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Discussion Starter · #1 ·
As you all probably know, Bose audiosystem on Macan has a subpar quality and it's quite mysterious why. Similar cars sound better even with basic audiosystems. Sound in Cayenne is much better.
I initialy planned to do a full replacement of speakers and amplifiers. The new amplifier is Helix V Eight DSP Mk2. As parts started to arrive I decided to perform some initial experiments. I decided to replace just Bose amplifier and keep the speakers.

The result was amazing - the quality of sound dramatically increased. I'd say it was near perfect.
I didn't tune up delay, just assigned the default filters to the speaker groups, all EQ flat.

In the next step I disassembled both amplifiers to see what is wrong in Bose:
BOSE:
DSP: ADSP-21365
DAC: CS42432 (24bit, 768kS/s)
AMP: Class AB, 12V unregulated rail

HELIX:
DSP: ADAU1435
DAC: AK4458 (32 bit, 192kS/s)
AMP: TPA3118D2 (Class D, but with rail control, lets call it Class DG)
Rail voltage: boosted up to 24V

So there's nothing wrong with BOSE hardware (of course it's much older). Most likely Bose DSP was programmed incorrectly. I've heard a gossip that BOSE has very little timefor customisation, mamybe thay just have the filter parameters incorrectly?

That else:
The boosted voltage rail on Helix could increase max power and also reduce THD at lower power levels.
I didn't believe I could hear the difference between 24bit vs 32bit DAC resolution, but may be it is one of the reasons?

Long story short, I plan to build my own amplifier in the form factor of old BOSE one. I don't like how new Helix amplifier is hanging out in the rear section like a foreign object with ugly wires. Porsche means attention to the details..

I'll let you know how's is going...
 

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As you all probably know, Bose audiosystem on Macan has a subpar quality and it's quite mysterious why. Similar cars sound better even with basic audiosystems. Sound in Cayenne is much better.
I initialy planned to do a full replacement of speakers and amplifiers. The new amplifier is Helix V Eight DSP Mk2. As parts started to arrive I decided to perform some initial experiments. I decided to replace just Bose amplifier and keep the speakers.

The result was amazing - the quality of sound dramatically increased. I'd say it was near perfect.
I didn't tune up delay, just assigned the default filters to the speaker groups, all EQ flat.

In the next step I disassembled both amplifiers to see what is wrong in Bose:
BOSE:
DSP: ADSP-21365
DAC: CS42432 (24bit, 768kS/s)
AMP: Class AB, 12V unregulated rail

HELIX:
DSP: ADAU1435
DAC: AK4458 (32 bit, 192kS/s)
AMP: TPA3118D2 (Class D, but with rail control, lets call it Class DG)
Rail voltage: boosted up to 24V

So there's nothing wrong with BOSE hardware (of course it's much older). Most likely Bose DSP was programmed incorrectly. I've heard a gossip that BOSE has very little timefor customisation, mamybe thay just have the filter parameters incorrectly?

That else:
The boosted voltage rail on Helix could increase max power and also reduce THD at lower power levels.
I didn't believe I could hear the difference between 24bit vs 32bit DAC resolution, but may be it is one of the reasons?

Long story short, I plan to build my own amplifier in the form factor of old BOSE one. I don't like how new Helix amplifier is hanging out in the rear section like a foreign object with ugly wires. Porsche means attention to the details..

I'll let you know how's is going...
Before you start please check all the other strings here, some going on for hundreds of pages, about how they did the same thing.
 

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As you all probably know, Bose audiosystem on Macan has a subpar quality and it's quite mysterious why. Similar cars sound better even with basic audiosystems. Sound in Cayenne is much better.
I initialy planned to do a full replacement of speakers and amplifiers. The new amplifier is Helix V Eight DSP Mk2. As parts started to arrive I decided to perform some initial experiments. I decided to replace just Bose amplifier and keep the speakers.

The result was amazing - the quality of sound dramatically increased. I'd say it was near perfect.
I didn't tune up delay, just assigned the default filters to the speaker groups, all EQ flat.

In the next step I disassembled both amplifiers to see what is wrong in Bose:
BOSE:
DSP: ADSP-21365
DAC: CS42432 (24bit, 768kS/s)
AMP: Class AB, 12V unregulated rail

HELIX:
DSP: ADAU1435
DAC: AK4458 (32 bit, 192kS/s)
AMP: TPA3118D2 (Class D, but with rail control, lets call it Class DG)
Rail voltage: boosted up to 24V

So there's nothing wrong with BOSE hardware (of course it's much older). Most likely Bose DSP was programmed incorrectly. I've heard a gossip that BOSE has very little timefor customisation, mamybe thay just have the filter parameters incorrectly?

That else:
The boosted voltage rail on Helix could increase max power and also reduce THD at lower power levels.
I didn't believe I could hear the difference between 24bit vs 32bit DAC resolution, but may be it is one of the reasons?

Long story short, I plan to build my own amplifier in the form factor of old BOSE one. I don't like how new Helix amplifier is hanging out in the rear section like a foreign object with ugly wires. Porsche means attention to the details..

I'll let you know how's is going...
By changing just the amplifier to a “Helix brand” was amazing, but it does not fit correctly like the “factory Bose “. Let me know if you find a solution because I
also would like to upgrade the subpar sound without having to replace and dismantle the complete system. Thanks
 

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Discussion Starter · #5 ·
Posting an update: working on the schematics and part placements: 75% is done (see the picture)
Reminder: my goal is to create a plug-in replacement PCB for the Bose amplifier, based on Helix (actually even better), and including MOST25 optical interface of course. No programming needed.
I expect to get a better quality even with existing speakers, (as I saw with Helix) in the same form factor, no extra wires.
Passive circuit component Circuit component Hardware programmer Microcontroller Electronic engineering
 

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Very cool and very interested. 👏
 

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Discussion Starter · #10 ·
Question to community: I still on the edge about middle connector: in Bose configuration it is not really used. I put a colayout of USB connector and DIN connector to connect Helix Conductor/Director modules. And one push button and LED.

Another option is to put the original connector (pictured half-transparent) and have a small external interposed board to convert this wired to USB/DIN/button:

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Very interesting project you have going on there. Following with interest, although I already spent a bunch of money upgrading everything…. That ship sailed for me…


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Really cool, I can see a LOT of Bose users adding this ……**** yeah….!

I am not of much help in the connector poll though Zeaman.

Not sure if it was posted above but what would be the power comparison between the Zeaman amp and OEM ?


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Discussion Starter · #13 ·
Another question is Bose AudioPilot function. One top microphone is routed to Bose amplifier. When option AudioPilot is on, it supposed to adjust volume ( maybe other adjustments too).
I tried it on original Bose and it looks useless. Especially considering how easy is volume adjustment by wheel control.

obviosly when connected to Helix this function doesn't work, no much regrets.

in theory, the microphone can be routed to inputs of Audio DSP and some corrections can be programmed using SigmaDSP Studio . But it is a stretch goal…
 

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Discussion Starter · #14 ·
The bottleneck for the output power for the new amplifier is actually a power connector and the power wires. The theoretical max power limit of the integrated circuit used is 70 Watt per channel ( 8 amplified channels + 1 routed to external subwoofer amp + 1 reserved)
 

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Another question is Bose AudioPilot function. One top microphone is routed to Bose amplifier. When option AudioPilot is on, it supposed to adjust volume ( maybe other adjustments too).
I tried it on original Bose and it looks useless. Especially considering how easy is volume adjustment by wheel control.

obviosly when connected to Helix this function doesn't work, no much regrets.

in theory, the microphone can be routed to inputs of Audio DSP and some corrections can be programmed using SigmaDSP Studio . But it is a stretch goal…
Audio pilot is a delete for me …. never use if for the reasons you state.


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The bottleneck for the output power for the new amplifier is actually a power connector and the power wires. The theoretical max power limit of the integrated circuit used is 70 Watt per channel ( 8 amplified channels + 1 routed to external subwoofer amp + 1 reserved)
My 2016 Turbo Sub has the self powered integrated Amp ( I did swap the speaker to a RF a few years back) , anyway, something to consider , I am not sure when……but at some point I think Bose moved the sub amp to the main board.


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Discussion Starter · #19 ·
Received the boards, bringing up. Waiting for some parts.. Please note this one is an overengineered prototype, I'm already working on cleaner design. Mechanical fit is OK.
Circuit component Black Hardware programmer Electronic component Electronic engineering
 
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