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Lectro 200 series companding issue


aristotle_kumpis

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I was on set last week using my Lectosonics UCR211 and UM200. What I thought was interference turned out to be something else. It seems that the compander was working overtime and only the dialog would come through. There was no breath or ambient sound that would come through. In other words, it sounded like a gate. Keep in mind that I was on a clear frequency.

 

This happened to me about month ago as well, and I could't figure out what was happening. I even tried a different block, and it did the same thing. The strange thing was that I tried my UCR411 and SM set, and it worked great. I contacted Lectro, but they couldn't really hear it or figure it out. Has anyone else experienced this? 

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" Has anyone else experienced this?  "

yes.

 

" I even tried a different block, and it did the same thing. "

how did you change the block on the 211/200 system ?

 

" The strange thing was that I tried my UCR411 and SM set, and it worked great. "

not strange, but tells me something pretty obvious!

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I was on set last week using my Lectosonics UCR211 and UM200. What I thought was interference turned out to be something else. It seems that the compander was working overtime and only the dialog would come through. There was no breath or ambient sound that would come through. In other words, it sounded like a gate. Keep in mind that I was on a clear frequency.

 

This happened to me about month ago as well, and I could't figure out what was happening. I even tried a different block, and it did the same thing. The strange thing was that I tried my UCR411 and SM set, and it worked great. I contacted Lectro, but they couldn't really hear it or figure it out. Has anyone else experienced this? 

Hi Aristotle,

If the unit isn't broken in the compander area (DC off sets, leaky capacitor, defective compander chip) then the only thing that would cause the symptoms with normal units is if you have the gain at the transmitter set much too low by 30 decibels or more. This would cause the noise reduction circuit to identify desirable background (ambiance) as noise. If the gain is set properly then the units have something broken.

Best,

Larry F

Lectro

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It was weird Larry. I was in this building for half a day, and I had the same issue on block 21 and 25. It drove me nuts. But this last time, it seems that the 411 set was immune to it, compared to the 211 set.

Hi Aristotle,

Could they have had a supersonic security system in the building? That will upset companders even though most people can't hear the supersonic sound. Lavalieres are very good at picking it up since the diaphragms are so small. We have filters in the audio path to reduce the stuff above 20kHz but the 200 series is analog filters where the 400 series is digital filters. They are many times sharper to prevent aliasing above 22 kHz.

Best,

Larry F

Lectro

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Thanks Larry. I never knew that a supersonic security system could do that. That might explain why it happened only on the analog system. I'll check to see if they have that type of security system. Do you think a high powered Wi-Fi system could also have an effect?

I don't think so. The compander circuits were being mucked up and that is all audio frequencies.

Best,

Larry F

Lectro 

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