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Thread: bye bye noise

  1. #1
    Variable Bitrate FPeter's Avatar
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    Cool bye bye noise

    Hi All!

    I started my CarPC project 3 years ago, and I met with the biggest problem at the first time when I turned on the new system in my car. Groundloop, generator noise, clacks at HDD, USB communication, and other annoying voices. I started with an old SoundBlaster PCI card, so I replaced it with an SoundBlaster MP3+ USB „card”. That was a bit better, but far from the heaven. I tried it at several place: under and in the dashboard, half way to back and in the trunk next to the audio amplifiers. One time there was less generator noise, but I experienced others. Other time generator noise disappeared, but I got another constant noise. I heard about ground loop isolators, but I think its only a „slap to the crap”... So I decided to solve this problem, by total isolation of the amps from the computer...

    The solution is the S/PDIF. I have never used before, and I had no experience with it, but I knew that this is the key. I searched the net for articles, and after a few week, I finished my first receiver:


    click to enlarge

    Based on Cirrus Logic CL8416 receiver and Texas Instruments PCM1754 DAC, with an Toshiba TORX173 optical receiver. I connected it to my MP3+ USB adapter, and I used it for month. After it, I built my other circuit with TI DIR9001 and the same TI DAC:


    click to enlarge

    Now I’m working on a C-Media CM108 chipset based USB audio adapter with some CarPC-related functions: rotary encoder knob for volume control, power on/off logic for amplifiers, and of coure the S/PDIF...

    Is here anybody, who has the same problems, and would like to solve it?

  2. #2
    Maximum Bitrate galvitron's Avatar
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    Nice. I'll have to give this a shot...
    2006 Lancer Evolution IX MR In-Dash PC Project - WIP

    Planning:
    [----------] 100%
    Purchasing:
    [----------] 90%
    Installation/Fab/Assembly (Revised v2):
    [----------] 90%


  3. #3
    Maximum Bitrate galvitron's Avatar
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    Any way you could post some detailed part numbers for what you used?
    2006 Lancer Evolution IX MR In-Dash PC Project - WIP

    Planning:
    [----------] 100%
    Purchasing:
    [----------] 90%
    Installation/Fab/Assembly (Revised v2):
    [----------] 90%


  4. #4
    Maximum Bitrate bes51659's Avatar
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    I want one FPeter, please.

    I have just installed (today) my PC in my car and had audio for the first time. Even though my RCA cable is only one feet long I had very much noise! I did expect total silence because of the PC and poweramp standing right next to eachother.

    As you I am bored with solving ground problems and prefer a final solution.

    I have Spdif out, so I only need your receiver... Any plans on selling it?

    As for the USB project; no, not interested. Sorry.

  5. #5
    Variable Bitrate eric_barcus's Avatar
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    how much where are the parts? do you have a parts list?

  6. #6
    Variable Bitrate FPeter's Avatar
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    Quote Originally Posted by galvitron View Post
    Any way you could post some detailed part numbers for what you used?
    there are several part that can be used, like CS8412,CS8414,CS8416,DIR1703,DIR9001 as receiver, and many many DAC ICs from different suppliers like Texas Instruments, Cirrus Logic, Analog Devices and others...

    i choosed the CS8416 (up to 192KHz 24bit, it was 1700Ft - ~10.3$ at local store) and TI PCM1754 (up to 192KHz 24bit SNR 106dB, i got it earlier from somewhere...), but I2S receivers and DACs are compatible in most cases, other types can be ok too, like CS4334 (up to 96KHz 24bit SNR 96dB)

    i used this guide to make my own circuit: DAC Final test and the DAC's reference pdf from the TI's website

    if you plan to use 192KHz, you need a high speed optical cable and receiver, like the TORX141P. i used TORX173 that can handle only the 96KHz, but i think resampling the 44.1KHz CD/Flac/Ape/MP3 source to higher level is a dummy thing, so i use 44.1KHz 16bit - like the source files...
    "case": Skoda Superb Elegance 1.8T
    Asrock G41MH-GE, E2180 2GHz dualcore, 1024MB DDR2/800, Samsung F1 750GB/7200RPM/32MB, M4-ATX, Lilliput FA1011 HDMI touchscreen, ASUS Xonar DG PCI, homemade Quectel L10 USB GPS

  7. #7
    Variable Bitrate FPeter's Avatar
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    Quote Originally Posted by bes51659 View Post
    I want one FPeter, please.

    I have just installed (today) my PC in my car and had audio for the first time. Even though my RCA cable is only one feet long I had very much noise! I did expect total silence because of the PC and poweramp standing right next to eachother.

    As you I am bored with solving ground problems and prefer a final solution.

    I have Spdif out, so I only need your receiver... Any plans on selling it?

    As for the USB project; no, not interested. Sorry.
    i have the plan to make a real product, but now its only a DIY thing... i write a pm to you...
    "case": Skoda Superb Elegance 1.8T
    Asrock G41MH-GE, E2180 2GHz dualcore, 1024MB DDR2/800, Samsung F1 750GB/7200RPM/32MB, M4-ATX, Lilliput FA1011 HDMI touchscreen, ASUS Xonar DG PCI, homemade Quectel L10 USB GPS

  8. #8
    FLAC greatwhite's Avatar
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    Guys, I'm not saying this solution doesn't work, I'm sure it does. But most noises in the audio is a result of the install being, well............shall we say "less than professional"

    My amp and puter are mounted back to back in the same cavity with the HDradio tuner and it's dead silent with the music paused and no interference problems. There's not even a layer of 3/4 MDF between them as the amp is in a hole and the puter is metal-to-metal with it.

    Like so:





    (Shameless plug for finished project)



    If this little gadget cures your noise woes, then great! Install and be happy!
    But it's not the only way.

    Just sayin'.........................
    For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return.
    Leonardo Da Vinci

  9. #9
    Maximum Bitrate galvitron's Avatar
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    Actually I want to use it to maintain a digital connection all the way back to the trunk.
    2006 Lancer Evolution IX MR In-Dash PC Project - WIP

    Planning:
    [----------] 100%
    Purchasing:
    [----------] 90%
    Installation/Fab/Assembly (Revised v2):
    [----------] 90%


  10. #10
    Variable Bitrate FPeter's Avatar
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    Quote Originally Posted by greatwhite View Post
    Guys, I'm not saying this solution doesn't work, I'm sure it does. But most noises in the audio is a result of the install being, well............shall we say "less than professional"

    My amp and puter are mounted back to back in the same cavity with the HDradio tuner and it's dead silent with the music paused and no interference problems. There's not even a layer of 3/4 MDF between them as the amp is in a hole and the puter is metal-to-metal with it.

    Like so:

    ...

    If this little gadget cures your noise woes, then great! Install and be happy!
    But it's not the only way.

    Just sayin'.........................
    metal to metal? the case of the amp should not be grounded! this is a very base thing in car hifi topics! in rare cases this can destroy the amp, loudspeakers and the source too! and make fire in the car...
    "case": Skoda Superb Elegance 1.8T
    Asrock G41MH-GE, E2180 2GHz dualcore, 1024MB DDR2/800, Samsung F1 750GB/7200RPM/32MB, M4-ATX, Lilliput FA1011 HDMI touchscreen, ASUS Xonar DG PCI, homemade Quectel L10 USB GPS

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