Simple guide to a miata trunk subwoofer
 

I made this up a while ago. It basically calls out a recipe for a good-sounding small trunk sub for a Miata. Ignore the naysayers. This is a proven and awesome setup.

http://fixjunk.com/index.php?title=Miata_Trunk_Sub

http://fixjunk.com/images/2/28/Trunk_sub_2.jpg

The theory behind this design is that it complements the small size of the miata and the peaky low end cabin gain from the trunk and interior. If you design your sub to have a flat response down to 20Hz, you end up with a giant gain in the low end and you'll just waste amplifier power and rattle your trunk apart.

More techy details of the testing done by Jason Cuadra can be found here:

http://www.diysubwoofers.org/projects/other/cartf/

Love the bungy cord! lol

Is it a 10" sealed?

where is the amp, spare tire well?

https://www.miataforumz.com/attachme...ine=1312157774

yes amp(s) are in the spare tire well. which is hard on an 01 because there is a spare mount there. was. :)

Unrelated question: I see that you have a hydraulic strut for the trunk lift. Is that stock for NB's? How well does yours work? I installed a an unused second-hand kit but it doesn't lift my trunk lid on it's own.

i used an aftermarket kit from moss I think.

it doesn't lift the trunk by itself anymore but it does hold it open. it never did open as far as the stock springs. I guess at this point it's doing nothing for me that the stock springs didn't do.

do you have a spoiler?

Dampening:

https://www.miataforumz.com/attachme...ine=1315421903

DIY rack & off the shelf amplified tube sub.

https://www.miataforumz.com/attachme...ine=1315421903

The amplifier on the rack is powering two 5x8 speakers with enclosures that sit on the parcel shelf. I can remove the rear speakers, the sub and the rack in just a couple of minutes for track duty.

While the sub definitely adds range, I think I might try opening up some of the parcel shelf to get more sound into the cabin. The rear speakers were by far the best addition to the overall sound quality in the car.

I will tell you, that "carpeting"/insulation/sound deadening you left on there is junk. It will mold if you spill water on it and its hardly worth keeping if you have dynamat. I would just take it out, put in sound deadening and either spray it with underbody spray or cut out some stock colored carpeting (I will sell you my carpet for shipping cost and a happy meal dinner lol).

It has been fine for 25 years, I'm not going to worry about it now.

Don't want to cover the trunk plugs in the floor pan because I have actually needed to use them to get into my locked trunk. Hopefully this won't ever happen again but if it does, I'd have to break the latch to open the trunk.

https://www.miataforumz.com/attachme...ine=1315424415

I also have the entire parcel shelf and behind both door panels covered with Dynamat.

ha! I wonder why mine was molding. Anyways, your setup looks very clean otherwise.

opening up the space between the trunk and the cabin will have almost no effect in a miata. the thin sheet metal does pretty much nothing to block low subwoofer frequencies.

Have you tried it? I have done it both ways.

What about the three layers of insulation that covers the parcel shelf? The carpet, padding/batting layer and rubberized layer of the uphostery along with the panel absolutely mute the amount of sound coming from the trunk. The apparent volume was much louder after I cut out the parcel shelf AND upholstery, then covered the hole with a speaker grill.

In addition, I removed the fuel line cover in the trunk, opening the pathway down the left side of the trunk just as it is on the right side. No cut-out of the parcel shelf on the left side yet, though I was thinking I might add one just to make it symmetrical. The woofer is a lot closer to the passenger side opening so I doubt I'd get much benefit from opening up the other side.

The parcel shelf was already partially cut to accept the roll bar - just cutting out a bit more material along with the upholstery was not difficult and it made a big difference.

No spoiler. All I have on it is some home depot dynamat that I put on there a week ago. It never lifted the lid on it's own to begin with. It will hold it in place wherever I leave it. Function is the same with the marginal added weight of the dynacheap. I may spec out a strut with more lifting capacity if I find some free time.

Jumbo, how many watts does that tube sub consume? I have an Image Dynamics IDQ12V3 in a .8 cu ft sealed box (Soon to be a ported box, 12 more db at 42hz OH YEAH) stuffed with polyfill hooked up to a RF 700watt rms amp. Also have 120watt rms powering 6.5" Polk door speakers. I am weary of cutting or removing the parcel shelf because my Walbro 190HP fuel pump whines like my girlfriend. For me, removing the shelf would outweigh the advantages of barely increased low frequency SPL.

I really went cheap on all my components. I had a very specific philosophy in the audio build. Be like Bose. Crap quality, but using crossovers you can tune each speaker to produce the absolute best range it was capable of. The Pyle subwoofer was leftover from an old project. It's got it's own switched power supply rated for 800W. I have the gain set to about half because more than that leads to distorted sound.

The rear channel speakers are hooked into the 100W/Ch amp and the front speakers are hooked into the aftermarket head unit/amp. The gain is down on the amplifed rear channel as well - in order to match the front channel volumes. Playing with the crossovers and gains took a couple weeks but once dialed in, I rarely have to change settings.

The small space in the Miata works well with this gear, but I can tell it is on the edge of capability. Trying for more volume usually results in clipping or low frequency distortion. I'd have to upgrade the front & rear speakers to take it to the next level but probably won't since it ain't broke as it stands.

the "bose" method is ok to a point. cheap components usually have much higher levels of nonlinear distortion when used near the boundaries of their comfort zone. without the proper equipment, it's hard to know where that is. you can compensate by playing things at lower volume, but you can't eliminate it.

That trunk sub better sound ------- amazing...cause there's no reason to take up the entire trunk with one.

I have a 2000 Miata, is it worth replacing the door speakers with a component setup? Will I need an amp to power it?

I am sooooo ignorant about car audio, just want something louder and clearer so I can hear it with the top down.

Thanks!

If you have a bose head unit you will have to get a different one as they use a difference speaker impedance.
But no, a decent head unit will be more than powerful enough to drive the door speakers.

It really depends on the speakers. If they're efficient (> 93 db/2.83V@1m sensitivity), it's like getting a free volume boost. if they're inefficient (<88ish) then they will do best with some amp power behind them.

Each 3 db you go up in sensitivity is equivalent to twice as loud / double the power. so if you compare a 90 to a 93 db speaker, the 90 will require twice the power to get to the same volume level. (assuming both are the same impedance)

Now... You dont need component if you replace them, but you should get a multi-driver setup. Coaxial is fine.

This has inspired me to attempt to make a sub woofer box for an 8" sub. I don't want to have to remove woofers and amps to travel in the car since my wife and I use our Miata to travel 'round Texas and further at times.

I'll bet this would be a decent solution:

https://www.miataforumz.com/attachme...ine=1320965111

I have the bose, I like the stock look, might try to add aux in, and something like this down the road hmmm.

peeps on m.net seem to be happy with those things. I like my little tang bang sub, but I would like a touch more umpfh.

tossing a setup in my DD next weekend because why not.

Russell,

I just added a set of component speakers to my front doors as well as replacing the head unit which was line-out only so I had to have an amp.

Anyway, all of this has made a HUGE difference in the sound inside the car.

:D

I am going to shoot down your idea harshly. You know nothing about the frequency response of the basslink other than "20-120Hz" which is enough to throw up a red flag.

Also it's 200W. Peak? RMS? who cares, it's all wasted below 50 Hz anyway.

I mean go ahead and try it and go join the legion of people who post that trunk subs rattle your car apart while I cruise around with my sweet sweet sounding system.

Shoot it down all you like I never said I knew it would be good. It simply appeared to be a simple, self contained solution, not trying to win any DB drags here lol but I appreciate your advice and comment, maybe it's not worthy.

dude, y8s doesn't even turn up his sub. im all like where is it? and hes all like, its there. then im like turn that up two notches, and he does. then I'm like oh yeah dawg.

2 notch head bobber :D

hahah

I TOLD YOU

I'm not a bass head. I'm closer to audiophile. I sometimes turn it up but I dont listen to thumpity bumpity often.

Next time we gym, I'll bring the bassssssss.

https://www.miataforumz.com/attachme...ine=1321029344

I have an alpine type-X 10" that I would sell. Its a ------- beast, works well as either SQ or SPL I mounted it in a sealed box and used a 600w amp with it. Let me know shane! I will sell it for cheapppp. especially if you buy the amp from me too. Only used it for 6 months, before wrecking my car. been sitting around for the last year doing nothing.

PM Sent

For the trunk sub lovers, here's the sub I used (well not exactly, mine was a prerelease) but it's a TC Sounds 10 inch.

http://www.parts-express.com/pe/show...r=293-656&FTR=

https://www.miataforumz.com/attachme...ine=1321153849

My dad has one of these in his SE-R. It's not awesome, but if you just want to add to what you already have it's pretty good.

Personally I'm going to go with the Rockford Fosgate R300-12 in my MX-5. It is a little larger then the Basslink but I think it would suit what I'm going after a little more.

http://www.rockfordfosgate.com/produ...300-12_1_l.jpg

I appreciate you guys posting crappy options for miata trunk subwoofers in this thread... but they will sound bad and rattle your ---- apart.

You want it to get worse? Turn up the bass boost and watch people make vomit-faces.

Seriously, these "one size fits all" subs are going to sound like ASS in a miata.

But it's your car and your ignorance... so you can do what you like.

Umm... ok. :rolleyes:

Roll your smiley eyes all you want. I think you have totally missed the point of this thread.

If you want to start a thread titled "I don't really understand how bass frequencies interact with a Miata trunk so I picked some random subwoofer and put it in my car and I'm really not able to critically judge how it sounds but that's OK because I don't know what a really good sub sounds like anyway and ignorance is bliss" you have every right to.

This aint that thread and I will call out and ---- on every bad suggestion in it.

And you have every right to.

Keep up the good work.

I aim to please.

seriously though, you'd be amazed at a back-to-back comparison.