running out of headroom in head worn omni

[audiothings]

we have been using samson head worn omnis on some theater/play performances. For some reason, they were giving us much better gain before feedback than the countrymans we compared them with. The sound quality is satisfactory, but the mic starts to distort severely when the performers are loud.

before you ask... yes the the sensitivity on the transmitter was set to -30 dB... max attenuation possible, gain is set to the minimum on the mixing console (yammie ls9... no pad but fully variable gain control)... there is no doubt that the signal is distorted before it hits the console... and yes, we tried moving the mic as far away from the mouth as we possibly could...

strange thing is that max spl is rated at 140 dB! can a dramatic oratory exceed 140 dB ?!?

what am i missing?

thanks,

[LX3]

Any input metering on the transmitter?

This suggestion is going to be a bit obvious, and feel free to say "No, we've tried that", but...

You don't mention what the transmitter is, but it's possible that the "sensitivity" setting indicates what signal level produces full modulation.... Meaning that the lower the number (-30 being lower than, say -20) the higher the gain. So you might actually be turning the input gain up, not down. Have you tried turning the sensitivity the other way?

I've also run across receivers that throw out so much signal level they cause the front end of whatever they're connected to to clip. It's often not clear whether a wireless receiver provides line level or mic level. If the gain on your LS9 inputs is all the way down, it's line level... so it might be worth turning the output level of the receivers down 6dB or so.

I agree that getting the gain structure right throughout an entire wireless system can be a bit of a game, especially when mixing and matching mics and transmitters. I recorded a stage show last year where all the head-worn mics seemed noisy most of the time, then distorted somewhere as soon as the actors started yelling (which they did a lot). It wasn't my radio system unfortunately, and the show's technical guys weren't too willing to let me investigate ("It's been working fine all week, why do we have to mess with it now that we're recording the show?")

(Answer: because you can't hear it properly in your PA, and the reality is it sounds like cr&p)

[audiothings]

You don't mention what the transmitter is, but it's possible that the "sensitivity" setting indicates what signal level produces full modulation.... Meaning that the lower the number (-30 being lower than, say -20) the higher the gain. So you might actually be turning the input gain up, not down. Have you tried turning the sensitivity the other way?

the transmitter/receiver is from sennheiser. and yes, subsequent to your message (thanks for the suggestion) we ascertained that the more the attenuation (-30 dB on the transmitter and -24 dB on the receiver, max attenuation possible), the less the input coming into the mixing console.

gotta bump this, 'coz the problem remains! looks like i'll be using this mic a lot in the days to come... both the rental company i work with and the concert hall where i often mix gigs have half a dozen each of this mic.

anybody??

[Jim vanBergen]

the real question is:
is the distortion happening at the mic element, at the transmitter, or at the receiver?

Listen at the receiver. Is the distortion there? Mic elements can be set up in different ways- many of them are designed for newscasters, and can't handle loud SPL regardless of whether the capsule itself is capable of 140dB, (notice they provide no weighting or distance, which makes a good bit of difference...)

Which Sennheisser TX and RX are you using? Did you try turning down the output of the receiver to make sure you're not overloading the LS-9 mic preamp? The output of the Senns are LINE level from the factory.

JvB