95 740iL Rear Deck Speaker Replacement / No Sound??

[cybertoyz]

Hello,
I am helping a friend out who owns a 95 740il who needs his 4 rear deck speakers replaced. They have been destroyed by heat and the foam rubber surrounds are gone. I replaced the speakers without a problem with 4 new drivers that were 4 ohms each. The problem is there is almost no sound coming out of the new speakers.

Can anyone venture a guess to what the problem might be? Maybe a blown amplifier??

[mojocoggo]

Sounds like you have my same problem. The speakers sound waaaay underpowered and overdriven. I ended up just installing an aftermarket subwoofer in the trunk.

[Edwin NL]

Those speakers are hard to find, only option for speakers that will fit are from the dealer

[dazednkenfused]

I think the factory speakers are 8ohms, that's probably why they sound underpowered if you're using 4ohm. 8ohm speakers are pretty hard to find in general.

[cybertoyz]

I measured the impedance of the original speakers and they were 6.2 ohms. I am going to try putting a 2.2 ohm resistor in series with the positive lead and see if that helps.
I will post results here.

If I understand correctly then, these 4 rear deck speakers are for Bass only? Is the crossover point for these adjustable?

[Edwin NL]

The issue is to find woofers that will fit in the deck

[rpape01]

Dont add any resistors.... You need the correct resistance speaker. If the factory installed 8 ohm (not sure what they are), then you need 8 ohm.

If you used a 4ohm in place of an 8, you will draw more current from the amplifier and may damage it.

Did you change the wiring at all? I would suggest adding a sub to the trunk. Even in good shape, the factory speakers provide very little bass.

[cybertoyz]

I did not change the wiring at all. I was going to add a Bazooka Sub in the trunk. I assume I could just tap off the terminals on the rear speakers to provide a signal to the bazooka sub. The sub accepts line or speaker level inputs.

[subspd]

Would this work? ^^^^^ My rear deck speakers are also blown and I need to do something about it...

[RomanN]

Hello,
I am helping a friend out who owns a 95 740il who needs his 4 rear deck speakers replaced. They have been destroyed by heat and the foam rubber surrounds are gone. I replaced the speakers without a problem with 4 new drivers that were 4 ohms each. The problem is there is almost no sound coming out of the new speakers.

Can anyone venture a guess to what the problem might be? Maybe a blown amplifier??

Those are not speakers at the back, they are subwoofers, they make bass.

[njdjh2o]

If BMW speakers are 8 ohms, then they are regular house speaker. They are not rare speakers, but you will not be able to find them at you Audio Shop. You will have to shop a place that sell house speaker.

This is probably why the speaker don't sound to good in the car, because they were built for a house enclosure.

In order to tell what ohms they actually are, pull one out (if not already) the ohm are printed on the button near the magnet.

Then all you have to do it match up the correct size for the enclosure and install an maybe enjoy.

This is a non dsp for the door it states 4/4 ohms

Label on the rear woofer deck

"Impedance, most car audio speakers are 4 ohms, most home speakers are 8 ohms. The reason car speakers are usually 4 ohms is because in the early days of car audio it was difficult for amp designers (or powered radio designers) to make much power from the measly 12 volts the car has to offer from the battery. So they by using 4 ohm speakers the amps make more power with less battery voltage. Now there is starting to be a push toward the 2 ohm capable amplifiers for even more available power. Check your amplifiers rating to see what impedance the amplifier will be happy with, and buy speakers that have he recommended impedance. Running a speaker with an impedance less than your amplifiers specs recommend will give you more output power at the speaker but may damage your amplifier from the added heat caused by increase in current caused by the lower impedance, do so at your own risk... "

Will these fit?

[hpbongers]

Some clarification on speakers. Most house speakers will work more efficiently in a trunk because there is less restricion on back presure due to the increase trunck volume. But there are speakers designed specifically for this aplication. 4 ohm will be a good replacement but will draw more current. A good car amp won't care.

An 8 ohm speaker is rated in impedance which is the DC resistance in parrallel with the AC inductance of the coil. An 8 ohm total speaker has aproximately 6 ohm resistance with 6 ohms inductance. Your meter will only measure the DC resistance but is good enough to use to figure the final impedance. Similarly a 4 ohm will read about 2.2 ohm on a meter or there abouts. BMW amps are limited in the lower frequency response power curve. Replace with a good aftermarket.

[subspd]

So if I add a rear sub with an amp to power it will I run into the same problem of damaging the factory amp? Is there anything to look for in an amp that would make it safe/safer to use?

I looked at BSW's website and they actually remove the rear deck speakers completely and add a sub to the back I think ill do the same but want to make sure I can find a good amp.

Well I took out the rear deck sub all the speakers were trashed. THANKS E38.org! So now before I go buy a sub for my 10" Kenwood sub (i'm going to build a custom box based off of the BSW box that hangs from the rear deck in the trunk) I would like to find out if there is anything special I need to keep in mind...

[OrientBlue740il]

Is there any way to take out the whole rear speaker deck? because mine is faded from blue to purple because of head and i'd like to either Re-dye it or get it CF wrapped. PM me if anyone knows thanks.

[lovelikewinter]

This question doesn't exactly have anything to do with speaker power, etc.. but does the non dsp 7 have speakers on the rear deck?

[cdriskell]

do you have the web site (url) for the steps? if so, i would like to get my hands on it.

[cloudsurfer]

Not exactly. First of all, there is no such thing as a "normal house speaker." Secondly, your "normal house speaker" is placarded with an impedance value for the entire enclosure, which is typically a multi driver system, which is not the impedance value of a single driver within the enclosure.

It is also true that one cannot measure the actual impedance of a driver by using a standard multi meter, because inductance cannot be compensated for.

Any decent amp will typically double its rated power with every halving of impedance (exceptions being the newer Class D designs, which are typically stable to under 4 Ohms, but that also have circuitry that maintains a constant power output without respect to load). Thus, an amp that makes 100W at 8 Ohms, should make 200W at 4 Ohms, and 400W at 2 Ohms. Something else that everyone should probably realize is that doubling amplifier power only results in an additional 3dB of loudness, so when the guy at Best Buy tries to tell you that amp "A" is better than amp "B" because "A" has 100W and "B" has 80W, he really has no idea what he's talking about

Problem is, the factory amps used in cars are not "decent amps" and are not rated for any impedance lower than what they were designed for.

There are plenty of higher end home and mobile, not to mention pro audio systems which run impedance values under 8 Ohms, and often, under 4 Ohms.

Getting this thread back on topic to compensate for the mis-information that has been shared, if you want any bass in one of these cars, you need to ditch the factory 5 1/4" "subwoofers" (which really is a laughable oxymoron) and install a decent amp and a real subwoofer.

If BMW speakers are 8 ohms, then they are regular house speaker. They are not rare speakers, but you will not be able to find them at you Audio Shop. You will have to shop a place that sell house speaker.

This is probably why the speaker don't sound to good in the car, because they were built for a house enclosure.

In order to tell what ohms they actually are, pull one out (if not already) the ohm are printed on the button near the magnet.

Then all you have to do it match up the correct size for the enclosure and install an maybe enjoy.

This is a non dsp for the door it states 4/4 ohms

Label on the rear woofer deck

"Impedance, most car audio speakers are 4 ohms, most home speakers are 8 ohms. The reason car speakers are usually 4 ohms is because in the early days of car audio it was difficult for amp designers (or powered radio designers) to make much power from the measly 12 volts the car has to offer from the battery. So they by using 4 ohm speakers the amps make more power with less battery voltage. Now there is starting to be a push toward the 2 ohm capable amplifiers for even more available power. Check your amplifiers rating to see what impedance the amplifier will be happy with, and buy speakers that have he recommended impedance. Running a speaker with an impedance less than your amplifiers specs recommend will give you more output power at the speaker but may damage your amplifier from the added heat caused by increase in current caused by the lower impedance, do so at your own risk... "

Will these fit?

[anaElBasha]

how do you remove the rear speakers? I am going to buy some but I will first need to take them out and get the exact part number.

[bandittwo2]

the dsp amp system is underpowered. best solution is to wire up an aftermarket amp, sub, and possibly speakers. I just replaced the factory head unit with an aftermarket alpine deck, and tapped in the factory amps speaker leads,and wired them up to my aftermarket jl amp. then i took the RCA's from the amp and ran them to the new deck. then, i tapped the sub lines and ran them to the amp also, and hooked the jl sub up to the amp as well. having the battery in the trunk is nice. will post pics if necessary.

[hyildirim]

Hello all:

I am not experienced with audio repairs or replacaments, so please bear with me. My local "sound" expert of course quoted me lot of dollars and I know it doesn't take that much to upgrade that much. I am just after some decent sound using the factory CD changer. I have a DSP 2001 740i sport with full screen navigation, bluetooth, sirius (which is disabled now so that CD changer can function)

From what I understand, tapping into the sub-speaker wires in the back using line output converter and feed it back to an amp/sub combination and this will disable the sucky rear-deck subwoofers. From what I understand the rear deck speakers are also 5 1/4 size speakers.

So with this setup, the rest of the speakers will still feed thru the DSP/non-DSP factory amp.

What I am wondering is have any tried to have another line output converter /stereo amp setup (let's say for the rear door speakers), and place some bigger 6 x 9 speakers in the rear-deck (this may require some cutting etc) just to have some decent sound.

So the end goal is to have 2 amps (one to feed the subwoofer and one to feed rear deck non-sub/3 or 4 way speakers). If this turns out to be satisfactory, I am even thinking about disabling the rest of the speakers or just replacing them with decent ones.

Any advise would be greatly appreciated.

Luke

[Groover]

Superdooper old thread, I know... (sorry) - Has anyone figured out what the ohm rating is on a DSP sound system for the doors? Also, I think those are 5.25" diamter as well.. correct?

The rear deck ones are 5.25, 8 ohms is what I'm gathering, correct?

The doors on the other hand are such a mystery.. I think I've searched the entire web, but can never find the answer. Looks to be 4 ohms for non-dsp... but what about DSP - Losing it, help please

[lollio22]

Hi there, I have a 2000 BMW 740i and the rear Deck speakers are actually individual sub's and probably the same in yours and that's why your sound is off..

QUOTE=cybertoyz;15401275]Hello,
I am helping a friend out who owns a 95 740il who needs his 4 rear deck speakers replaced. They have been destroyed by heat and the foam rubber surrounds are gone. I replaced the speakers without a problem with 4 new drivers that were 4 ohms each. The problem is there is almost no sound coming out of the new speakers.

Can anyone venture a guess to what the problem might be? Maybe a blown amplifier??[/QUOTE]

- - - Updated - - -

Hi there, I have a 2000 BMW 740i and the rear Deck speakers are individual sub's and probably the same in yours and that's why your sound is off..

[quakefiend420]

Holy thread necro batman!

[RicoE381995]

Easiest and cheapest fix is to use these: http://www.speakerworks.com/5_1_4_in...t_p/swk525.htm

remove rear covers,
remove speakers (cut wires with 1" minimum tail to speaker to use Scotchlock to splice wire),
follow repair instructions included in kit,
use these to reconnect wires: Scotchlock,
replace covers.
Done

Total cost about $30 for everything.