Re: Possible speaker damage

<mickwaltersuk@xxxxxxxxxxxxxx> wrote in message
news:1175085488.900321.130940@xxxxxxxxxxxxxxxxxxxxxxxxxxxx

Can any PA/audio experts help with this please? I have
recently "inherited" the running if my church PA system
but my knowledge is pretty limited. We have a couple of
radio microphones and I'm being told that to turn them on
and off at the transmitter, without turning them off
first at the mixer, will harm the speakers. Is this
true?

Anything can harm speakers if loud enough. Nothing can harm speakers if its
soft enough, and with a credible SR er PA system, that can still be pretty
loud.

There is no "thud" or other noise from the speakers when
they are turned on and off.

There might be some ultrasonics, or not.

To my un-trained mind that
seems to suggest that there is no signal of any great
strength being sent to the speakers and so no harm should
be done.

Depends on a lot of things. For example, do your receivers have a squelch
feature and if it is adjustable, how is it adjusted?

What happens when you power the wireless transmitter off? If you have good
squelching action in the receiver, then the sound will just go away, and
then you are good.

Any system that can be damaged by a wireless transmitter going down with the
fader up is inherently unstable. What does this mean if a wireless
transmitter battery runs down in the middle of a service - do you quick run
out and buy a new SR system or what? ;-)

Is my assumption correct?

Probably more right than wrong, but not everything is obvious.

I think what *may*
cause some damage is the occasional heavy-handed tapping
of the microphones "to see if they are on" or
plugging/un-plugging the leads from the transmitters
which does cause load "thuds" through the speakers.

If you have a good limiter in your system adjusted right, then none of the
above can hurt.

If it makes any difference, we have two TOA radio
microphones, via a TOA WT-770 receiver, through a Yamaha
EMX-5000E-20 powered mixer with amplifier.

YOu didn't mention the speakers. If you have a high-powered amplifier, and
weak speakers, then you have a recipie for disaster. If you have speakers
that are a good match for availble amplfiier power, then you might even be
inherently safe.

BTW the EMX 5000 spec *** mentions a power select switch. It might work
for you something like the limiter I mentioned above. You might try
experiementing with setting it as low as possible without it adding audible
distortion in normal use. Then, it will limit the amount of power that an
*accident* will cause to be applied to the speakers.


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