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Aftermarket audio upgrade - persistent distortion problem

Discussion in 'Model S: User Interface' started by thnp, Aug 24, 2016.

  1. thnp

    thnp Member

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    Hi everyone!

    I have an persistent issue that I can't seem to figure out, and I'd hope to get some input from you lot! :)

    I live in Norway and bought a NVX BOOST subwoofer Kit through a local webshop. They have partnered up with a car hi-fi shop that has performed the installation of the subwoofer-kit.

    At the same time the shop installed the NVX B.O.O.S.T kit, they also installed a high-end 2ch amplifier (DLS Reference CC-2), along with a front speaker-kit (Focal 165KR2)…

    As this is a Tesla without the upgraded factory sound, there is no pre-amp out signal (to my knowledge), and the shop wired the DLS-amp (for the front speakers) through a signal-converter that was supplied along with the NVX-kit (it is designed to handle signal output to both Sub and front channels)...

    So the stereo speaker signal goes into the LC2i, and is split between the NVX-AMP and the new DLS CC-2 amp)…

    Initially I was very impressed by the new sound, but I shortly discovered that something wasn’t right…. The sound from the front-speakers are distorted, especially when producing «full tone» signals (acoustic instruments/classical music/voice)… The bluetooth is practically unusable, as the incoming voice is very distorted. The best way to describe it is that the speakers sounds «blown out», and very distorted. It's the same with AP engage/disengage/backing up chimes... They are distorted and doesn't sound right.

    Playing music without an acoustic presence produces no problem at all…
    The shop has been trying to fix this for quite a few days now, and I reckon they have spent 10-15 hours troubleshooting. They are the largest provider of aftermarket audio in Norway, and they are very knowledgeable…

    They have tried the following:
    - New speakers (both new Focals and different brand).
    - Wired the speaker-amp directly to the "speaker out signal" from the large screen (the amp has integrated line converter), i.e omitting the LC2 line-converter all together.
    - Re-wired with temporary cables.
    - Tons of adjustments of gain/volume/volume in.
    - Removed the speakers from the car mounts and ran them outside the car.
    - Different amp.
    - New audio crossovers unit (between mid-tone and treble-units).
    - Different sound source (iPhone minijack).
    - "Crossed" the R/L-channels to see if the problem is more pronounced on one of the sides.

    The only thing that produced a better result was running the system from the iPhone-source instead of from the head-unit. This fixed "90% of the distortion" according to the guy in the shop.

    I live 6 hours by car and ferry from the shop, so it’s a rather taxing experience to say the least…

    They have now concluded that the «last option» is to try another «high-low-converter» instead of the LC2i. They claim the Tesla audio-system produces too high an output for the LC2i to handle, and that it produces excessive noise…

    I’m at my wits end, and I’m uncertain that this approach will alleviate the issue. I’m not looking forward to a 12 hour roundtrip again for them to tell me that they are out of options…

    I would really appreciate any advice anyone can offer me. I figure someone here has done similar audio installs, and are familiar with the car and its limitations….

    Or have they «miscalculated» the ohm’s involved?
    Links:
    CC-2 amplifier: Reference CC-2 - 2 x 170 Watt amplifier
    Focal KR 165 K2 technical sheet: 165 KR - Technical sheet
     
  2. zambono

    zambono Member

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    You should contact the NVX guys they might have some input
     
  3. Trustno1

    Trustno1 Member

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    Mar 25, 2015
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    Location:
    Norway
    Hello thnp

    Where in Norway do you live? I might be able to take a look on your system if you're ever around. I live nearby Kongsberg

    I've done a complete rebuild on my system by incorporating a DSP on all speakerchannels + a new subwoofer, so I have some experience with the Tesla sound system.
     
  4. thnp

    thnp Member

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    Zambono: Thanks for the tip, but I already did that. Also contacted the producer of the high-low-converter (I have pasted their replies below).

    Trustno1: thanks! Check your PMs (in 3 minutes!) :)


    Response from NVX:

    The LC2i can be used to feed the BDA7501 BOOST amp and another full range amp.
    See below for installation method
    [​IMG]
    The SUB AMP is the BDA7501. The HIGHS AMP is DLS Reference CC-2
    Make sure you have matched the gain on the LC2i to both the sub and main amps. There is a separate gain for each output on the LC2i. They are independent and need to be set separately.
    Are you using the networks that are included with your Focal speakers or are you running them with the active cross over on the amp?
    If you are using the speaker networks, the amp should be set CROSSOVER OFF position.
    Be sure the speakers are connected to the correct terminals on the network.
    If you are not using the networks included with the speakers, be sure to set the HPF on the DLS Reference CC-2 to cut off the bass frequencies. I would start at 80hz and adjust to make the bass sound as if it is coming from the front of the vehicle.
    Try to cut the tweeter frequency switch to see if that changes anything.
    To me, it sounds like the gains are not matched and tweeters are possibly connected where the woofer should be connected.
    If this does not work, the DLS amp will take hi level signal directly from the speaker leads of the Tesla audio system. I would say connecting directly to the amp is the best solution.


    Response from Audiocontrol (LC2i):

    Thank you for contacting us about this issue.
    First off, you are correct, the LC2i speaker inputs can handle up to 400 watts, so I don’t think the LC2i inputs are being overloaded.
    The first thing that I thought of is the LC2i outputs and what the aftermarket amp is rated for.
    The first thing I would suggest (and I’m sure either you or the shop already did this) is turn the gains down on the LC2i to see if that distortion on the acoustic material goes away. Turn the gains all the way down if need be. Bear in mind, this is just a test to see if gain is the cause of the distortion. If the LC2i gains, and the gains on the inputs of the amp for that matter, are turned down all the way and you still get distortion, then it’s probably not a gain issue.
    If we’ve confirmed its not gain related, the other thought I had is then we might need to put some resistors on the inputs of the LC2i.
    A lot of the newer factory systems being installed today are designed where they are expecting to see some sort of load(or resistance) on the outputs of the speaker connections. Meaning, they are expecting a speaker to be connected to factory system. And since the LC2i does not put a load on the output, as far as the factory system is concerned, there is no speaker connected.
    So, in this instance, different systems will manifest different symptoms. The most common being it just won’t output a signal whatsoever.
    In other instances, like this one, it’s outputting at maximum since it sees no resistance thus the distortion.
    Here is an article on our knowledgebase about putting resistors on the inputs of the converter:
     
  5. cryptyk

    cryptyk Member

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    Did you ever get this figured out? I have the exact same problem and the guys in the shop aren't being helpful.
    It's only when the volume is at 8+. The song "White Clouds" by Decaf has some piano in it that really triggers it noticeably. It sounds like the speakers are blown, but they're brand new Focals.
     
  6. Xenoilphobe

    Xenoilphobe Active Member

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    check the polarity of the speakers..
     
  7. thnp

    thnp Member

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    Hi!

    Sorry for the late reply.

    The shop figured it out in the end...

    The problem was that they installed the amplifier in the trunk, and pulled the original sound-signal from the left- and right doors.... The signal got distorted on the way from the front end to the back end of the car (where the new amplifier was located).

    They spent maybe 8-10 hours rewiring the car (paid out of their own pocket), so that the new amplifier is behind the instrument cluster, with speaker-cables going to the doors. Completely fixed the problem, and the sound is now phenomenal!
     
  8. cryptyk

    cryptyk Member

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    Thanks for the replies :)

    Polarity is good and my amp is already in the front. The shop is still trying to figure it out. I'll let you know what end up happening.

    Thanks!
     
  9. wigalo

    wigalo Member

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    Cryptyk, did you ever get your problem resolved? Curious as I'm going to be doing the same upgrade soon.
     
  10. cryptyk

    cryptyk Member

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    Never figured it out.
     
  11. wigalo

    wigalo Member

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    Ok, thanks for responding.
     
  12. fabricator

    fabricator Member

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    With any modern OEM system you should be using a true DSP to correct the OEM signal. Considering technology has advanced so much in modern years, the OEM still uses cheap paper and plastic speakers (yes even the UHFS system). So what they do to combat that is to EQ the speakers to make them sound the best way possible. Due to construction of the speakers, lets say the tweeter has a hard time playing 3,500hz-8,000hz. Well the OEM will spike the signal at those frequencies to flatten out the interior frequency response of the speakers. Well guess what....... When you install your kevlar Focal speakers you will have a massive peak at those frequencies causing distortion. You will find this all across the frequency bands if you are not correction the OEM signal. The LC2i is not going to do that, that is mainly for a 2 channel subwoofer amplifier and has somewhat of a bass restoration if your OEM signal may be hi-passed. Great piece for a sub amp.....not your interior speakers. At minimum you need to run the OEM output of the factory amplifier into a Fix82. Use a Fix 86 if your Model S came with the front 3 way speakers (mids in the upper dash, and 8"s in the doors). That will completely level match and flatten the signal and de-time align the OEM signal. Now you have the starting point of an aftermarket radio (not a wild and crazy EQ curve that will cause distortion.

    This should be done by a competent shop that has the tools necessary to check the signal (RTA and Oscilloscope) to make sure you have a nice (unclipped) frequency response going to your aftermarket speakers. A step further would be to then add a JL Audio TWK or Mosconi 6to8 or 8to12 DSP. This way you can time align all your speakers and flatten and set the frequency response to a target curve by taking the interior of the Tesla into consideration. This will improve overall sound quality and help with imagining and separation within the music.
     
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  13. fabricator

    fabricator Member

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    Here is a video of me describing how the Fix works with RTA proof.
     
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