2017 Hatch 8" subwoofer install

allenc209

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Some awesome pics of subs in this thread. Good job guys.
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curt d

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You'll have to cut either way. Just knock it out. No biggie.
You will have to cut for large baskets or cast ones. My Focal 165V1s dropped right in. You just have to index them to clear the 2 stupid ears on the speaker opening.
 

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Damn the JL audio 8inch sub I am looking at requires at least a suggested .875cuft. Gonna ask around the local shops and get an est on cost to build a box. Maybe I'll just have to build one myself.
DIY gets my vote every time - that's how I got my start in audio almost 30 years ago!

Bear in mind it's not just "the sub"... there's laws of physics at play that say you can only have two of the following three things:
1) small enclosure size
2) low frequency extension
3) high efficiency (loudness per watt)

By manipulating different variables in both the subwoofer itself (namely the moving mass of the cone assembly, somewhat the suspension compliance, but primarily the enclosure design and volume (which is far more significant in overall compliance than the suspension dictates), the overall system can be optimized, but only for two of these three variables.
  • If you want a small enclosure, you WILL compromise loudness, or low frequency extension, or both.
  • If you want low frequency extension, you WILL need a larger enclosure, or you'll need to find a subwoofer that can handle a ludicrous amount of power and an expensive amp, and even still it won't get all that loud.
  • If you want a subwoofer that gets very loud, you'll need a larger enclosure or one that's tuned so high that it won't play low.

In fact, those super-high SPL competition vehicles can destroy their own subwoofers easily, by physically bottoming them out, simply by playing below the tuning frequency [where the subwoofer is essentially not supported by any moving mass of pressure in the vent or enclosure] even at low volumes (read: low wattage). Those vehicles are tuned very high, to exploit the subwoofer's (and vehicle's!) own resonant frequency, which is in part high because the suspensions are so stiff (despite a high moving mass that otherwise would lower resonant frequency)

I'm not saying that all subwoofers are the same, either. If you go the small box route, you'll need lots of power, so you'll need one that can handle lots of power - which makes it heavier and less efficient inherently, especially if they also designed in a competently heavy duty suspension. All that moving mass makes the resonant frequency low - but a stiff suspension raises it back up, and then the stiff mass of air of a tiny enclosed volume of air raises it even higher. It won't play low, even sealed. (and a sealed enclosure by virtue of what it is, won't play as loud as a ported box, which requires the volume of a port inside, plus sacrifices output below the tuning frequency to give you more output at and above the tuning frequency... and note that the lower you tune a vented box, the longer the port needs to be - making the enclosure larger.

Bottom line-
If you want to play low frequencies at any sort of reasonable volume, physics dictates that you'll need a larger enclosure - the subwoofer, not so much.
Small subwoofer enclosures are a bitch - partly because you have to mitigate customer expectations.

The flip side of this, of course, is that if you properly engineer in a large enclosure - you can almost drop in any POS subwoofer and half an amplifier, and it'll play low and loud.

It really matters... maybe more than anything else.

Food for thought.
 

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Thank you for all the info. The JL I am looking at is the 8W7AE-3 8inch sub. On their website it says that it's optimized to operate in a .875cu ft sealed box including the sub. Since my knowledge of subs is very limited I just went with what the company recommended.

Any input on this specific sub?
 

curt d

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Thank you for all the info. The JL I am looking at is the 8W7AE-3 8inch sub. On their website it says that it's optimized to operate in a .875cu ft sealed box including the sub. Since my knowledge of subs is very limited I just went with what the company recommended.

Any input on this specific sub?
Prob 8 yrs ago I ran the 8w7 in a ported box (never ran ported before) getting 600 from a Phoenix Gold 600ti. It was in an ext cab p/u. It hammered and sounded good doing it. If you give it enough power, it should sound great sealed.
For the hatchback I’m going with a Stereo Integrity 12 MK V flat sub in the spare tire or flush in the side wall behind the wheel well.
 


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Hi guys I'm new to the audio forums and with no experience. Has anyone ever thought of doing a sub install where the spare tire is? If I don't need a spare tire, would mounting the sub there be any good?
 

curt d

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geolemon

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Thank you for all the info. The JL I am looking at is the 8W7AE-3 8inch sub. On their website it says that it's optimized to operate in a .875cu ft sealed box including the sub. Since my knowledge of subs is very limited I just went with what the company recommended.

Any input on this specific sub?
No personal experience other than lots of general JL experience, and I do own a 12W7. They make high quality stuff, and that 8" is notably more ludicrous than most subs. They have engineers that know their stuff. You can be assured there won't be any silly problems like a high moving mass to create a low Fs and a soft suspension that can't control the mass or any such ugliness. .875 isn't tiny for an 8, but note even subs "optimized" for smaller boxes will be subject to the same laws of physics... if there was one that was "optimized" for a 0.25" box it wouldn't play as low and wouldn't be as loud per watt.

To clarify if it wasn't clear from the earlier post, there's 2 design balances that have to be struck:

1) the subwoofer driver itself needs to be engineered so that it's components are all in balance for particular target applications. For example, a "small box" subwoofer might have an intentionally higher moving mass (to lower the Fs) and higher powerhandling to overcome the decreased efficiency, and stiffer suspension (Vas) to control the mass. Or, a competition subwoofer might be designed with as light of a moving mass as possible, but still needs heavy gauge wire in the windings (which does add mass, you can't get around it), and a soft suspension - anything to get efficiency up, and we even want a high-ish Fs on a competition subwoofer to steer that efficiency towards where it'll align with the car's interior resonance, when it's in a giant ported box tuned specifically to exploit frequencies very narrowly burped at nearly exactly that tuning frequency. Whatever the intended application is - the subwoofer needs to have it's components aligned for that application.

2) The enclosure. That ultimately determines how that subwoofer plays. If you put the SPL-designed sub in a tiny box, you'd be incredibly disappointed and calling it a POS, even feeding it thousands of watts. You should always start with "what are the goals of my install?" That will first lead to an enclosure design - and then you should find a subwoofer that fits that application:

Want sound quality? Sealed is always great. Small box won't get loud, large box can be pretty loud, but in either case you are limited by how much air you can move by whatever cone size you bought times the excursion capability of that subwoofer. The smaller the box you put the sub in, the less excursion you can reach, per watt of input... hence it's not as loud. That also limits your low frequencies (via the same mechanism - the lower you play in a sealed box, the more excursion the sub needs to reach with those slower waveforms, to produce the same dB level of output. So, if you restrict excursion, you restrict not just loudness, but low-ness too.

Want a little louder? Vented is probably the way to go. Sure, there's some exotic designs out there, bandpass, transmission line... they also have vents and end up taking up even more space than vented, so vented is usually the best call. All that port in the box does (besides taking up space... all the rules of above apply - technically that eats up space inside your box, making it effectively smaller - so your box needs to be bigger) is hold a specific quantity of air. When the subwoofer starts moving, that air mass starts moving: the sub moves in and out, the air in the box gets compressed and expanded, and that in turn pushes and sucks on the air mass in the port, which starts to invisibly oscillate in and out as well. It's tuned to a specific frequency - the closer you get to the tuning frequency, the more "in phase" that moving air mass is with the motion of the cone, and the displacement of the air moving in and out of the port will contribute to the SPL caused by the cone moving in and out. Hence, it's louder. And since none of the frequencies are exactly "in phase" with the cone, the bass isn't quite as sharp as with a sealed box, from a sound quality purist audiophile perspective. But it still can be very good, and much louder, compared to sealed.

One big caveat here is that you don't want to tune too high, because if you play notes that are much LOWER than the port tuning frequency, the air mass in the port cannot support the moving mass occurring in the box, and it simply acts like a hole in the box... making it very easy to bottom out your subwoofer and "blow" it physically, even with a fraction of it's rated powerhandling (which is always only a rating of how much heat the voice coil can dissipate at any rate - how much power you "need" determines entirely on this enclosure you are designing!)

And one alternative you almost never see outside of home audio and cheap bluetooth speakers is the passive radiator. Where a port uses air mass to resonate, it uses a "drone cone" type assembly that has physical mass... and it's always much heavier than the mass of air inside a length of pipe so it's always tuned low. I have two decent 8" subs (private label, buddy's small company, I didn't do the engineering but know it and like it!) and two hard-to-find 10" flat panel passive radiators. This combo works even in an uber-tiny box and you'd think i had a vented 12" sub back there. Essentially it's the same as a vented box tuned quite low... not tuned for efficiency but louder than those 8's in the same size box sealed.

Anyway - not trying to steer you one way or the other - I'm a lifelong JL fan myself. Sometimes the specs on subs tend to favor the smaller cone subs in vented boxes, however, and larger cone subs in sealed boxes...
That 8W7 is probably more representative of a standard 10" than most 8" subs at any rate... but if that wasn't the exact sub you had, I'd suggest you might look into a 10" sub and compare specs. The 10" sub may have a deeper mounting depth than most 8's, will take up more space inside the box that has to also be accounted for of course (it's only the "air space" inside a box that counts!), but most often a 10" sub that's in a slightly smaller than ideal enclosure will be better than an 8" sub that's in it's "ideal" sealed volume... it'll have a lower Fs that will make it play lower, and sometimes the "less than ideal" response curve actually will result in a slight boost in bass right where it's nice to have, rather than being a penalty - plus the larger cone and longer throw suspension can produce significantly more output even in a compromised enclosure.
Food for thought for the rest of the readers.

And note with regard to the 8W7... it's deeper than most 8's. It takes up more space in the box than most 8's. It has more excursion than most 8's. It has a larger cone than most 8's. Which, by most accounts, would essentially mean it's more like a 10 than an 8... so yes, it'll kick some butt for you.
 
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geolemon

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Hi guys I'm new to the audio forums and with no experience. Has anyone ever thought of doing a sub install where the spare tire is? If I don't need a spare tire, would mounting the sub there be any good?
Stay tuned.
I've had a million projects keeping me down, including leading a big corporate project in my IT career, siding a shed at the girlfriend's house before the snow starts to fall, and tying up a million loose ends and renovation projects at my house so that I can put it on the market...
...but once those are done (before winter I hope), this is exactly what I'm doing with my 8's and the passive radiators. And in my case (sport hatch) will be lowering the trunk floor to standard (non-sport) hatch levels in the same fell swoop.

We'll see when I can finally start this project. Over the winter, for a spring install, would be nice.
 

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Sure! They actually drilled a small hole somewhere on the inside for a mounting screw that is not visible when the sub is removed and the spare tire tools are put back in. I originally left out the name of the company because I wasn't sure what forum rules are. I'll post it for now but if it is against the rules please let me know, I'll delete the post and take it to PM.

Sun Valley Stereo
sunvalleystereo.com
(602) 957-3397
2809 E Thomas Rd
Phoenix, AZ 85016

Ryan is who helped me and got me setup with everything.


Interestingly, there was another 2017 Civic Hatch there that day getting a system installed. Though this guy had the Sport 6 Speed Manual. Ryan told me he had to travel to Colorado from Arizona to get it. I would have loved to get a Sport 6 speed but I wasn't willing to go the extra mile to get it. CVT isn't too bad though :)
Has anyone else called up the audio shop to see if theyre interested in selling/shipping these out of state? Looks like a decent stealthy box which is something many of us are interested in when upgrading their audio.
 

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Im getting the new kxa kicker amp for my civic it uses the FiT2 technology where you dont need any LOCs the amp does all the work, so im gonna tap the rear speakers
 

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I have since installed the box a bit more permanently but here are some pics. I did MB Quart ZLine components, but after I got them I found out they were sold to Maxxsonics years ago. I am SUPER happy with how they sound for the price, thankfully.

I have a Skar 75x4 amp driving the components and a 600x1 driving the sub.

I built boards and carpeted them....the Skar Amps fit just fine but I had to trim the foam under the board (This is a Sport...other models have a different hatch setup due to not having the center exhaust).

I originally used my factory head unit with an AudioControl LCQ-1, but had some issues and gave up and put a Kenwood head unit in and ran RCAs. Super happy with it now.

UXjJYlf0eiYSY5JSUtuvU-z8SfqQu9j4baN2mGCaIsR3VC9ACemYp-8ayCYSjKpKXzQI6RZkhYBXbc59c=w1577-h1182-no.jpg


MRj_3HlmYMzoPgJ9qhsXjw01MOiThtkvM7qv-A0wPCodEh66wQiNWIucio3UtAxAMiffZd--GB6yW7ZVo=w1577-h1182-no.jpg
How did you do the amp board. Single piece of plywood cut out or 3 pieces. And any pointers on where to run a 0 gauge and 4 gauge power wires? Btw putting in 2 skar ddx 10's in the hatch
 

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How did you do the amp board. Single piece of plywood cut out or 3 pieces. And any pointers on where to run a 0 gauge and 4 gauge power wires? Btw putting in 2 skar ddx 10's in the hatch
3 separate pieces. I have a bolt coming through from the bottom at each end of the middle piece, with a wing nut on top to hold them together (and being together holds them in place).

I ran 4 gauge through an existing hole just above the fuse panel to the left of the drivers foot. 0 likely wouldn't make it through there. I just came down the left side with the power cable...there's plenty of room at the bottom edge of the door sill under the carpet. Nice on the DDX10's. That's going to be insane! I love my Skar amps...if I had known how good their stuff was before trying it, I would have bought their sub.
 

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3 separate pieces. I have a bolt coming through from the bottom at each end of the middle piece, with a wing nut on top to hold them together (and being together holds them in place).

I ran 4 gauge through an existing hole just above the fuse panel to the left of the drivers foot. 0 likely wouldn't make it through there. I just came down the left side with the power cable...there's plenty of room at the bottom edge of the door sill under the carpet. Nice on the DDX10's. That's going to be insane! I love my Skar amps...if I had known how good their stuff was before trying it, I would have bought their sub.
Thanks I upgraded the HU to a AVIC-8200NEX and front doors are going to be soundstream rc.6 and backs will be ppi P.65C2 powered by a ppi p900.4, and the ddx 10's ran off a masssive d8000. I picked up some 80mil sound deadener by noico and some foam speaker rings by soundskin audio(the only thing im waiting on coming in). Ill build a box 14x14x 40.5 tuned to 34hz to fit nicely in the hatch, but first I need to find the best way to get 0 gauge to the hatch.
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