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MCU2 Upgrade Audio EQ Balancing - Coming From MCU1

Discussion in 'Model S' started by agtdDelirium, Aug 12, 2020.

  1. agtdDelirium

    agtdDelirium Member

    Joined:
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    Location:
    Colorado
    Background as to why I did this project:

    I own an October 2016 model S 90D. This was one of the first autopilot two cars made (which I paid for), ordered with the premium sound upgrade, and came with MCU 1. When I first took delivery of the car, I thought the sound system was excellent and much better than most I had experienced in a factory car (all much lesser premium vehicles). Over the years, with ongoing software updates, that sound changed and became more limited, but I was always able to retune the system back to sounding very good. I have never been unhappy with the sound system.

    Then came my decision to upgrade to MCU 2. With all the great benefits to the new MCU, the one detriment I noticed immediately was the sound from the system. It was drastically different than MCU 1. My equalizer settings from MCU 1 carried over to MCU 2, but they sounded like crap. The bass was overwhelming; the vocals were harsh; it was just not well balanced. I have always considered myself to be a "budget audiophile." I can appreciate when an audio system is well-balanced, but I am not sure I could tell you a $2,000 amp sounds that much worse than a $20,000 amp.

    With MCU 2, I spent a lot of time messing with the EQ settings trying to get something close to what MCU 1 sounded like. I could tell things were still wrong, but I was struggling with manual adjustments. Even bringing out my trusty 25-year-old RadioShack SPL meter and recordings of my Sheffield/A2TB Test CD was only partially helpful. I needed better data, so I decided to make some objective measurements.

    Equipment used:
    • Rode NT1A microphone mounted at head-height between the front seat headrests.
    • Focusrite audio interface connected to my laptop
    • Audio samples were recorded directly into Adobe Audition software, and then frequency analysis grafts were generated by Audition.
    • MP3 recording of track 57 on the Sheffield/A2TB Test CD (320 kbps) played from a USB drive. This track is a 20 Hz to 20 kHz continuous warble designed to evaluate the overall smoothness of the acoustic response in a listening area. The sweep is warbled to eliminate the standing waves that would normally occur with a simple swept tone. This is essential when evaluating the frequency response of a car stereo within a very enclosed listening environment where standing waves reflecting off glass are all over the place.

    What I did:

    I imported the test MP3 into Adobe Audition and used this as a baseline to compare recorded samples obtained in the car. This test sample maintains a constant volume across the frequency spectrum, and therefore the dB grafted at the low-end are much greater than those produced at the high end of the spectrum. Human hearing perceives high-frequency sounds to be much louder than lower frequency sounds produced at the same dB level. Nonetheless, I am using a perfectly recorded sample as the baseline audio file and directly comparing the playing of the sample recorded directly in the car from the sound system.

    The sound samples recorded in the car are then overlaid on top of this baseline to show the relative dB difference throughout the frequency spectrum. A perfect sound system in a perfect listening environment with perfect recording equipment should produce an identical graft to the test MP3 sample.

    There are several limitations to my set up.
    • First, I am not an audio engineer. This was a makeshift recording set up using equipment that I have available. I recorded with all the windows up in the sealed car in a quiet garage. I was seated in the driver seat of the car with my laptop. Climate control was off. The laptop fan was running, but the base recording audio level was at about -45 dB. Recorded samples peaked at about -5 dB.
    • The Rode NT1A microphone is known to be a particularly good basic studio recording mic, but it has its own frequency response curve that is well documented. This frequency response will taint recordings and must be taken into consideration when interpreting the recorded samples. It is also a directional mic with a cardioid polar pattern. I faced the mic pointing forward just behind and between the front seat headrests. The balance of the sound system was set at the center default point. Most of the sound in the Tesla system is produced by the front speakers, with rear speakers producing more fill and obviously the subwoofer base. Most of that sound reflects off of multiple surfaces before reaching the driver seat. Although the mic pointed away from the rear speakers, I believe the recordings reproduce a good sample of what is heard by front-seat passengers.

    The Rode NT1A microphone response curve:

    [​IMG]

    And now the data:

    First, I recorded the sound system with all EQ settings at zero. The graph shows the baseline MP3 test file in orange versus the recorded sample in blue. The positioning of the baseline is somewhat arbitrary, and simply what I chose to be a good neutral target to allow subsequent adjustments to the equalizer bands. This baseline could easily be moved up or down and was just a choice I made looking at the initial frequency response graft. It is also important to note that the graft is a plot of the relative dB change on the X-axis versus the logarithmic scale of frequency on the Y-axis. The zero point on the dB axis is also placed arbitrarily and is only a reference point. Each horizontal line on the graph represents a 2 dB change in volume. Click on any image for full-size versions to read more carefully.

    [​IMG]

    The results in this graft show a huge dB boost in frequencies below about 1500 Hz. There is also a significant bump in the 3500 to 6500 Hz range. Somewhat surprising is a very steep drop off after about 14,000 Hz. However, the human ear in a moving car is going to have great difficulty in appreciating anything above that frequency.

    Next, I needed to find out where each of the 5 EQ adjustments affects the overall frequency curves. I went through the process of recording five samples, each with individual EQ bands set at "-8" (slider fully down). I will talk about the EQ bands numbered from one through five, left to right on the settings page, from bass to treble, respectively. Each graph has the baseline target again shown in orange, with the recording of the default EQ setting in blue, and the "-8" EQ setting is in green. I am only altering one EQ slider at a time, with the rest kept at the zero default. The green line should, therefore, mimic the blue line (within sampling error) with the deviation only where the targeted EQ slider is affecting frequencies.

    EQ slider one:

    [​IMG]

    The slider begins to affect frequencies below 600 Hz to frequencies off the graph to the left, well below 100 Hz. I suspect the peak influence is off the graft below 100 Hz.

    EQ slider two:

    [​IMG]

    The slider begins to affect frequencies at about 800 Hz with a maximal deflection around 450 Hz but continues to affect even well below 100 Hz. There is a crossover with slider one in the lower frequencies. This EQ band is well within the human singing voice.

    EQ slider three:

    [​IMG]

    The slider has a frequency range beginning at 2000 Hz down to about 400 Hz with maximum effect at about 900 Hz. The band will again significantly affect human female singing voices, especially high soprano.

    EQ slider four:

    [​IMG]

    The slider has effects on frequencies between about 1.5 kHz and 6.5 kHz, with maximal effects centered around 3 kHz. This is well within the range of hearing the crack of consonants in speech and "S" sounds.

    EQ slider five:

    [​IMG]

    The slider has effects between 4 kHz all the way through the very higher frequencies with a maximal broad impact between about 6 kHz to 12 kHz. This is the range of "airiness" or "breathiness" in recordings and the high-pitched crack of symbols.

    Now to try and make it sound better:

    So now what to do with all this information? Unfortunately, Tesla has chosen only to give us five frequency bands to play with. These bands do have some crossover at certain points, but some of them are much broader frequency ranges than I would like. I miss the eight-band equalizer that was present on my model S when I first bought it. Why did they get rid of this? But we are left with what we have, and I set forth in trying to do the best I could with what is available. I ended up with the following changes to the five equalizer bands.

    [​IMG]

    And here is the final frequency curve that I was able to generate with the above settings.

    [​IMG]

    It was the best compromise. I left the base frequencies slightly pushed since car stereos tend to need extra base to overcome road noise. I wish I could have pushed the 2-3 kHz band higher, but unfortunately, this lies at the crossover between slider three and slider four. Pushing slider four higher ends up producing undesirable increases at the 4 kHz to 6 kHz range. Pushing slider three higher significantly affects female singing voices, and is the reason I initially thought voices sounded so harsh. After listening to many different types of music, I am happy with the results, and the system sounds infinitely better than when I started.

    I hope this might give some general starting points for those in a similar situation. Ultimately, EQ choices are based on your individual ear and how you like your music to sound. My settings are for my desire to have a very flat response out of the system. I listen to a vast variety of music, everything from classical, the 1930s and 40s standards, jazz, current and classic alternative rock, and on the rare occasion, even modern pop music (I do have teenage daughters). I am happy with this baseline EQ setting but may overtime tweak it slightly.

    I have no idea if these settings crossover from my October 2016 model S to the current model S, X, or even 3 and Y. I am not sure if speaker manufacturers used by Tesla have changed over the years, and I suspect the 3 and Y are entirely different. The settings are probably utterly wrong if you do not have the premium sound option. I would love to hear what others have come up with within their own experimentation.
     
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  2. ucmndd

    ucmndd Well-Known Member

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    Very detailed, thanks for taking the time to do this. Question, what setting are you using for the "immersive sound" option on the options tab?
     
  3. agtdDelirium

    agtdDelirium Member

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    For all the graphs that I posted above, immersive sound is off. In the end, when I dialed in my EQ settings, I did run a test with it on maximum, and there were no significant frequency changes. The best I can tell, it is using some digital signal processing to create a wider soundstage, but it is not improving the sound in any way. It is also not degrading the sound. So use it if you like it, but personally, I leave it off.
     
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  4. Topgun66

    Topgun66 Member

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    Lifesaver. I have been trying for weeks to get my sound dialed in. Right when I left the dealership after the upgrade I knew something was wrong. Stereo was horrible. I used to own a 14 model S with UHFS and that was the best sounding system I had ever heard. I now drive a late 17 model S and the sound was pretty good. Nothing compared to my 14 S but with an addition of the NVX sub package my car rocked. Then came MCU2. Wow. Sound is junk now with my old eq settings. I have included the way I have tuned every stereo that had a eq for the last 30 years or so.
    42586FEC-B2AE-42A6-A262-0B0ED62057BC.jpeg
    as you can see I have the Treble turned way up and it was blasting my ears 61D07E1F-5A69-4830-9E1B-3DBAFF1A23F1.jpeg

    This is close to the settings you provided changed slightly to my liking.

    Now my sound is better but still not the same as the MCU1 was. I will continue to play with the setting to dial further, but this a good start. Is there anyway you could post the audio MP3 you used so I could do a similar test? Or PM me if you do not want to post publicly?
    Anyways great job as this got me closer to a usable system. MCU upgraders beware. Your sound will dramatically change. Take this into consideration if you are a audio enthusiast. I know some don’t care much about sound but my sound system was one of the parts of the Model S
     
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  5. tcoombes

    tcoombes Supporting Member

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    Glad you are making progress. It would be nice if they had a 10 band integrated EQ.
     
  6. WASD

    WASD Member

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    Culver City
    Ooof. This is bad news for me. I'm in the middle of an audio install on my car and I planned to get MCU2 upgrade when it's available. This means I'll probably have to re-tune the inputs after getting it.

    Too bad you don't have the MCU1 readings to compare. Would be interesting to see what changed. I wonder if it's a bug ...
     
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  7. Topgun66

    Topgun66 Member

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    I agree 5 is not enough. We need someone with some twitter punch to ping Elon to fix this for us.
     
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  8. agtdDelirium

    agtdDelirium Member

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    I'm glad to hear this helped. Looking at your settings, I think you hit on what is most important, which is EQ slider 2 and 3. These control the frequencies of the human voice (roughly 100 Hz to 1000 Hz). If that is screwed up, music tends to sound terrible, and the default in my Tesla was boosted 6-8 dB. The decibel scale is logarithmic, so that amount of increase is in the range of nearly doubling the perceived volume for those frequencies.

    If you like thumping bass, then, by all means, crank slider one up. Same for the ultra-high treble. Those frequencies are perceived as much less critical to the human ear and become a matter of choice/style in music. Thus the classic "V" EQ settings that have worked for you in the past. The bottom of the "V" typically needs to be at the mid voice frequencies for a baseline. Tesla's baseline was just screwed up. I have rarely had to have such a skewed EQ setting to get a good sound.

    The test tracks I have used for decades when setting up any new audio system are still readily available and a cheap investment if you care about sound quality.

    https://www.amazon.com/Sheffield-A2TB-Test-Disc-My/dp/B000V93NKY
     
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  9. Topgun66

    Topgun66 Member

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    agtdDelirium
    After Mobile appointment they ran diagnostic and they all failed for the sound system so something is going on. As usual I had to book another appointment now to go into the service center which is 2 1/2 weeks away. Most likely they will have to order parts(Maybe another MCU2?). Could be months before I get this fixed. Service has not changed in the 4 years of owning a Tesla.:(
     
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  10. tcoombes

    tcoombes Supporting Member

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    Did they provide you with the test detail and specific results?
     
  11. Topgun66

    Topgun66 Member

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    They did not give me any specifics.
     
  12. tcoombes

    tcoombes Supporting Member

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    Too bad, it would be interesting to know exactly what was failing. I guess you will learn more in a couple of weeks.
     
  13. Doanster1

    Doanster1 Member

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    Wow!!! I haven’t heard anyone mention the Sheffield test disc for decades. That’s like the Video Essentials disc when people really started caring about HD.
    Great work and results!!! My MCU1/UHFS system does indeed have the modified V-pattern for the EQ. :)
     
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  14. beatle

    beatle Member

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    Good info for anyone considering an upgrade to MCU2. Even for those with aftermarket DSPs, if you're using the stock output, they will use that as their baseline. If the baseline changes, so will the effective tune.
     
  15. WASD

    WASD Member

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    Exactly what I'm worried about. My car is getting tuned right now on MCU1 and I plan to upgrade to MCU2 as soon as I can. I hope that it is indeed just a bug and not a "feature" of the new MCU. Worst case is that I get it retuned, but I'd rather not have to.
     
  16. FlatSix911

    FlatSix911 Porsche 918 Hybrid

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    Well done!
     
  17. t-money

    t-money Member

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    Hey OP, I just want to say that I appreciate a good, scientific analysis of a problem you had and and a write up on your solution. It always makes me happy to see skilled people do their thing! Have a good day!
     
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  18. colojohn

    colojohn Member

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    So, I see you're in Colorado. Personally not a huge audiophile myself, but if you're interested, I'd be happy to meet up with to do some analysis on the 3's speakers to publish a similar guide for that car. I'm in the greater Denver area, but I'm open for a reasonable drive.

    Certainly don't have any expectations that you'd want to, but I thought I'd volunteer at any rate. This was a pretty fascinating write up to me.
     
  19. Mx Nightrider

    Mx Nightrider New Member

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    Wait. You got your in October 2016? I got mine in November 2016 and i have HW1.0. How is that possible?
     
  20. CraigE1965

    CraigE1965 Member

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    Can any of you audio experts that have the MCU2 upgrade and regular sound system please check if putting the balance all to the two rear speakers, do they work properly, or is the volume about half of what it should be and with absolutely no bass at all? It seems like after the upgrade all bass is directed to the front center speaker and nothing two the two back door speakers. It is very odd, and I would like to know if any of you experienced this after the upgrade. MCU1 had perfect sound and bass in the two rear speakers for 2 years before I "upgraded"
     

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