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Electronics Circuit to downmix 5.1 TOS to stereo line-level

Discussion in 'Modding' started by dragon2309, 13 Jan 2009.

  1. dragon2309

    dragon2309 techie

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    Hey all you electronics gurus, need a hand on where to start with this one.

    I have a non-dolby-DTS 5.1 optical signal coming into an amp that im building, the amp is only 3 channel (2.1) but i still want it to be able to play from non-dolby TOS sources.

    I say non-dolby because i know dolby encodes its DTS otpical outputs and its a bugger for a homebrew application that I can build to decode it all again. If anyone knows of an easy way to do this though, please let me know.

    So yeh, the pre-amps can deal with pretty much anythig as im building/have built from scratch. Line-level would be perfect for what im working with. All i need is a way to convert optical into a line level analogue signal.

    Help please, cheers, dave
     
  2. dragon2309

    dragon2309 techie

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    55 views, no replies, wheres everyone like cpemma when you need them??? haha

    pleeease help!! :)
     
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  3. ch424

    ch424 Design Warrior

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    I looked into this several years ago and it's very complicated. You can't do Dolby/DTS because you need a license. However, you've said you don't need that so it's a bit easier.

    I've just found this DIY decoder project. It looks pretty well explained, except he doesn't mention converting the optical signal into the coax or TTL signal that the circuit requires. You could buy a complete unit to do the optical to coax conversion, or buy an optical receiver and wire it up yourself, which would save a fair amount of money.

    Have a look at the DIY project and work out how much it's going to cost you. There have been converters in the past (apparently Creative made one, and Toshiba too) but they're out of production.

    Hope that helps! :thumb:

    ch424
     
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  4. dragon2309

    dragon2309 techie

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    Hey ch242, thanks for the reply, yeh i saw that project in my endless searching, that seems to be the easiest way, i've already started drawing the schematic up in Isis 6 for that one, will get it netlisted into Ares by tomorrow, etch it at the weekend and see how it runs next week.

    Thanks for your help matey :D
     
  5. ch424

    ch424 Design Warrior

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    Awesome!

    Have you managed to find somewhere to buy those chips he lists?
     
  6. dragon2309

    dragon2309 techie

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    I'd been looking for a while prior to asking on here, the main DAC you can either scrounge samples for from cirrus or farnell sell them

    farnell code : 1023373 - £1.80 a pop

    luckily you can buy singularly, lol

    The CS8414 he uses is now not recommended for use in prjects by cirrus themselves, tis been replaced by the CS8416

    Not overly good because i can only find a SMT package in the uk market

    again, farnell code : 1023451 - over £4 each....

    so they are available, just not very readily... or very cheaply, lol
     

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