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Author Topic: Wireless lav audio problems  (Read 1923 times)

Keith Broughton

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Re: Wireless lav audio problems
« Reply #10 on: February 05, 2021, 07:12:47 am »

Matt, you say "when you come back". Is no one monitoring the audio on location? If not, why not? If so, at what point in the signal chain are you monitoring?
I think those Sony's have a headphone out on the RF receiver so you can check audio starting at the receiver.
On location is the place to trouble shoot this problem if, as you say, the equipment works correctly in studio.
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Matt Hill

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Re: Wireless lav audio problems
« Reply #11 on: February 05, 2021, 10:04:56 am »

Matt, you say "when you come back". Is no one monitoring the audio on location? If not, why not? If so, at what point in the signal chain are you monitoring?
I think those Sony's have a headphone out on the RF receiver so you can check audio starting at the receiver.
On location is the place to trouble shoot this problem if, as you say, the equipment works correctly in studio.

These are all great suggestions, thanks everyone.
Am about to head back to location we had this problem yesterday to test everything and will post back results.
I work for a school district so am on several of our 42 school campuses, and this is happening more and more frequently on several campuses. It is worse in some locations within those campuses. At some campuses there is no issue at all. That makes me think it is something to do with frequency or wireless connection? I have auto-set numerous times at the location with no improvement in results.
Mic is always approx. 6 inches from mouth. Level received into field recorder is always low even when pushed when this problem is happening.

Will go test this morning with all your valuable input and post back results. Thanks again everyone.
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Tim McCulloch

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Re: Wireless lav audio problems
« Reply #12 on: February 05, 2021, 10:16:18 am »

These are all great suggestions, thanks everyone.
Am about to head back to location we had this problem yesterday to test everything and will post back results.
I work for a school district so am on several of our 42 school campuses, and this is happening more and more frequently on several campuses. It is worse in some locations within those campuses. At some campuses there is no issue at all. That makes me think it is something to do with frequency or wireless connection? I have auto-set numerous times at the location with no improvement in results.
Mic is always approx. 6 inches from mouth. Level received into field recorder is always low even when pushed when this problem is happening.

Will go test this morning with all your valuable input and post back results. Thanks again everyone.

What frequencies are you using? Anything above 600mHz?
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Keith Broughton

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Re: Wireless lav audio problems
« Reply #13 on: February 05, 2021, 11:22:22 am »

When you get on site, turn on the receivers but do not turn on the transmitters and check the RF meter on the receiver to see if there is any RF in that location.
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Matt Hill

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Re: Wireless lav audio problems
« Reply #14 on: February 05, 2021, 03:52:33 pm »

When you get on site, turn on the receivers but do not turn on the transmitters and check the RF meter on the receiver to see if there is any RF in that location.

Tested at problem location (school library) and discovered it is 100% related to specifically where I was. Listen to the file below - begins outside the library in a boomy hallway and sounds OK ... once I step into the library within seconds all the audio is sucked away and I am back to the same problem.

Test Outside to Inside Library

This makes me feel it is absolutely signal interference, maybe frequencies or something. But it is happening on many of our campuses so could it be related to the wifi system or something? Any settings or frequencies I could choose that avoid those of wifi?

To answer earlier post questions and suggestions, I'm running battery onsite and in studio - literally not a single change in setup between locations, but studio offers perfect audio.
Played with companders on both RX and TX - every single combination of UWP. UWP-D and WL800, none fixed they problem, audio was almost the same every time, but always bad.
The levels are all low when this problem happens - 1/2 and lower on TX, 1/3 and lower on RX, and very low into 702T and MixPre-6 and I switched limiter off completely so I don't think the levels are the issue or anything is overloaded.
I have been monitoring audio directly from the receiver and have exactly the same results as my recording equipment. Really believe this is a signal issue somehow. Any help again truly appreciated.



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Russell Ault

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Re: Wireless lav audio problems
« Reply #15 on: February 05, 2021, 04:18:03 pm »

{...} The levels are all low when this problem happens - 1/2 and lower on TX, 1/3 and lower on RX, {...}

At the risk of some postmortem equine flagellation, this still sounds like not enough TX input level to me. In your most recent test audio, to me the door sounded about the same both inside and outside the library, but you started speaking more quietly (and therefore closer to the RX's noise gate) when you entered the library (which, to be fair, we all do when we enter libraries). :) From your description, the meters are backing me up on my "not enough level" assessment.

While some companding circuits are more forgiving than others, they all work best with an input signal that's close to the TX's limiter threshold. As long as you're seeing such anemic levels on the TX and RX I'd expect to have weird audio problems, and the only solution to my knowledge is getting more audio level into the TX.

What are your IN LEVEL and ATT settings on the UTX-B03?

-Russ
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Tim McCulloch

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Re: Wireless lav audio problems
« Reply #16 on: February 05, 2021, 04:23:01 pm »

At the risk of some postmortem equine flagellation, this still sounds like not enough TX input level to me. In your most recent test audio, to me the door sounded about the same both inside and outside the library, but you started speaking more quietly (and therefore closer to the RX's noise gate) when you entered the library (which, to be fair, we all do when we enter libraries). :) From your description, the meters are backing me up on my "not enough level" assessment.

While some companding circuits are more forgiving than others, they all work best with an input signal that's close to the TX's limiter threshold. As long as you're seeing such anemic levels on the TX and RX I'd expect to have weird audio problems, and the only solution to my knowledge is getting more audio level into the TX.

What are your IN LEVEL and ATT settings on the UTX-B03?

-Russ

And to my point - desensitizing of the receiver inputs by other RF sources.  We need to know where he's at and what frequencies he's using.
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Matt Hill

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Re: Wireless lav audio problems
« Reply #17 on: February 05, 2021, 04:29:15 pm »

And to my point - desensitizing of the receiver inputs by other RF sources.  We need to know where he's at and what frequencies he's using.

Hi Russ - IN LEVEL is set to MIC and I just left ATT at 0. I did try pushing ATT up and up while testing this morning, but this just seemed to increase the volume and the problem. Also, the male voice level in the original clip2 was much stronger but still had same underlying audio issue. Shouldn't I be able to throw a lav on someone and even if they have low level, be able to capture something without this "gating" effect?

Tim - I was AUTO SET-ting in group 1 from my receiver and for this test it was giving me 478.125. BAND on receiver set to TV14-17 but I have tried it on the other settings, 18-21 and 22-25. Have AUTO-SET many times and keep getting same result.
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Mike Caldwell

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Re: Wireless lav audio problems
« Reply #18 on: February 05, 2021, 04:41:52 pm »

Like Keith asked with the transmitters off do you see any RF receive level on the receivers?
What frequency group are you using, It does appear that Sony uses any WIFI bands for that series of wireless.

A really wild idea..do they use lots of LED lighting in the library, some LED lights pump out a lot of RF noise.

Going with Russell's idea bring up the transmitter audio level till you just at the point of hitting the peak light.

For what it's worth from the wording on the wireless system info I think it's an analog system that uses digital companding.


I type slow you answered some of those questions while I was typing!!
« Last Edit: February 05, 2021, 04:43:55 pm by Mike Caldwell »
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Russell Ault

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Re: Wireless lav audio problems
« Reply #19 on: February 05, 2021, 04:57:58 pm »

{...} Shouldn't I be able to throw a lav on someone and even if they have low level, be able to capture something without this "gating" effect? {...}

It depends on the companding circuit, but basically, no.

Without a companding circuit, the dynamic range of a US-legal UHF FM wireless microphone is only about 50 dB from noise floor to max level. Obviously, 50 dB is...pretty terrible, and ideally should be about twice that. To fit 100 dB of signal into 50 dB of actually dynamic range, wireless microphone manufacturers use various forms of companding, similar in nature to Dolby B, but with some added twists.

The exact makeup of any given companding style is a trade secret, but the gist is that there are one or more compressors on the TX to reduce the signal's dynamic range, and then one more expanders on the RX to restore it. Of course, if you've ever tried to run a compressor and an expander in series, you'll know that you'll never quite get out what you're putting in, so there's a great deal of artistic license that goes into designing these systems, with different trade-offs being chosen even for different product lines from the same manufacturer.

In the end, though, the result is the same: the appearance of significantly increased dynamic range, but with significantly reduced linearity. How well these systems performer at the fringes (i.e. with a really hot or a really cold input signal) is one of the many compromises to be made, and a design choice inherent to the specific companding style.

Something else I should have asked earlier: given that you're already at ATT 0, what capsules are you using?

-Russ
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Re: Wireless lav audio problems
« Reply #19 on: February 05, 2021, 04:57:58 pm »


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