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2022 Volvo C40 Recharge (harman/kardon) - Measurements

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:
Screenshot 2024-07-08 170023.png

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:
Screenshot 2024-07-08 170722.png

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:
PXL_20240708_163308876.png

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:

2022 Volvo C40 Recharge (Harman) FR.png
(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:
2022 Volvo C40 Recharge (Harman) Surround.png

The built-in GEQ has adjustments from -12 to +12 (no units).

Here's what Bass does:
2022 Volvo C40 Recharge (Harman) Bass.png

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

Subwoofer:
2022 Volvo C40 Recharge (Harman) Subwoofer.png

Seems to be an exponential transfer function WRT gain, weird:
Screenshot 2024-07-08 183559.png

Resulting in:
Screenshot 2024-07-08 184543.png

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 o_O

Treble:
2022 Volvo C40 Recharge (Harman) Treble.png


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):
2022 Volvo C40 Recharge (Harman) Sweeps.png

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):
2022 Volvo C40 Recharge (Harman) THD 1.png 2022 Volvo C40 Recharge (Harman) THD 2.png

THD (dBr):
2022 Volvo C40 Recharge (Harman) THD 3.png 2022 Volvo C40 Recharge (Harman) THD 4.png

THD (%):
2022 Volvo C40 Recharge (Harman) THD 5.png 2022 Volvo C40 Recharge (Harman) THD 6.png

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:
SBC Reference THD 2.png SBC Reference THD.png

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):
2022 Volvo C40 Recharge (Harman) Decay 2.png2022 Volvo C40 Recharge (Harman) Decay.png2022 Volvo C40 Recharge (Harman) RT60.png2022 Volvo C40 Recharge (Harman) GD.png2022 Volvo C40 Recharge (Harman) Step.png

Attached below is the MDAT file with both sweeps and the main MMM measurement.

Thanks for reading!
 

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I have in the past put in custom head units and Speakers. The issue with testing these units is that often rather than fix rattles etc, the entertainment system is tweaked to avoid problem frequencies. Therefore it's not really just a entertainment system test. An example was a ford which I swapped out the entire system. The original systems tweeters were total eq'ed off.
 
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