staticV3
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Below are measurements of the 2022 Volvo C40 Recharge with harman/kardon sound system.
I had little time to do these, so please excuse the mediocre measurement quality.
Measurement chain was Laptop->Alternative A2DP Driver ->Bluetooth (Stereo SBC 16/48)->Volvo->UMIK-1->Laptop.
I/O was set to Wasapi Exclusive (bit-perfect).
First, here's the Volvo's Bluetooth HCI Snoop Log which shows the supported Bluetooth codecs:

Sadly, just SBC and AAC. At least SBC is not sandbagged by a low max bitpool value. 53 is the norm.
Analyzing the Log in Wireshark shows that EDR 3 Mbps is supported as well:

I did not immediately achieve stable playback in SBC's higher quality Dual Channel mode (672Kbps), so stuck to the default Joint Stereo (357Kbps).
In hindsight, I should've used Mono as all my test tones are Mono anyway. Oh well.
Here are all sound settings available in the Menu:

While sitting in the driver's seat, setting the sound focus to Driver ("Fahrer") resulted in higher quality audio than All or Back seats, subjectively.
Surround adjusts the Stereo width (focused<->diffuse). The adjustment is subtle, there is no clear advantage either way.
First, the MMM Frequency Response with Driver focus, Surround Off, Default GEQ (all zero), while sitting in the driver's seat set all the way back, Mic about 20cm in front of my face at ear height:

(0.7dB/Octave overlaid as a typical far field in-room response of a neutral loudspeaker)
Next, here's the effect of Surround on frequency response:

The built-in GEQ has adjustments from -12 to +12 (no units).
Here's what Bass does:

PEQ Equivalent, roughly: 80Hz, Q 0.55, -6dB to +6dB in 0.5dB steps
Subwoofer:

Seems to be an exponential transfer function WRT gain, weird:

Resulting in:

Sadly, I was not able to find consistent equivalent PEQ parameters for EQ modeling. A Low Shelf with Q 1.0 matches the slope, but frequency seems to vary with gain
Treble:

These are really poor quality measurements, barely readable only due to heavy smoothing. In hindsight, I should've close-mic'd a tweeter somewhere for these.
I won't attempt to estimate equivalent PEQ parameters. SNR is just not there.
Lastly, I made two Sweep measurements to measure THD, CSD, Step Response etc.
I was aiming for 84 and 94dB SPL at 425Hz, but ended up with closer to 90 and 98dB SPL (sans bass shelf):

As before, settings were Driver focus, Surround Off, Default GEQ, but this time I had the Mic mounted on a tripod on the driver's seat (ear height), while I sat on the passenger's seat.
THD (Absolute):

THD (dBr):

THD (%):

If you're wondering how much the SBC Bluetooth Codec might've contributed, here's a reference sweep using Laptop->Alternative A2DP Driver->Bluetooth (Stereo SBC 16/48)->BerryBak BEA-1->Toslink->Hifime UR23->Laptop:

Basically, identical setup to the Volvo measurements, but purely WAV->SBC Encode->BT Transmission->SBC Decode->WAV.
The rest of the Volvo data (90dB sweep):





Attached below is the MDAT file with both sweeps and the main MMM measurement.
Thanks for reading!
I had little time to do these, so please excuse the mediocre measurement quality.
Measurement chain was Laptop->Alternative A2DP Driver ->Bluetooth (Stereo SBC 16/48)->Volvo->UMIK-1->Laptop.
I/O was set to Wasapi Exclusive (bit-perfect).
First, here's the Volvo's Bluetooth HCI Snoop Log which shows the supported Bluetooth codecs:

Sadly, just SBC and AAC. At least SBC is not sandbagged by a low max bitpool value. 53 is the norm.
Analyzing the Log in Wireshark shows that EDR 3 Mbps is supported as well:

I did not immediately achieve stable playback in SBC's higher quality Dual Channel mode (672Kbps), so stuck to the default Joint Stereo (357Kbps).
In hindsight, I should've used Mono as all my test tones are Mono anyway. Oh well.
Here are all sound settings available in the Menu:

While sitting in the driver's seat, setting the sound focus to Driver ("Fahrer") resulted in higher quality audio than All or Back seats, subjectively.
Surround adjusts the Stereo width (focused<->diffuse). The adjustment is subtle, there is no clear advantage either way.
First, the MMM Frequency Response with Driver focus, Surround Off, Default GEQ (all zero), while sitting in the driver's seat set all the way back, Mic about 20cm in front of my face at ear height:

(0.7dB/Octave overlaid as a typical far field in-room response of a neutral loudspeaker)
Next, here's the effect of Surround on frequency response:

The built-in GEQ has adjustments from -12 to +12 (no units).
Here's what Bass does:

PEQ Equivalent, roughly: 80Hz, Q 0.55, -6dB to +6dB in 0.5dB steps
Subwoofer:

Seems to be an exponential transfer function WRT gain, weird:

Resulting in:

Sadly, I was not able to find consistent equivalent PEQ parameters for EQ modeling. A Low Shelf with Q 1.0 matches the slope, but frequency seems to vary with gain
Treble:

These are really poor quality measurements, barely readable only due to heavy smoothing. In hindsight, I should've close-mic'd a tweeter somewhere for these.
I won't attempt to estimate equivalent PEQ parameters. SNR is just not there.
Lastly, I made two Sweep measurements to measure THD, CSD, Step Response etc.
I was aiming for 84 and 94dB SPL at 425Hz, but ended up with closer to 90 and 98dB SPL (sans bass shelf):

As before, settings were Driver focus, Surround Off, Default GEQ, but this time I had the Mic mounted on a tripod on the driver's seat (ear height), while I sat on the passenger's seat.
THD (Absolute):


THD (dBr):


THD (%):


If you're wondering how much the SBC Bluetooth Codec might've contributed, here's a reference sweep using Laptop->Alternative A2DP Driver->Bluetooth (Stereo SBC 16/48)->BerryBak BEA-1->Toslink->Hifime UR23->Laptop:


Basically, identical setup to the Volvo measurements, but purely WAV->SBC Encode->BT Transmission->SBC Decode->WAV.
The rest of the Volvo data (90dB sweep):





Attached below is the MDAT file with both sweeps and the main MMM measurement.
Thanks for reading!
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