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Author Topic: interesting artifact with Senn G3  (Read 4070 times)

Keith Broughton

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interesting artifact with Senn G3
« on: March 01, 2016, 08:02:36 pm »

So I'm working with a rack of Sennheiser EW500 G3 transmitters with lavs(golds) and when I solo a channel or listen to the direct out of the receiver, it sounds like there is a soft gating action on the audio.
It only happens when the background is very quiet and once someone is talking, it sounds normal.
This happens on all 5 receivers.
If I set up a hand held, it sounds just like you would expect an open mic to sound.
Very odd.
Thoughts?
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John Chiara

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Re: interesting artifact with Senn G3
« Reply #1 on: March 01, 2016, 08:45:55 pm »

So I'm working with a rack of Sennheiser EW500 G3 transmitters with lavs(golds) and when I solo a channel or listen to the direct out of the receiver, it sounds like there is a soft gating action on the audio.
It only happens when the background is very quiet and once someone is talking, it sounds normal.
This happens on all 5 receivers.
If I set up a hand held, it sounds just like you would expect an open mic to sound.
Very odd.
Thoughts?

Squelch?
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Luke Geis

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Re: interesting artifact with Senn G3
« Reply #2 on: March 01, 2016, 09:56:53 pm »

That is Squelch. It is probably set to high for the low incoming level from the bodypack / transmitter. In the little window you can view the Squelch level. It is the dotted shaded area at the bottom of the RF window. With the wireless units off you want to set the squelch as low as you can and still not have any RF information go above the shaded area.



See the two sides marked RF and AF?

The RF is the amount of signal the unit is getting. With the transmitter off, you want the RF level to be below the dotted shaded area in the RF window. You can see the dots on each side of the RF image.

Assuming this unit had no connected transmitters the AF would be pinned and you would hear horrible static noise. This is because the RF is above the squelch threshold. Now since this is a shot of the unit with a connected  transmitter, it is showing the actual AF out and RF level. The unit will not pass audio cleanly ( you will hear companding of it anyway ) that is not above the squelch threshold. This is why you adjust the squelch with all transmitters off. You are looking to see the noise floor for the RF so you can set the squelch. If you have a high noise floor you use a higher squelch setting, but the goal is to use one that is as low as you can that is above the RF noise floor.
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Keith Broughton

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Re: interesting artifact with Senn G3
« Reply #3 on: March 02, 2016, 06:12:35 am »

I thought it was squelch as well and changed it to a lower value but it didn't seem to make a difference.
Also, the hand held mic receiver has the same squelch setting and doesn't have the same issue.
Will try changing the squelch setting again today but I'm in a high RF noise environment so the squelch needed to be set higher than usual.
I have been working with RF systems a lot, this one  regularly, and didn't know about the squelch visual reference line on the RF meter of the G3.
Learn something every day  :)
« Last Edit: March 02, 2016, 06:19:50 am by Keith Broughton »
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Keith Broughton

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Re: interesting artifact with Senn G3
« Reply #4 on: March 02, 2016, 08:24:01 am »

Nope...not the squelch. Dropped it down to 5 and still hear, what I assume is, companding.
Interesting that it's not the same on the hand held.
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Mark Rombouts

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Re: interesting artifact with Senn G3
« Reply #5 on: March 02, 2016, 09:05:55 am »

Same issue when you adjust sensitivity ?
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Keith Broughton

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Re: interesting artifact with Senn G3
« Reply #6 on: March 02, 2016, 09:54:50 am »

Same issue when you adjust sensitivity ?
Same.
I will contact Sennheiser later today.
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Jens Palm Bacher

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Re: interesting artifact with Senn G3
« Reply #7 on: March 02, 2016, 11:57:26 am »

So I'm working with a rack of Sennheiser EW500 G3 transmitters with lavs(golds) and when I solo a channel or listen to the direct out of the receiver, it sounds like there is a soft gating action on the audio.
It only happens when the background is very quiet and once someone is talking, it sounds normal.
This happens on all 5 receivers.
If I set up a hand held, it sounds just like you would expect an open mic to sound.
Very odd.
Thoughts?
Are you in a place with ultrasonic noise? Old TVs, insect repellers, ultrasonic security systems etc. maybe LF rumble This could trig the compander in the TX, but being inaudible as it is filtered away in the Rf link...
Otherwise you are just hearing the "edge" where the compander starts to work.
« Last Edit: March 02, 2016, 11:59:51 am by Jens Palm Bacher »
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Luke Geis

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Re: interesting artifact with Senn G3
« Reply #8 on: March 02, 2016, 01:11:01 pm »

The incoming signal still has to be higher than the squelch setting. That is why a lower squelch setting betters the odds of not hearing the companding. The resultant companding can always be heard if listening for it. Anytime the incoming signal from the transmitter falls below the squelch threshold, it will gate the audio. It is not as noticeable when you have a hot signal and the ends of the words are sharp. If it does it to all five units, then it is one of two things. A low transmitter level allowing for the squelch to gate the signal, or the squelch being set too high for the level that the transmitter is sending. Again though, if you have a quiet signal coming into the receiver you will hear the companding.

The HH mic having better results than the Lav mics is no surprise really. The HH will have a less sensitive capsule that is more directional and is invariably closer to the source of noise. You can usually run a lower sensitivity level with the HH mics and since the source audio is pretty loud in comparison to the background noise, companding is hard to notice. With Lav mics, it is further from the source and much more sensitive. It picks up a lot of the background noise. So as the speaker ends a word the tail of it can become part of the background noise. Since you also have to have a higher sensitivity setting with a Lav mic the background noise is higher as well. This background noise when someone talks softly can be gated by the companding if it falls below the threshold.

It is something to try in a better environment one day. Setthe squelch fo rthe lowest setting it has and talk really quietly into the mic. It should be pretty hard to hear the companding. Now as you raise the squelch higher and higher, you  should notice the gating much easier and easier. It is a threshold setting like that of a gate, so it requires a certain level of incoming noise before it opens up. Which also means it will cut of words that have a soft ending too.
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Corey Scogin

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Re: interesting artifact with Senn G3
« Reply #9 on: March 02, 2016, 01:20:19 pm »

Anytime the incoming signal from the transmitter falls below the squelch threshold, it will gate the audio.

Setthe squelch fo rthe lowest setting it has and talk really quietly into the mic. It should be pretty hard to hear the companding. Now as you raise the squelch higher and higher, you  should notice the gating much easier and easier. It is a threshold setting like that of a gate, so it requires a certain level of incoming noise before it opens up. Which also means it will cut of words that have a soft ending too.

This may be a very dumb question but isn't the squelch just a radio signal level gate?
How then would the audio signal level have any affect on it? 
Do the transmitters decrease radio power when the audio drops below a certain threshold in order to extend battery life?
How does the radio squelch threshold correspond to an audio signal level?
« Last Edit: March 02, 2016, 01:38:58 pm by Corey Scogin »
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Re: interesting artifact with Senn G3
« Reply #9 on: March 02, 2016, 01:20:19 pm »


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