Fizzing, crackling and popping belt packs

[Animal]

Did an install in a church a few weeks ago and have had endless problems with the beltpack making fizzing and crackling noises. It cuts out completely on occassion even with full signal and it occassionally gives off a loud bang sending the fear of death into the oldies.

 

Any ideas?

 

Apparently their was a theatre tech in last sunday and he told them that it was static from the minister. I've tried just about everything I can think of to resolve this. They are going to try isolating the beltpack by putting it in a cotton pouch (suggestion of the theatre tech). Anyone come accross this before?

[Andrew C]

Could be static I suppose, but I'd check the wiring to the capsule first. Probably a break in the wire that remains in contact until it moves, then BANG!

[WiLL]

Sounds far more like a faulty mic lead or capsule than any kind of interference to me, but it's hard to say without actually hearing it

IMHO I would try GENTLY manipulating the lead (once it's off the minister of course) to try and recreate the problem and thus diagnose the point of failure. That is if the mic actually IS a lavalier, i.e. a long thin lead with a mic head which plugs into a belt pack.

A lot of radio mic leads fail because when they are taken off, the lead is viciously wound tight around the belt pack which can break the very delicate solder joins, and seeing as a new lead can cost anywhere from £150 upwards, it's best to avoid doing this :D

On the plus side, depending on the make and model of mic, simple resolder repairs to faults like this are doable if you're soldering skills are up to scratch.

 

EDIT: On rereading your post I would say that this is almost certainly the problem, because interference would affect the signal which you said still shows at full. Whereas a mic fault would broadcast at full strength whatever it was picking up, which includes snap, crackle and granny startling pops :)

[Animal]

I have tried different belt packs, mics and recievers but the problem still occurs.

[paulears]

If you have another similar channel that does not exhibit the fault, then you have everything you need to fault find - assuming the transmitter can operate on more than one channel.

 

As the mic fault is more likely, can you replicate the fault on another person, or is it only when on a certain person - the minister?

If it is only when it on him, then he is the problem. Common causes are man made fabrics, that on some people charge up, and then the crack you hear is the static discharge - sometimes made worse by layers - does he have two layers of man made fabric? So look for a jacket over a shirt - trousers over pants etc. Introducing natural fibres may help.

 

If the problem is one everyone who uses this particular set up, swap another mic/pack combination onto the problem frequency and see if the problem is still there. If so, then it is a receiver issue - so you are looking at the receiver, antenna cabling, grounding - that kind of thing. If the fault disappears with the new pack/mic, then go back to the first and swap the pack, but keep the mic. If this is trouble free, it's the pack - if it still has the noise, it's the mic.

 

It is just a case of swapping things one at a time to track down the guilty party.

 

The only thing that can sometimes confuse this is when the problem is the voltage supplied to power the mic capsule. A fault in the transmitter pack can make any mic plugged in be unreliable. Reduced voltage, or current limiting make the mic elements behave in odd ways. One common fault with the mics is poor soldering at the capsule end in the cheaper brands - a dry joint here can be very difficult to spot.

 

 

Anyway - a few ideas that could help?

[Animal]

Anyway - a few ideas that could help?

 

Thanks for that. I'll try some of your suggestions. The mics are Audio Technica 3000 series with micro head mic. I chose them for the installation as we use some ouselves and have never had a problem with them.