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Hiss raises with voice in lavalier

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Carlos Pino
Hiss raises with voice in lavalier
on Dec 20, 2009 at 12:15:29 am

First of all, i apologize for my english, i'm from Chile.
My problem is as follows: I used Sony UWP-C1 wireless mic system to record an interview for a documentary feature. When the interview began, i noticed something strange - to me - was happening: every time the subject speaks, the constant noise that i suppose is inherent to the mic would raise with the voice.
Here's a sample of the interview. The problem i'm trying to explain is noticeable in the final seconds of the segment.

I don't think that noise is normal, and it certainly bothers me and find it ugly.
If anyone knows what could be happening here, i'll be very grateful.

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Jordan Wolf
Re: Hiss raises with voice in lavalier
on Dec 20, 2009 at 12:44:00 am

Your English is fine, Carlos. No worries...

I did notice the fluctuating noise you refer to. First, there are a few questions that you need to answer for us:

1. What frequency range does your wireless microphone system operate in? This will be expressed in MHz

2. Did you search for already-occupied frequencies in the area in which you were recording this audio?

3. If there is an adjustable squelch setting available on your wireless system, it should be set to the lowest setting while still not allowing static to enter the signal. What is it set to currently?


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Mark Barroso
Re: Hiss raises with voice in lavalier
on Dec 20, 2009 at 4:43:48 am

I agree with the frequency issue. It may also be a signal to noise issue. Make sure your receiver is getting a really strong signal. Secondly, if you have the ability to plug in the lav to a power supply and hardwire to your recording device, you can eliminate if it's an issue with the mic or an issue with the radio transmission.

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Carlos Pino
Re: Hiss raises with voice in lavalier
on Dec 20, 2009 at 3:24:47 pm

Many thanks, Jordan & Mark.
In response to Jordan:
1. The freq range: 782-806 mhz
2. No, I think i did not any search at all.
3. The only setting in the transmitter resembling squelch is called "RF out", which settigs are H (30mw, for long distance function) and L (5mw, for multiple channels)

In response to Mark:
I'll make the test you suggest. The quality of the mic is a possiblity i'm considering, since the wireless system i'm using is low cost.

Thanks again.

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Ty Ford
Re: Hiss raises with voice in lavalier
on Dec 20, 2009 at 3:47:14 pm

Hola Carlos and welcome to the Cow Audio Forum,

In listening to your sample (thanks so much for providing it) it sounds like possibly AGC in your camera audio input or compander noise in the wireless system.

First check your camera to see if the AGC is engaged. Disengage it and see what happens.

Check your transmitter settings. See if the noise goes away when you increase or reduce the input sensitivity of the transmitter. This may change the action of the compander and may change the hiss.

As others have mentioned, try choosing another operating frequency for the wireless system.

Finally, is this the mic that came with the transmitter? Sometimes certain mics don't match well with certain transmitters.


Ty Ford

PS: My apologies for not being able to communicate in your native language. I appreciate your effort.

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

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