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Audio Question: Equalizer/Line Driver/Loc??

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  • Audio Question: Equalizer/Line Driver/Loc??

    Hi Guys,

    my project is almost finished.
    The carpc in working. will put the project in the project section.
    My concern right now is :

    I'm using the onbaord sound card (RealTek) with an Intel Motherboard (Intel D945GCLF2).
    I'm using to 3.5 jack (line out and line in) out of the sound card and into 4 inputs of my OEM Audi Amp.
    the Audi amp outputs sound to 9 speakers.

    the sound resulting from this is ok, but not two strong and some MP3 or even Flac files sound distorted when volume is pushed higher and bass sounds muffled.

    Solutions (let me know your opinions here)

    Line driver
    Line output converter (this is only for speaker level inputs I suppose)
    Equaliser with integrated line driver

    Note:
    I don't want to change the OEM amp and the cabling.
    I don't want to put an equalizer in the dash.

    Question: if I go for a line driver only is the mixer or equalizer of Centrafuse (or any software equaliser) enough to tweek the sound coming out of the sound card.

    Please you ffedback and comments.

    here is a video of the carpc (the car is an 2009 Audi TT MK2)

    http://www.youtube.com/v/4GBfYxLbRsQ

  • #2
    get an auzentech card.

    Comment


    • #3
      your right about the line output converter-- that would convert speaker level(high voltage) to line level(low voltage) signals-- so it doesn't really apply here.

      for the low level, a preamp would be your best option-- it is kind of up to you wheather you want a eq/line driver, or just a plain line driver.

      try to use the centrafuse eq a little to determine if it has enough adjustablity for you-- even at a low level, you should be able to decide if it is enough for what you want to do.

      this is where i would insert my review of the jl audio cl-rlc as a preamp, and a volume control. it works great for me, but is a little pricey @ $50 ea. but don't worry, there are alternatives that are cheaper-- just look around for them.
      My OLD 2001 Mitsubishi Eclipse GT:
      "The Project That Never Ended, until it did"


      next project? subaru brz
      carpc undecided

      Comment


      • #4
        Originally posted by soundman98 View Post
        your right about the line output converter-- that would convert speaker level(high voltage) to line level(low voltage) signals-- so it doesn't really apply here.

        for the low level, a preamp would be your best option-- it is kind of up to you wheather you want a eq/line driver, or just a plain line driver.

        try to use the centrafuse eq a little to determine if it has enough adjustablity for you-- even at a low level, you should be able to decide if it is enough for what you want to do.

        this is where i would insert my review of the jl audio cl-rlc as a preamp, and a volume control. it works great for me, but is a little pricey @ $50 ea. but don't worry, there are alternatives that are cheaper-- just look around for them.

        That's some real feedback :-) thanks SoundMan.
        can you please just elaborate on how you're using the jl audio cl-rlc.
        my carputer ar, car battery and oem amp are in the trunk, does this device ned to be in the front of the car; i don't want to audio cables cables to the front of the car.
        How do you connect this device to have four channels output ?
        The price is ok if this device will do the job right.

        Waiting your explanations befor I make the order...

        Comment


        • #5
          Ok, I just read your review. great post.

          still I need to know how many devices will I need?

          I need 4 channel output. I have an OEM 9 speaker system setup with an OEm amp which has 4 inputs. FL-FR+RL-RR.
          My soundcard has a quadrophonic settings which enables the use of the four channels.
          I don't really need the knob. i'd rather use Centrafuse to control the volume.

          Comment


          • #6
            I found this 4 channels line driver at 64$

            HIFONICS HFEQ 4 BAND CAR EQUALIZER



            Half-DIN, 4-Band preamp EQ with front/rear active crossover features
            Line Driver circuit delivers 9-volts of preamp level signal through the RCA's
            Audio input selector for switching between headunit and another audio source
            Input level controls for both the car radio and any media device to insure identical volume levels
            Master volume control of the SPL-Level for both sound sources
            Front to rear dual-amp fader
            2-Audio inputs with level matching
            Selectable 12dB high-pass crossover and low-pass sub output
            Selectable for mono or stereo subwoofer setups
            45Hz sub-bass control
            120Hz mid-bass control

            Comment


            • #7
              another question: the OEM AMP does not have RCA inputs. It has proriotory connector. I tapped into the input cables coming from the head unit to connect the ouitput cables coming from the sound card. Does this have any negative effect on the sound card output level? will this have any negative effect if I use a line driver?

              Comment


              • #8
                the cl-rlc wouldn't really support fading, and the knob would need to be plugged in for it to work(the knob tells the preamp how loud to make it, so without it, the preamp defaults to the quietest setting). you could use 1 or 2 depending on the amount of control you want:
                if you use 1 you can just use rca y-adapters off that to get 4 channels, but would not have any fade control.
                if you use 2, you can have independent fade control, but have the extra cost, and 2 units to mess with.

                that hifonics unit looks good for what you want to do.

                i tried looking up your amp, but some of the areas on the audi forums needed me to create a username(not until i consider getting a audi)...

                the amp might be looking for a speaker level signal(high voltage), so you would need to use a amp before it to work.

                but, if the amp is looking for a line level signal(low voltage) then the preamps should work fine.

                you'll have to do some of your own research on the audi forums for that(primarily to learn if it takes high level, or low level inputs).
                My OLD 2001 Mitsubishi Eclipse GT:
                "The Project That Never Ended, until it did"


                next project? subaru brz
                carpc undecided

                Comment


                • #9
                  Edit: NM, I see you have removed your head unit.
                  I have too much time and too little aggravation in my life, so I built a carPC. ;)

                  Comment


                  • #10
                    Originally posted by hithere View Post
                    Edit: NM, I see you have removed your head unit.
                    ask away-- i ran a hu setup for about 4-5 years before ditching it for the carputer, so i would say that i am fairly well practiced in generic audio connections (can't help you much on the audio specific stuff without help though).
                    My OLD 2001 Mitsubishi Eclipse GT:
                    "The Project That Never Ended, until it did"


                    next project? subaru brz
                    carpc undecided

                    Comment


                    • #11
                      here is a page where I got info about the Audi AMP J525. I have a standard System. HeadUnit + Amp + 9 speakers:
                      http://www.audi-portal.com/en/diagno...u_12457.html#1

                      General system description, standard sound system



                      The standard digital surround sound system uses 5 audio channels. A total of 9 speakers are connected to the digital sound package control unit -J525. In the dash panel are the centre mid-range/treble speaker -R158 and the two treble speakers R20 and R22. These two treble speakers are connected in parallel to the bass speakers R21 and R23 located in the front doors. Behind the rear side trim are the treble speakers R14 and R16, connected in parallel to the mid-range/bass speakers R159 and R160.



                      By way of the coding, the sound system settings must be adapted to the vehicle's equipment specification.



                      The Digital Sound Package control unit -J525 is switched on by a switching voltage from the radio -R.

                      Diagnosis is carried out between the data bus diagnostic interface -J533 (gateway) and the Digital Sound Package control unit -J525 over the infotainment CAN data bus. Over CAN the sound system receives information such as the road speed signal.

                      Comment


                      • #12
                        still cannot find any info on what level is needed fro this unit.
                        I will measure the level coming out of the the HeadUnit.
                        What is the difference between high and low level?
                        Minimum/maximun Voltage of both levels?

                        Comment


                        • #13
                          'usually' low level is typically around 0.5 volts, most stay under 2 volts (2 volts and up preouts are usually used on aftermarket hu's). high level would be anything above that 3+ (speaker voltage varies widely with the power of the deck).
                          My OLD 2001 Mitsubishi Eclipse GT:
                          "The Project That Never Ended, until it did"


                          next project? subaru brz
                          carpc undecided

                          Comment


                          • #14
                            Low level is usually defined as pre amp signals between 0-4 volts. High level signals from head units are strong enough to drive speakers directly and generally in the 5-15 volt range. 5-15 volts corresponds to power ratings of 6-50 watts into 4 ohm loads. Good quality head units should be in the 9-15 volt range.

                            The advantage of high level signals is that they are isolated from the vehicle ground system and more immune to picking up alternator noise because the higher voltage yields a better signal to noise ratio (SNR) compared to low level signals. This is all good as long as the head unit high level output amplifier is clean. Nissan Bose systems are a classic example of poor quality high level output signals from head units.

                            I don't know anything about the Audi head unit ouputs. There is a forum member over on diymobileaudio.com that is something of an expert on OEM integration issues. His forum name is VP ELECTRICITY and I think he has set up a web site with OEM integration information for most auto makers. I don't know the URL. You can probably find it with some time spent searching the diymobileaudio forum.

                            I am using a pre amp equalizer made in the 1990's by Precision Power to interface my PC to factory Nissan Bose amplifiers. It is a high quality piece of equipment with low distortion 10 volt peak output voltage. It also has a fader and 5 bands of parametric equalization. Parametric means that the center frequency and filter 'Q' are selectable. Most equalizers are paragraphic with fixed center frequencies. Paragraphic EQ is fine for most users. You really have to be into fine tuning sound quality to make effective use of a parametric EQ. The old Precision Power EQ preamps are good choices but might be voltage limited in some applications. You need to find out what the OEM Audi head unit output voltage is to help you select the right preamp.

                            Comment


                            • #15
                              thank you guys. really helpful info here.
                              I re-installed my carpc after a screen repair and the difference in sound is very noticeable. especially the bass. I tried playing with the CentraFuse EQ but nothing came out of it. I found this unit, 4 channels and not that expensive:

                              http://www.crutchfield.com/S-DKIPCtD...PAC-OEM-2.html

                              Comment

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