Subwoofer install question - tire holder removal

[BigKriss]

I doing a stero upgrade on the car shortly. I'm thinking of not carrying the spare wheel in the car and using that space for a subwoofer. I don't know the size on the spare tire compartment, I'm guessing 30L.

Whats the best way to remove the tiire holder?

[netmgr]

angle grinder....bet u get a flat tyre though a week after its all fitted!!

[Derek A.]

There are other ways to do a sub without sacrificing your spare. I did a 10" box in my trunk - with quick disconnects.

[RobPatt]

..don't know your stereo tastes, but I've got an Infinity Basslink from e-bay for about $125 and it sounds great lying flat deep in the trunk on that metal shelf and knocked out that skibag panel.... -Rob.

[Johntee540]

The key is you have to remove the Ski Bag Pass thru in order to get the bass from the trunk into the cabin. Otherwise you are wasting your money.

I built a cabinet that houses 2 12" Alpine R12 Subs facing forward. I cut holes in the metal behind the rear seat as well as took out the SKI Pass through. The Subs fire into the cabin through the rear seats. Works great - JT

[Mobius]

The key is you have to remove the Ski Bag Pass thru in order to get the bass from the trunk into the cabin. Otherwise you are wasting your money.

Absolutely not true. Though there is a lot of insulation between the cabin and the trunk behind the seats, there is very little through the rear deck. I have a pair of 10" Kicker Competitions in a bandpass box and they're only marginally quieter in my trunk than in the open trunk area of my friend's wagon. Bass is really tough to muffle. The E34 trunk does a very poor job of it; despite the many layers of insulation. There is little reason to remove the ski pass-thru, unless you actually want to pass things through it (which would be nice).

If you're running smaller subs and you're trying to get some midbass out of them, then you're going to run into insulation issues. The rear deck is practically transparent to anything below 100hz.

I built a cabinet that houses 2 12" Alpine R12 Subs facing forward. I cut holes in the metal behind the rear seat as well as took out the SKI Pass through. The Subs fire into the cabin through the rear seats. Works great - JT

This is a less-than-optimal setup. Though it makes logical sense that you'd want the sub ports facing the sound stage, the opposite is often true. It depends entirely on the accoustics of the car. In the case of the E34, there is a very obvious decrease in sub volume when I turn my box around so it fires forward. It can be very beneficial to utilize the trunk as a sort of 'secondary enclosure'.

[Incantation]

I have had a different experience. I have found the e34 trunk to be extremely restrictive letting bass through, so much in fact, that even after removing the ski-pass, firewall insulation, and also custom building a back/seat mount for amps out of 3/4 mdf, you can still hear more bass in the car if you open the trunk and allow the sound to come from outside the vehicle. I had the same setup in my acura legend and the bass pounded far harder through the back seat.

e34 trunk muffles everything.

[Mobius]

e34 trunk muffles everything.

Huh. Really don't know how you can come to that conclusion. My subs are only even getting about 100w a piece.

This box is much louder in this car than in my previous car (Volvo 240!) which had no trunk insulation to speak of (and a ski pass-thru, even). It's still being powered by the same amp.

Really, though - it's crucial that the subs fire towards the rear. There is a night and day difference in sound output when you turn them around. It's very tempting to think that firing them at the 'audience' is the best method, but that is not the case.

[rockyfeller]

I agree with Mobius. There are 2 way subs will sound good in a sedan....if you have fold down seats, like some other cars, if you place the box all the way to the rear of the car facing forward you will get phenomenal sound. Otherwise with cars without fold-down seats of at least with the ski-pass through like our E34s defintely a rear facing enclosure will yield the best results. Remember bass is low-frequency and you don't "hear" it from the front of the speaker. 90% of bass comes from the back of the woofer and out the ports. Once this resonates throughout the trunk the bass sounds wicked. Try it both ways if you don't believe me...I did.

[Johntee540]

That's interesting. This was a professional setup. They do the local Ferrari shops installs. Brian Mitchell's New Ferrari was in getting his usual A/V set up installed.

The Ports are also vented forward through one of the holes in the completely solid steel panel that BMW puts between the seats and Cabin.

There is this one legendary e34 on the IASCA Pro Series Stereo Circuit I had seen years ago - and this was the set up it had. This particular car is available to be seen on CarDomain if you search on 1994 540.

Based on a 2 hour commute (my Ear Dyno) and having done 6 of these types of systems in the past with IASCA contest winning Audio Techs whom I trust - I respecfully disagree.

Unless you open the sound passage from the trunk to the cabin you have no where for the low frequency a sub produces to travel. In otherwords you have nice eye candy for your trunk but no sound quality. My set-up can break up any Kidney stones you have using sonic waves if you are sitting in the back seat. - JT