[bmw335ie90]

Originally Posted by sfinxvc

nope

Okay, if you do not have navigation there are certain years that require ICOM to re-code to hifi but it is possible to do as ctuna mentioned. Changing head unit to aftermarket has a few downsides (including low fidelity) so I would caution against that route.

I was more curious if you did have navigation as there are certain instances where the head unit cannot be coded hifi at all, doesn't matter the type of cable.

[sfinxvc]

Thanks. I found a local who would be willing to do it with the ICOM.

I've also gotten a quote on wiring the whole car up to support an aftermarket amp, and it's...high! $500-1,000! So say middle of the road estimate is $750.

[sfinxvc]

Also, I've no idea if the JBL amp supports balanced RCA inputs...that's what the stock HU will output once recoded to HiFi.

[sfinxvc]

One more thing I don't get is why/how recoded HiFi output is supposed to provide balanced signal. I understand balanced to mean differential, i.e. +, - and ground. That's three wires. And how would a balanced signal be transmitted via RCA? RCAs have 2 wires...

[bmw335ie90]

Originally Posted by sfinxvc

One more thing I don't get is why/how recoded HiFi output is supposed to provide balanced signal. I understand balanced to mean differential, i.e. +, - and ground. That's three wires. And how would a balanced signal be transmitted via RCA? RCAs have 2 wires...

This video explains the difference between differential and regular coaxial RCA. The differential output from the head unit isn't true "balanced" inputs because, as you said, there are only two wires and not three.

Any decent quality Amplifier will accept differential inputs, read the user manual/documentation and it will usually call it out.

[sfinxvc]

Originally Posted by bmw335ie90

This video explains the difference between differential and regular coaxial RCA. The differential output from the head unit isn't true "balanced" inputs because, as you said, there are only two wires and not three.

Any decent quality Amplifier will accept differential inputs, read the user manual/documentation and it will usually call it out.

Maybe ground is coming from somewhere else? Remote? Power? Lol. But that ought to be different from audio ground.

Nw, I'll just leave it at that. I'm okay with some mystery.

[ctuna]

There are only two wires in what is considered RCA's . These have been used
forever to hook up Record Player and CD's up to receivers and amps in Home
Stereo . This means a single ended signal travels down the middle wire surrounded
by a Shield that is attached to a common ground.
This is not what comes out of the back of a BMW head Unit.
What comes out is basically a reduced speaker out when programmed for Hi Fi .
That means neither wire is common ground. There is no third wire when you
hook this system up . Also because the signal in each wire is of equal an opposite
value it provide a noise canceling function.
Read OP amp theory and differential Inputs if you want to understand the
theory.
The better amplifiers will detect the non common ground and convert to dual ended
differential Inputs.

There is no ground in differential signals.

[ctuna]

There are only two wires in what is considered RCA's . These have been used
forever to hook up Record Player and CD's up to receivers and amps in Home
Stereo . This means a single ended signal travels down the middle wire surrounded
by a Shield that is attached to a common ground.
This is not what comes out of the back of a BMW head Unit.
What comes out is basically a reduced speaker out when programmed for Hi Fi .
That means neither wire is common ground. There is no third wire when you
hook this system up . Also because the signal in each wire is of equal an opposite
value it provide a noise canceling function.
Read OP amp theory and differential Inputs if you want to understand the
theory.
The better amplifiers will detect the non common ground and convert to dual ended
differential Inputs.
Because it has twisted wires also known as a twisted pair this keeps the noise down.
You should Run a differential RCA Cable on all long runs to keep noise down.

[sfinxvc]

I think I've finally figured out a potential low cost solution involving DSP and keeping everything else stock. I will post it in a separate thread.

Just wanted to clarify two things...

1) I've seen a YT video where someone added HiFi tweeters to an otherwise base audio system. The connector is apparently behind the door panel and is in parallel with the door woofer. There's a series capacitor in line with the OEM tweeter. Do you think all base audio systems have similar connectors?

2) Apparently that door woofer is already in parallel with the underseat woofer. If those are 4 ohm speakers, we're talking a 2 ohm load for the HU. Adding a tweeter in parallel further reduces nominal impedance, making for a tough load for the already strained HU. Should I be concerned?

Looking for a technical pov from someone familiar with the above.

I'll create that other thread soon after trying my fix this week, if it works, might help others in the future.

Thanks guys, you've all been super helpful.

[ctuna]

Right from the first Link

Base audio

The "base" audio system has been around since the early days, although it only made it to the US in 2010.

It uses four channels of deck power (yes, that's right, good old 50Wx4 when lightning strikes, 18Wx4 if you're charitable, and 12Wx4 if you do the actual 12V math into 4 ohms and 1% THD).

The front channels drive:

- 6.5" woofers underseat in 8" frames and molded plastic enclosures. The underseat enclosures are identical for all systems. There is uncertainty regarding whether the duct connecting the enclosure to another chamber in the frame is actually a tuned port, or simply a funny-shaped sealed box. The woofer is not crossover-filtered. The only things taking mids and highs out of the audible output are the driver's own mechanical rolloff, and the acoustic filter formed by the seat and your rear end.

-4" mids in the door. These have a capacitor on them, acting as a high-pass crossover filter and also making the two-speakers-in-parallel a load the deck can handle.

The signal is heavily equalized to the front speakers, and has a subsonic filter around 40 hertz.

The rear channels drive only a pair of 4" mids in the back. This channel is high-pass crossover filtered around 160 Hertz, so connecting a subwoofer to it is a disappointing experience. It is also heavily equalized.

There is a low-current-output remote turn-on present with base audio systems, but it's not controlled by the radio play state. It turns on when the doors are unlocked and stays on for a while after ignition is turned off.



HiFi or Premium system

Some US folks call this the "base" system since it was the entry-level audio offered in the states until MY2010. This is a US-centric POV, though, and for clarity, let's call it the HiFI system.(It's HiFi in the service docs and Premium in the marketing lit).

This system is the easiest to perform performance-minded upgrades with, since it has flat, full-range analog outputs (two pair, front and rear). The processing and crossover-filtering happens in the HiFi amplifier (in the trunk, L rear corner, under the plastic snap-off plate in sedans and coupes, behind the cargo door and under a plastic bolt-on guard in wagons. There is a remote turn-on wire present at the amplifier, similar to the base audio system in operation.

Speakers

Front door mids and tweeters (highpassed between 100 and 160)

R door or deck mids and tweeters (ditto)

Underseat 8" flat woofers (low-passed around 100 to 160 with significant stopband output)

There is no center channel, and no rear effects speakers.

[mrberry]

if you code to hifi and then either purchase the technic harness, the etok bak harness or the audison prima biamp harness you get a plug n play harness that lets you pick up the signals from theunderseat sub and add a 4 chanel amp to power the sub and the front . this with a decent 4 chanel amp is a good starting point and shouldnt cost to much if you go used

if you search the harness name on here you should fine more posts with details

[sfinxvc]

Originally Posted by ctuna

Right from the first Link

Base audio

The "base" audio system has been around since the early days, although it only made it to the US in 2010.

It uses four channels of deck power (yes, that's right, good old 50Wx4 when lightning strikes, 18Wx4 if you're charitable, and 12Wx4 if you do the actual 12V math into 4 ohms and 1% THD).

The front channels drive:

- 6.5" woofers underseat in 8" frames and molded plastic enclosures. The underseat enclosures are identical for all systems. There is uncertainty regarding whether the duct connecting the enclosure to another chamber in the frame is actually a tuned port, or simply a funny-shaped sealed box. The woofer is not crossover-filtered. The only things taking mids and highs out of the audible output are the driver's own mechanical rolloff, and the acoustic filter formed by the seat and your rear end.

-4" mids in the door. These have a capacitor on them, acting as a high-pass crossover filter and also making the two-speakers-in-parallel a load the deck can handle.

The signal is heavily equalized to the front speakers, and has a subsonic filter around 40 hertz.

The rear channels drive only a pair of 4" mids in the back. This channel is high-pass crossover filtered around 160 Hertz, so connecting a subwoofer to it is a disappointing experience. It is also heavily equalized.

There is a low-current-output remote turn-on present with base audio systems, but it's not controlled by the radio play state. It turns on when the doors are unlocked and stays on for a while after ignition is turned off.



HiFi or Premium system

Some US folks call this the "base" system since it was the entry-level audio offered in the states until MY2010. This is a US-centric POV, though, and for clarity, let's call it the HiFI system.(It's HiFi in the service docs and Premium in the marketing lit).

This system is the easiest to perform performance-minded upgrades with, since it has flat, full-range analog outputs (two pair, front and rear). The processing and crossover-filtering happens in the HiFi amplifier (in the trunk, L rear corner, under the plastic snap-off plate in sedans and coupes, behind the cargo door and under a plastic bolt-on guard in wagons. There is a remote turn-on wire present at the amplifier, similar to the base audio system in operation.

Speakers

Front door mids and tweeters (highpassed between 100 and 160)

R door or deck mids and tweeters (ditto)

Underseat 8" flat woofers (low-passed around 100 to 160 with significant stopband output)

There is no center channel, and no rear effects speakers.

Hey ctuna, I appreciate this but it doesn't really answer my question...

It does sort of answer my 2nd question, which was whether I should be concerned about the stock HU if I add a tweeter in parallel from the door woofers. An answer is implied in this part...

"-4" mids in the door. These have a capacitor on them, acting as a high-pass crossover filter and also making the two-speakers-in-parallel a load the deck can handle."

The 1st question I'm afraid I'm no closer to answering...on the HiFi system, the door woofer has a connector for tweeters. I'm wondering if this connector is there for the base audio system as well, EVEN though it would be unused from the factory. Sometimes manufacturers find it cheaper to prep for different options even if they will go unused. This matters b.c. if I integrate a tweeter, I'll know whether I have to solder a direct connection or can just plug and play the tweeter.

If you know, let me know!

[sfinxvc]

Originally Posted by mrberry

if you code to hifi and then either purchase the technic harness, the etok bak harness or the audison prima biamp harness you get a plug n play harness that lets you pick up the signals from theunderseat sub and add a 4 chanel amp to power the sub and the front . this with a decent 4 chanel amp is a good starting point and shouldnt cost to much if you go used

if you search the harness name on here you should fine more posts with details

Thanks - I'm trying an alternative even cheaper route and will post about it if it works out this week.

[ctuna]

On the Hi Fi system the door speakers have two plug in connectors
mounted to the speaker one for the incoming signal and one for the
tweeters . I have never seen a pair of Base system speakers.
In any case it would only require crimp connectors or soldering to
hook stuff. Some type of permanent connectors are better for easy
of install and servicing.

[andrewbr]

Originally Posted by sfinxvc

The 1st question I'm afraid I'm no closer to answering...on the HiFi system, the door woofer has a connector for tweeters. I'm wondering if this connector is there for the base audio system as well, EVEN though it would be unused from the factory. Sometimes manufacturers find it cheaper to prep for different options even if they will go unused. This matters b.c. if I integrate a tweeter, I'll know whether I have to solder a direct connection or can just plug and play the tweeter.

If you know, let me know!

Yes, the base speakers have the connector to add a tweeter.

[sfinxvc]

Sweet, thank you andrewbr and ctuna