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SRb antenna switching sound


Ed Denton

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I've been having a problem with my SRb making a clicking sound in the audio when switching antennas. I've included a sample recording of the sound as I heard it through my 552. I realise that it is the sound of the antennas switching due to inadequate range or other interference. My question isn't how to solve these problems but I'm wondering whether this is a known problem and whether there is something I can to do fix it or whether it is a software or hardware issue that need to be repaired. Given that it is a diversity receiver designed to switch antennas for the best signal I can only assume the sound of the antennas switching is not normal.

To help diagnose, my set up was this: In a bag there is 2 UCR411a's and a SRb into a 552 with direct outs to Zoom F8 XLR inputs and also a boom running through the 552 into the Zoom. Also a Senn G3 tx in the bag sending scratch to camera. I had two SMDa's transmitting to the 411a's and one UM400a transmitting to channel 1 of the SRb, the other channel was not in use. Again, my question is not how do I get better range from my transmitters but can I/how do I avoid the clicking sound coming from my SRb.

Thanks in advance,

Ed

Antenna switching sound.aif

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I could see the little triangular diversity indicator flipping up and down as it made the clicking noise which is how I narrowed the issue down to the receiver. The transmitter gain was in the usual range for speaking voice.

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9 hours ago, Ed Denton said:

I could see the little triangular diversity indicator flipping up and down as it made the clicking noise which is how I narrowed the issue down to the receiver. The transmitter gain was in the usual range for speaking voice.

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What is the "usual range" you have set on the transmitter - relative knob position?  What is the behaviour of the audio LED's? Are you getting activity on both?  If not, try a higher input gain setting on the transmitter - compensate by reducing input gain on the zoom or output gain on the receiver.  And Mungo is correct, you can optionally put the SRB into ratio diversity mode and go from antenna phasing switching to utilizing BOTH receivers since you are using only one transmitter to the SRb in this case. Ratio diversity mode is a mix of the two receivers without switching.

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The dialogue ranges from quiet talking to yelling in the one scene so there was quite a large range but at its loudest part it was just engaging the limiters. I'm fairly confident it is not a transmitter problem as I could see that the clicking sound was happening as the diversity phase indicator on the SRb screen was flipping. Regardless, I did some more tests to see. The problem did not happen when I put the Divmode to "ratio". However the problem still persists when I have a second transmitter on and use it in dual receiver (switched) mode. Also I tried using a different transmitter and the problem still persists.

This is a fairly new SRb (less than 2 years old) bought new from reputable dealer in Australia.

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I've used lectro since 300 series and the anntena switching clientscks has driven me crazy at times ,rf looks good but you can hear the clicks on.srb in switch mode on 5 different srb units i own most of the time you don't hear the antenna switching but other times it's noticeable no real reason I can't pinpoint I always fully modulate into limiters in ratio mode no probs, I am convinced smart squelch has something to do with the clicks n switch mode only happens 10% of the time but it's enough to wish it was always clean like ratio..hoping SRC switch mode is better than the SRB...Richard

 

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Ed, don't worry about channel selection (which is higher or lower) the SRB will tell you if you are setting it up wrong there - you'll get a warning on the screen.  Try upping your levels more - even for those soft to loud scenes.  The limiter is soft kneed and can handle over 30dB before you get into trouble.  When you say the level is just hitting red when they are shouting, then your overall level is too low.  What is happening is during the low scenes, the transmitter is barely getting modulated so the signal to noise ratio is compromised - that's why you hear the clicks.  By turning up the transmitter just a bit more, you increase your S/N significantly and the clicks get shoved down into the noise floor.  If you get distortion during the shouting periods - remember, we can handle an additional 30dB there - the distortion may be due to clipping at the input stage of the recorder or camera - compensate by dropping the output level of the receiver or dropping input gain on the mixer. Try making small changes - don't go from barely on to full on, make little changes - you will find the happy medium somehere in the middle.  For most mics, I find being around the 12 O'clock to 1" O'clock position is a good starting point - I've gone as high as 3 O'clock - even with loud sources without getting that compressed squishy sound.

Gordon

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Thanks for your response Gordon that was good info for me. However I am convinced that what I'm experiencing is not normal operation. I'm using a red dot cos11 but the gain is up around the 3 o'clock position on the UM400a, well within what I would consider an acceptable range and it should be able to tolerate the dynamic range that I am giving it. I really dislike the sound of the limiters engaging. For me they are a fail-safe for unexpected yells, not something that I would allow in general recording. Furthermore is doesn't happen in ratio mode or when I have the same setup with my UCR411a's. Think perhaps it is a faulty unit and I'll contact Lectro directly I think.

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Not sure if you are aware Ed, but Gordon is the CEO of Lectrosonics. He goes a little stealthily, as Larry does...  

Probably wise to give his advice another try before you "contact Lectro directly"  - which you kind of just did...

Cheers,

Brent Calkin

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Appreciate the heads up there. I'll try and work with the information you provided Gordon and see if I can find a happy medium with transmitter adjustment and drive the clicks into the noise floor. Cheers

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