[RyanCT]

It would require cutting two holes, one through the sheet metal, one into the cabin.

[mathematics]

sending you a PM

Originally Posted by RadRyDawg

It would require cutting two holes, one through the sheet metal, one into the cabin.

[aznbo187]

Love this thread!

Kaigoss, I'm actually thinking about stepping down from a 15" IB to a 12" IB. How much bass can I expect to lose?

[kaigoss69]

Originally Posted by aznbo187

Love this thread!

Kaigoss, I'm actually thinking about stepping down from a 15" IB to a 12" IB. How much bass can I expect to lose?

There are two considerations:

Displacement. This is a combination of cone area and excursion capability (xmax). The more displacement, the more volume.

Distortion. The more the cone has to travel, the more distortion is produced.

So once you understand the relationship between displacement and distortion, it should be clear that CONE AREA is the most important property in IB.

The question of whether a 12" subwoofer in IB can get loud enough - without producing any audible distortion - is totally subjective. It may be enough, it may not. There is only one way to find out. However, if you consider the fact that 15" subwoofers are not that much more expensive than 12s, and that the 15 will always play with less distortion, and if your install can fit a 15", then it should be a no-brainer to select the bigger size subwoofer.

If a 15 can't physically fit, or if there is another reason for going with a 12, then you should select an SQL type driver with a large xmax. My "short list" of drivers would be as follows:

IDMax 12
JBL w12Gti
JL 12w7

[safe d]

Hi Guys.

I am also on the IB tip, but coming across obstacles like I never have before in any other car. I have fold down seats and no ski pass (whats the point o that?)

Anyway, just coming to fit the baffle to the car body, and need some ideas on how to secure. From the top, I have taken the similar route as Kaigoss ( nut and bolt under the parcel shelf and next to folding seat catches). But I would also like to secure from the side as well, to reduce air gaps. Something like the metal equivalent of a wall plug.

That is unless the side popper holes can take thread?

What do you guys reckon?

[kaigoss69]

I'm not sure there are an metal surfaces on the sides that you can drill through (just going by memory though). What I did is I laid a layer of thick weatherstripping on the wood surfaces on the sides of the baffle, then wrapped the carpet around. That way, there is a better seal to the side trunk panels.

From a structural standpoint, I think you can get away with bolting top and bottom, and "wedging" on the sides, AS LONG AS you are using a thick enough baffle. 1.5" should be the minimum I think, ideally thicker.

[e90TiAg335i]

You could use some 90 degree brackets on the front of the baffle to the side of the car at the top sides of the back seat.

[safe d]

Some pics of my mock ups. Really don't wanna cut up this car.

[kaigoss69]

You need to at least double up on the thickness and you need to seal all around the baffle. This is a MUCH more difficult job compared to a fixed rear seat. Look at diyma for some ideas.

[kaigoss69]

I completed the next stage of my IB install. I went with a different subwoofer - the IDMax 15 - because I got bored and wanted to try something different.

The IDMax is a lot heavier than th AE sub, plus it can handle more power and get louder, so I decided to make the baffle the full width and height of the back seat. I also decided to double-up on the material - 3/4 birch plywood - and make it 1.5" thick for added rigidity.

I started with making a template out of cardboard:



Test fit of the single cut-out:



Dremeling the speaker opening:



Doubled-up baffle:



Test fit (there was a LOT of grinding and sanding involved to get it right):



Finished baffle:



Baffle & Sub installed:



Wiring tidied up:



Shot from the front (carpeting separated a little during install):



Cover with speaker cloth (I don't like how it looks and I may do something different later):



How does it sound?

[bmw325i]

Originally Posted by kaigoss69

I completed the next stage of my IB install. I went with a different subwoofer - the IDMax 15 - because I got bored and wanted to try something different.

The IDMax is a lot heavier than th AE sub, plus it can handle more power and get louder, so I decided to make the baffle the full width and height of the back seat. I also decided to double-up on the material - 3/4 birch plywood - and make it 1.5" thick for added rigidity.

Nicely done

[mob17]

Always doing something better than before kaigoss! Bet it sounds bloody awesome.

[kaigoss69]

Thanks guys! E90TiAg335i did pretty much the same thing, and he likes it, too!

[Wongway]

Curious. (as this is more of a 'what if' kind of question)...

Since you'd be going through that much trouble for it anyways, would it be possible to simply delete the rear deck speakers and maybe make the opening bigger to allow for something like 2x8" speakers set up in an infinite baffle? I would think it would allow for just as much cone area as 1x15" speaker and you'd lose less trunk area for it, with possibly less difficulty cutting and sawing around.

First car I bought back in the day, I put one of these in there...

which worked to great effect. It was basically a JL Stealth box that set up 2x8" speakers in an infinite baffle setup under the rear deck. It just deleted the rear deck speakers.

[kaigoss69]

Yes, that is possible. You would need openings of at least 5x5 I would think. You would need to cut the rear deck metal, as well as the top (and the foam in between), and then install some sort of grilles in place of the OEM ones. Definitely doable.

[e90TiAg335i]

Originally Posted by kaigoss69

Thanks guys! E90TiAg335i did pretty much the same thing, and he likes it, too!

Yes it does sound pretty good. I may be adding another one or a 1k watt amp instead of the 500 watt on the current one. Decisions, decisions!

Originally Posted by Wongway

Curious. (as this is more of a 'what if' kind of question)...

Since you'd be going through that much trouble for it anyways, would it be possible to simply delete the rear deck speakers and maybe make the opening bigger to allow for something like 2x8" speakers set up in an infinite baffle? I would think it would allow for just as much cone area as 1x15" speaker and you'd lose less trunk area for it, with possibly less difficulty cutting and sawing around.

First car I bought back in the day, I put one of these in there...
[which worked to great effect. It was basically a JL Stealth box that set up 2x8" speakers in an infinite baffle setup under the rear deck. It just deleted the rear deck speakers.

You could but it would actually be a LOT more work. The rear deck is not entirely flat but their may be enough room for 2 8s. I highly doubt they would sound as good though. The two 8s would only equal half of the cone area of the IDMax15. Keep in mind ID runs their speakers an inch wider than standard. The IDMax15 is actually a 16" driver!

[Wongway]

Originally Posted by e90TiAg335i

Keep in mind ID runs their spekers an inch wider than standard. The IDMax15 is actually a 16" driver!

ahh, gotcha!

[joeyc123]

Kai, I'm curious to hear your opinion of your new toy versus the SBP15!

[kaigoss69]

double post, sorry.

[kaigoss69]

Originally Posted by joeyc123

Kai, I'm curious to hear your opinion of your new toy versus the SBP15!

I will try

The SBP15 sounds very natural/neutral, it disappears very well into the sound stage. It is incredibly efficient, hardly needs 250W to get very loud. I think it is a pure "SQ" subwoofer, and best suited for people who are not looking for overwhelming bass. If you want that - I mean deafening bass - you need to install two.

The IDMax is in another league. It is more of an SQL sub, meaning it does both SQ and SPL very, very well. It has a much stronger motor, and stiffer suspension, which means higher power handling, but also results in more "attack" and impact (that kick-you-in-the-back/chest sensation). At the same time, it plays just about anything you throw at it with incredible detail, and unless you crank the bass way up, you will never know that there is a beast in the trunk!

The IDMax 15 is an amazing subwoofer, perhaps one of the very best "all-rounders", but it also costs twice that of the SBP15, and it weighs twice as much.

With both subs, I have found that you need to set the crossover no higher than 55Hz, otherwise it will pull towards the back.

[bmw325i]

I think with any sub you should set your crossover no higher than 55-60hz.

[joeyc123]

Thanks Kai, looking forward to using the SBP!