Amp and Subwoofer Install

[bahamutcog]

Hi Guys,

Just picked up a mint 840ci and now its time to have a little fun.

Looking to pop in a couple subs behind the rear seats and amp to serve them.
Literally thinking of cutting holes behind each seat and placing the subs directly in.
I drive with the rear seats down any ways so no problem.

I have never done it before, but I got time so no problem there.

Anyone done this before in the 840ci? Any lessons learned before I start digging?

Thanks for the help and have a great day!

Cheers,

[6speeder]

ive done it before in an e28 but a single sub with dual coils, and i installed it behind the middle arm rest instead of behind each seat. granted i was 15 when i did it so it was a long time ago. it was a "free air" sub so it used the trunk as the enclosure. these types of subs do not hit as hard as their "sealed" or "ported" enclosure cousins but it was an Advent 12" and it sounded nice, tastefull and not to boomy.

all that said, i would N O T do it again. fast fwd decades later - i still have that original e28 but now it has a huge hole behind the armrest and although you cant see it i know its there. i suggest you buy a prefab sub enclosure and put it in the trunk this way when you or the next owner want to remove it (and someone at somepoint deffinately will) your not left with an abomination rear seat with 2 gigantic holes in it.

[bahamutcog]

I will be starting from scratch on thsi project and relly appreciate your input and the standard box design vs messing with my resale value!
That being said, IDK crap about amps/subs/etc.
Do you know of any forum thread that delves into:
-good sub/amp packages
-wiring/install guide

Thanks again 6speeder and have a good one

[6speeder]

I am a purist so I might not be the right one to ask however if I wanted to do something to the cars audio system I would pick from these options, and in this order.

1. I wouldnt touch the stock amp or stock head unit I would however replace ALL of the speakers in the car with brand new oem ones. i'm guessing the speakers in your car are original which makes them 25 years old. speakers produce 3 ranges of sound: high (cymbals) mid (voices) lows (bass). overtime (especially the ones on the rear deck that get hit with sunlight) the highs and lows get distorted, the tweeters that produce the highs are the most sensitive and blow out easily, the speakers also have a hard time reproducing the lows because they vibrate instead of pulse creating a muddy sound. so if your lucky the only thing that SOUNDS like the day it left the factory is the mid range and a speaker change will be like night and day... all while keeping it 100% stock.

2. dont touch anything that already exists, leave the head unit, amp and all speakers the way they are, and instead install TWO 8 inch powered active subwoofers from Blaupunkt. they are flat boxes only 13in x 8in x 3in high each and are designed to go under the 2 front seats. you can also put them on the back of the rear seats inside the cabin (if they fit), one on each side, firing into the back of the rear seats... you could "show them off" at any time by lowering the top of the rear seats, or keep the rear seats up for an oem stealth look. i actually prefer to mount them this way instead of under the front seats... its tastefull but since you can hide them at any time its not over the top, and there only 8inch subs. Or you can also install them in the trunk on the rear shelf firing down. its a sub and amplifier all in one box, just wire it and done. and its completely reversible later on. install is MUCH easier than option 1 or 3. bass will be moderate.

3. dont touch anything that already exists, leave the head unit, amp and all speakers the way they are, and instead add a dual 10 inch SEALED (not ported) sub enclosure in the trunk firing INTO the back seat about 12 inches away from it, do not have it face out towards the tail lights. this will allow a smaller woofer to sound 2 inches bigger allowing you to go with a TASTEFULL thump, which will allow you to get a cheaper box thats also lighter and smaller. also buy two MONO amps (1 for each sub) and mount them on TOP of the box. side benefits of this setup is 1. it will look stealth, 2. as the air is moved by the woofers they will hit the back seat and travel up over the amps cooling them down. if going this route i would also change the two ground cables from the batteries to thicker gauge ones and keep the original cables when you or the next owner reverse the install later (and you can count on it being undone later at some point). you may also need to do this for option 2 if your ligts dim or flicker during bass notes. again i would use a Blaupunkt box and matching amps, its a german company and is period correct, cant stress that last sentence enough. this install is the hardest of the 3. bass will be high but not crazy high because they are only 10's.

4. if either of those 3 options are not enough you could also do BOTH options 1 and 2, or BOTH 1 and 3. if you dont have the cash OR the technical ability to replace all the oem speakers i would choose option 2 and put them on the back of the rear seats if they fit... the more i think about it the more i like that idea.

[DriftGirl]

Take ALL of that OEM garbage out....just do it carefully and try not to cut any wires in the process. put it in a box and store it someplace dry. :p

You can get just about anything to sound better than the stock system...it may have been stat-of-the-art at one time, but that time has long passed

[rjbaren]

I used a JL Audio 300 watt amp mono bloc amp for motorcycles. It fit right next to the amp in the shelf that lowers down. It's a very small amp and you don't have to do much of anything to get it to fit right in place . I also used a JL Audio 10" in a single cabinet and leave it sitting on it's back in the trunk. No need to cut any holes at all, the bass comes through loud and clear.

[bdiefAZ]

RJbaren, would it be possible for you to upload photos and show where the wires for the amp are tapped into the system?

I have updated my system with CD43 head unit and all new speakers, but the system needs bass and sounds anemic.

[e31gixxxer]

Short of swapping the head unit there is no halfway house with this one.

Like DG said remove everything OEM and start again, or don't touch it, bar replacing old speakers. You will be amassed at the heap of electrics that come out of the car.

The ski hatch makes an excellent sub location, unless of course you put your skis in it.

[rjbaren]

It's been a couple of years since I did this change. I used a Becker Traffic pro and ran wires from the head unit to the line in on the amp.

[bahamutcog]

Thanks for all the input everyone. I like the idea of the boxed subs or throwing one into the ski hatch since both are non-invasive.

Anyone have pics or a design for me to follow. The only stereo wiring I did was for my 96 camry back in college...and this seems a far cry from that.

[e31gixxxer]

^
The ski hatch sub install as you say is non invasive, I can run mine at virtually full power, with the centre first aid bolster in place, looks oem, but still kicks some bass. Remove it and put in the trunk for full effect.

Mine has an enclosure built into the trunk, so not free to air. The reduced space is negligible and I can still fit two decent sized cases, shoes, coats in there.

Sorry all my pics have now gone, as in my signature due to the photobucket bandits, can't be asred to replace 10 years worth of links. Will have a look when I get time and see if I can dig a few out.


The sub is set back, allows plenty of clearance to the bolster.
P1000210.jpg

Sub enclosure, 4 channel amp under rear deck, sub amp located in ex CD multichanger position, cooling fans above.
P1000207.jpg

This set up doesn't disappoint, far better than stock. This looks easy, but it's all about the quality of the install, this had dynomat everywhere and took me around 2 weeks to everything, speakers etc.

[6speeder]

i am putting in a new fuel pump and hoses so i have my rear seats and first aid kit (to get to the bolts on my 91 bah) out right now. my kit measures 9.875inch wide means your gona have to get an 8 inch sub or gamble on tryin to make a 10 inch fit without affecting the "throw" of the woofer. when the speaker hits the cone travels past the frame of the sub as much as 1 inch, if this throw is interupted by say the frame of the rear seats it destroys your sound and very quickly the sub itself. i went thrpugh this nightmare with my advent in the e28 in my 1st reply. its highly technical and i dont reccomend it since you said yourself your a novice. your also gona have to make sure its completely sealed off from the trunk air and thats no easy task since the sheet metal behind the rear seats isnt flat. your also gona need to reinforce the sheet metal with dyna mat and even that wont stop it from vibrating like crazy making your "sound" terrible. also keep in mind the ski hatch will only allow for ONE sub... it will only be an 8 or 10 inch, and it it will be a "free air" sub at that, they are the weakest by far of the enclosure types. also the ski hatch will require some type of modification which will effect resale which is why i think u should go with the flat powered sub boxes as it can be undone or a box in the trunk but that takes up valuable realestate and puts weight behind the trans axle which will put a sag in the rear of your car while driving, then add more weight when you add things in the trunk like luggage and it will really be noticeable. given your experience trust me when i say you dont want to cut into the rear metal not for 2 subs or 1 in the ski hatch, the end product EVEN IF PERFECTLY INSTALLED will still dissappoint you due to free air sound. its a very very weak bass, a very dirty sound. the enclosure produces the bass sound/feel not the speaker itself which only moves the air, the tuned enclosure turns that movement into thump. go with two flat powered Blaupunkt subs, either under front seats or behind the rear ones. if you go that route you can easily run the 12v power by following the red battery cable on the passenger side and pickup the speaker level inputs from the rear speakers just a foot or two away, doesnt get easier and the sound will be very clean and wont disappoint and can be completely undone.

[Support528]

Get rid of the head unit, connect all speakers to a after market amp. Run a aux cable to the import of the amp. You won't have radio, that's up to you. I always use my phone for music anyway.

[e31gixxxer]

Get rid of the head unit, connect all speakers to a after market amp. Run a aux cable to the import of the amp. You won't have radio, that's up to you. I always use my phone for music anyway.

Not quite that simple, the oem speakers have Xovers, the system is not 4 channel, and the oem speakers will likely be the week point in the above plan, as I said, no easy halfway house.

[Budget M3]

^
The ski hatch sub install as you say is non invasive, I can run mine at virtually full power, with the centre first aid bolster in place, looks oem, but still kicks some bass. Remove it and put in the trunk for full effect.

Mine has an enclosure built into the trunk, so not free to air. The reduced space is negligible and I can still fit two decent sized cases, shoes, coats in there.

Sorry all my pics have now gone, as in my signature due to the photobucket bandits, can't be asred to replace 10 years worth of links. Will have a look when I get time and see if I can dig a few out.


The sub is set back, allows plenty of clearance to the bolster.
P1000210.jpg

Sub enclosure, 4 channel amp under rear deck, sub amp located in ex CD multichanger position, cooling fans above.
P1000207.jpg

This set up doesn't disappoint, far better than stock. This looks easy, but it's all about the quality of the install, this had dynomat everywhere and took me around 2 weeks to everything, speakers etc.

Adding a sealed or ported box takes up too much room and free air mounting can get in the way when you are packing the trunk full, so this is the way I'd go. That's a nice clean looking install and remains completely hidden when you want it to.

[e31gixxxer]

Adding a sealed or ported box takes up too much room and free air mounting can get in the way when you are packing the trunk full, so this is the way I'd go. That's a nice clean looking install and remains completely hidden when you want it to.

Don't know if I am misunderstanding, but the sub enclosure is a sealed box, fixed to the rear bulkhead, approx to JLs specs.

[jinbal]

It is possible to upgrade all the speakers in the car with correctly sized drop in replacements - parts express has the speakers you need I used a combination of drop in replacements and larger speakers that required trimming of the enclosures, this let me re-use the existing wiring and amp.

I upgraded the head unit to allow for an active sub and am very happy with the results

Heres a write up, with the parts you need
http://www.bimmerforums.co.uk/forum/...grade-t466537/

[G8nightman]

Here is what I did..

[8Tech]

And mine......

jlsub1.JPG

ps11.JPG

ps13.JPG

sub5.JPG

sub6.JPG

[8Tech]

sub8.JPG

cap.JPG

And this is how I got my car back from the shipping company....

av2.JPG

[Budget M3]

Don't know if I am misunderstanding, but the sub enclosure is a sealed box, fixed to the rear bulkhead, approx to JLs specs.

Understood. Your sealed box, however, is custom sized to minimize intrusion on luggage space. Perhaps I should have more clearly said a SEPARATE sealed or ported box takes up too much space.

- - - Updated - - -

sub8.JPG

cap.JPG

And this is how I got my car back from the shipping company....

av2.JPG

[G8nightman]

sub8.JPG

cap.JPG

And this is how I got my car back from the shipping company....

av2.JPG

They stole everything???

[e31gixxxer]

And this is how I got my car back from the shipping company....

WTF Gerry!!!

[8Tech]

They stole everything???

Not everything, just the amplifiers, DVD changer, CD changer, steering wheel remote and head unit.

Then did burn-outs in it until the clutch caught fire because the traction control was on and so they could not break traction.

Then stole the 12V air pump and phone.

I had to have it lifted and transported home because it would not even drive. Apparently hugely common on cars shipped by roll-on / roll-off international shipping and the shipping company are protected by marine law against claims.

[alex840]

!! Sorry to hear that man......just horrible!

Not everything, just the amplifiers, DVD changer, CD changer, steering wheel remote and head unit.

Then did burn-outs in it until the clutch caught fire because the traction control was on and so they could not break traction.

Then stole the 12V air pump and phone.

I had to have it lifted and transported home because it would not even drive. Apparently hugely common on cars shipped by roll-on / roll-off international shipping and the shipping company are protected by marine law against claims.