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going all out, sound quality questions

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  • going all out, sound quality questions

    well I've been reading these forums for a VERY long time, and finally have time to do my project and time to post/be active here.

    I'll be competing in USACi/IASCA sound quality when I'm done, and I'd like some input. so far my car is completely gutted (no interior or dash), and I have removed the hack job stereo system the previous owner paid $14,000 for spaghetti anyone? on the bright side I will be reusing most of the parts (MBQuart Q-series w/kick pods -- not sure yet if I will use this or make waveguides in the dash)

    so anyway the vehicle is a clean slate. I only want to do this once, and I want to do it right. I will be making a 3 piece dashboard from scratch and this brings some interesting possibilities. because I am also relocating the battery to the back (midsize SUV), I will also be making an enclosure back there anyway.

    so the first question is -- should I mount the computer in the dash or in the back? I have to redo the HVAC vents anyway, so I could set it up to cool the PC with A/C but I am very concerned about electronic noise/EMI and how this will affect my sound quality. here's one interesting catch. I am going to be using sound card analog outputs. yeah, thats right. I know everyone says go with optical. but I got a good deal on a pro studio mastering sound card which has DAC's beyond those in an Alpine PXA-H700, and possibly better than Alpine's F#1 status units! so I want to work around it and be different. it also has hardware time delays, equalizers, etc. built in to the card.

    decided to go with a pentium m "dothan" 1.7 w/abit's new i855 microatx mb, underclocked to an amazing 10 watts cpu. opus 150w ps. still shopping around for an lcd.

    so basically if you had an empty SUV as a clean slate... what would you do? I am looking for ideas, nothing is too crazy. should I worry about putting the computer close to the battery -- keeping in mind this is a sound quality competition system?

  • #2
    Sounds like you're doing the same thing I am. Which sound card are you using? One of RMEs? Lynx? I'm not sure I'm aware of one with hardware equalizers?

    What software are you planning to use with the card?

    I'd put the computer in the back. If your going to all the trouble to eliminate interference, why not just have a short ~1 foot RCA run from the sound card to the amps? A 10 watt CPU shouldn't have any trouble in the trunk without the benefit of an AC connect (plus AC can result in condesation, and thats a no no).

    You can always put a 2nd battery in the back if that concerns you.
    2000 Grand Prix Carputer Project


    • #3
      skarsol, very cool. never seen speed stepping working on a mobile amd/desktop mb before.

      thanks for the input as for putting the pc in the back. the short rca's is a great point. and the pentium m is supposed to be very heat efficient, especially underclocked. the only thing is i'll be moving to california in a couple months. if the car reaches 150F ambient thats a pretty bad start. I know the cpu can take it but I dont know about the motherboard components and sound card.

      for software I'll be using foobar 2000 mostly. the sound card is made by E-MU.

      any cool dash ideas? I am going to scrap all my vents except for defroster, which should be adequate especially in an extremely well insulated vehicle, I have a rediculous amount of sound deadening already and putting more in. I would love to swap in a digital HVAC from the junkyard, but I don't have time to go take all the dashes off to see how they work... have you thought about going that route?


      • #4
        Which EMU card? How many analog outs does it have? From what I saw looks like it only has a 3 or 4 band EQ on the cards themselves?

        I'm in Texas and from everything I've read, anything under like 30 watts should be decently okay. Havent ever really thought about the external cards and stuff. Could look into some of the stick on ram/chip heatsinks and stick em on the sound card if you're worried.

        Hum, now that you've got me thinking about it I'm gonna have to see how much my card puts out going full bore. Least with my set up the soundcard is split into two parts so I can separate them for better airflow if needed.

        You're going to scrap the vents and you're moving to cali? Hopefully this is a comp car and not a daily driver? :P I was contemplating migrating the HVAC controls to the computer and stashing the HVAC box sans faceplace someplace else (its only 8 control wires so shouldn't be too difficult).
        2000 Grand Prix Carputer Project


        • #5
          for competition sound quality concerning the in car computer, your biggest issue is going to be wiring. and there will be a TON of it! for your max install points, youll have to do some pretty amazing cable routing. Lucky for you that your car is gutted, it will be easier.

          there are two schools of thought to the matter, I like both. the first is to mimic the stock wiring scheme. this means runs of cable are E-taped disguised to look stock. I like it, if you chose to use black rather than seperate colors for signal, power, output, and computer, everything would look stock. dont forget to take pictures!
          The other thought is to use wire look and ziptie it, then bolt to the frame. This is the IASCA standard, I have mixed feelings. loots neat enough, keeps things seperate, but its not very stock. You can do either one you want. just make sure you take pictures of absolutely everything! and dont skimp on the terminals, you are judged on that too! everything form battery terminals to spekaer terminals. all documented by many photos!

          last thing to think about during build up is what we call "attention to detail". stick a box in your trunk and its bland. integrate it into the car and dont make it look tasteless or flashy, and get more judging points. your car must be a show car on the day of the competition!

          here are a couple examples:
          poor attention to detail:

          good attention to detail:
          edit: linked due to image size

          good luck getting your stage done and all the aesthetics completed, you've certainly got your work cut out for you!


          • #6
            Using an in car computer actually makes wiring easier. You have power running from the battery back, speaker cables going from the back to the front, and a video and usb cable connecting the computer to the screen (assuming a touchscreen). All your RCAs can be very short and are entirely contained in the trunk.

            How is that first pic poor attention to detail? I don't see any scratches in the paint job, the speakers are visually mounted well, there is a bare minimum of wiring exposed and the whole assembly is obviously fitted to the car. Compare that to the irregularly edged vinyl around the sub and amp in the second pic and also notice how it is in the worst possible place for an inverted sub (anything at all loose in the trunk will end up bouncing on the cone).
            2000 Grand Prix Carputer Project


            • #7
              the first picture is flashy, tasteles. you can see wires. the borders between the box and the car are nonexistant, you could take that box out and put it in a rav4 and you wouldnt notice a difference. thats poor attention to detail!

              second is a false floor, so its all covered by a hatch. nothing ever gets to the subwoofer. quality is low, so you cant see its actually a painted panel, not vinyl there. the irregular edging is a trick of the color splotches caused by the photograph. good eye, though.


              • #8
                I think we're going to have to agree to disagree. I think the color matching in the first one is decent enough to mark the box as belonging to that car. The black/grey/silver/white theme is pleasing to my eye and what I can see of the wires is acceptable to me since it isn't a true recessed mount. (Unless you're arguing that a recessed mount is the only way to do things properly?) As for being able to put it in a Rav4, I'll agree that perhaps it's poor *integration* but thats entirely different from poor attention to detail in my book.

                If thats really a paint job and not vinyl then there is no excuse for the edge irregularities I'm seeing and I can't buy attributing it to camera/color error (the flat parts of the circle are too obvious). I'll give it the benefit of the doubt on the amp edges though.
                2000 Grand Prix Carputer Project


                • #9
                  I say both are poor. The fiberglass work and paint is good on the first pic but the enclosure does not fit. They did not take the time to make it fit properly. The large gap where the enclosure meets the rear panel should not be there. A little more time taken and the piece would fit tight.

                  The second pic the fiberglass work is wavy, the edge around the sub is unfinished, and the finish on the fiberglass looks lousy. I totally understand what WhiteRabbit is trying to say....a true show car is made up of the details. The details will make or break the car.