and am not getting another amp. Not trying to be rude, and thanks for the suggestion.

 

Run a single JL12W7 and use a JL Audio 500/1 to power it. It won't take up too much space and it will sound awesome and have damn good output. (I have a new one of each for sale if you're interested pm me.)

 

Just to clear things up I am debating what to do still. I do not want another amplifier. I'm debating getting ONE sub @ 4ohms and run it by itself, or use the PAIR of Fosgate HX2 subs that I currently own with them wired up to make a 4 ohm load. I have taken out the back seats and am prepared to build a box with a friend that worked with fiberglass for years. This is the recommended ported box from the user manual for each sub.



From this pic it has a range all the way up to 4.0 cu ft for the box. What would a box this big do different from the 2.0 cu ft? Sorry for the noobish questions... my experience in these things is limited.

 

This was taken from another site:

The box size requirement is dependant upon many factors, including the subwoofers suspension, motor strength, cone mass, size, as well as many other factors. A sealed box is simply a specific mass of air that reinforces the subwoofers suspension, a more efficient sub, like those designed for ported boxes, will have low mass cones, a loose suspension, or a very strong motor. These subwoofers will work well in a smaller sealed box. Subwoofers with a tight suspension, weaker motor, or heavier cone need a larger suspension to take advantage of it. If you go too large, you'll end up with good transient response and bandwidth, but you lose mechanical control over the subwoofer. Too small, and the resonant frequency of the system will be high, the sub will have a very peaky response, and will require more power to reach it's excursion capabilities.

Also, keep in mind that a dual 2ohm speaker wired in series will achieve a 4 ohm load as well. So, an IDQ, eD Ov2 (essentially the same as the IDQ), and Oz audio Matrix elite would work fine as they are all offered in dual 2ohm configurations.

 

That makes sense because I have had subs in boxes that were too small and know what that sounds like. I've just never had a sub in a box that was too big.

 

Keep in mind also, that most enclosures built in the back seat will not be as good overall (sound quality and Low bass extension) then one in the rear of the car. You need atleast 8 ft. for a 12" sub to generate it's full soundwave at lower freqencys. I hope that makes sense, I tried to say it basic.

 

I'm not going to use the rear hatch space for any of this stereo equipment. If I have the ports aimed up would that give the space needed for it to produce the sound? This is turning into a real pain in the ***.

 

If you are looking for SQ, I'm still curious why you're planning on going ported. Regardless, speakers in the hatch area will be fine no matter if they're vented or sealed.

 

This amp only puts out 200W to the sub channels, 371W max according to the spec sheets. I've always steered toward ported boxes for subs that weren't going to get a lot of power. If this is a mistake then please let me know. In my experiences a sealed box needed a good deal of power to get them sounding good where a ported box was louder with less power.

I'm also wondering if I would be better off with a pair of 10s intead of 12s due to the point of throw distance brought up previously. I had my 12's in the trunk in my Mach 1 and they sounded good, but required a ton of power to get them to hit.

Again I am working with the back seat area, not the hatch...

 

Anyone ever built a speaker box that fit in the back seat area that had a really good sound? If so what speakers and box type did you use?

And again... I am using the rear seat area, not the hatch area.

 

Sorry, i misread your post about where the sub was going. I am not sure how the sub will perform in the backseat area. i have seen it done, but I am not aware of the performance of it back there. I would imagine that it would suffer some cancellation, but again I am not sure. I would post on fbodyaudio.com. They have a few really knowledgeable guys there (cliffj and djsexay) that I'm sure can answer your question.

Anyways, I am confused about going with two 10's. If you think you don't have enough power for 1 sub, then why do you think you'll have enough for two?

 

I have 2 12's now and one person posted about distance from speaker to end of cabin. I was wondering if 2 10s would work better for the shorter distance... I will post on fbodyaudio and see what they say.

 

It's all in the enclosure design. 10s do sound better for most applications, but do not have the impact that 12s have down low. In my opinion a good single 12 glassed into the rear somewhere will yield the best results. No cancellation and enough wavelength. Also, Alpine's 5-ch for the most part has NEVER had good sub section in it. Even most their sub amps are weak in comparison to others. If you are going to do this right, get a good amplifer that can control the subs, and you will be A LOT happier in the end.

 

I would like to restate yet again that I am not putting the subs in the hatch and I am not using another amplifier... I got some specs on boxes and such from a guy at fbodyaudio.com that helped me out. As far as I am concerned this thread is now closed... thanks.

 

Good thread. Good topic to discuss.

Doubling of either Cone area or Power is a 3 dB increase. So going from 1 10" to 2 10" and the same amount of power into each, is 3dB. Double the power into a speaker is 3 dB. Double power and Double Cone area is 6 dB. Our human ears can perceive a Doubling of volume between 7-10dB. So just putting in more subs for a 3 dB increase doesn't mean it will be perceived as Twice as loud.

Porting can be used to either lower the Fs (increase the extension of the freq range) or can be used for large gains. Just saying 3 dB is not that good of a rule of thumb. Most manufacture specs for port enclosure (Bass Reflex) is around 2-5 dB gain. Not bad.

Down side of porting is that you Need a Subsonic filter, or be really carefull what you play. Playing Freq's below the tunning frequency will make the Suspension system loose control. There-for, there is uncontrolled excussion that will damage the speaker in the long run or imediatly.

It is actually better to go for Cone area than for power. Power requires more Current (I.E. More costly upgrades to support that. Alt, 4ga 1/0 ga wire, Bigger gnd's, Larger or better Capacitors). This also places more strain on the motor structure and Suspension system (Worn out speaker). Also causes more heat to be disapated. So it is actually better to go for a second sub over 1 beacuse it is better.

Down sides are: More space consumed. Our cars are not all that friendly more subs and their enclosures. This is also more weight to drive around daily.

1 10" (Good sub) in the Drive's side cubby hole, has pretty good output. IT also makes the best sence as far as space is concerned. When I 1st installed a JL enclosure in that spot, I was very impressed with the output from that spot. (Physics Cabin gain works well in our cars).

If you want 2 subs, go for either a Well enclosure (Look in the faq for examples) or go for enclosures on both sides.
Pros and Cons:

Well:
Pro's Places subs in the best spot for output. Can Tune phase of output for Imaging easiest. Also allows for up to 15" subs reasonably, and an 18" (Not recommended)

Cons: Not stealth. Takes up a lot of space. T-Tops people really have one choice for this.

Cubby hole mounted:
Pro's: Space. Uses basically dead space in the car. Very Stealth.

Cons: Limited to 10" and 12" (Must fabricate). Not much Air space to work with and limits what subs to use. Can sound Peaky.