External mics running into video camera always distort; line/mic level confusion

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Chris F

Chris F

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I'm trying to run a pair of external mics - in this case MXL 603s - into the mic input of a Canon Vixia HF M300 video recorder recording instructional double bass videos. Since the 603s are condenser mics, I'm running them through an M-Audio DMP3 and then sending an 1/8" stereo feed from the output of the DMP3 to the camcorder. It sounds fine for the voice part, but distorts every time I play the bass. I had this same distortion issue when sending the same mic signal in the same way to an Edirol R-09 audio recorder and plugging into the "mic" input, but was able to solve it by plugging into the "Line" input on the R-09 instead. The problem is, the Vixia video recorder doesn't have a "Line" input, and no matter how low I set the "mic input" controls, I still get distortion.

So it seems I must be sending a line level signal to a device not equipped for it. My question, then, is how to convert this signal (these mics and preamp sound great for my needs when recording audio into the R-09) into one that I can feed to the camera to eliminate the distortion? I have a cheap mixer (Alesis iMultimix 9R) to work with if that could be part of the solution. Thanks in advance!
 
Edit: I have read This article and looked at This solution it mentions, but was hoping that there was a cheaper and easier way to switch from one level to another.
 
You can either find a way to pad the signal, or find a different way to power your mics.

If you used a phantom power supply rather than the preamp, you'd still be passing out a microphone level signal.

Alternatively, I think you could use a DI box.
Traditionally they take line or instrument level, and output at microphone level if I'm remembering right.

You could probably use the mixer preamps and line out, but use the fader to attenuate the signal heavily.
I don't imagine it'd be great though, cos there'll be impedance problems too.
 
Thanks for the info. I'm not averse to buying a box to do the conversion, but most of the DI boxes I see have XLR outs, and the DMP3 has balanced 1/4" outs. So what's the simplest way to convert two 1/4" outs to attenuated 1/8" stereo? For the forseeable future, the projects I'm doing will be recorded here in my home studio, and it would be great to be able to use the gear I have and just add a single box to do the conversion if needed.

Eventually, I was thinking about getting a Rode NT4 because of the built-in Phantom power for this purpose. I trust that would be a good solution?
 
Sorry for the incessant edits, but: as long as I'm trying to get decent mics that have built in phantom power, how could I be sure what kind of output they offer? For instance This mic looks to be the perfect solution if the signal it puts out would be mic level, and I'm guessing it wouldn't be too far off from the cheap MXL 603 mics in terms of sound quality (and it would be portable besides). But I can't tell from the specs what the output level would be (I'm almost certain it's mic level, but not quite $250 certain). Any and all input welcome on this.
 
Record the audio on a laptop, using the mics you have and a USB-powered audio interface, then with your video editing software, import the audio tracks and edit.
 
Unless you are willing to drop VERY serious cash into high-end cameras,
NONE of them are built to handle audio well. The all have nasty limiting
circuits and cheap audio chips.

If you want really high-quality sound, record it separately as mjbphotos noted above
then drop the audio into the video in a video editor.
 
Your question would be better answered in a videoing forum.

There is a small adaptor box designed to make a consumer camcorder accept line level and mic signals via an XLR socket. I think one of the brands was Beachtek.

It's true the audio is not wonderful at best but an external mic, properly set up via an adaptor box can sound a whole lot better than the internal mics in many camcorders. You can also take the feed from a mixer as you wanted to do.

Just make sure your signal is not too heavy, otherwise the internal limiter will compress it excessively.

Actually padding the line level signal down to mic level is simplicity itself from an electronic point of view. Two 5 cent resistors!
 
Thanks for the replies, everyone. in no particular order:

TimOBrien said:
Unless you are willing to drop VERY serious cash into high-end cameras,
NONE of them are built to handle audio well. The all have nasty limiting
circuits and cheap audio chips.
Click to expand...



I wouldn't touch the limiting circuit with a 10 foot pole. Fortunately the Vixia allows for manual audio settings for external mics so that you never have to use the limiter. As for the audio chip, I guess this is really the question mark. The internal mics on the Vixia sound very thin and noisy compared to what I got with the external mics even when the external mics were set to line level. This suggests that an external mic that input at the correct level would probably be a lot better than what I currently have. I guess I'll have to pony up to find out for sure, though.

If you want really high-quality sound, record it separately as mjbphotos noted above
then drop the audio into the video in a video editor.
Click to expand...

I'm sure that eventually, I'll do exactly this. For the moment, though, I have no idea if the software I'm using would be much help in aligning the audio and video. Once I move up to Final Cut X, I'm sure this will be an option.

Tim Gillett said:
Your question would be better answered in a videoing forum.

There is a small adaptor box designed to make a consumer camcorder accept line level and mic signals via an XLR socket. I think one of the brands was Beachtek.

It's true the audio is not wonderful at best but an external mic, properly set up via an adaptor box can sound a whole lot better than the internal mics in many camcorders. You can also take the feed from a mixer as you wanted to do.

Actually padding the line level signal down to mic level is simplicity itself from an electronic point of view. Two 5 cent resistors!
Click to expand...

True re: the video forum point... I'm just now getting used to audio geeks, and think that video geeks might make my head explode!

The cheapest adapter like you mentioned that I found was This one, and at that price it's only about $75 cheaper than the AT mic, and still relies on the sound chip of the camera to a certain extent.

Thanks for the help. I think that at this point, the stereo mic looks like the next thing to try, especially as it would also allow me to shoot some concerts at my university with the mic up close and the camera further back. I'll report in again once I see how it goes.
 
Found the AT 2022 at MF with 15% off, ordered it, and it arrived today. It's exactly perfect for what I was hoping it would do as regards the video. Since the camera has a manual level feature, I can bypass the internal mics and automatic gain control and use the external mic closer to the sound source and set at a specific level so that it won't clip. It sounds great, and the XLR to 1/8" stereo adapter is perfect for going into camcorders and will also be perfect for using with a field recorder like the Edirol R-09 and that class of recorder. Two thumbs up so far. :)
 
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