[Runnin'Rich]

I have an e91 with Hi-Fi and doing Technic's poor man's speaker upgrade with Individual audio EPS speakers and an e70 hifi amp that has central speaker output.

I purchased some used EPS speakers & tweeters from an e93.
However when I removed the foam from the front door tweeter housing I see they are 8ohm and not 4ohm like e90 / e91 units

8ohm eps tweeter is 65137839851 e93 & e92
4ohm eps tweeter is 65137839500 e90 & e91

There is no part number on my crossover box but real OEM states the same part number for e90/e91/e92/e93 65137838929

All other speakers / tweeters in the set I bought match part numbers & ohms to the e91.

My understanding is that the 8ohm tweeter will draw less power from the amp and therefore be quieter.

I have also read the individual audio EPS amplifier for the e93 is less powerful than other models (less speakers I guess).

Q1) should I try to purchase 4ohm tweeters because the 8ohms will be too quiet ?
Q2) should I try to purchase matching crossovers from an e90/e91 because they are different inside and tuned for a 4ohm tweeter even though part numbers are the same?
Q3) why would coupe and convertible have different ohm tweeters??

Thank you

[ctuna]

The individual amp speaker setup comes with a physical door crossover.
At least I have seen them before.

https://www.bimmerfest.com/threads/e...n-752.1275694/

https://www.e90post.com/forums/showthread.php?t=1402992

there is very little info on this, or at least it is not commonly discussed.

A Hi Fi amp is not enough to drive these speakers . It already does a poor job
with 2 ohm speakers .
This will end up with no volume for any of the speakers getting rid of the HI Fi amp
should be the first step in upgrading a Hi Fi system . It's not much more than weak
Head Unit power .

[Runnin'Rich]

Just to clear up, I'm aware of the dedicated cross over that's in the black plastic box on the EPS system. If you want to see what it looks like Google the part number I stated above.

In Technic's Ultimate HiFi Upgrade:
https://www.m3post.com/forums/showthread.php?t=637056

Technic says: "Idea: The E70 X5 uses the exact same HiFi OEM amp connector as the E9x. The difference is that the E70 HiFi OEM amp has 7-channel outputs (center channel) and the E9x has only 6-channel output (no center channel). If an E70 OEM amp is plugged in my system then the center channel will also sound as the center channel pins were inserted in the E70 center channel pin slots. And most probably it will sound quite decent with it and these speakers(EPS)"


I'm fitting EPS speakers including centre speaker because they sound good according to experts but more plus they look cool with the silver covers / beige cones.
Also they are 4ohm which matches the e70 Hi-Fi amp.

E90 hifi
door speakers 2ohm
Underseat subs 2ohm

E70 hifi
Door speaker & centre speakers 4ohm
Underseat subs 2ohm

So as I'm sticking to the right impedance I don't expect to have any volume problems. Technic also says in another thread how good the EPS speakers sound with the original e90 Hifi amp even when the impedance doesn't match.

If the sound isn't good enough I'll sell my $63 dollar e70 hifi amp for $63 and purchase a better amp for 10 times the price.

Can anyone help with my original tweeter questions?

[ctuna]

Hi Fi amp is the weakest part of the Hi Fi system but
the speakers aren't far behind.

[Hoody007]

Originally Posted by Runnin'Rich

Just to clear up, I'm aware of the dedicated cross over that's in the black plastic box on the EPS system. If you want to see what it looks like Google the part number I stated above.

In Technic's Ultimate HiFi Upgrade:
https://www.m3post.com/forums/showthread.php?t=637056

Technic says: "Idea: The E70 X5 uses the exact same HiFi OEM amp connector as the E9x. The difference is that the E70 HiFi OEM amp has 7-channel outputs (center channel) and the E9x has only 6-channel output (no center channel). If an E70 OEM amp is plugged in my system then the center channel will also sound as the center channel pins were inserted in the E70 center channel pin slots. And most probably it will sound quite decent with it and these speakers(EPS)"


I'm fitting EPS speakers including centre speaker because they sound good according to experts but more plus they look cool with the silver covers / beige cones.
Also they are 4ohm which matches the e70 Hi-Fi amp.

E90 hifi
door speakers 2ohm
Underseat subs 2ohm

E70 hifi
Door speaker & centre speakers 4ohm
Underseat subs 2ohm

So as I'm sticking to the right impedance I don't expect to have any volume problems. Technic also says in another thread how good the EPS speakers sound with the original e90 Hifi amp even when the impedance doesn't match.

If the sound isn't good enough I'll sell my $63 dollar e70 hifi amp for $63 and purchase a better amp for 10 times the price.

Can anyone help with my original tweeter questions?

I have the EPS speakers in my car as well, driven by an aftermarket amp (Helix PP82 DSP), and I upgraded them from the Logic 7 units (I originally had the hifi system).

There was no notable difference in volume between the Logic 7 units & the EPS units. Perhaps the crossover is of suitable resistance to make the load on the amp still be 4 ohms? Haven’t done any measurements to confirm, though…

Also, the speaker wire length of the tweeters is longer for the E90 / E91 vs. the E92 / E93 (hence different part numbers).
Both tweeters are 8 ohms, though.

Also, if you decide to go the aftermarket amp route, and use a Helix amp (which I recommend as the EPS units sing with more power going to them) I can upload my PP82 DSP amp file, which is time corrected and equalized for EPS mids and tweeters + hifi “subs”.

Hope that helps!

[Runnin'Rich]

Thanks for the tip on the Helix amp - I'll check it out if my e70 amp doesn't sound good. Really kind of you to offer to share your set up file too. Thanks for noting the wiring length maybe that's why the impedance is different. Here is some real OEM and photos, you can see the impedance is printed on the green sticker

[Hoody007]

Here’s the weird thing - I remember looking this all up before I upgraded to the EPS system.

It would seem that BMW changed the impedance of the tweeters for the E90/E91 at some point.

Look @ this eBay listing: https://www.ebay.com/itm/14359232012...4AAOSw-PFc6K1x



Same part number (65137839500), yet 8 ohm resistance… Really odd.

[david in germany]

The resistance of the actual tweeter is not going to make that big of a difference anyways, the amplifier will “see” the resistance of/at the filters (aka, crossovers) the 8 ohm version will have a VERY slightly lower output but with a similar frequency response as the 4 ohm version. I would be willing to bet that if you measured both sets after the crossover, both will be around 3 to 3.5 ohms at rest.

As for the output power of the amp, the amps are the same for the e series but are coded to the car to turn on or off the additional channels.

[Runnin'Rich]

Thank you very much the replies Hoody and David
That's awesome to know that even the e90 got 8ohm tweeters at some point.
I'll now fully install my 8ohm tweeters, seeing as it doesn't make much difference

You're right the top Hi-Fi amps like individual and logic 7 are the same except for coding.

It looks like the e90 hifi amp changed design in September 2010

The original 2004 to 2010 (e.g 65129143156) this is black with less heat sink fins

September 2010 to present day(e.g 65129233962) silver multiple fins over the whole surface and looks the same as the e70 and some f30 hifi amps (both have centre channel)

I wonder if the Sept 2010+ model e90 Hi-Fi have the capability for centre channel by simple adding the wiring