Sennheiser EW100 G3 - mysterious volume drop

[Stuart91]

I'm going to call Sennheiser in the morning about this, but I thought I'd see if anyone here has come across the problem before.

 

A G3 EW100 beltpack system being used in a church. Sometimes, but not always, the output level drops steadily. It's the same person using it throughout the service, and there's no real change to what's being done with the mic. The operators are novices, but sensible, and showed me the amount they needed to push the fader to compensate. It looks like around 40dB of a difference. Apparently it comes on gradually rather than in one sudden drop.

 

I couldn't replicate the problem when I was with them, and I can't think of anything obvious that could cause these symptoms. There doesn't seem to be any pattern to how long it lasts before dropping - at least nothing that they can discern. Has anybody come across this issue before?

[peza2010]

Silly question, but its not the person talking is it?

 

Some people can very funny about hearing their own voice that to them, sounds very loud and might start talking quieter, your engineer pushes volume, person talks quieter.

 

Long shot I know.

[Solstace]

40dB? That's a LOT of level-drop for a nervous speaker. Are we sure the mic capsule itself isn't playing up? Although, that would usually coincide with pops, bangs and other more sudden symptoms I guess... I'd be curious to know what happens to the noise floor as the usable signal level goes down - does it go down too?

 

I remember a number of our G2 EW's had a problem with phantom power breaking down output stages, and this sounds like a curiously similar onset-pattern to what happened with ours. Eventually the output stages in two, maybe three of our installed receivers died completely and needed complete replacement. In the words of I believe a Dad's Army character - Jones I think? "They don't like it up 'em!"

 

I've been reassured time and again that this could only ever happen to early-model G2 receivers, and that they'd been redesigned to avoid that flaw, but I was never able to trust them again - so I always (re)installed them behind isolating transformers if I in doubt as to whether they might ever see phantom, to prevent the issue ever happening again with the repaired and remaining stock. Upon receiving G3 stock, I felt confident enough that the design had changed enough that this should never be an issue again having run the previous experiences past Sennheiser's engineering team, so began to eliminate the isolating transformers.

 

DEFINITELY worth getting in touch with Sennheiser though - even for non-warranty repairs their fixed-price scheme is quick, easy and remarkably good value when I've had to use it.

[Stuart91]

Thanks for the replies.

 

We're fairly sure that it isn't the person speaking - as Solstace says 40dB is quite a lot, and the room is small enough that people would notice the drop in acoustic level too, irrespective of what the PA is doing.

 

Phantom power had crossed my mind - the receiver is being fed phantom and I didn't have the chance to do anything about it. We've had hassles with G1 and G2 receivers not liking phantom but G3 have been fine, but that's not to say

 

Mic capsule is a possibility, we're shipping a new mic out to them. I did have a good muck around with their existing mic and couldn't get any misbehaviour out of it at all. However they have at least two other dead mics, so it seems likely that it's suffered some ill-treatment.

 

Sennheiser have also suggested overheating, either of the receiver itself or the PSU powering it. The receiver is sitting under a table, not too tightly hemmed in, certainly no worse than the dozens we have sitting in racks without problems. The PSU I didn't see, so I do wonder if it is sitting under a pile of rubbish down the back.