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 - JTThis 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

[Johntee540]

I dont think people realize that the e34 trunk is an encapsulated space. There is no connection between the trunk and cabin.

Insulation is not what prevents the sound from traveling. It is STEEL. There is a wall of Steel at the front of the trunk that your rear seats are attached to.

This prevents any air pressure movement from the trunk to the cabin. Thus defeating the purpose of the sub. I am not using a Bandpass Box. I had a custom enclosure built that is ported forward into the cabin. The Subs also face forward.

A band pass box in an e34 trunk with out the requisite opening of the Ski Pass thru to allow the Low frequency sound into the cabin. Well - <imho> you have nice eye candy for your friends to see in your trunk. - JT

[pmlmotorsports]

the metal of the chassis will create a resonance that will cause harmonic "dirt" and make the sub sound less than accurate, so excessive Dynamat must be used. Furthermore the trunk compartment of these cars is like a vault and will smother all bass notes unless an opening to the passenger compartment is created. I suggest either opening the panel behind the rear armrest, or creating opening in the rear deck (I personally refuse to cut into the rear deck) Good luck

[RobPatt]

... if you want nice bass, and not thunderous 2x12" megawatt woofers bass, the infinity basslink (think it's max 100 watt? 10" active & 10" passive) placed horizontally on it's feet by the ski pass through hole works well....

[Derek A.]

http://www.opus45.com/pics/e34_sub.jpg

A single 10" put right up against an open ski pass through works great. I have a nylon strap that keeps it centered and secure. The two quick-disconnect plugs allow mw to get it out in a matter of seconds if I need extra storage space. Unless your goal is to piss off people at stoplights a single 10" is plenty for this car.

[Johntee540]

that would deliver a nice bottom end sound to the cabin. The key again is to open the trunk to the cabin. - JT

[Mobius]

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.Because that matters... how?


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.Completely solid - yep. It's also completely impossible for sound to move through "completely solid" objects. I mean, when I close the door to my room, I can just crank up my stereo as loud as I want and nobody can hear it.

I wish.

Bass frequencies are the LEAST restricted by objects in their path. There's a reason you can hear the kid in the Civic thumping from a block away, through three insulated walls and into your bedroom at 3 in the morning. However, you can't hear any sort of midrange or high frequency sound until you're in close proximity to the source of the sound.

I'll say it again: It is very hard to stop bass from penetrating things. There are some not-so-crazy physics formulas (http://www.tpub.com/neets/book10/39f.htm) that will relate sound velocity with material elasticiy and density. Not surprisingly, thin-gauge sheet steel is almost completely transparent to frequencies below 100hz.

I only wish the science of acoustics was simple enough to say "hey, you point the bass port at you and you get the most sound" - but it is abolutely not that simple, and that statement is absolutely not true.

Regardless of how hermetically sealed you think the BMW trunk is, I assure you it is barely sealed at all. If you wish to disagree with that, you are welcome to. It seems, though, that you're only talking about your own experience with having someone else install a system in your car, and have never actually played around with a freestanding box in your trunk yourself.

If you live anywhere near NW Washington State, you're more than welcome to drop by and hear just how "little" bass manages to escape the precisely engineered acoustic confines of my trunk. I think you'd be shocked.


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.Great. There was also a guy with a E34 525 who won IASCA trophies for mounting subs in his front fenders so he could listen to his Disney music in the most pleasing way possible (I'm not even joking).

If you want to push past, I don't know, say 140dB - then I can see the argument for needing some sort of method for increased airflow between the cabin and the trunk. There's no point of 140dB unless you're trying to win SPL competitions, so I think it's out of the scope of this discussion.


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. That's wonderful. You never say you've ever actually tried to mount a sub in the 'sealed' trunk, though. That's what I'm arguing here.


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.Again, thanks for the posturing - it's nice and all. But you're still wrong. Bass doesn't need a 'passage' to move in, and the E34 trunk is nowhere near sealed enough to need any sort of pressure-equalization ports to the passenger cabin unless you're really pushing some high SPL.


This prevents any air pressure movement from the trunk to the cabin. Thus defeating the purpose of the sub. I am not using a Bandpass Box. I had a custom enclosure built that is ported forward into the cabin. The Subs also face forward.From your earlier description, it sounds like you are using a bandpass (http://www.the12volt.com/caraudio/boxes4.asp) box? Then again, it was a vague description.

Again, to everyone else in this thread: Based on my experience with my car, punching out the ski pass-thru is completely unnecessary. Your mileage may absolutely vary; but before you go punching a hole there - try experimenting with the placement of the sub in your trunk. Just turning it around makes a LOT of difference.

Oh yeah, and if this is all eye candy, as you say, John - why does my box look like I stole it from a Civic (http://home.comcast.net/~rjchristie2/SA/535i/2909m.JPG)? Sub-Tek.. haha.. I've had it and the amp since I was 16. :)

[Johntee540]

I especially like the picture of sound traveling across the curature of the earth. Look - I have thought and experiences on this subject. You seem to have different thoughts and experiences. We seem to disagree.

I am traveling to Seattle the week of Dec 13-16 and would love to see your set-up. Staying in Bellevue.

The reason I mention the shop and their expertise is for legitamacy. It is the best shop in DC and they consistently build IASCA Contest winners. Several Washington Redskins; Philadelphia Eagles and even NY Giant Players travel there to have their rides done. It may not matter to you - but these guys are not stoners playing with Car Audio in a casual manner. That was the point I was trying to make

You are very knowlegeable about this topic. You have strong views. Again - I disagree and thats cool. Where did you get that you are stealing Subs from a civic? I dont understand this one.

I have done several systems prior to this. I am particularly happy with the way this one turned out. This is the first system I have done- yes its only a month old - where once I am finished I would not change a thing. Most of my other Systems have been done in Landcrusiers; 4Runners with Open cabins and a lot of air to move to make sound. So yes I have never done a system in a trunk before - I am relying on professionals advice and expertise in this area. That's why you hire professionals. BTW - I had been planning this system for over a year - this story of opening the cabin to the trunk was a consistent theme at all the shops I spoke to and even on the AudioPhile Board here at Roadfly. The results I got compared to the system in my current Landcruiser is night and day.

So if you are up to it - I would love to hear your system if you are anywhere near Seattle the week of 12/13. We can meet have a coffee - listen to some good blues on your rig and compare notes about Sound. I would love to be schooled. - JT

[Jason]

of my basslink firing right into the cabin, i used to have it going the other way, im extremely impressed by the quality bass the unit puts out given its compact size. i've toyed w/the idea of adding another.

[AZ_Jason_S]

Technically, I think in most cases the sub should face rearward and the box should be at the back of the trunk. Reason, reflected waves positively reinforce the speaker waves with minimal cancellation.

Now my opinion of the e34, it sucks for bass. I have a sealed box with an Image Dynamics 10 pushed with 300 watts of PPI Art Series power. I do have the ski-hole punched out. But my system is almost a 1 note system. Why? Because the trunk is like a vault and the ski-hole is a port. Now, my sealed box turns into a big ****in bandpass box. I don't like it. Every car stereo "expert" I talk to tells me BMW's and Mercedes are the most difficult vehicles to get quality bass from. Sure, I can get alot of bass up front through the ski-hole, but it comes in a narrow band.

The reason I am ranting about this is because I just tore my car apart to look for another solution. My next plan is to try the sub IB in the ski-hole since its rated for IB.

Johntee540 lets see some pics of that setup.


I especially like the picture of sound traveling across the curature of the earth. Look - I have thought and experiences on this subject. You seem to have different thoughts and experiences. We seem to disagree.

I am traveling to Seattle the week of Dec 13-16 and would love to see your set-up. Staying in Bellevue.

The reason I mention the shop and their expertise is for legitamacy. It is the best shop in DC and they consistently build IASCA Contest winners. Several Washington Redskins; Philadelphia Eagles and even NY Giant Players travel there to have their rides done. It may not matter to you - but these guys are not stoners playing with Car Audio in a casual manner. That was the point I was trying to make

You are very knowlegeable about this topic. You have strong views. Again - I disagree and thats cool. Where did you get that you are stealing Subs from a civic? I dont understand this one.

I have done several systems prior to this. I am particularly happy with the way this one turned out. This is the first system I have done- yes its only a month old - where once I am finished I would not change a thing. Most of my other Systems have been done in Landcrusiers; 4Runners with Open cabins and a lot of air to move to make sound. So yes I have never done a system in a trunk before - I am relying on professionals advice and expertise in this area. That's why you hire professionals. BTW - I had been planning this system for over a year - this story of opening the cabin to the trunk was a consistent theme at all the shops I spoke to and even on the AudioPhile Board here at Roadfly. The results I got compared to the system in my current Landcruiser is night and day.

So if you are up to it - I would love to hear your system if you are anywhere near Seattle the week of 12/13. We can meet have a coffee - listen to some good blues on your rig and compare notes about Sound. I would love to be schooled. - JT

[Johntee540]

Funny - I just bought my first Digital Cam yesterday. I am finally going to do the CarDomain thing. I am taking pics of the New Tranny / New Suspension/ New Brake System Process that is going on down at the shop to post there. When I get the car back home and off the lift I will post the picks of the install. And I will ask if my installer will entertain Email inquiries about e34 installs. - JT

[callen]

Need Help on this Subject.....

Am much more comfortable and capable adjusting the floats on a old Holley than with Stereo installs. I've read the posts and have just tried to recessitate an old system put into the 735il I bought. It has 4 Rockford Fosgate amps built into 3/4 mdf thats mounted Vert. and Screwed onto more 3/4 MDf that's in turn screwed onto rear deck behind rear seat. Metal was cut for two 10" holes for two subs that have long been removed. I installed two Pioneer 10's facing upwards(screwed into the MDF that's screwed to the deck) but the bass is far from thundering.....should I cut out ski pass? Turn the Subs around and point down towards trunk? The work seems to be top notch from what I can tell.
Callen

[AZ_Jason_S]

Are your subs mounted infinite baffle (no boxes)? If so, you should make sure the subs are rated for IB. Most aren't and require enclosures to perform properly. How are the subs wired? You can play with the wiring and increase or decrease the impedence of the driver. Wired in parallel=more watts, wired in series=less watts. Have you played with the gain or the crossovers on the amps? This could also be your problem.




Need Help on this Subject.....

Am much more comfortable and capable adjusting the floats on a old Holley than with Stereo installs. I've read the posts and have just tried to recessitate an old system put into the 735il I bought. It has 4 Rockford Fosgate amps built into 3/4 mdf thats mounted Vert. and Screwed onto more 3/4 MDf that's in turn screwed onto rear deck behind rear seat. Metal was cut for two 10" holes for two subs that have long been removed. I installed two Pioneer 10's facing upwards(screwed into the MDF that's screwed to the deck) but the bass is far from thundering.....should I cut out ski pass? Turn the Subs around and point down towards trunk? The work seems to be top notch from what I can tell.
Callen

[632 Regal]

i was having a problem where i couldnt get it to hammer cause everything was wired correctly, finally (out of dispair) switched the + & - on one side and wham! Kidney stone crushing sonic waves.

[callen]

They're sort of in a box....have MDF on top, behind with metal on other sides. Have two channels...L & R with one running each sub. Have Base and Treble adjustment on Amps with Treble turned off. Also my head...Pioneer DEH-P3600 has dedicated RCA's for Sub amp so I can select what frequency I send back......think 50-80 or 120. Not using crossover. Currently selected 50. They are cheaper Pioneers so not sure about the IF thing on subs. I do notice when I disconnect one of the subs the other gets louder...or thumps better. Mosfet?

[callen]

do have that correct...

[632 Regal]

1000 rmsx2 should be sufficient

[632 Regal]

swap the + & - on one side.


They're sort of in a box....have MDF on top, behind with metal on other sides. Have two channels...L & R with one running each sub. Have Base and Treble adjustment on Amps with Treble turned off. Also my head...Pioneer DEH-P3600 has dedicated RCA's for Sub amp so I can select what frequency I send back......think 50-80 or 120. Not using crossover. Currently selected 50. They are cheaper Pioneers so not sure about the IF thing on subs. I do notice when I disconnect one of the subs the other gets louder...or thumps better. Mosfet?

[callen]

I love my music and crank it but trying to get what I have to sound as good as possible without replacing the amps that I have......also will probably sell the 7 so don't want to put too much money into it.

[AZ_Jason_S]

That sets the upper bound of the frequencies you will send to the Sub amps. Try setting it to the other values. Right now you are only sending frequencies of 50Hz and lower. Also your amps probably have a crossover setting too. Try using one amp per sub bridged. This would double the power. If you are not sure how to set up the amps, go to RF's website and download the manual. You should be fine with those amps. But, you may have the wrong drivers for that setup.


They're sort of in a box....have MDF on top, behind with metal on other sides. Have two channels...L & R with one running each sub. Have Base and Treble adjustment on Amps with Treble turned off. Also my head...Pioneer DEH-P3600 has dedicated RCA's for Sub amp so I can select what frequency I send back......think 50-80 or 120. Not using crossover. Currently selected 50. They are cheaper Pioneers so not sure about the IF thing on subs. I do notice when I disconnect one of the subs the other gets louder...or thumps better. Mosfet?

[Jon K]

I think this is the type of setup that was in question?

http://e34.digital7.com/E34%20Pictures/IMG_1819a.jpg

this is a 10" alpine type R dual voice coil with ~250 watts to it, .68 cu ft box in the spare tire hole, with a beauty board over top. ski bag is cut out.

http://e34.digital7.com/E34%20Pictures/2.jpg