Multi sound-cards to single speakers

Discussion in 'NZ Computing' started by Chris, Nov 15, 2003.

  1. Chris

    Chris Guest

    Hi there all,

    I want to know if there's a way I can connect 3 sound cards (on three
    separate PC's) to a single set of speakers.

    I know this can be done by using an expensive KVM switch that handles sound,
    but I already use a cheapie KVM that works well for me and I don't really
    want to go and buy another one.

    Thanks,
    Chris.
     
    Chris, Nov 15, 2003
    #1
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  2. Yes, of course, just buy a Y-shaped audio cable that can do this for you.
    Inside will be a transistor that combines the signals.

    Cheers,
    Nicholas Sherlock
     
    Nicholas Sherlock, Nov 15, 2003
    #2
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  3. Chris

    Murray Symon Guest

    A Y shaped cable will only give you 2 inputs into 1 output.
    A transistor is not used for combining signals, that will be
    done (if you are lucky) by resistors.
    However, most Y leads seem to not even bother with resistors.

    Using a many-into-one cable will combine the outputs from all
    the PC soundcards all of the time. You may not want this.

    Seeing as you mentioned using a KVM switch, you might be best
    to get an audio switching box (such as sold by Dick Smith).
    These allow you to manually select which input goes to the
    output.

    Murray.
     
    Murray Symon, Nov 15, 2003
    #3
  4. Chris

    harry Guest

    Switch them with an audio switch box, from Jaycar or Dick
    Smiths, $50
    http://www.dse.co.nz/cgi-bin/dse.storefront/3fb5a1170f9822d62740c0a87f990740/Product/View/C2505
     
    harry, Nov 15, 2003
    #4


  5. Are these amplified speakers..?

    If not its a BIG NO..

    Then you will need a 3 Way Audio Mixer, and then it will depend on the Input
    resistance of the amplified speakers, some are set for 8 ohms, so then again
    its a BIG NO..
     
    Gregory Parker, Nov 15, 2003
    #5
  6. Chris

    harry Guest

    If he does want to have the six signals on all the time he could passively
    combine the three lefts with ~4k7 series resistors to the input of
    one powered speaker and the rights the same to the other input.
    There will be an insertion loss but there's plenty of gain on powered PC
    speakers.
     
    harry, Nov 15, 2003
    #6


  7. Useless if the powered spwkers have a 8 ohm input, and yes they do as I have
    some..
     
    Gregory Parker, Nov 15, 2003
    #7
  8. Chris

    harry Guest

    It will work even better, nice low impedance at the summing point, all the
    resistors are doing is stopping the sound card outputs from loading each
    other. An even better solution is to use a dual op amp as a virtual earth
    mixer.
    http://www.all-electric.com/schematic/simp_mix.htm
    There are plenty of project boards that will do the trick, but the passive
    combiner is the cheapest.
     
    harry, Nov 15, 2003
    #8


  9. And will not work..
     
    Gregory Parker, Nov 15, 2003
    #9
  10. Useless if the powered spwkers have a 8 ohm input, and yes they do as I have
    Err, 47kohm will drop about... well more then 40dB on the origional signal into
    8 ohms.

    It may "work" but it depends on how far you want to stretch the definition of work.

    Best not to use no resistors as most computers have no true line out instead
    going for something with a relativly low impedance aimed at driving headphones
    to an ok volume. Wouldnt be happy fighting against an ouput from another
    motherboard.

    Perhaps locate a bedroom dj that has given up and offer them some beer for there
    mixer?
     
    Richard Malcolm-Smith, Nov 15, 2003
    #10
  11. Chris

    harry Guest

    4k7 is what I said, but you have been reading the thread haven't you ?
    There are plenty of op amp project preamps available from dse and jaycar
    to make a virtual earth summing amp easily.
    Wait on, thats just what I wrote above with a link to schematics.
    But if he has a second hand DJ mixer well golly ! all he needs is one with
    three stereo channels and blah blah blah blah blah lets have a big roger
    sheephard pissing match about nothing.
     
    harry, Nov 15, 2003
    #11


  12. Seems from you comments that you have never ever developed any thing at all,
    my developments ever got in the Dom news paper, and is a few Data Bank
    magazines, I can post the Facts here if you like.

    were are yours..?

    And will these Amps will drive into 8 ohms, I don't think so.

    Gee I do think you need to take a Basic course in Electronics..


    If you can't post FACTS, do not post at all, in only confuses the recipient..
     
    Gregory Parker, Nov 15, 2003
    #12
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