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Thread: Optical to Analog Convertion

  1. #1
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    Optical to Analog Convertion

    Hello forum. i am pretty sure that this topic has come up in the past some times, but i couldent find the info i was looking for...
    In my car i use this Sound card : http://us.creative.com/p/sound-blast...rround-5-1-pro
    SPECS Here: http://www.cnet.com/products/creativ...-series/specs/

    I have an amplifier, that only receives analog input. at the moment i run RCA (high quallity) from the dashboard, all the way back. i want to somehow , be able to use an optical link to transfer the signal, and convert it to analog on the back of the car...
    The main reason for this, is that as of now, i have a ground loop, that i cant seem to be able to fix, which DOES go away, if i use an RCA ground loop isolator... but they tend to distort the lower frequency's, so this is not a good solution for me...

    Also, digital signal is always noise free, which is pretty nice for a car environment with all that noise around... so my opinion is, the less distance the signal has to be analog, the better...

    i have seen some things like that : http://www.ebay.co.uk/itm/Digital-Op...item5b028686a6

    but i dont know what i sould look for?? my main concern, is that most of them, say "digital optical input LPCM" my sound car says DTS... so will they work together? or should i find something that has as an input DTS only??

  2. #2
    Maximum Bitrate Borte's Avatar
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    Hi,

    I had a terrible ground loop in my car which I was able to get rid of (and get better audio quality) by using this:

    HiFimeDIY USB Isolator: http://hifimediy.com/usb-isolator

    And this USB DAC: http://hifimediy.com/DACs/ready-made-dacs/U2-DAC

    To get the solution you want with digital all the way you can use a USB cable to the back where your amplifier is and then go from USB to analog right by the amp.
    Failure is not an option...
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    The only full multizone / multiscreen cross platform open source Front End -> OpenMobile

  3. #3
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    that is a good idea! but do the USB isolators support the Highest transfer speed? becouse i think i had seen somewhere that they didint.... but then again, the Sound card might not need the highest speed
    Well, i also have a mic connected to my sound card... so if i move the sound card to the rear of the car, then i would have to have longer analog signal for the mic... :/

  4. #4
    Maximum Bitrate Borte's Avatar
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    The HiFimeDIY DAC doesn't have a mic input. It's only an analog 3.5mm jack and an SPDIF optical output. So for your mic you'd still use the same input as today.

    As for speed there's no issue. It supports the highest sample rates for the DAC.
    Failure is not an option...
    __________________________________________________ ______________________________
    The only full multizone / multiscreen cross platform open source Front End -> OpenMobile

  5. #5
    Maximum Bitrate rray's Avatar
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    I also have the HiFimeDIY DAC. All I can say is it's Superb!

  6. #6
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    It seems very nice inded! but i arledy have a DAC... so i am trying to find a solution with it !!

  7. #7
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    hello again So.... i bought an optical to analog converter. it requires a 5v power supply to work obviously. unfortunately it did not solve the problem... but it DID change it..
    with the previous set-up (pc->usb->dac->Amplifier):
    If i had the DAC connected with RCA, then i would have loads of humming..(clear alternator whine)
    If i had a ground loop isolator in the RCA line, the humming would almost be eliminated.But some small humming would still be there... (Some times alternator whine ,some other times, a noise with no particular patern, that existed even with the IGN off..)

    with current install (pc->usb->DAC->fiber->optical to analog-ampfier):
    The noise is the same, as with the previous isntallation (With the ground loop isolator installed)... : Very low alt whine + non particular pattern Noise.. i need to mention that this noise, tends to change, if i "touch" the amplifier, or its inputs. and even go away for some time...(even with the IGN on).

    So i have come to the conclusion that the DAC itself produces noise for some reason... So now my best option seems to be the USB isolator that Borte posted!! What do you guys thing??

    PS1: i am planning on hooking the DAC, on a laptop and see if the noise disapiars... if that is the case, then the USB isolator will solve the problem.. right??
    PS2: My AMP is 4channels. ONLY one of them (channel 1) , has noise... the other ones are noise-free! which is very strange... BUT if i hook my smartphone instead of the carpc, then Channel 1 is also noise free

  8. #8
    FLAC SNOtwistR's Avatar
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    Sounds to me like you do not have a common ground amongst your connected items. Just a thought SNO

  9. #9
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    Well yea... ampfier and optical convertee are connected on the back. The carpc is supposed to be connected on the exact same spot, BUT, it has a metal chasis (i tried ro isolate it but it seems i failed:P) which touches the car chasis.. but i am prety sure that the noise presumes even if i un-screw the carpc... (in which case, everything is 100% grounded on the same spot). Will try it next week!

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