I got a new pioneer 500w free air subwoofer and an avalanche 500w four channel amp, just had to tell.

Installed it in the rear parcel shelf and then bought one of those pioneer subwoofer covers to put on it, looks shmico sitting there, and has heaps of bass, love it.

Has anyone else used the space there for a sub yet??? My te had a removeable cover with four screws for the sub, kool.

Generally using 8" or larger speakers in the parcel shelf, it would be good to sound deaden the underside of the panel and possibly brace it with MDF if you are putting heaps of power through.

I put this idea to the forum ages ago and did a bit of research into it.

Anyways, there's a couple of threads on Car Audio Australia that I read about it. One was from a guy who had a Magna and had put a sub in the 8" Parcel Shelf mount, another was a guy who had a mate who had just bought a Falcon with the premium sound system (which comes with an 8" Sub in the parcel shelf). :roll:

The verdict? DON'T MOUNT A SUB ON THE SAME SURFACE AS YOUR 6x9s! :evil:

The problem is the sub frequencies are transferred mechanically into the drivers in your 6x9s and cause all kinds of hassles. The guy with the Falcon ended up destroying his 6x9s during a 2 hour trip. :oops:

My own theory is that if your run the sub at a lower level mainly for bass reinforcement and not for Doof you should be okay. But who gets a 500w sub and doesn't want doof? 8)

Suggestions: Well, sounds like you've gone to a lot of trouble to mount it in the parcel shelf so my first suggestion of mounting the sub against the ski-hole probably isn't ideal. My second suggestion of removing your 6x9s isn't very good either. Also, you may want to consider security because everyone can see your sub when they walk passed. #-o

As Damien said, do not ever mount your subwoofer drivers in the same enclosure of any other drivers. In this case, your boot is acting as an enclosure.

In fact, your subwoofer would not be working as efficiently if you do use the boot as an enclosure because:

1) The boot is not a totally sealed compartment
2) The "venting" of the boot is not tuned (Yeah the air holes!)
3) The volume of the boot is most likely inaccurate for your subwoofer driver.

But these are free air subs, so they don't need an enclosure if i remember correctly...

Free air subs need an enclosure too, but the bigger it is the more they love it. If you had a sub in true free-air (held it in your hand) it wouldn't make any sound at all.

I think what Tecodan said was a bit confusing, in that he is first referring to the boot acting as a sealed enclosure, then after that as a ported enclosure. The boot can only ever act as a sealed enclosure even though it is not 100% airtight. It will be sufficient as an enclosure for freeair sub though as it would give it a good 5-6cubic feet of volume.

IMHO there shouldn't be too much of a problem having subs and 6x9s on the rear shelf except for rigidity issues. 6x9s themselves are freeair speakers too and having them in the same "enclosure" as the sub simply reduces the amount of volume available for each of the 3 speakers.

Possibly try high-passing your 6x9s at 80-100Hz, then low-pass your subs at the same figure.

Remember guys this is a FREE AIR SUB, I went to great lengths to get one of these things, I did my research on them, and they dont need any enclosure to work properly, and it sounds bloody unreal, the 300w 6x9s in the rear shelf are having no problems at all, and that was driving around in 40 degree heat for about 5 hours, it is pure bliss, I mean bass!!!

The whole car has become a five seater massage chair!!! :badgrin: Especially on some of the techno tracks, gives a fine massage for five adults, hehehehe. 8)

Oh and damien that was half the reason for putting it there, so people could see it, do you know how hard it is to install a sub there, you have to remove the back seat alltogether and unclip the rear shelf before you can even think about unscrewing the thing so I highly doubt it will get stolen, but get lots of attention.

The problem is that they don't know that it is hard to steal; they only see it and give it a shot. Unfortunately they usually get pissed off if they can't get it out and use the screwdriver for more destructive means.

hmm, free air subs? Sorry I didn't quite read the original post properly. THough this is the first time i've heard about free air subs, I might have to look into it and the physics of it. I'm an old skool audio enthusiast, I still like tube amps :)


Basic physic theory for speakers are that they need to be mounted on some sort of a baffle to prevent sound waves coming out from the front of the cone interfering with the air behind it.

So as tek pointed out, just holding a speaker in your hand will not make much sound, and I would also think its the same for free air subs.

When I said boot space used as a sealed enclosure is not the right assumption, thats because the boot isnt really air tight due to holes going into the interior, holes into the bodywork for cabling and what not. This isn't efficient for subwoofers. Volume will need to be accounted as well, a huge box than required for a subwoofer will lead to loss of bass at specific octaves/freq.

In the case of free air subs, if what I hear is correct that they dont need an enclosure, then the boot space is ok and theres no harm. But this is not the case for traditional subwoofers!

okay found this that explains a bit of free air subs

http://www.google.com/search?q=cache:qPI2vtrHDQIJ:www.decware.com/secrets3.htm+free+air+subwoofer&hl=en&start=20&ie=UTF-8


The gist is, you still need an enclosure for a free air sub, or at the very least....a baffle. The point being of a free air sub is that the volume of the enclosure and the air tightness of the enclosure is no longer critical. So your boot is acting as a sort of an enclosure with the rear seats and the parcel shelf as a baffle.


What I still don't recommend is having the 6x9's in the same space as the subs. If you do, maybe make some sort of enclosure for each of the 6x9's. That way the air the sub is producing will not affect the 6x9's cone.

I think tek's suggestion of putting a high pass filter will work too, to preventing the 6x9's woofers moving too much.

But I still have a feeling the sub will still interfere with the 6x9's at high volumes. You could try disabling the 6x9's and see whether the 6x9's are making any noises when the sub is pumped.

The 6x9s are only running off the head unit, so are getting a 45w channel each, the only thing the amp is powering is the sub.
I set it up so I only need a small amount of noise coming from the rear speakers and the front speakers but alot of bass from the subwoofer, works very nicely, so I dont get ear splitting high tones from the little speakers just enough to hear singing etc but heaps of bass with it.
So the 6x9s arent doing much at all just a complement to the sub.

Thanks for that article too dude, I did read it, and I am obviously getting NO cancellation from my install as it is extremely bassy, I am very happy with it indeed.

I did have to cut out a circle in the rear parcel shelf material to mount it properly though, so yeah it is using the boot as a box, but it sounds so much better then other subwoofer setups I have heard, like my brother inlaws car, he spent $500 on a sub and amp with it in the boot in a box and it sounds no where near as good as my setup.
Also my cousin has two subs in the ski hole all proffesionally setup and it still does'nt sound as good as mine.

And I dont lose any boot space at all, that was the main reason for going this way.

it all comes down to box design and positioning......u can have a $10,000 sub sounding shit if its in a crap box and sitting in a crap spot.......

it all comes down to box design and positioning......u can have a $10,000 sub sounding shit if its in a crap box and sitting in a crap spot.......

Yep especially true for non free air subs. A friend bought two JL Audio 12" drivers from somewhere then gave it to Autobahn who installed the two drivers into one sealed enclosure (generic box). There was no seperation of the two subs, plus the guy set it up to run the drivers in stereo :shock:

Don't worry, he has chucked the old box out and had it redesigned, and its so much better now ;)

Oh and Damien that was half the reason for putting it there, so people could see it, do you know how hard it is to install a sub there, you have to remove the back seat alltogether and unclip the rear shelf before you can even think about unscrewing the thing so I highly doubt it will get stolen, but get lots of attention.
Yes I do, as I said previously, I spent a lot of time looking into it because I wanted to do the same thing. But as somebody else has mentioned, a thief will not know how hard it is.

Don't get me wrong, I really do hope that this setup works for you, and I know how much better it will sound having the sub driver in the cabin with you as you will be getting a much more aligned group of compressions and rarefactions (not to mention you still have your whole boot). But I just wanted to let you know that there is very little proof that it won't cause problems over time. The cones in your 6x9s are not gonna like the conflicting frequencies coming out of that sub, that's all. You won't notice it straight away, it will slowly degrade over time.

Filtering may be a good preventative option, and I'm just thinking out aloud here, but you would probably need to go for a third order filter (18dB/8ve) for it to be effective, and you should make sure you design the filter to the highest degree possible. For example, work out what the specific impedance is at your chosen filter frequency and then source caps that are ideal for the respective power, accurately wound inductor, etc.

Damien, any chance of you coming to brisbane and giving me a few tips dude, any time your up here pm me so we can hook up, and you could show me a few things, cause you seem to know what your on about with this stuff.

Cheers.

(Wipes single tear from eye) Wow man, nobody's ever said anything like that to me before. I'm truly flattered. :oops:

Well, I have no immediate plans to come up to Brisvegas, although I may be down in Adelaide soon. I'm also hoping to be at Magna Meet, but we'll see. However, if I am ever up north I will certainly get in contact.

Cheers dude.

[quote:b88fea4947]avalanche 500w four channel amp[/quote:b88fea4947]

Did you bridge it for more power?? ;) What are the other 2 channels doing? I hope for your sake the amp lasts long than 3 months.

Mr charisma, yeah I bridged one side of it for the sub, but the other side is doing nothing at the moment, probably get another sub???