# Best way to face subs in a hatchback Mustang?



## victor's gt (Dec 4, 2009)

What's the best way to face subs in a hatchback Mustang?


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## 2fast4thelaw (Jul 5, 2009)

Optimal: rear firing with the back of the sub enclosure up tight against the back seat. 

Good: Choose a rear corner in your trunk and have them fire towards the opposite corner.

Good but complicated: Bandpass enclosure that vents directly into the cabin of the car through the rear deck. Will require flexible vent tubes.


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## sam3535 (Jan 21, 2007)

victor's gt said:


> What's the best way to face subs in a hatchback Mustang?


OR.... just move them around in the trunk and listen and stop moving them when you find the best spot.


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## victor's gt (Dec 4, 2009)

2fast4thelaw said:


> Optimal: rear firing with the back of the sub enclosure up tight against the back seat.
> 
> Good: Choose a rear corner in your trunk and have them fire towards the opposite corner.
> 
> Good but complicated: Bandpass enclosure that vents directly into the cabin of the car through the rear deck. Will require flexible vent tubes.


I am speaking specifically about a *hatchback mustang.* So there is no trunk and obviously no rear deck.


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## benny (Apr 7, 2008)

Tight to the rear, subs upfiring against the glass.


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## victor's gt (Dec 4, 2009)

sam3535 said:


> OR.... just move them around in the trunk and listen and stop moving them when you find the best spot.


That would be something to consider but that would require a "test enclosure" to do so


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## victor's gt (Dec 4, 2009)

benny said:


> Tight to the rear, subs upfiring against the glass.


"Tight to the rear" meaning right behind the the seats?


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## benny (Apr 7, 2008)

victor's gt said:


> "Tight to the rear" meaning right behind the the seats?


No, the other rear.  Meaning as far back in the car as you can.


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## victor's gt (Dec 4, 2009)

benny said:


> No, the other rear.  Meaning as far back in the car as you can.


Well....there is approximately 11" from the rear of the hatch to where the glass begins. Then there's approximately 19" from that point until the back seats are reached. So the enclosure would basically end up right behind the seats in order to fire "upwards" into the glass


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## victor's gt (Dec 4, 2009)

Like this....


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## benny (Apr 7, 2008)

Yeah, except Id try the subs where the amps are, and put the amps in front.


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## Mike Hall (Jun 30, 2006)

I used to have 4 JL 10W4s in a 8th order bandpass in a 90 GT and man would that thing jam. I had it tuned so it would beat the snot out of you and the ID full body horns and old Rockford Power 6.5 midbass drivers flat out got down. I wish i had some pictures but that was way before I had a digital camera. Anyhow, I had my box firing up at the back glass. 

Mike


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## 2fast4thelaw (Jul 5, 2009)

Mike Hall said:


> I used to have 4 JL 10W4s in a 8th order bandpass in a 90 GT and man would that thing jam. I had it tuned so it would beat the snot out of you and the ID full body horns and old Rockford Power 6.5 midbass drivers flat out got down. I wish i had some pictures but that was way before I had a digital camera. Anyhow, I had my box firing up at the back glass.
> 
> Mike


I bet that sounded sweet! I had (2) 10" JL W6s in a 4th order bandpass enclosure with external JL flex ports that vented into the cabin through the rear deck in my Maxima. It was as close to perfect sounding bass I have ever achieved. No trunk lid rattle at all!


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## Lanson (Jan 9, 2007)

8th order? I'm just visualizing the phase variance in a system like that. It must have been a wild beast to tame if at all possible.

I agree with other posters, line up your subs with that back line. Serves as a horn loading against the back glass, and will really ramp up the bass output. I think you'll also have less cancellation because of this horn-loading phenomenon. 

You are going to need to deaden the living hell out of that hatch structure and the back and side metal. Its going to flex like crazy.


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## Mike Hall (Jun 30, 2006)

Well, i have to admit, I didnt design the box but i built it. A good buddy of mine in Tallahassee, FL designed some of the best sounding 8th order bandpass' ever. I take that back, He gave me the front and rear chamber volumes as well as the front and rear port area and length and i designed the box to fit in the car. If Im lucky I might find my old hand drawn plans but i kind of doubt it. lol 

Mike


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## victor's gt (Dec 4, 2009)

fourthmeal said:


> I agree with other posters, line up your subs with that back line. Serves as a horn loading against the back glass, and will really ramp up the bass output. I think you'll also have less cancellation because of this horn-loading phenomenon.


You mean put the subs where the amps are as benny suggested? The hatch glass doesn't start until the the top edge of the amplifiers in the above pic.


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## Lanson (Jan 9, 2007)

Correct, Benny is 100% right.

That system above isn't bad by any means, but there is a little lost opportunity doing it like that. The subs near the back and properly flushed up should make for a hell of a horn loading.


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## Lanson (Jan 9, 2007)

A system like that is going to be so easy. Just build MDF boxes 3/4" to 1/2" below where you want the system to terminate. Consider having the sub boxes sit as high as possible to maximize both airspace and subwoofer loading. Then, just build a trim board that matches all the curves in that trunk, and drop it on top. You could secure from underneath with L brackets, or similar. Then build your amp rack at an angle from the subwoofer deck down to the floor which will accentuate the horn effect a bit. Plus you'll get more storage space, if you make the amp rack sturdy enough to let things get thrown on top of it.

I wish all systems were that easy to build.


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## victor's gt (Dec 4, 2009)

Not sure that I totally understand. Forgive me for my crude pic but this would be a side view with the hatch closed. The filled in dark area would be the enclosure with the subs firing upwards into the metal portion of the hatch? 

The vertical line all by itself is my back seat.


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## benny (Apr 7, 2008)

perfect!


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## victor's gt (Dec 4, 2009)

benny said:


> perfect!


Sealed box with 1/2" - 3/4" space left between it and the metal part of hatch as suggested by fourthmeal?


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## benny (Apr 7, 2008)

not necessarily sealed, I like ported myself, but I would leave a little more room than 1/2". Maybe more like 2-3".


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## victor's gt (Dec 4, 2009)

benny said:


> not necessarily sealed, I like ported myself, but I would leave a little more room than 1/2". Maybe more like 2-3".


That would leave me with the enclosure having only about 7" for height (outside dimensions)? Also if I went ported, in which direction would you suggest the port face?


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## 94VG30DE (Nov 28, 2007)

I agree, my Z has the same hatch glass setup (i.e. the sub would be facing directly up into the metal/plastic trim, not the actual glass) and that placement seems to be the best place for me too. Like was said earlier, just make SURE you rattle-proof that hatch panel, because you are definitely going to get some flex and panel resonance in that spot.


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## Lanson (Jan 9, 2007)

Ported will probably be much louder, but also the cabin gain itself is like a port here so you might get way too much gain at a certain frequency if the port tune and cabin gain peak are the same. As Andy at Harmon says, build the box as big as you can, tune as low as you can, and EQ out the peak. The power handling of the system goes up dramatically and the distortion profile drops as well.

I'd port on the same face as the subs, to reduce phase cancellation issues. Or go sealed. That totally depends on your subs, the amount of airspace you wish to give to the project, and your demands on SPL and SQ.

BTW, I wasn't saying go up to 3/4" away from the metal part of the hatch, I was talking about sealing up all the area around the box with a trim board precisely made to match the contours of the trunk so there is a defined path the bass wave has to take, and then slant an amp rack down from there to continue the horn. 

If you took pics of your empty trunk w/ measurements at the critical spots, I can Googlesketch a 3D visual of the proposed design. Do you already know what other gear you are installing? subs, amps, extra stuff?


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## victor's gt (Dec 4, 2009)

fourthmeal said:


> Ported will probably be much louder, but also the cabin gain itself is like a port here so you might get way too much gain at a certain frequency if the port tune and cabin gain peak are the same. As Andy at Harmon says, build the box as big as you can, tune as low as you can, and EQ out the peak. The power handling of the system goes up dramatically and the distortion profile drops as well.
> 
> I'd port on the same face as the subs, to reduce phase cancellation issues. Or go sealed. That totally depends on your subs, the amount of airspace you wish to give to the project, and your demands on SPL and SQ.
> 
> ...


The Mustang pictured above is what is actually in my car now. I am trying to decide if it is worth the effort to change the set up or just leave it alone and attempt to adjust gains and crossover frequencies to get it to sound more to my liking.

.


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## Fixtion (Aug 25, 2006)

LOL!


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## Lanson (Jan 9, 2007)

Well you can always optimize, no doubt. I see little things here and there with your previous install that could be improved.

Will you notice massive differences? Not sure. 

Most of us like changing things around just for the sake of change. Sometimes its fun, sometimes its necessary because of equipment changes. Whatever the case, you can always change it to something else if you aren't pleased.


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## foosman (Oct 14, 2007)

Or something like this, depending if you are wanting a street beat type of tune or strictly SQ.


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## victor's gt (Dec 4, 2009)

I've read in another thread on this forum where a build log was started for a hatchback Mustang but was never finished. Many suggested the enclosure sit behind the seats with subs firing toward the rear. That's why I wasn't sure if my enclosure design was optimal for my vehicle and was willing and open to change it if the general consensus was to do so.


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## Lanson (Jan 9, 2007)

If you do that, you can run into cancellation effects of course. Horn-loading the sub will cause it to sum-up in the cabin as the wave travels to your ear. I suppose the logic of facing it the other direction is so the bass wave has time to propagate, but bass waves are quite long. Even a 1/4 wave is many feet. So horn-loading seems the smartest. Like any car, testing proves the hypothesis.


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## victor's gt (Dec 4, 2009)

fourthmeal said:


> Well you can always optimize, no doubt. I see little things here and there with your previous install that could be improved.
> 
> QUOTE]
> 
> Where would you suggest that I make the improvements?


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## Lanson (Jan 9, 2007)

Try the horn loading thing we're chatting about, for instance.


Where is the system lacking?


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## AudioBob (May 21, 2007)

I owned a 1990 Mustang LX hatchback and tried several different sub woofers, sizes and configurations. The best results that I had were 2 12" woofers in a sealed box with separate chambers for each woofer firing backwards with the back of the sub box up against the rear seat.

I could never get decent low end extension with any set firing up at the hatch glass. The 12's were ran off of 500-600 watts RMS of a Rockford Fosgate Punch 200DSM. A 12" woofer was the largest that would fit in that area. I spent several thousand dollars trying to get it right and built numerous boxes because I competed on the IASCA circuit at the time pretty heavily.


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## Lanson (Jan 9, 2007)

AudioBob said:


> I owned a 1990 Mustang LX hatchback and tried several different sub woofers, sizes and configurations. The best results that I had were 2 12" woofers in a sealed box with separate chambers for each woofer firing backwards with the back of the sub box up against the rear seat.
> 
> I could never get decent low end extension with any set firing up at the hatch glass. The 12's were ran off of 500-600 watts RMS of a Rockford Fosgate Punch 200DSM. A 12" woofer was the largest that would fit in that area. I spent several thousand dollars trying to get it right and built numerous boxes because I competed on the IASCA circuit at the time pretty heavily.


Did you try the horn-loading technique I'm suggesting?


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## victor's gt (Dec 4, 2009)

fourthmeal said:


> Try the horn loading thing we're chatting about, for instance.
> 
> 
> Where is the system lacking?


Another drawing...my current view from the side. The enclosure (in black) and my amp rack (the white box to the left of the enclosure). The enclosure is on a very slight angle towards the hatchback glass. Doesn't exactly pass for "horn loading" or close to it?










I am lacking low end extension as well. My enclosure is sealed.


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## Lanson (Jan 9, 2007)

I need to get on my Googlesketch at home (can't play w/ that at work), and show you what I'm visualizing. But for the moment, visualize a horn, think how the mouth slowly opens up. Consider that your hatch IS one of the horn portions, and the sub box could be the other, and finally your amp rack could continue the contour. 

I'm getting the feeling that firing backward from the rear seats lets a longer wave propagate and therefore becomes audible to your ear. Outside the car, I'm betting it all is a wash. Inside the car, this might be the issue.


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## victor's gt (Dec 4, 2009)

AudioBob said:


> A 12" woofer was the largest that would fit in that area.


One 12" was the largest sub that you could fit in what area?


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## 94VG30DE (Nov 28, 2007)

fourthmeal said:


> I need to get on my Googlesketch at home (can't play w/ that at work), and show you what I'm visualizing. But for the moment, visualize a horn, think how the mouth slowly opens up. Consider that your hatch IS one of the horn portions, and the sub box could be the other, and finally your amp rack could continue the contour.
> 
> I'm getting the feeling that firing backward from the rear seats lets a longer wave propagate and therefore becomes audible to your ear. Outside the car, I'm betting it all is a wash. Inside the car, this might be the issue.


In my car, with two Alpine E-10s sealed facing backward, with the back of the enclosure against the backs of the seats, you could hear the subs pretty well outside the car. Lots of rattling. Not crazy levels of output in the car, but definitely could get loud. It just sounded sloppy doing it. 
When I switched to 1 Dayton 10HO ported facing straight up in the center rear of the hatch, there is almost no bass outside of the vehicle, but in vehicle response is tons of output, and very clean. If you open the hatch and put your head RIGHT IN FRONT of the sub, you can barely hear that it is even turned on. But close the hatch and sit in the driver seat, and output is like quadrupled.


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## Lanson (Jan 9, 2007)

LOL, MS paint for the LOSE.


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## Lanson (Jan 9, 2007)

Notice the horn-like effect of the contours.


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## victor's gt (Dec 4, 2009)

fourthmeal said:


> Notice the horn-like effect of the contours.


I think you are suggesting this. The angle being the amp rack, correct?


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## victor's gt (Dec 4, 2009)

94VG30DE said:


> In my car, with two Alpine E-10s sealed facing backward, with the back of the enclosure against the backs of the seats, you could hear the subs pretty well outside the car. Lots of rattling. Not crazy levels of output in the car, but definitely could get loud. It just sounded sloppy doing it.
> When I switched to 1 Dayton 10HO ported facing straight up in the center rear of the hatch, there is almost no bass outside of the vehicle, but in vehicle response is tons of output, and very clean. If you open the hatch and put your head RIGHT IN FRONT of the sub, you can barely hear that it is even turned on. But close the hatch and sit in the driver seat, and output is like quadrupled.


Do you think it could have been a combination issue between subwoofer choice and enclosure design rather than enclosure placement? You went from sealed to ported with different subs as well...


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## victor's gt (Dec 4, 2009)

Got this pic of internet with regards to the "horn effect"


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## AudioBob (May 21, 2007)

Victors GT it was a pair of twelves with about 1.75 cft per sub enclosure. 

I tried sealed and ported both. I had tried a somewhat horn loaded configuration with the subs more towards the rear, but there was not much room there as I would not do without my spare tire. My advice would be to build a test enclosure and see for yourself by moving it around in the hatch area.


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## 94VG30DE (Nov 28, 2007)

victor's gt said:


> Do you think it could have been a combination issue between subwoofer choice and enclosure design rather than enclosure placement? You went from sealed to ported with different subs as well...


The short answer is obviously yes, it certainly good have been the gigantic switch in equipment. But, when I was installing the new Dayton, I threw it in a 0.66 ft^3 sealed enclosure and moved it around the hatch area while listening. The best spot seemed to be in the back facing straight up. But yes, my switch was definitely not a controlled experiment. Good catch.


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## victor's gt (Dec 4, 2009)

I have to take an accurate measurement but I think the area furthest to the rear (currently where my amp rack is) will be too shallow of an enclosure therefore narrowing the choice of subwoofers down alot.


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## 94VG30DE (Nov 28, 2007)

Yeah that would be a good dimension to figure out. With my current sub enclosure project the first thing I decided was what kind of space I had to work with, and then decided what I wanted to fill it with.


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## Lanson (Jan 9, 2007)

Notice how I angled the subs down slightly to form a true horn mouth. I wonder if you could also block off and seal the hatch's part of the "horn" here, too. That way it makes a smooth transition from hatch to glass to cabin.

Another thing I'm thinking about, fold the horn again...btw this is more difficult but the pathlength is better...









Lots of options. Not sure what it would do in each situation since it is impossible to understand the variables involved well enough to perform a simulation or calculation, but wood is cheap, experience is invaluable, and experimenting is fun. Just look at Patrick Bateman here, he's a huge experimenter and has great results (after many failures, just like all inventors.)

Edison said once while inventing the lightbulb, "I have not failed. I've just found 10,000 ways that won't work."


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## victor's gt (Dec 4, 2009)

I have to wait until I get home to view your pics. I can't see them here at work!


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## 94VG30DE (Nov 28, 2007)

fourthmeal said:


> Notice how I angled the subs down slightly to form a true horn mouth. I wonder if you could also block off and seal the hatch's part of the "horn" here, too. That way it makes a smooth transition from hatch to glass to cabin.
> 
> Another thing I'm thinking about, fold the horn again...btw this is more difficult but the pathlength is better...
> 
> ...


Cool pic! Folded horn mouth using the deck lid. Did not think of that...


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## Lanson (Jan 9, 2007)

They are just horrible, I did them at work w/ mspaint.


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## victor's gt (Dec 4, 2009)

fourthmeal said:


> LOL, MS paint for the LOSE.


I see the enclosure is angled down a little in your pic. Actually, my hatchback is angled slightly upwards in the area above the proposed location of the enclosure in your picture. So I wouldnt have to angle the box down.

I took some quick measurements that are as follows based on your pic: 

L= 46.5"
H= 8.25"
D= 11"

Using 3/4" MDF would gross me only approx. 1.67 cu.ft.


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## victor's gt (Dec 4, 2009)

Im basing those dimensions on assuming the enclosure ends where the hatch glass begins.


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## Lanson (Jan 9, 2007)

There's some wicked math to be performed here but if you want to mess with ideas, I recommend it. Stick with 2 or three of the same songs, same gains, same everything else, and mess around with things.

Wood and stuff is still cheaper than buying new gear usually.


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## Untamedm3 (Dec 31, 2009)

2fast4thelaw said:


> Optimal: rear firing with the back of the sub enclosure up tight against the back seat.
> 
> Good: Choose a rear corner in your trunk and have them fire towards the opposite corner.
> 
> Good but complicated: Bandpass enclosure that vents directly into the cabin of the car through the rear deck. Will require flexible vent tubes.


Agreed I've tried it all


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## ghostmechanic (Mar 2, 2009)

2fast4thelaw said:


> Optimal: rear firing with the back of the sub enclosure up tight against the back seat.
> 
> 
> > I used to own several hatch Mustangs back in the '90s & this always worked best for me. A ported box with the subwoofers & the ports firing towards the back. If I recall the biggest I could use was a pair of 10s but it always did better than anything else I tried firing up.
> ...


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## victor's gt (Dec 4, 2009)

If I were to aim the subs firing to the rear, would it be best for me to try and mate the enclosure to the hatch as in the top picture or leave space like in the bottom pic?


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## ghostmechanic (Mar 2, 2009)

IIRC with mine, it was a big box that was the same width as the are between the shock towers & came all the way back to where the glass starts at the bottom. More like your top drawing. The bottom drawing would probably be better. My 10s were OLD Pyle something or others that required something like 3 cu ft each in a ported box. That was way back before they started building subwoofers that'll work in smaller boxes. 

Id just do like suggested & do some experimenting to see where the box will sound best. I really like that elaborate folded horn idea, I wish I could try it now.


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