Using Old Batteries In radio Mics

[rob.williams]

We have a 16 Way shure SLX System at our theatre and lately for tech runs we have been using old Procell batteries that we have used for actual performances. However we have massive problems with radio mics during these rehearsals including

 

Drop Out

Feedback

And Just Generally not working

 

We always then 'play around' with the system aand not knowing what we have actually done at the end of it (and after the sound engineer wants to jump off a bridge as the rehearsal went badly wrong) and when it comes to dreess run with new batteries everything is working perfectly

 

Any Suggestions or genreal help

 

Thanks

[DaveP]

Any Suggestions

 

I learnt through bitter experience that radio mics chew up batteries (and packs are worse than hand helds)

 

So the moral is... fresh batteries every time

 

Theres a thread here... http://www.blue-room.org.uk/index.php?showtopic=33636

[Biskit]

We have a 16 Way shure SLX System at our theatre and lately for tech runs we have been using old Procell batteries that we have used for actual performances. However we have massive problems with radio mics during these rehearsals including

 

Drop Out

Feedback

And Just Generally not working

 

As you say it is difficult to be sure (shure :D ) of the cause of intermittent problems, unless you change just one thing and it makes the issue go away.

 

Regarding old batteries: my systems are Sennheiser G1 EW100 series (beltpacks rather than HH) and I always work on getting two full shows from a 9V (PP3) Procell. This has always been reliable for me, but I know from experience that if I used the same batteries for a third show/rehearsal, they would start dropping out. Two shows probably amount to approx. 7-8 hours use when switched on 30-45 mins before each show and left on throughout.

 

I occasionally hire in G2 systems (which use AA not PP3) and these tend to last 3 shows, but the battery meter makes it easier to keep an eye on them, and I'd never risk starting a show with any less than two bars out of three on the meter still showing 15 mins after switching on (battery meters tend to show an artificially high reading for the first few mins).

 

The specific problems you mention: Dropout: If your receivers are accessible during the show, keep an eye on RF reception (if these systems show it - I'm not familiar with them). Weak RF with the mic close to receiver (and having ruled out intermod and interference problems) could be a symptom of low battery, but can also be caused by poor positioning of transmitter, eg. under 20 layers of clothing or inside a suit of armour! Do the cast wear full costume during your tech runs, or their 'normal' clothes? This could make a difference.

 

Feedback: Unlikely to be caused directly by battery failure, but if you are pushing faders hard (perhaps on your general cover mics) to compensate for RMs dropping out, this could be an indirect consequence.

 

As a general rule, make sure your kit, especially cables, are 100% reliable and working before any setup/rehearsal. This way, you will hopefully prevent silly niggly issues during the first run through.

 

HTH

 

Ben.

[paulears]

Low batteries do mean the RF output drops off a little, but if you run them flat, then just before they switch off, you do get plenty of drop outs, and when they are flat, they generally don't work. Actually - when they are flat, they never work.

 

One thing you need to do with radio systems is not fiddle. In practice, there isn't a huge amount you can fiddle with? Making sure aerials are in the clear, not hidden behind metal panels, or loads of local steelwork is a sensible move. Many radio systems have a squelch control hidden away or on a menu, and making sure this is set to mute the channel when the signal gets very weak is normally a one-off adjustment, and once done, you can forget it. There's not much else you can do.

 

Feedback is a microphone/system issue and not really anything to do with it having no cables. I assume you have packs and mics, not handhelds?

 

At your soundcheck you attached the mics to the people in their show clothes. Where did you put them? Feedback from omni mics takes careful planning. How loud is the stage? If it's a noisy place, then mics need to be close in to the mouth, so you can get plenty of volume before feedback. Whoever's at the desk will spend plenty of time tweaking eq to get good sound v loud sound at a happy compromise. There are plenty of radio mic topics on here that explain a bit about placement - stuck on/hairline/booms/mini-booms etc. The worse place is clipped on, a foot away from the mouth.

 

 

I'd not worry about using part-used batts. We all do this for rehearsals, and as long as they are not flat, no probs. At the first sign of trouble, check that they haven't gone flat, and if so replace automatically.

 

The other problems are just sound issues, and just need careful work to make them behave. 'Playing around' with them isn't a very scientific way of trouble-shooting, as you cannot be sure what you did really solved the problem, or did it go away by coincidence?

[Tony Gayle Audio]

I would always advise using new batteries, whether for tech or performances ( 2 shows max ). Instead of disposing of yur used batteries, leave them in a box at stage door or green room and encourage everyone to help themselves to the used batteries. A part used battery works for ages in a remote control, camera etc.

 

As for the feedback and dropout issues, these have been explained by the guys above.

 

Good Luck

[rob.williams]

Thanks for the advice the mics are worn in the centre of the forehead as it is a musical

 

I think the problems resolving are just coincidental

[Gareth Owen]

Have a read of :

 

http://www.shure.co.uk/stellent/groups/pub...ophonesy_ea.pdf