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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > AUDIO/VIDEO + BLUETOOTH + Electronics/Alarm/Software > Logic 7 head unit replacement question - Optical conversion



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      08-28-2024, 05:01 PM   #1
Noquills
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Logic 7 head unit replacement question - Optical conversion

I am exploring "upgrading" the head unit on my logic 7 system (E92, 2008) with a new in-dash android unit as the pixels now disappear as the unit heats up on the L7 unit. Still works fine and sounds great. Lots and lots of posts/YouTubes showing how to swap the head unit out for an android unit and I have read/watched a lot of them. Pretty straight forward.

However, most of these installs were not Logic 7 systems.

I know that an optical converter (sold separately) is required to hook up an android head unit to the Logic 7 amplifier. However, in reading some of the reviews for this conversion, several have pointed out they were disappointed in the result due to the limitations of the optical converter that typically only uses two RCA inputs (right front, left front outputs) from the android unit to the optical converter. One supplier even has a section on their webpage tempering the purchaser's expectations when using the optical converter.

Short comings called out in the reviews:

- There is no front to rear fading available.

- The amp would send full range outputs (as opposed to high bypass and low bypass) to the tweeters and the subs resulting in poor sound quality.

Q: For those folks who have actually replaced the factory head unit with an android head unit on a Logic seven system:

- Do you have front to rear fading?

- How is the overall sound quality?

Recommendations on the unit and the converter would be appreciated

Yes, I know I can fix the pixel issues on the factory unit, but I would like to bring the functionally into this decade if possible (USB music would be a nice start)
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      08-28-2024, 05:15 PM   #2
ctuna
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The Head unit may be sending more than just audio over the optical interface .
Logic 7 Head Unit has different music modes plus a graphic equalizer. You loose all that with aftermarket head unit . These signals are used to set up surround modes plus eq.
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      08-28-2024, 09:50 PM   #3
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Thanks for the info.
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      08-29-2024, 07:36 AM   #4
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Hi, see my recent post. I went down a similar path with my 335d and Logic7. I installed the optical decoder, it required yellow power, red power, ground, optical cable, then L & R RCA inputs from the Android head unit.

At first I wasn't happy with the sound quanlity. Too flat and no base response. But I spent time dialing it all in. I used the EQ within the Android unit, set it to a smiley face curve with greater emphasis on lower frequencies to try and dial in the balance. Then I turned on loudness on the Android EQ and Bass enhance. These steps helped, but still left me hoping for slightly more. Then I found the magic key. I use Carplay with Spotify as my primary music source. I enabled high quanlity audio. I also used Spotify's built in EQ on their App. WOW......it sounds much better than the stock radio ever sounded. Lindsey Sterling sounds crisp with a broad sound stage. The Weeknd sounds strong with broad response and base is felt from the OE subs.

I did lose fader capability. You'll also lose the SOS call feature and you'll get a momentary on dash warning at every startup, but this can be coded out if you like. Below is the link to my review. The second link is the unit I bought and installed.

https://www.e90post.com/forums/showthread.php?t=2128358

https://www.aliexpress.us/item/32568...-specification
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      08-29-2024, 09:10 AM   #5
Noquills
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Mark M (and ctuna), Exactly the info I needed.

Two more questions.

What decoder did you purchase (and where)? I see dozens on AliExpress from $7 to 107$, all looking the same.

Which fuse did you tap into for constant power?
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      08-29-2024, 09:49 AM   #6
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I purchased the Eonon decoder off Amazon. ~$100.

I don't recall the fuse I tapped. I accessed the fuse panel behind the glove box, then left the passenger door open for a half hour. Confirmed the car was in sleep mode (orange light in Park was off). Then I used my voltmeter and began seeking a constant fuse. Found one and tapped it.

Sound will be somewhat flat at first, you'll need to play around and dial it in. What head unit are you planning to use? Share the link.
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      08-29-2024, 02:14 PM   #7
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There are two units that come up on the AliExpress link you posted. Will likely be one of those although I am having trouble recognizing the difference between the two. I need to see if they support heated seats in those units. Does the one you purchased support heated seats?

Again, thanks for the information.
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      08-29-2024, 02:29 PM   #8
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The difference between the two units in my link, one includes the generic rear camera, the other doesn't. Both units come equiped with rear camera capability.

Yes it supports heated seats, but it is a couple menu levels deep to get to it. Fortunately for me, my HVAC panel has the integrated heated seats buttons.

Good luck!
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      09-14-2024, 10:35 PM   #9
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Keep the stock system just replace the old with a used one with working pixels, then and carplay or an Android system. If y9u want to replace amp the get the audison bit DMI... Pulls signal from fiber optic and sends to either analog or digital amp or processor.
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      09-15-2024, 11:56 AM   #10
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BMW optical signals use a proprietary code the only things that will decode them available that are known to work come from Mobridge.
There are optical converters mentioned that convert to two channel analog but Mobridge has the only optical pre amps and amps that work properly .
At least last time I looked.
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      09-28-2024, 05:10 PM   #11
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Follow-up:

Based all honest and timely responses I decided to keep the L7 head unit and get a carplay screen as suggested by Eturnulrs704. I felt that an SOS error and loss of sound enhancement/direction on a pretty good sounding stereo (for it's day) was not going to fly. So, I did what a lot of the earlier conversions did, change what feeds the Aux input to something other than a Bluetooth adapter.

This is not a promotion or sales pitch for this product. It just happens to be what I choose based upon my research.

For about $130 I purchased this carplay screen. It fit my needs. It allowed me to mimic the "cut the dash" style replacement head unit at nearly the exact location and form factor without damage to the dash and give me "Apple car play" functionality. There are hundreds of variations for sale. This one also has a built in 4K dash cam and a rear camera/harness which I have not installed yet that also functions as a MUCH needed backup camera. I can see easily over the unit when mounted as shown using the telescopic suction mount on the window.
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https://www.amazon.com/dp/B0CRYZVZ6Q...fed_asin_title

I took it on a 500+ mile shakedown and it met/exceeded my expectations. No dropouts, nice display, and worked well. Waze worked great on one part of the screen and music on the other. Only downfall is the screen is like a mirror and you get reflections from inside the car. Need to work on the wire management. Also, don't forget to adjust your "aux volume" on the L7 unit to match the output of the carplay unit. Too high and you get distortion.

To the folks who say the Aux input is not the best audio input you are right, but it is the one I have been using for 10 years and, other that using an FM simulator, the only other which can be used on this iteration of L7 without coding (from my research) to supply an audio signal.

While I was setting this screen a friend came over and tried this carplay display in his older BWM 3 series (E36?) which had an aftermarket Bluetooth enabled Kenwood head unit. He streamed the audio from the Car play screen to his head unit via bluetooth and all I can say was "wow" great sounding stereo with this input. Guess what he ordered so he could navigate without the small screen phone to squint at

As a side note: 335i/N54 1,000 mile round trip I just finished, 80% interstates, got 32.2 MPG and 57 mph average for the whole trip...........Not a misprint and the second time I ran this 1,000 mile lot of Appalachia loop at 31+ mpg. The best I have every done was a 120 mile loop locally at 35+ mpg. Not bad for a 300hp/300 ft-lbs car celebrating almost 17 years of age and, yes, I drive like an old man by definition. PS. I find that A/C use= 1.5 MPG penalty at highway speeds as opposed to closed windows on a cool day.

Last edited by Noquills; 09-28-2024 at 07:00 PM..
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