How do I record on Soundcard Line-In Using Circuit?

Discussion in 'Homework Help' started by Chritoph8r, May 5, 2010.

  1. Chritoph8r

    Thread Starter Member

    Jan 19, 2010
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    How can I do it. suppose to be from speaker out the connect it into the mic jack on soundcard without using a microphone.

    my concern is how to protect the soundcard from voltage come from speaker out

    any idea?????
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    If you are talking about using a standard dynamic speaker (no additional electronics) they are pretty much a standard microphone equivalent. I'm not sure this is what your asking though. If it is you can use a plain 8Ω speaker as is.
     
  3. retched

    AAC Fanatic!

    Dec 5, 2009
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    I think the OP is talking about using the SPEAKER OUT jack into the LINE IN.

    I think.

    If you are using an amplified signal, you dont want to input it into a line in.

    See if you have a LINE OUT, which will have a non-amplified signal used to get the audio to amplified and recording devices.

    A bad way to do it, is to meter the speaker out, and turn the volume down until it is very low. 1/4 watt is average line wattage for signal lines. Then use software to normalize the signal.
    How important is distortion?
     
  4. Chritoph8r

    Thread Starter Member

    Jan 19, 2010
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    I wonder if the speaker output is loud the line-in of soundcard is overdrive or the recorded sound output become clipped , i thinking of using attenuator. bcoz it directly connected the speaker output (wired)to the line-in (mic input of soundcard).
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
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    It may kill it. You DONT put an amped signal into a line IN.

    re-read post #3, we cross-posted, any you may have missed it.
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    On most sound cards. You can record the output directly without a mic. You must select "What U Hear" as input in the record control. If you use XP this option may hidden. Go to properties in the record control and set this option visible
     
  7. retched

    AAC Fanatic!

    Dec 5, 2009
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    Are you going from a record player to a PC or something like that?

    You can get level converters that convert SPEAKER signals to LINE signals.

    They use them to add amps to vehicles by using existing speaker wire in the trunk for the line inputs into the amp without having to run the signal wires from the head unit.
     
  8. Chritoph8r

    Thread Starter Member

    Jan 19, 2010
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    :) thats my concern how to make a protection on soundcard from excessive volt come from speaker-output

    I thinking of put a trimmer or a series of resistor with a low resistance.

    any IDEA?
     
  9. retched

    AAC Fanatic!

    Dec 5, 2009
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    Read post #8, it has a solution for you. (we cross posted again)

    A trimmer would not be the best option because the speaker signal can change, so without a constant meter and adjustment of the trimmer, you will end up with a smoked souondcard (or motherboard)
     
  10. Chritoph8r

    Thread Starter Member

    Jan 19, 2010
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    yup.

    I have from external source
     
  11. Chritoph8r

    Thread Starter Member

    Jan 19, 2010
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    where i can find post #8 sorry I'm new here :)
     
  12. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    Your last post was #11 ... it's in the blue field on the right hand side, above your name.
     
  13. Audioguru

    New Member

    Dec 20, 2007
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    An attenuator is made with two resistors.
    Simply calculate the max output voltage from the speaker output, look up how much signal the mic input needs then calculate the values for the two resistors.
     
  14. Chritoph8r

    Thread Starter Member

    Jan 19, 2010
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    0
    what if I create a simple amplifier using lm356 then instead of using potentiometer I use low resistance resistor, then the alternator, is this a good idea? I'd also thinking of diode protection.
     
  15. Chritoph8r

    Thread Starter Member

    Jan 19, 2010
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    0
    by the way it is good enough that I use a series of 7.5 Ohms and .5 ohms

    to speaker-out-------/\/\/\/\--------|----------/\/\/\/\/\------------- to line-in
    | 7.5 ohms 0.5 ohms
    -
    ^
    |
    | two diode protection
    V
    _
    |
    gnd---------------------------------------------------------------------

    is this good enough?
     
  16. Audioguru

    New Member

    Dec 20, 2007
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    Your resistor values are way too low! They will waste power and get very hot.

    It seems that you did not calculate the max output voltage of the amplifier's output.

    If the amplifier has a max output power of 20 RMS into 8 ohms then its max voltage is 12.65V RMS.
    Your mic input might have a max allowed level of 100mV.
    Then you need to attenuate the signal 200 times.

    A solid state amplifier does not need a load but a vacuum tube amplifier needs its rated load all the time. So if your amplifier is solid-state and has a max output of 12.65V RMS Then use a 4.7k resistor feeding a 22 ohm resistor.
     
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