FORUMS: list search recent posts

mixer into camera = noise

COW Forums : Audio Professionals

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Mike Cohen
mixer into camera = noise
on Mar 12, 2009 at 6:21:05 pm

I have 4 lavalier mics going into a Behringer UB-1204 mixer. I know, it's cheap, but let's continue.

Two Sony mics and two from Samson - XLR cables to and fro.

Headphones into the mixer the sound is clean.

XLR from main outs into a Sony PD-170, input set to Mic, manual gain for a good level, but on headphones out of camera there is a hum.

Granted the audio monitoring on the PD-170 is marginal, but the hum is distinct. It goes away when I lower the mixer's main mix to 0.

On playback of the DV tape, the hum is not as bad, but still there.

I am running the camera on batteries - the mixer requires AC so it is plugged into wall current.

As a test, I switched the Behringer to an older Mackie 1202-VLZ. Same situation. (I would use the Mackie but the inputs are very staticky.)

I can plug any of the mics into the camera directly without a hum.

So the problem seems to be coming from the mixer.

As a final test, I switched to the Alt 3-4 outputs from the mixer. This is a phono plug out. I used a phono plug to XLR cable, into the camera, and the hum is almost completely gone. This seems to be the trick.

Thoughts, comments?

Is the ground in the XLR likely the culprit?

Thanks to all.

Mike Cohen





Return to posts index

Thax Clave
Re: mixer into camera = noise
on Mar 12, 2009 at 8:55:25 pm

[Mike Cohen] "XLR from main outs into a Sony PD-170, input set to Mic, manual gain for a good level, but on headphones out of camera there is a hum. "

The Behringer UB-1204 has LINE-LEVEL outputs.

Set the camcorder to LINE-LEVEL and the noise will disappear.
(Or at least drop down to a very acceptable level.)





Return to posts index

Jordan Wolf
Re: mixer into camera = noise
on Mar 12, 2009 at 9:43:18 pm

+1 to that!

Line level is the way to go. Also, make sure you are using balanced cables with balanced connectors.

Typical Balanced Connectors:
XLR
TRS

Balanced Cabling Explained


Wolf
<><


Return to posts index


Ty Ford
Re: mixer into camera = noise
on Mar 13, 2009 at 12:37:16 am

Hello Mike and welcome to the Cow Audio Forum.

While the comments concerning using the line level inputs on the PD170 are inviting and correct, my questions is how are you feeding line level into mic level without overdriving the input of the camera?

Regards,

Ty Ford




Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






Return to posts index

Jordan Wolf
Re: mixer into camera = noise
on Mar 13, 2009 at 1:53:01 am

I just now realized that the OP said "hum" and not "noise". If we are talking about the same thing, then this sounds like a grounding issue.

Have you tried a different AC outlet to power the mixers? There could be something else on the same circuit that is causing the problem (a dimmer for lights, etc.).

Oh, and just to make the point...NEVER, EVER, EVER, EVER cut the grounding prong off of an AC connector. You are correct about lifting Pin 1 (the ground/drain) in the XLR connector in order to deal with the hum, but there are usually better solutions. If you do decide to lift it, lift it as close to the desitnation as possible - that way the signal has a floating ground until it reaches the other end of the cable and doesn't just start out with no ground at all.



Wolf
<><


Return to posts index

Mike Cohen
Re: mixer into camera = noise
on Mar 13, 2009 at 5:19:47 pm

Thanks for the very helpful suggestions. I will report back with the result


Return to posts index


Mike Cohen
Re: mixer into camera = noise
on Mar 13, 2009 at 9:17:45 pm

Switching the audio input on the PD-170 to LINE results in a very weak level, barely perceptible, in the camera. I would need to adjust the mic input trims on the mixer to get a usable signal on the camera, however these result in distortion and feedback.

This makes me think the output of the mixer is not line level, or a line level that is somehow incompatible with the camera's version of line level. If the mixer is outputting -10db and the camera is expecting +4, could that be it? The manual does not make it clear what level the line level output actually is.

I know the unbalanced tape outputs via RCA jacks are -10db line level, but not appropriate for camera inputs.

This makes me think that the attentuation of the line level in the camera is lower than the output of the Behringer mixer.
Oh bother.

As stated earlier, the 1/4" output from the mixer is clean with no electrical noise. There is hiss, but hiss is easy to remove.

On Monday I will test a battery powered field mixer and see what happens.

Thanks

Mike


Return to posts index

Ty Ford
Re: mixer into camera = noise
on Mar 13, 2009 at 9:51:25 pm

Mike,

Just switching from mic to line doesn't work. You need to recalibrate by adjusting the camera audio inputswhen you switch from one to the other. That may be part of your problem.

Regards,

Ty Ford



Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






Return to posts index

Thax Clave
Re: mixer into camera = noise
on Mar 14, 2009 at 12:34:01 pm

[Mike Cohen] "This makes me think the output of the mixer is not line level, or a line level that is somehow incompatible with the camera's version of line level. If the mixer is outputting -10db and the camera is expecting +4, could that be it? The manual does not make it clear what level the line level output actually is. "

The output of the Behringer UB1204 is +4 LINE LEVEL
Image below is from the USER MANUAL available on-line at

http://www.behringerdownload.de/UB-Mixer_/UB-GROUP_2_ENG_Rev_D.pdf


Photobucket


You definitely need to adjust the camera's manual level controls to match the output of the mixer.

FWIW, at least for checking... try the AUTO level setting on the PD-170. It will quickly give you a better idea of true input signal.



Return to posts index


Allen Zagel
Re: mixer into camera = noise
on Mar 15, 2009 at 1:45:27 am

Ummm you don't have any of your audio wires crosing electrical wires at 90ยบ do you? That'll cause a 60 cycle hum for sure.

I do legal video work. Used a Sure M2367 mixer. 4 Sure lavs in (XLR) XLR out to my DSR-250. Had the camera set to -12db and the limiter on the mixer on and never had any problems with the audio.

My camera always ran on Anton Bauer Hytron 140 batteries and the mixer in my gator case through a power conditioner out to a wall plug. The lawyers blackberrys never even caused me problems.

Have you checked your cables? You could have a bad plug. But like mentioned above you really need to have the mixer and camera audio set right.

Allen

ASX Media Group, Inc.
http://www.asxvideo.com
NEW DVD - Europe, Trains-n-Trams


Return to posts index

Ty Ford
Re: mixer into camera = noise
on Mar 15, 2009 at 4:26:23 am

Actually, Alan meant 90 degree crossings are good. Running power and audio lines in parallel will get you in trouble. Right Alan?

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]