Question about line to mic levels...

mikemc · Post by **mikemc** » Mon Jul 09, 2007 8:51 pm

I have a consumer video cam that has an 1/8" stereo external microphone input jack. I would like to record audio direct from my mixer or my interface to the video cam while it videotapes live action.

I find that running a Y cable(1/8" stereo on the camera input, two 1/4"s from the interface) out from my interfaces produces a lot of noise, even when I take the level on the outputs way down.

Do I need some kind of impedance matching/DI box to do this better?

[edit] (ah, hmm... 1st I will try the pad switches on the MOTU inputs 1/2)

Tone Deft · Post by **Tone Deft** » Mon Jul 09, 2007 9:30 pm

did you check the manual? is it really a mic jack or a line input jack? do they suggest any mics for use with it?

mikemc · Post by **mikemc** » Mon Jul 09, 2007 10:06 pm

Tone Deft wrote:did you check the manual? is it really a mic jack or a line input jack? do they suggest any mics for use with it?

"any commercial condenser microphone with their own power supply", does not mention anything about line in being supported.

The specs on the mic input are
"-57dBV (with a 600 ohms microphone)/5 kohms or more"

It sounds pretty good when there is a lot going on in the mix, but there is lots of hiss during quieter portions. I'll post the resulting video at some point.

Tone Deft · Post by **Tone Deft** » Tue Jul 10, 2007 3:31 am

googling "line level to mic input" brings up some tips on possible tweaks, basically putting a 600 Ohm resistor in parallel with the wires going into the input might/should/could help. If you really want to dig into this bug me about it, for now it's monday night

and I'm playing with my monome.

Practically speaking I'd raise and lower the levels of both until I got as little noise from both, you know the drill.

600 Ohm is an old standard going back to telegraph lines, 75 ohms came out of that, high impedence is the modern standard. 600 ohms in parallel with a high impedence (50k-100k or more Ohms.)

hth maybe you can find another way to mix audio and video outside the camera.

mikemc · Post by **mikemc** » Tue Jul 10, 2007 4:19 pm

cool, thanks for the info. I will try running it through my mixer first, then, as opposed to directly from the output of the motu.

scrawn · Post by **scrawn** » Tue Jul 10, 2007 4:50 pm

A DI box would do the trick, though to maintain stereo image you need two and then have the problem of getting the outputs down to a single 1/8" jack.

Some mixers (like mackie 1202) have a little button next to the main out to choose between mic and line levels, maybe you could beg or borrow one?

mikemc · Post by **mikemc** » Tue Jul 10, 2007 8:58 pm

scrawn wrote:A DI box would do the trick, though to maintain stereo image you need two and then have the problem of getting the outputs down to a single 1/8" jack.

Some mixers (like mackie 1202) have a little button next to the main out to choose between mic and line levels, maybe you could beg or borrow one?

I'll take a closer look at the mixer I have, it may have something similar.

RE: DI boxes, fwiw, I found a unit called a "Beachtek DXA-2s" that will accept two XLR ins down to a stereo 1/8" jack, but it's around $180.

maybe for another time.

laird · Post by **laird** » Tue Jul 10, 2007 9:21 pm

what about a stereo 1/8" to stereo 1/8" cable connecting the headphone out to the camera input?

When there are cables involved, it almost aalways pays to just try another cable first. Never spend $$$ on gear before making sure its not just an old, crusty cable or a cheap, defective cable.

What sort of noise are we talking about? Clipping? Interference from using a long unshielded cable? Hiss and background noise from over-amplification?

but, then, it might be a problem from the mix input on the camera providing a little boost, and you compensating by turning down the volume on your soundcard... thus increasing your signal/noise ratio.

PS: aren't those switches on the MOTU are for the MOTU's inputs... and you aren't recording into the MOTU, but into the camera, right?

Sales Dude McBoob · Post by **Sales Dude McBoob** » Wed Jul 11, 2007 1:21 pm

Gentleman, gentlemen, please.

Boomshanka:
http://www.bhphotovideo.com/c/product/3 ... l_XLR.html

mikemc · Post by **mikemc** » Wed Jul 11, 2007 2:59 pm

Yeh, the Beachtek gizmo seems great for recording directly in from mics,

it would definitely work using 1/4" outs from the interface into two DIs to the Beachtek unit, which equipment would cost about as much as the silly camcorder itself (despite the reasonable prices at BHPV)

but it would work.

laird wrote:what about a stereo 1/8" to stereo 1/8" cable connecting the headphone out to the camera input?

When there are cables involved, it almost aalways pays to just try another cable first. Never spend $$$ on gear before making sure its not just an old, crusty cable or a cheap, defective cable.

What sort of noise are we talking about? Clipping? Interference from using a long unshielded cable? Hiss and background noise from over-amplification?

but, then, it might be a problem from the mix input on the camera providing a little boost, and you compensating by turning down the volume on your soundcard... thus increasing your signal/noise ratio.

PS: aren't those switches on the MOTU are for the MOTU's inputs... and you aren't recording into the MOTU, but into the camera, right?

Re; the PS, right, I had a bit of a brainfart there, that would not make any difference. I'm recording into the camera from the main outs.

Yeh, there may be some boosting going on, the noise is very evident during the quieter parts.

Thanks for the inputs, I'll mess around with it some more.

Sales Dude McBoob · Post by **Sales Dude McBoob** » Wed Jul 11, 2007 3:08 pm

mikemc wrote:Yeh, the Beachtek gizmo seems great for recording directly in from mics, it would definitely work using 1/4" outs from the interface into two DIs to the Beachtek unit, which equipment would cost about as much as the silly camcorder itself (despite the reasonable prices at BHPV) but it would work.

laird wrote:what about a stereo 1/8" to stereo 1/8" cable connecting the headphone out to the camera input?

When there are cables involved, it almost aalways pays to just try another cable first. Never spend $$$ on gear before making sure its not just an old, crusty cable or a cheap, defective cable.

What sort of noise are we talking about? Clipping? Interference from using a long unshielded cable? Hiss and background noise from over-amplification?

but, then, it might be a problem from the mix input on the camera providing a little boost, and you compensating by turning down the volume on your soundcard... thus increasing your signal/noise ratio.

PS: aren't those switches on the MOTU are for the MOTU's inputs... and you aren't recording into the MOTU, but into the camera, right?

Re; the PS, right, I had a bit of a brainfart there, that would not make any difference. I'm recording into the camera from the main outs.

Yeh, there may be some boosting going on, the noise is very evident during the quieter parts.

Thanks for the inputs, I'll mess around with it some more.

You don't need DI boxes with a Beachtek. Whatever outs you have from the DAW or mixer or whatever line level signal it is, you just get cables to run from there into XLR male into the Beachtek. Flip the switch on the Beachtek to line and you're good. I know this 'cuz I own one and I do this.

mikemc · Post by **mikemc** » Wed Jul 11, 2007 7:12 pm

Sales Dude McBoob wrote:
mikemc wrote:Yeh, the Beachtek gizmo seems great for recording directly in from mics, it would definitely work using 1/4" outs from the interface into two DIs to the Beachtek unit, which equipment would cost about as much as the silly camcorder itself (despite the reasonable prices at BHPV) but it would work.

laird wrote:what about a stereo 1/8" to stereo 1/8" cable connecting the headphone out to the camera input?

When there are cables involved, it almost aalways pays to just try another cable first. Never spend $$$ on gear before making sure its not just an old, crusty cable or a cheap, defective cable.

What sort of noise are we talking about? Clipping? Interference from using a long unshielded cable? Hiss and background noise from over-amplification?

but, then, it might be a problem from the mix input on the camera providing a little boost, and you compensating by turning down the volume on your soundcard... thus increasing your signal/noise ratio.

PS: aren't those switches on the MOTU are for the MOTU's inputs... and you aren't recording into the MOTU, but into the camera, right?

Re; the PS, right, I had a bit of a brainfart there, that would not make any difference. I'm recording into the camera from the main outs.

Yeh, there may be some boosting going on, the noise is very evident during the quieter parts.

Thanks for the inputs, I'll mess around with it some more.
You don't need DI boxes with a Beachtek. Whatever outs you have from the DAW or mixer or whatever line level signal it is, you just get cables to run from there into XLR male into the Beachtek. Flip the switch on the Beachtek to line and you're good. I know this 'cuz I own one and I do this.

Ah, great, thanks, good info. I'm definitely considering one-- I hate those videos where there is wild stuff going on and the sound is totally crap.

Btw, here is a snippet from this particular 'experiment', my signature super sloppy

electric guitar over an odd time signature Ableton set. You can hear a brief bit of the noise I'm talking about at the very end of the snippet.

http://youtube.com/watch?v=gXOK_JdQMUE