[mweisdorfer]

Can anyone tell me the absolute lowest point regarding mounting depth that can be installed in the OEM boxes under the seats?

I know the earthquakes are 2 1/8. I read that the Kicker SSMB 8" mid-base subs were 2 5/8 deep and could be installed under the seats.

Does anyone thing 2 3/4 could be done ?

Please advise

[ctuna]

Look at what VP Electricity did to squeeze a bigger speaker
into the under seats in this thread.

https://www.e90post.com/forums/showthread.php?t=833581

[mweisdorfer]

Originally Posted by ctuna

Look at what VP Electricity did to squeeze a bigger speaker
into the under seats in this thread.

https://www.e90post.com/forums/showthread.php?t=833581

Ok, so I looks like there's additional depth available under the sub box. So, VP used some sort of poly type board to make a shim or sorts in order to capture the additional depth.

Nice.

I am looking at the Kenwood KFC - XW800 F

It has a frequency response of 50hz to 500hz.

I really like Technique's ultimate upgrade. I noticed that his underneath subs had a similar frequency response and they had a mounting drop of 2 5/8", which is of course only 1/8" shorter then 2 3/4.

This 8" sub gets a lot of 5 stars on multiple sites.

I will probably take 6 months to a year, in order to "collect" all the BMW IA speakers. I like JBL amps, so I'll probably get a couple of those unless a find a great deal on a JL xd600/6. I think technique had 2 Alpine amps. I have one 2 channel JBL running my subs now; so, I'll just get 2, four channel amps & call it good.

My most recent cross overs I used are 55 for the subs w/ 12db; I tried 18 & 24, but didn't like either. 18 wasn't too bad. I've tried 50 too.

All the other speakers I used 220 at 24db except the sides. I think a had them at 120 or so at 24db.

I've played with the EQ a little too.

I've almost got it dialed in. Just need a little more bass response. Not totally sure how to get that. If I just use the amp to give that little extra or play around with the EQ and other settings in the JBL MS 8.

[mweisdorfer]

Originally Posted by ctuna

Look at what VP Electricity did to squeeze a bigger speaker
into the under seats in this thread.

https://www.e90post.com/forums/showthread.php?t=833581

Ok, so crutchfield recommends 2" from the back of the magnet of a subwoofer to the inner wall of a sub box, for proper fitment and room to breath.

I admittedly have not taken the OEM subs out to see exactly how much room is in the sub box.

Is there 2" of space from the back of the magnet of the oem subs to bottom of the underseat sub box ?

[kaigoss69]

The mounting depth of the Kenwood sub is 3 5/16", or 84 mm, because you have to account for the height of the flange, since it has to fit under the seat rail. The total space available, from the bottom of the floor pan to the bottom of the seat rail, is about 80 mm. I'm saying "about" because the floor pan is sloped and the wider the magnet, the more the sub will be pushed upwards and the allowable height will be less than 80 mm. I installed Morel HCW-10 mid bass drivers with about 80 mm total height, and the seat rail was about 1 mm away from the top of the rubber surround. The magnet on the Morel was fairly narrow which allowed me to squeeze this in. I am 100% sure that the mentioned Kenwood sub will not fit, because its total depth exceeds 80 mm.

Besides the physical limitations, I believe I have mentioned dozens of times before that the underseat location is not made for bass and sub-bass, because there is not a suitable enclosure for the sub to "breathe" on the back side. Also, there is not enough space under the seat for a standardized subwoofer enclosure, and even if you were to mold a fiberglass enclosure in there, I doubt you would be able to get much more than 0.2 cubic feet (the OEM enclosure has 0.1 cubic feet volume). Most subwoofer drivers will not work properly in anything less than 0.5 cubic feet. In my mind, the absolute only way to make a true subwoofer work in that location - assuming you can fit it - is to cut open the bottom of the floor pan and to allow it to breathe to the outside of the car and play infinite baffle. I almost did that once, but decided it was too much effort and from a standpoint of sound quality, it is much better to use the underseat location for mid-bass, and have a separate trunk sub for the low bass. That is what it really comes down to, if you want the absolute best results, you can't compromise and you must have dedicated/separate drivers for mid bass and sub bass. Underseats handle roughly 60-250Hz, trunk sub handles 60Hz and down. Anything else is a compromise with mediocre sound.

[mweisdorfer]

Originally Posted by kaigoss69

The mounting depth of the Kenwood sub is 3 5/16", or 84 mm, because you have to account for the height of the flange, since it has to fit under the seat rail. The total space available, from the bottom of the floor pan to the bottom of the seat rail, is about 80 mm. I'm saying "about" because the floor pan is sloped and the wider the magnet, the more the sub will be pushed upwards and the allowable height will be less than 80 mm. I installed Morel HCW-10 mid bass drivers with about 80 mm total height, and the seat rail was about 1 mm away from the top of the rubber surround. The magnet on the Morel was fairly narrow which allowed me to squeeze this in. I am 100% sure that the mentioned Kenwood sub will not fit, because its total depth exceeds 80 mm.

Besides the physical limitations, I believe I have mentioned dozens of times before that the underseat location is not made for bass and sub-bass, because there is not a suitable enclosure for the sub to "breathe" on the back side. Also, there is not enough space under the seat for a standardized subwoofer enclosure, and even if you were to mold a fiberglass enclosure in there, I doubt you would be able to get much more than 0.2 cubic feet (the OEM enclosure has 0.1 cubic feet volume). Most subwoofer drivers will not work properly in anything less than 0.5 cubic feet. In my mind, the absolute only way to make a true subwoofer work in that location - assuming you can fit it - is to cut open the bottom of the floor pan and to allow it to breathe to the outside of the car and play infinite baffle. I almost did that once, but decided it was too much effort and from a standpoint of sound quality, it is much better to use the underseat location for mid-bass, and have a separate trunk sub for the low bass. That is what it really comes down to, if you want the absolute best results, you can't compromise and you must have dedicated/separate drivers for mid bass and sub bass. Underseats handle roughly 60-250Hz, trunk sub handles 60Hz and down. Anything else is a compromise with mediocre sound.

The Kentwood has a mounting depth of 2 3/4".

It's frequency response is 40 to 500hz.

The kicker SSMB 8 had a mounting depth of 2 5/8"

It's frequency response was 30 to 500hz. This is the sub technique used in his ultimate upgrade (kicker SSMB 8).

The Kenwood KFC XW800F is fairly close to the Kicker SSMB 8 when comparing frequency range.

The only item the Kenwood XW800F differs is sensitivity dB at 78 vs 88 of the Kicker SSMB 8.

Kenwood XW800F -

https://www.crutchfield.com/S-BWLmXE...SAAEgLr7PD_BwE

Kicker SSMB 8 -

https://www.crutchfield.com/S-Cwo25o...ker-SSMB8.html

The only thing is the Kicker SSMB 8 is really hard to find even used. The Kenwood XW800F is easy to find brand new and cheap at $85.00 a piece on eBay brand new.

If I'm wrong on the mounting depth of 2 3/4 by not taking into account something, I apologize. I by no means pretend to know as much about car audio as most people on this forum let alone someone of your stature.

Please advise...

[kaigoss69]

Originally Posted by kaigoss69

The mounting depth of the Kenwood sub is 3 5/16", or 84 mm, because you have to account for the height of the flange, since it has to fit under the seat rail.

I'm just going to say it again, and include a picture from the Kenwood manual for visualization...

Edit: Also, did you read the second paragraph of my post?

[bigjae1976]

You need room on the backside if the voice coil is vented which most subs are. This promotes cooling the coil. Otherwise there is no minimal clearance as long as there is some clearance

[Emilime75]

Originally Posted by mweisdorfer

The only item the Kenwood XW800F differs is sensitivity dB at 78 vs 88 of the Kicker SSMB 8.

That is a terrible efficiency rating. Also, even though I've been out of the car audio scene for a while, Kenwood has never had a worthy component if better than average sound quality is expected.

[Emilime75]

Originally Posted by kaigoss69

I'm just going to say it again, and include a picture from the Kenwood manual for visualization...

Edit: Also, did you read the second paragraph of my post?

I understand what you're saying with the seat rail and all, but 84mm here isn't the "mounting depth" in this situation. There are 2 concerns with trying to fit a driver under the seats. The first being what physically fits inside the enclosure, the second being what fits under the seat rail and grill once mounted in said enclosure...not to mention mounting cutout diameter, overall diameter, mounting screw holes...

[mweisdorfer]

Originally Posted by Emilime75

That is a terrible efficiency rating. Also, even though I've been out of the car audio scene for a while, Kenwood has never had a worthy component if better than average sound quality is expected.

This particular 8" sub has 4 & 5 star ratings on every website I have looked at.