Phonic PCR2213

[jonwhittaker]

Hi Guys

 

Just have a question regarding an installed PA in a nightclub. The system currently has a Phonic PCR2213 crossover before the amps, this crossover also has a built in limiter feature. My question is, our amps are (very occasionally) clipping at high volume levels by DJs. Our amps are rated correctly to the speakers that are installed (all QSC amps). The input and output gains on the crossover for the tops and bassbins are set at 0db.

 

My question is, would altering the threshold of the limiter on the PCR2213 so the limit lights on the crossover flash occasionally (instead of the clip lights on the amps) be a safe way of protecting our speakers? Or, should we be reducing the channels on the amps?

 

Many thanks.

[KevinE]

I assume the Phonic is locked away to prevent the phantom dabbler?

 

I would set the gain structure as per your usual way, so that going into the red on the DJ mixer is at the same time as the amps peak.Then wind the threshold of the limiters down till the amps stop peaking, and check that advancing the mixer levels well into the red does not allow the amps to peak at all. If the DJ then decides to run into the red all night, he will be into limiting; and if he plays sensibly then the odd slip into the red won't hurt the speakers either.

 

You can set the gain and limiter thresholds with the speakons unplugged if you like.

 

Be aware that if a DJ thinks he needs it louder, he will wind the mixer channel gains up to full, then the channel EQ's all up, the channel faders and master fader. He will check the back of the mixer to see if there's a preset master level, then turn that up with the sharp end of a dinner knife. If physically possible, he will try to unplug the XLRs on the back of the crossover-limiter to bypass it if he realizes what it is. Then he'll wind up the amps to max. Best lock the door to the amp room.

 

This is all academic unless it's all secured or tamperproofed!

 

 

 

 

A somewhat naive electrician at a local (now defunct) nightclub did an amateurish install with some rather nice equipment. To protect the speakers, he played a test CD and whacked all the controls on the Formula Sound mixer to full then turned the amp gain pots down till they stopped clipping. Then he stuck a couple of strips of gaffa tape over the amp pots as a 'limiter'.

 

You can imagine exactly how long those strips of tape remained on the amps!

[jonwhittaker]

I assume the Phonic is locked away to prevent the phantom dabbler?

 

I would set the gain structure as per your usual way, so that going into the red on the DJ mixer is at the same time as the amps peak.Then wind the threshold of the limiters down till the amps stop peaking, and check that advancing the mixer levels well into the red does not allow the amps to peak at all. If the DJ then decides to run into the red all night, he will be into limiting; and if he plays sensibly then the odd slip into the red won't hurt the speakers either.

 

You can set the gain and limiter thresholds with the speakons unplugged if you like.

 

Be aware that if a DJ thinks he needs it louder, he will wind the mixer channel gains up to full, then the channel EQ's all up, the channel faders and master fader. He will check the back of the mixer to see if there's a preset master level, then turn that up with the sharp end of a dinner knife. If physically possible, he will try to unplug the XLRs on the back of the crossover-limiter to bypass it if he realizes what it is. Then he'll wind up the amps to max. Best lock the door to the amp room.

 

This is all academic unless it's all secured or tamperproofed!

 

 

 

 

A somewhat naive electrician at a local (now defunct) nightclub did an amateurish install with some rather nice equipment. To protect the speakers, he played a test CD and whacked all the controls on the Formula Sound mixer to full then turned the amp gain pots down till they stopped clipping. Then he stuck a couple of strips of gaffa tape over the amp pots as a 'limiter'.

 

You can imagine exactly how long those strips of tape remained on the amps!

 

Thanks Kevin.

 

Yes the Crossover/limiter is behind a rack security screen, the amp channels are un-protected but they are up full wack already. Thanks for your help in this

 

The original installer of this club system had the unprotected amp channels turned to just 1 o'clock (with gaffa tape over, as you also say!), with the locked down limiter producing +6db of gain output. This made no sense to me whatsoever, which meant DJs were sneaking in and turning up amp channels which meant we were losing Bass bins every month. This as well as them running their mixers well into the red.

 

The amps are rated perfectly for the speakers (ie we have an amp giving out 600w at 4ohms per channel supplying 2x 300w tops per channel).

[KevinE]

we were losing Bass bins every month

 

So was the venue I mentioned. I remember when The Prodigy 'Breathe' came out the DJ waited for the long sustained bass note on that record and whacked everything up to eleven to create a floor-shake effect. Unfortunately it made the bass bins sound like someone was inside and hammering nails! A few days later and they were dud.