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I have a old video camera that has a mic level input for connecting stereo mics. When I connect a line level device (computer, etc.) to it it sounds horrible. Is there a relatively cheap way to convert the line level to mic level and feed it into the camera while still having good quality?

By the way my camera doesnt have a mic level/line level switch, so dont talk about that.

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I don't get it.. You connect a computer to your video cam mic input??? –  Eugene S Mar 28 '13 at 3:39
    
As Eugene said - what? Can you explain what you are trying to do. –  Rory Alsop Mar 28 '13 at 9:33
    
I'm just being curious... I wanted to know if I could use a USB mic connected to my laptop to output sound directly from the mic (through the computer) to my camera. –  d.free Mar 28 '13 at 21:45
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2 Answers 2

Your mention of a computer apparently confused some people. The actual question is just: how do I connect a line-level source to a mic-level input?

You use an attenuator or 'pad' to reduce the level. At its simplest, this can be a 2-3 resistor network, even a single resistor in line with the signal. Or you can buy a line-to-mic attenuator at an electronics hobby store (RS etc). Some have adjustable or switchable attenuation -- you probably want something on the order of 40-60 dB.

Pay attention to the impedance of the source and the input for best results. You want the input level somewhere around the middle of its range.

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I've used the schematic here: epanorama.net/circuits/line_to_mic.html Very easy to build, works decently. –  Brad Mar 28 '13 at 13:26
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As Jim mentioned, the device you are looking for is called a pad. It will drop the level as necessary, you can either get an adjustable one or simply get a 60db pad and you should be ok, but you should also consider whether your current approach is the best.

If you are playing back some electronic file in to the mic input, it would be a better bet to simply combine the audio electronically in video editing software after you have captured the video. This is a process called dubbing and is done regularly to achieve higher quality results. The reason is that it avoids something called generations of loss. Any time that you reproduce an analog signal, a portion of the signal is going to be lost. The more times you reproduce it, the worse it will get. A lot of effort goes in to minimizing the generations of loss and is a big part of why lossless digital work flows are so popular.

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Unless, of course, the objective is to introduce loss. –  ObscureRobot Mar 28 '13 at 18:02
    
@ObscureRobot - sure, but there are also good ways to make loss cleanly too and control what is lost. :) –  AJ Henderson Mar 28 '13 at 18:34
    
Why the downvote? –  AJ Henderson May 1 '13 at 17:04
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