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Connecting xlr mic directly to laptop

Discussion in 'General Discussion' started by kmetal, Jan 11, 2020.

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    The New AT5047 Premier Studio Microphone Purity Transformed

  1. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Hey. Im looking at snagging a beater laptop to mess around with until my larger desktop system is built, and the space in the house cleared.

    The laptop has an 1/8" combination mic/headphone jack. Commonly used for headset mics for gaming. Im presuming this is a trrs connector.

    Im thinking i can hooking up my sure beta 57 to it via one of the adapters in the link below. Im just wondering if i should expect this to work.

    Otherwise ill have to dig out my 11r and tabketop rack, or order a basic interface.

    Im just trying to keep things minimal, and don't need high quality. The mic would be for sketching ideas, and Skype ect. Nothing serious.

    Thanks!

    https://www.google.com/url?sa=t&sou...FjABegQIBRAI&usg=AOvVaw3jopOGlPj0bZ4gyXGS1YDD
     
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  2. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    I'd say there's a good chance it will work, with some potential for noise/hum issues or low input sensitivity. If you get it perhaps you could put a meter on it and identify the wiring arrangement. For example, is the shield of the TRRS connected to pin 1 or pin 3 or both?
     
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  3. dvdhawk

    dvdhawk Well-Known Member

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    It will probably work to some extent, but there's no way I can see that the mic signal would be balanced. The impedence probably won't be ideal either, but again, it will probably produce sound good enough for a cheap soundcard on a beater laptop.

    This is where one of my old bandmates would say, "Sounds like a helluva plan. Look at the nickel you saved."
     
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  4. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Im deficient in electronics to an alarming degree. Im assuming you mean multi meter. How would i identify which pin is which, like what am i looking for?

    Lol thats hilarious. Maybe instead of throwing ten bucks at it, ill just use the built in mic on the laptop. The only thing that can improve my singing is the mute button.

    What creates the impedence mismatch?

    Would testing it with a meter reveal if its balanced or not?

    (Its remarkable some of the fundamental knowledge i still lack)
     
  5. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    Yes, a multimeter set to continuity or resistance.

    The middle pin is 3. If you look into a male connector with 3 on the bottom, pin 1 is on the left and pin 2 is on the right. If you look into a female connect pin 2 is left and pin 1 is right. Pin 1 is always ground. Other than some older gear, pin 2 is positive (hot) and pin 3 is negative (cold). Memorize: ground, hot, cold for pins 1,2,3.
    [​IMG]

    The source needs something to push against. Impedance is the AC equivalent of DC resistance. If the receiving device's impedance is too low the signal will not transfer properly. Imagine holding a piece of paper up and trying to write on it. Putting it on a hard surface gives the pen or pencil something to push against.

    Some sources, generally those driven by active circuits, are fairly immune to input impedance. Dynamic mics and guitar pickups are generally sensitive to impedance. Piezoelectric pickups are extremely sensitive and require impedance in the 10MΩ range.

    That adapter is unbalanced. The question I have is how it makes the change from a balanced source to the unbalanced input. There are different ways of doing it that may or may not work, well or at all, depending on the source. If you really want to get into it I'd suggest Rane Note 110. It used to be a webpage hosted by Rane, but now it seems to be available at the link below.

    https://www.yumpu.com/en/document/read/46700632/rane-note-110-sound-system-interconnection-avw
     
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  6. dvdhawk

    dvdhawk Well-Known Member

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    TRRS = 4 conductors.

    I could be wrong in this case, but I think these typically use 1 conductor for the left headphone + 1 conductor for the right headphone + 1 conductor for the positive of an unbalanced microphone + 1 conductor for the common shield shared by the mic and L/R headphones. If you can find a pinout or test it when it arrives, as bouldersound suggested, that would confirm whether that's right.

    (And I see he's added more good advice, so I can keep this short.)

    The typical cheap mics I see for gaming and computer use are much higher and unbalanced. The output impedance of your Beta57 is 150Ω (low) and transformer balanced. Chances are that TRRS adapter shorts Pin 1 and Pin 3 together making your Beta57 an unbalanced low impedance mic.
     
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  7. Boswell

    Boswell Moderator Distinguished Member

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    The adaptor cable that has an XLR(F) socket on it may be the best solution, but only if it has a large value capacitor in the hot lead of the microphone. The TRRS sockets on most phones and motherboards have plug-in power available on the mic input pin, and, while this won't actually damage a moving-coil mic such as an SM57, the d.c. flowing through it will push the voice coil out of its normal position, leading to distortion.

    I'm speaking as an engineer who has used a pair of SM57s as headphones when my normal phones fell out of my gear crate at a gig and got run over by the lighting truck. I got some strange looks, but they worked well enough.
     
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  8. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    Good point about DC.

    I remember plugging a dynamic mic into the earphone jack of a desktop type cassette recorder and hearing the playback back in the 70s.

    More recently, probably around 1995, I had two sets of headphones on a Y-cable. You could talk into one set and hear it on the other.

    The point being that dynamic mics work both ways, as do headphones.
     
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  9. dvdhawk

    dvdhawk Well-Known Member

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  10. Boswell

    Boswell Moderator Distinguished Member

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    That's a pretty accurate representation! I had managed to salvage the headband from the flattened phones and so gaffer-taped the mics to it. Working out how to connect the two balanced XLR mics to a single unbalanced stereo jack outlet was more of a problem.
     
  11. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    That's a great visualization! Thanks. Gonna check out that rane link.

    Interesting about the power delivery, i didnt know that was the case.

    Lol "why is the sound guy mic'ing his head?"
     
  12. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    Because he's of sound mind.
     
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  13. paulears

    paulears Well-Known Member

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    Simplest way to find the right pin is to get the software running you will use, stick in a 4 conductor 3.5mm plug and watch the meters when you stick your finger on each of the four terminals. One will make the meters kick and you will hear a quiet buzz. this becomes your hot connector from the mic XLR - so that one goes to pin 2. The sleeve of the jack plug - as in the one closest to the cable goes to pin1 and 3 on the XLR and that's the wiring done without needing the meter. Only requirement is being able to solder properly. There are ones ready made that often use a 3 circuit jack, and while this isn't ideal, they do generally work. They short one of the headphones channels, but on my computers it seems to cause no actual problems.
     
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  • AT5047

    The New AT5047 Premier Studio Microphone Purity Transformed

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