I really want to try this but obviously those C-pillar cavities are far from an ideal location for subs. However, I recently learned about aperiodic membranes which permit tiny enclosure size and think it might work in this application. My idea is to fab a baffle board from 1" MDF and mount it into the C-pillar cavity. I would cut a ~4" hole in the back of the panel opposite the driver and place the AM there. An 8" driver would fit provided that it's mounting depth is less than 4". The speaker cavity is approx. 7" x 9.5" x 3" but the baffle board will add 1" of depth and the taper of the basket will allow it to fit the 7" dimension.

Now the problem is finding the right driver. I don't want to spend a lot because this might sound like crap. According to informed sources, AM enclosures work best with drivers having <.45 QTS. So far I've only found a few choices and I'd like to get some opinions on both drivers and this whole crazy idea. I'm not expecting to get the bass of even a single 10" sub in a small sealed box but it seems to me that a pair of 8's in the c-pillars should exceed a small, powered sub like the 6.5" Kenwood or 8" Blaupunkts under the seat.

What do you guys think about the following drivers?

http://www.partsexpress.com/pe/showd...number=295-480

http://www.partsexpress.com/pe/showd...number=295-545

http://www.daytonaudio.com/loudspeak...reference.html

http://www.partsexpress.com/pe/showd...number=264-832

I'd really appreciate your opinions and any suggestions.

Good info on aperiodic membrane sub enclosures: http://www.elitecaraudio.com/article.php?sid=18

 

That's an interesting place for subs, however, a proper aperiodic enclosure has the back of the membrane venting into some open space (such as the outside of the car) to work properly. Sometimes an install is done with the subwoofers behind the seats in a sedan (which is an infinite baffle installation) and small boxes behind them with aperiodic membranes that vent into the rest of the trunk. Other times the space behind the membranes is vented outside the car (as I said before) or into the frame somewhere.

 

According to the author of the AM how-to article I posted, as long as the air volume behind the membrane is significantly larger than the air volume around the woofer, it should sound good. Although he also mentions, as you did, that it should vent outside in an application such as this one. My thought was that there are openings to the outside in the body sheetmetal behind the C-pillar panel. However, after closer examination of the actual interior panels, I've decided to scrap this idea. I don't think the panel is rigid enough for a sub and would have to be reinforced with fiberglass or similar. Then there are seams between the panels and openings that would probably have to be sealed air-tight. All things considered, those C-pillar cavities are best suited to full range speakers but no good for subs without a ton of work. Since I have no use for extra fill behind my front sound stage, I guess those C-pillar cavities will remain useless. Oh well...

I'll probably just buy an eD enclosure or make my own. I could still do AM in back but it's so much easier to stick with a sealed box. I do like the idea of flipping the spare tire over rather than removing it as eD did.

 

Aperiodic enclosures could work if designed right, but I don't think you'll be able to make it work. You still need strength in the enclosure (not panel plastic) and you'll need to attach to the body to hold it in place. Lots of obstacles. My computer speakers are actually aperiodic (built them myself, the transmission line versions were just too big) so I do know some things about the topic. You may want to buy a Variovent from Madisound or some place similar. This will help.

If you're set on trying, consider Dynaudio, Morel (mine) or Scan Speak drivers. They work very well in aperiodic configurations. In cars, the only car-specific drivers I've seen used in aperiodic installations are Image Dynamics. (use to be an IASCA SQ judge)

Don't use a large-displacement sub as the aperiodic enclosure has too little volume to help driver (like a spring on the back side that too stiff). Infinite baffle car subs seem to work the best. They have the mechanical stiffness (Qms) to control the sub without it being stifled.

The drivers you're considering could probably be mounted in a sealed enclosure in the location you're looking at. They're all fairly small, and you'd be hard pressed to make the aperiodic enclosure smaller and main the back side of the membrane free of obstacles. The 210 would work nicely, IMO.

 

You could put some kind of small processors in the C pillar space, and there is *plenty* of room around the spare tire and those plastic storage bins on either side of it. The foam tray is also just about perfect to be duplicated in wood and fiberglass and act as an amp/processor rack.

 

I was thinking of using the space for rear fill speakers (5.5" or smaller, upto 7k Hz), but I like your idea as well.

The first time I picked up the foam tray, I noticed how much space it wasted and how easy it would be to replace with stronger, small materials.

 

It would be cool if the speakers had a rubber membrane around them and they could rotate by remote control on a motor. Scott Buwalda did this in one of his old Nissans. He had speakers mounted in rotating steel kickpanels with rubber membranes to seal off the front and back waves. He used a rearview mirror motor to move them around.

You can read his official page here:

http://www.buwaldahybrids.com/The%20Expert%20240SX.htm

 

I've seen 6x9's put in there and they fit perfect. A little bit of modding had to be done, but the end result was some nice sound from the rear.

 

Thanks. I think you're right about my aperiodic C-pillar sub idea being overly ambitious. It would be much more work than I'm willing to do and probably still wouldn't work very well. I was looking for something a lot easier like simply mounting drivers to the interior panel.

Speaking of which, IYO how would a pair of 8 or 6x9 sub drivers sound if mounted into the c-pillar panel on a 1" thick MDF baffle board using the plastic panel as a sealed enclosure? Would I get a lot of unwanted panel resonance? Would the panel absorb most of the subsonic wave energy? The enclosure size is only 7"x9.5"x3" (.12cf). I'm not looking for much here. I just want to reinforce the bass that's missing from the 6.5 and 5.25" door speakers. TIA.

 

Great ideas but I'm doing a very basic system here. In fact, I'm only using the base HU a small 120Wrms sub amp under the passenger seat, Infinity 6012i coaxials in the front doors and the stock 5.25" rear door speakers. If I can't place subs in the c-pillars my next preference would be to flip the spare tire and put a single sealed 10" in the rear cargo floor.

 

I think you'd definitely want an MDF enclosure but it doesn't have to be 1" thick. 3/4" or for a box that small, 5/8" would be fine. I think the panel might vibrate, but it's easy to "mass load" them with roofing rubber or Dynamat. And you might have to use weather stripping on the panel joints. I don't think the panel would "absorb" any of the energy. You will have to bolt the box to the metal of the car. I don't know what's behind the panel at the c-pillar so that may be your first task is to look for attachment points.

If the enclosure is really that small, you could put the box into the center console, between the front seats, or under the seat. It'd be a lot simpler. JL make the 6W0 which can be put into very small places. I've heard of people actually building a false floor and installing these subs. I designed an enclosure for a pair of them that fit onto the floor, straddling the hump, in front of the rear seat. I even designed it with cup holders. In the xB, that type of solution could have a large volume yet look like a stock console.

One place I always wanted to use is the roof, just in front of the rear gate. Roofs typically have stiffeners that become attachment points. And the curvature of the roof is usually fairly large. This would keep the drivers out of harm's way too. This would be for an experienced installer only.

Lastly, consider just below the shifter pod. I think you'll find this area may be easier to mod than the c-pillar and those little subs would be close to the listeners.

 

The Rumion has a ported enclosure in the c-pillar:




It looks to me to be about an 8" driver - but of course that is a guess. Just basing it on measuring the area in my Xb and estimating based on picture.

You can see more pictures here:

http://www.carview.co.jp/magazine/ph...fault.asp?p=32

I have been asking in other threads if anyone knows how to get Rumion panels. I would be very interested if anyone has any info about this. It is the factory subwoofer which is probably not something that will win SPL contests but might be just enough for some of us interested in supplementing the audio.

(I am more interested in the panels for the tweeter pods - you can see in the picture.)

 

If I were to build a 5/8" MDF box, the enclosure dimensions could be increased to almost 10x10x4 (.2 cf). I'd have to cut out the back of the panel cavity and attach the box to the c-pillar metal behind it. I suppose the first step is to remove the panel and see if there is a decent attachment point there. If not, time to move on...

I think the center console enclosure and the roof mount are both beyond my capabilities and it appears that the area between the shifter console and the center console is too small for what I want. Under the seat is a definite possiblity for my modest skillz.

Thanks so much for the great ideas and all your help.

 

That is just sooooo unfair! The Rumion seems to have everything that Scion forgot to include or even make available for the XB. I want paddle shifters and a factory c-pillar sub too, dambit!

 

Import it! It looks like the Rumion has lift-up rear seats. The shelf underneath is a good place to hide processors or amps. Of course in the xB, I don't think you can just lift up the seats :\ The foam storage tray looks deeper and more useful too.

EVERYTHING IS COOLER IN JAPAN

 

You sir are correct on all counts except one. The Rumion doesn't have the 2.4L available. Just an anemic 1.5 and a slightly better 1.8L... I want everything else.

 

The Rumion c-pillar is even a ported enclosure. It's definitely possible to replicate if you're willing to work with fiberglass.

I'd do it by glassing the back of the panel, and the top corner of the xB. Then join the two onto the panel. When reinstalling the panel, I'd attach the fiberglass enclosure to whatever supports were there. (or install some wood to give it support.) IMO, more effort than worth it unless you're looking to sell a kit or enter shows.

 

I'm about ready to give up on the c-pillars. Putting subs there is more work than I want to attempt. I'm looking instead to a simple down-firing box under the passenger seat. It appears that a 12x9x7 box with a 8" sub would fit well. It would be much more in line with my modest abilities. I'd actually prefer to just buy one.

 

After searching for many hours I could only find one under-seat box for a 8" driver. It's a very nice box from Pioneer but at $100, it's pricey, small (.16cf) and only accepts shallow drivers. I also found a 10" box on ebay for <$50 shipped that has 4.25" of mounting depth. I'm thinking about getting the 10" .3cf ebay box but have to decide on a driver. I'm torn between the Pioneer TS-SW2541D and the eD SQ10.

eD SQ10 - $70 - sealed vol. = .3cf -.6cf

Pioneer - $100 - .35cf-.70cf

From the comments I found on both, most seem to prefer the Pioneer but some say the SQ10 has better SQ but lower spl. My biggest concern is that I found some complaints about eD's quality and not honoring their warranty. I'd hate to get the SQ10 and it not last.

 

You won't be happy with the Pioneer. Basically, the driver motor isn't strong enough and the sound is "tubby".

Note, if you have the sub firing down, it changes the box "alignment" in to effectively a bandpass arrangement because the small ported volume on the front side of the driver. If it doesn't sound good after install, flip the box.

If you can't find a suitable driver (and I'm sure there are more than the two you mention), you could attach another baffle onto the purchased box to use an 8" driver. Many 8" subs work well within a .3 cf box.