Re: Compression Driver Protection Circuit

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ADLOG
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Joined: Thu Apr 08, 2010 6:06 pm

Re: Compression Driver Protection Circuit

Post by ADLOG » Sat Apr 10, 2010 1:32 pm

We have 3 Renkus Heinz TRX81/9 boxes covering our sanctuary. We had a problem with one of our amps sending a pulse through the speakers at turn off, even though the ASHLY amp as load disconnect relays that open before the amp powers down. This abnormal condition did not always occur, but it eventually it damaged a Mid/Hi Driver's voice coil. At power Up, this problem was not apparent. The amp was sent to the factory and returned as repaired at no charge. They said that a loose internal ground connection caused the problem. Well, I am doubting that, since it is back. When the amp was in the shop, we used a QSC amp that was elsewhere in house, without any pops at all. We think that the manufacture did not take the time to really troubleshoot this issue and catch the spiking on a storage scope or recorder. Now, we are planning to replace the amp with a Face Audio model. Meanwhile, I am disconnecting the loads before turn on and especially before turn off. An we do follow the correct power up/down order: Up: Amps on last; Down: Amps off first.

Our engineer is aware of our situation and will be checking with R-H on this idea. I only want to make sure that the drivers are protected from these problems that can come up. We do not run high volume/ power levels for our services. The gain structure is correct as I can tell system wide. The speakers are rated: 200w program @8 ohms. The Compression Driver is rated 30w program. There are no fuses in line with the boxes. Two are run off one channel of the amp,(4 ohms), and one on the other, (8 ohms). A RANE RPM series processor feeds the FOH amp.


Thanks

wwallusa
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Joined: Fri Oct 26, 2012 1:06 pm

Re: Compression Driver Protection Circuit

Post by wwallusa » Tue Nov 12, 2013 4:18 pm

I never trust these protection circuits. I am old school. Power amps on last with volume potentiometers turned down to zero. On shutdown turn volume potentiometers down to zero before turning the amp off. If you always do this you should never blow a driver due to turning on or off.
Depending on these circuits is just lazy....Good luck....

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