HI, my radio mic that never give me any bother over this last years is now starting to give me a cracking sound mixed into my audio.
I would place the receiver in the grooms jacket pocket, I always did this btw and never had a problem with the sound, it was always very clean.

Now, for some reason this is happening, it doesn't happen all the time, and the groom doesn't have a mobile phone on him at all.

Would moving to a different channel / frequency help?

Thanks in advance.

Can you post a short demo of the noise somewhere?
Occasional clicks or crackling type noise is usually an indication of a compromised transmitter mic/cable. OTOH, Interference is typically a spitting-whoosh type of sound and can be accompanied by drop-outs. A faulty receiver output cable could also exhibit this behavior, specifically if bias current is present. Phantom Pwr fed to the Rx via an XLR connection can also produce noise and/or rapidly drain the Rx batteries, and in some case or fry the device.

A faulty receiver output cable could also exhibit this behavior, specifically if bias current is present. .

Hi Rick, odd you should mention that, I shaked the XLR cable that's connected to the receiver while making a test recording and on playback, I did hear the cracking sound.
It looks like its the cable.

Thanks.

Can you post a short demo of the noise somewhere?
.

Yes, I'll try and get that sorted, thanks

I got the same cracking audio tonight again and the camera was locked off. So I can't blame the XLR cable from the receiver this time...I think.
The cracking sound just comes into it at random, other than that, its perfect.

Can you post a short demo of the noise somewhere?
.

Hope this link help.

Thanks.

https://www.dropbox.com/s/kj6onuy7x8opqmf/Cracking%20audio.ac3?dl=0

What freq are you using on these. This could be the cause of the noise as 4g is below the 863.000mhz and if you are below this I would say its 4g that causing your problem. I would try 864.000 to 865.000 and see if it still happens

Firstly, to rule out interference, try another bank/channel.
Sounds like a mic issue though, i.e: exposure to water or something shorting the bias voltage to the audio Try another mic

OK Thank you guys.

I always had it set at 839.100 without problems.

Hi Rick, the mic is always used in doors but i'll try a different mic anyway.

Thanks

Uesing that freq is asking for trouble as its now part of the 4g band which phones now use and you will have problem there for sure. Try and go to 865.500 and see if you have any problems.

I do sound and lighting with a friend here and we also had problems using mic below 863.000 it all to do with 4g. we have 12 body packs and of that 8 of them we can not use as there is not enough room for them between 863.000 - 865.000.

try and change the freq first as it will cost nothing I don't think is the mic.

The 70 and part of 69 was sold off for 4g all over europe when the tv channels where changed to digital

Anthony here is a site i found and it may help.

https://www.spectrummonitoring.com/frequencies/#UK

look at the 800Mhz and you will see that 839.100 is in the middle of the 4g band and its the uplink from the phones that's causing the problem.

this is why I am telling you to go to any freq above 863.000 to 865.000 and you may get good luck on 865.500

Well, my opinion is different. It doesn't sound remotely like digital noise from a sideband of a cellular network - which is a horrible really loud digital scream! That to me is a mic fault where the DC polarising voltage is compromised - simple dry joints, dodgy capacitors that are fixable. The test is disconnecting the microphone. If the transmitter then transmits silence then the fault is either in the preamp of the transmitter, or in the cable. It's possible the noise could be from the capsule - especially if it got very damp at some point and the tiny gap between diaphragm and backplate has moisture in it. Dry joints can produce this sound too.

I've had this probably three, maybe four times. Twice replacing the mic cured it, a dry joint in the preamp on another, and the first time I had it was a proper fault in the pack, which Sennheiser swapped out, so I don't know the exact fault.

Paul,

I know this as when the radio mics that where 830 to 840 mhz where fine when the room was empty and when the room had about 200 people in it at a school show that when we had problem with pop and cracks.
The school itself is about 15 - 20 mile as the crow flies from the 4g tower as well.

I have also done some test myself after this and did get the same problem when 3 or 4 phone with 4g switch on about a meter from the transmitter and about 4 meters from the RX and it just cracked and popped.

When we first heard it we did swap mics on the kids but the problem was still there, we even changes the pack as swapped the body pack at one point thinking it was faulty but the noise was still there.

Also 4g is packed based and also hopes from one freq to another within the carrier's band plan.

Thank you Tony and Paul, I will try changing the mic and freq.

Tony, regarding changing freq, I'm using setting Bank 1, do I have to change bank or will bank 1 still be ok?

Thanks again guys for your time and the link.

I've got an RF Explorer - a very useful diagnostic tool, and they are handy showing you visually channel occupancy - and cellular signals are very different to look at.

A good tip is to turn off pilot tone and open the squelch if you can - digital noise, even when listened to on an analogue receiver is very obvious. There's a very similar, but different characteristic sound that happens when the wide band digital signals create receiver desensitisation by being very close, but not on top of, the audio channel - and a fluttery, phutty result appears - that changes as the receiver is oriented in different planes. What I hear in the sample is something caused in the transmitter electronic chain - from mic to the inout of the RF stage, or possibly in the discriminator output of the receiver, through to audio output.

Anthony, I am using bank U and just tuning to the freq I want to use as I have set on mine at the moment is 865.000 or 865.500 from memory as I do not have the packs beside me. I do have the same ones as you also have plugin TX and hand held mic as well.

From memory if you use banks ie as in bank 1 or even 2 there is some freq you can not go to that why I am using bank U (as in user tune able)

Paul, Know what you are saying but when there is a load of phones near by as they have about .6w to 3w of tx power can be enough. I also have a rf spectrum analyser as in usb one for my pc/laptop also have a lab one that I got via very good friend.

Anthony, I am using bank U and just tuning to the freq I want to use as I have set on mine at the moment is 865.000 or 865.500 from memory as I do not have the packs beside me. I do have the same ones as you also have plugin TX and hand held mic as well.

From memory if you use banks ie as in bank 1 or even 2 there is some freq you can not go to that why I am using bank U (as in user tune able)

Paul, Know what you are saying but when there is a load of phones near by as they have about .6w to 3w of tx power can be enough. I also have a rf spectrum analyser as in usb one for my pc/laptop also have a lab one that I got via very good friend.

OK Thank you Tony,

And thank you too Paul.

Strictly speaking, we should be in channel 70 in the UK now, so 863-865MHz which should be free of the digital dividend channels which finish at 862MHz. I see very little cellular spurious output in this band, and while it can leak directly into audio systems, I don't find it a major issue. Putting the phone near the RF Explorer does show some low level hash in 70, but from more than a metre away - it's gone. Even when you're a way away from a cell tower and the phones are polling on full power to wake another up, there's little issue really.

..... I would try 864.000 to 865.000 and see if it still happens

Tony, I had a wedding on Saturday past and I did change the freq to 864.000 and it seemed to help a lot.
Its a lot better than it was, little or no cracking at all this time :)

I'm getting the loan of a mic from a friend, just to try that out too and see if the mic was to blame :)


I have a cable like the one below but it didn't come with the mini-jack fitted.

https://www.proav.co.uk/sennheiser-cl-100-xlr-cable-for-ew-series-kits

I've a new 3.5 locking mini-jack plug and I now need to solder the 3 wires (red, white and the ground) to the plug but don't know the soldering connection.

Could someone advise please.

Thanks again for your help.

Anthony,

I will pin mine out when I get a chance at some point to day and let you know

A good rule of thumb is to stay away from frequencies that end in .000 Switch mode power supplies put out all sorts of crud, and much of it is mathematically linked to frequencies we use. For example - I still do two way radio hires and because of my studios here with zillions of switch mode power supplies, I can not test radios on the coastguard private channel 156.000MHz, because there is so much interference here. 156.025MHz is totally free of issues. Up in the UHF band its not quite so bad, but using an analyser shows the band is far from free of sproggies - and they concentrate on the maths friendly frequencies. As a result, consider using spots frequencies, NOT the ones in the band slots - which are determined as intermod free channels so you can put many channels into the space with minimal interference. If, for example a set of pre-programmed channels has 864.000 then 864.700, there is no reason not to explore anywhere between them. Turn the squelch off, switch off pilot tone and see if they are quiet. If they are, try them.

I hate the scan function - it often gives a false sense of security, because just because the scan function indicated a clear channel - it could be one affected by harmonics and sproggies from phones when one comes close. People assume that a frequency found by scanning is safe - they are NOT!

Anthony,

I will pin mine out when I get a chance at some point to day and let you know


Thank you Tony.


A.., for example a set of pre-programmed channels has 864.000 then 864.700, there is no reason not to explore anywhere between them. Turn the squelch off, switch off pilot tone and see if they are quiet. If they are, try them.

I hate the scan function - it often gives a false sense of security, because just because the scan function indicated a clear channel - it could be one affected by harmonics and sproggies from phones when one comes close. People assume that a frequency found by scanning is safe - they are NOT!

OK Thank you Paul for the advice, I'll try that, thanks.

Hi Anthony

On my lead which is home made. I have red going to tip of the 3.5mm jack and nothing connected to the ring blue and sheld is are connected together and connected to the sleave of the 3.5mm jack.

If you have a multimeter you could do continuity test from pin 2 on the XLR to see if it is the red on your lead.

Pin 1 on the XLR will be the sheld of the cable and 3 maybe the blue on yours.

http://mcgcs.net/xlrto35mm.png



Hope this helps

Thank you Tony, yes, that does help, i'll check that out :)

I have a cable like the one below but it didn't come with the mini-jack fitted.
https://www.proav.co.uk/sennheiser-cl-100-xlr-cable-for-ew-series-kits

I've a new 3.5 locking mini-jack plug and I now need to solder the 3 wires (red, white and the ground) to the plug but don't know the soldering connection.
.

The CL 100 XLR cable is for the portable receiver, to a balanced XLR input.

If your are putting a 3.5mm TRS plug on a lavaliere mic to plug for a SK100 Tx. The mic cable shield is connected to the Sleeve and Ring terminals, The other two wires go to the Tip.

Hi Rick, I’m putting the 3.5 mini-jack plug on to the end of the lead thats in the link above. I’ve one like that in the link but it hasn’t the mini-plug fitted. Thanks