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Rat Sound Message Board
Posted by Dave Rat on May 21, 2004 at 11:56:33:
In Reply to: Loudspeaker protection posted by RJ on May 19, 2004 at 06:38:59:
: Could someone please explain to me in detail the topic of 'loudspeaker protection', in particular how to effectively set limiters on DSP units
Setting limiters on a DSP is the same as on an analog unit.
Our theory applied to the Rat Trap 5 system is to:
Set fast hard limiters as close to the absolute maximum power handling of the system.
For V-Dosc, we use the L'Acoustics presets
and how to configure a dummy proof system whereby all the input sensitivities on amplifiers are in there most sensitive position so that people do not have to worry about the settings on the amplifiers, this also ties in with the problem of what to do you an amplifier has more power than required to power a driver.
My suggestion would be to match all amps at the desired sensitivity, not the max. Then limit the ability of people to access the sensitivity switches if possible.
There are two scenarios I can envision for people changing amp sensitivities:
1) Innocent, accidental
or
2) Malicious, sneaky
If #1 is your concern, then a clear label well attached to the back of each amp stating the correct sensitivity should suffice.
If it is #2 and people are going into your amp racks to get more gain, then you need to either lock the amp racks, add more PA so they don't need the gain or find a way to attach financial responsibility to the people doing the sabotaging your system.
: What calculations are involved in match drivers, amplifiers and set limiters?
There is no 'math' that will account for every variable so ultimately it comes down to setting the limiters so that:
1) No audible farting or clipping is coming from the system.
2) You have an acceptable level of driver failure. For some system applications, this may be 'none', for other applications it may be that you lose no more than one or two components a week. Depends on system size, amount of use and how much volume you need per cubic foot/pound of system.
Assuming you are using 'Post X-Over Limiters'
I recommend setting them so your amps are just about to clip and running the system. If you run out of volume, try letting the lows and mids clip a little as long as the amp does not make a bad sound on clip.
If you start losing components, then clamp down the limiters on that output.
With a bit of care, you should be able to zero in on an acceptable balance between system volume and component failure. If components are failing and the system is still not loud enough, then you may need more PA.
: Any help would be much appreciated.