Discovery! 10 inch sub opening in rear deck panel

[Frenche]

After messing around with options on how to set up my car stereo I decided to investigate this hole/sub mount I have in my car. I really almost forgot about it.

Has anyone ever seen an instillation like this on an e30? it looks fairly clean so I've decided to use it. How should I mount the sub to this? I imagine it would sound like crap without a box. But if you look closely I only see 2 pairs of bolts and nuts.

If it were your car, how would you mount it?

[xtos]

Back in the 90's i used to do installations like that using aperiodic membranes. What they would do is mount on the front side of the sub and act as a box, controlling the air the sub had to push and not letting it play as free to air and thus damage its suspension. They sounded excellent. In many apps much better than a box but they never got around much, they were expensive and needed a little unit connected to the amp called wave brain...so ppl just kept on making boxes.
Anyway,if you use it as free to air=no box , it will sound like crap yes. but you will get some low end bass.But everything in the trunk will resonate so loud you probably be hearing a more metallic noise:)
So either try to find an aperiodic membrane and put it on the top with no box or make a box and screw it underneath the opening. Dynamic Control used to make the Wave mod ap. membranes, not sure if they still exist. If you already have the sub you're going to use I suggest you find it's thiele small parameters(specs), decide what bass you like, high kick or low bass(bigger box) and decide on what kinda box you're gonna make.

[Frenche]

Back in the 90's i used to do installations like that using aperiodic membranes. What they would do is mount on the front side of the sub and act as a box, controlling the air the sub had to push and not letting it play as free to air and thus damage its suspension. They sounded excellent. In many apps much better than a box but they never got around much, they were expensive and needed a little unit connected to the amp called wave brain...so ppl just kept on making boxes.
Anyway,if you use it as free to air=no box , it will sound like crap yes. but you will get some low end bass.But everything in the trunk will resonate so loud you probably be hearing a more metallic noise:)
So either try to find an aperiodic membrane and put it on the top with no box or make a box and screw it underneath the opening. Dynamic Control used to make the Wave mod ap. membranes, not sure if they still exist. If you already have the sub you're going to use I suggest you find it's thiele small parameters(specs), decide what bass you like, high kick or low bass(bigger box) and decide on what kinda box you're gonna make.

Thanks for the explanation and background information on this set up. I looked it up and like you said, no one uses aperiodic membranes anymore. My favorite type of music is electronic. Trance, House etc. A punchy bass. So I would need to make a smaller box but then I realized that mounting it would be a pain in the ass, and it would be a lot of weight hanging from that frame. If I can't figure how to create a small safe lightweight box then I will probably look at IB subs. I saw some reviews on how well this kicker does in free space environments. The problem is I'm not looking for that low bass it would prob give. I might give it a shot considering its only 50$ on amazon. If I had a nicer budget I would go with a Luke box but I feel like I can still work something out to my liking with my options.

http://www.crutchfield.com/p_20610C104/Kicker-10C104.html?showAll=N&search=Kicker_10C104&skipvs=T#details-tab

Other ideas and thoughts are welcomed.

[kmarei]

The tightest bass I've ever heard was a similar setup
It was a hatchback, with a 1" wooden rear shelf with a 8" sub installed in the middle
Sunded damn good
You just have to seal the heck out of the trunk
It basically means you're using the entire trunk as a box
Which means you need a sub with a very stiff surround or if you give it too much power
It will over extend and blow

[StereoInstaller1]

The big issue you are gonna have is that modern woofer suspension has evolved to the point that an appropriate suspension for that type of install, or an Aperiodic install, simply do not exist anymore. So few ever were actually designed for that application even back in the day, but now it is rare to find anything.

The big trick is you need a stupid-high Qts, (over .9 is best) a fairly high Fs (about 30Hz for a 10") and HUGE excursion. If you wanted to play even 110db, you would want to see an XMAX of at least 8mm and power handling over 300 watts.

Way back when these cars were new, I had a bunch of 8" woofers made to my specs by Eminence. I used them in groups of 4 and powered them with Zapco amps, which have excellent cone control (slew rate and damping factor is what controls cone motion). I really enjoyed the bass I got from 4 of those 8" woofers running off of 600 watts of nice quality power...but a $50 woofer in one of the boxes I build these days would just destroy those old systems using 1/4 the power. The whole concept of "use the trunk as a box" pretty much guarantees rattles, and is incredibly inefficient.

So, that being said, I have a really nice condition JL Audio 10IB4, arguably the best sounding mass market Infinite Baffle woofer ever made. If you really wanna pursue that setup, I will gladly sell it to you. It will certainly preform very well in that particular install, as good as can be expected from a diaphragm flapping around in a baffle like that.

Luke

[Frenche]

The big issue you are gonna have is that modern woofer suspension has evolved to the point that an appropriate suspension for that type of install, or an Aperiodic install, simply do not exist anymore. So few ever were actually designed for that application even back in the day, but now it is rare to find anything.

The big trick is you need a stupid-high Qts, (over .9 is best) a fairly high Fs (about 30Hz for a 10") and HUGE excursion. If you wanted to play even 110db, you would want to see an XMAX of at least 8mm and power handling over 300 watts.

Way back when these cars were new, I had a bunch of 8" woofers made to my specs by Eminence. I used them in groups of 4 and powered them with Zapco amps, which have excellent cone control (slew rate and damping factor is what controls cone motion). I really enjoyed the bass I got from 4 of those 8" woofers running off of 600 watts of nice quality power...but a $50 woofer in one of the boxes I build these days would just destroy those old systems using 1/4 the power. The whole concept of "use the trunk as a box" pretty much guarantees rattles, and is incredibly inefficient.

So, that being said, I have a really nice condition JL Audio 10IB4, arguably the best sounding mass market Infinite Baffle woofer ever made. If you really wanna pursue that setup, I will gladly sell it to you. It will certainly preform very well in that particular install, as good as can be expected from a diaphragm flapping around in a baffle like that.

Luke

Thanks for being unbiased on trying to sell me your product.
How much would you let that JL go for? I'm pretty set on that cheap kicker to test out what that set up will sound like after I sound deaden my trunk.

Thanks

[Dozyproductions]

A thread all about this!

http://www.diymobileaudio.com/forum/member-reviews-product-comparisons/136195-best-subwoofer-infinite-baffle-application.html

[Frenche]

Quick update to this thread. First of all, thanks to Eric Berger for helping me with the wiring.
As much as I want to say I told you so to everyone that put me down for wanting to do my own thing and not use a damn box I wont say it.(Not targeting this thread in specific). That's because I don't have solid proof of how badass it sounds through video. For everyone that's local thats another story and you can come check it out.
It also turns out the hole is actually for 12 inch woofer. My buddy gave me an old 4ohm bazooka EL series sub for free that must date back to at least 10 or more years ago. I threw it in and... well it works great.
Have no clue what the damn qts of fz's are but it was free$ so it sounds badass and I don't care if it blows. No vibrations and I'm not even done covering the trunk with deadner and properly sealing it.
I will admit to having some distortion and vibration when I turn it up to an unbearable amount of bass. Which means shaking the whole damn car. So I could care less about the buzz since it won't be turned up that loud.
The only drawback for me is that I'm receiving a lot of low end bass as predicted. Not something I'm going to cry over considering how cheap I got this all together.
Thanks for the amp recommendation Luke it works great. I will take pictures of my install once I'm done. Nothing much to see but I have realized that there isn't many different kinds of documented set ups on here.

[StereoInstaller1]

Congrats!

And just to explain, Box sales are not why I came here. I am here for the community. Most of my friends and most of everything I do revolve around this forum in one way or another.

This forum named my company, created the logo and basically, this forum forced me to produce the products we sell.

The least I can do is offer some advice, right?

Sometimes, it even works out pretty well.

Glad you have some decent music in your car.

Luke

[Cabriolet]

Ya that install wasnt the worst. Now more than ever, i wont be recommending the Kenwood HU. The Alpine easy mode interface is just too good. However, for a system than was about $300, that shit ain't bad. the near infinite baffle does make the base muddy but it still hit pretty hard for being such low Wattage. i think we are mounting the amp this weekend and just tidying things up. I had to spend about an hour cleaning up the 2 previous stereo installs and cutting out what was left of the 90's alarm system. the 5m steetwires RCAs seem to be a very good option and i'm forsure getting them for my next installs.

[StereoInstaller1]

Ya that install wasnt the worst. Now more than ever, i wont be recommending the Kenwood HU. The Alpine easy mode interface is just too good. However, for a system than was about $300, that shit ain't bad. the near infinite baffle does make the base muddy but it still hit pretty hard for being such low Wattage. i think we are mounting the amp this weekend and just tidying things up. I had to spend about an hour cleaning up the 2 previous stereo installs and cutting out what was left of the 90's alarm system. the 5m steetwires RCAs seem to be a very good option and i'm forsure getting them for my next installs.

*like*

[Frenche]

Okay so I usually hate showing things without it being completely done but here is the amp finally mounted. Now I have to obviously clean up the wiring.

The muddyness of the sub is actually already starting to piss me off. I've covered a lot of holes with deadner but not enough. I'm about to go crazy and deaden the hole trunk.
I'm going to read up more on how to get a successful IB sub running. I've read a bunch of threads on the audio forums about how this can work. I just need to learn more about it. I don't want to blame it on the sub but well see. (not enough wattage?)
I saw that you recommended special specs on the sub Luke but it is damn hard to find subs made for IB nowadays. Especially for under 200! I have found an old school IB JL 12 inch on ebay new in box for 120. The whole point of this install though was to make it really cheap and see what I could pull off. Or else I would have gotten a box. But... now I feel kind of motivated to see what I can do with this.

[StereoInstaller1]

Frenchie, the other issue you are gonna have is the amp really wants to see a 2 ohm load.

What that means is that you are getting half the power out of that bass amp.

Finding a 2 ohm woofer (DVC 4 ohms/coil) is gonna be tough, I don't think any of the "classic" IB woofer were.

I am really curious though, have you heard any of our E30 subs, aside from Erics' 'vert?

Luke

[Frenche]

I'm off to see what all this 2ohm 4ohm stuff means.
I have only heard Eric's. My friend Albert has the box an the amp rack. Ill listen to his when its hooked up.

[StereoInstaller1]

I'm off to see what all this 2ohm 4ohm stuff means.
I have only heard Eric's. My friend Albert has the box an the amp rack. Ill listen to his when its hooked up.

Albert hasn't gotten that done yet? WTF, what a slacker!

Amplifiers make more power the harder you "load" them. Theoretically, if the load double, the power does too.

so, your amp makes 350 watts on a 2 ohm load, or about 180 on a 4 ohm load. if you had an 8 ohm woofer, that same amp will only make about 75 watts.

On the other hand, if you did a 1 ohm load, it would just smoke instead of trying to make 700 watts.

Ohmage has NOTHING to do with size, shape, big magnet, small magnet, nothing, it is only how it is wired internally, and there is nothing you can do to change it. DVC is only intended to wire the same woofer 2 ways. For example, a DVC 4 ohm per coil woofer can be wired for either 2 ohms or 8 ohms, but that is the only choices.

HTH,
Luke