How to hook an XLR microphone to a 1/8 jack

Discussion in 'Video' started by steve_hovland, Oct 1, 2010.

  1. If you're just starting with video you need to know that "sound is 60% of video." People will tolerate low-res visuals, but not low-res sound.
    The key to getting good sound is getting the microphone close to the speaker, which often means running some length of cable.
    Most professional microphones have the 3-pin XLR connector which allows you to run a long cable without picking up hum.
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  2. The key to making this work is the Lo-Z to Hi-Z transformer. This one is the Audio-Technica CP8201. About $20 at Guitar Center. Radio Shack has something similar.
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  3. Then comes an adapter from Radio Shack and others to go from 1/4 female to RCA male:
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  4. Then an RCA Splitter, F to 2 Male, to make two channels of sound.
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  5. Finally, two F to F adapters on one end of a stereo cord, a stereo cord about 3 feet long, and an RCA (two F) to 1/8 stereo adapter from Radio Shack.
    This is a lot of bother for a short distance, but you can put a long XLR cable between the microphone and the transformer to mike a subject that could be 100 feet away. In that case you would want to use a battery-powered condenser mike. I have a Rode M3 which I like a lot- around $150.
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  6. Hi Steve, that seems like more adapters than necessary.
    It's probably easier to use a direct XLR to 1/8" adapter which will also alleviate the weight that the final 1/8" receptor must bear. You then use a XLR to XLR cable of necessary length from the microphone to the adapter:
    [Link]
     
  7. The transformer option (or a pre-amp with balanced line input) is the best and correct way to do it. However you could get a simpler method to work.
    Get a 3 pin XLR cable fit socket and a 1/8" jack and some shielded cable to connect them together. Connect XLR pins 1 and 3 to the ground connection of the jack plug using the outer shield of the cable and connect XLR pin 2 to the tip connection of the jack plug using the centre conductor.
    The microphone source will be a lower impedance than the input to the pre-amplifier but it should be o.k. as this is a preferable scenario than the other way round.
    EDIT - Like this: http://www.mediacollege.com/audio/connection/xlr-jack-mono.html
     
  8. Michael - true. I did this mostly with stuff in my electricals junk box collected over many years :)
    One thing to watch for with adapters is that manufacturers don't seem to follow any standards for dimensions, so sometimes the connections are sloppy. I had a 1/4 to 1/8 that was really bad. That one I threw away.
    Steve: Preamp is a good idea. I think I would prefer to buy one built in to something like a Mackie 402-VLZ mixer. That way I have stereo outs with level control over each channel. I have also thought of getting a Rolls MP13 preamp.
    The "problem" with the mixer or preamp is that you get a line level out rather than mike level. This is OK if you are doing dual sound and your recorder has a line level input option.
     
  9. The "problem" with the mixer or preamp is that you get a line level out rather than mike level. This is OK if you are doing dual sound and your recorder has a line level input option.​
    Agreed although you could make a lead with a potential divider at the recorder input end to drop the level down to microphone signal level. Not ideal but it does work.
    I have also thought of getting a Rolls MP13 preamp.​
    That little pre-amp looks ideal for this sort of thing. I make microphone pre-amps myself but not portable, on location types like that one: http://www.freewebs.com/stevesmithphoto/valve.html
     
  10. In his book on sound for video Jay Rose recommends having a 6 db difference between left and right to protect against peaks that distort. A mixer would be a good way to handle that.
    Sound Professionals also has a little attenuator with 1/8 connections that they say takes off 6 db when turned as low as possible.
     
  11. To take line level of around 300mV down to a microphone level of just a few millivolts will need more than 6dB of attenuation.
    Experiment with a 100K resistor in series with the signal at the input end of the cable and connect a smaller resistor between 1K and 10K from the input to ground. A 1K resistor in this position will attenuate the signal down to 3mV which should suit most microphone inputs.
     
  12. Steve Smith: I'll take your word on that because I'm not far enough into electronics to know :)
    What I was meaning more specifically is that if you had split a mono mike into two channels and were running into a 1/8 stereo jack you could patch the attenuator into one channel to reduce the signal.
    Kinda messy. If I wanted to do this I'd get a little mixer like the Mackie 404.
    This assumes that your field recorder can't adjust the channels separately.
    I'm using a Tascam DR-07 which doesn't adjust channel level separately, but it only cost $150 and adding a $100 mixer would give me additional functionality like good preamps.
     
  13. This whole issue is one reason I'm leery to use DSLRs for video. I kinda like my Panny's dual XLR inputs that give me thumb wheels for level adjustments, plus line/mic, attenuation, and phantom voltage switches for each channel. I've got a little mixer that could do the same thing, but that means I have to carry an extra piece of equipment...
     
  14. Matthew - I basically agree. People are a little too excited about DSLR's right now, but on the full-frame cameras it's more affordable than a Red :)
    With a field recorder I can get HD audio and good enough video from a lot of cameras, so it's a very democratic medium these days.
    Here's my latest fusion photography:
    http://www.youtube.com/watch?v=AFqsVC1fh0Q
     
  15. www.markertek.com sells every audio and video cable you can think of, and can custom make ones you haven't thought of before. I have two cables from them that let me connect XLR mikes to 1/8-inch inputs. One is for a single mike, sending the mono signal to both L and R channels. the other has two XLR connectors and sending the mono signal from one mike to L and the other to R. The 1/8 connector is right angle to help reduce stress on the camcorder jack (or DSLR if that's what you use) and the cable is about a foot, but you can get them in longer lengths.) They're maybe $20 each, no more than what it would cost for the connectors and my time to make one. Some people prefer units like the Beachtek adaptor boxes but I've been very happy with these cables. I agree with Matthew and Steve that DSLRs are not the way to shoot video. Too much need for complicated and sometimes expensive workarounds to do what is cheap and simple on a real video camera.
     
  16. Although I prefer a real camcorder when doing video, there are times when some kind of video is better than none.
    One of the events I photographed this summer was a gathering for a man who was dying of cancer.
    At one point he started showing us and telling us how his hobby of beekeeping had turned into a passion and a business for him.
    I shot a lot of pictures with my DSLR, but I still regret not having my pocket camera with video along that day.
     

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