Yet another ps-15 thread

[upsuEnts]

Hey all.

 

I suspect you're all bored of reading about ps-15's but I am hoping for some help.

 

This is the situation:

We've had pd-15's with A driverack PA, nexo TD controller and a camco tecton amp.

The problem is that we seem to go through drivers with scary regularity.

There seems to be no pattern to the failures so tracing the cause has been difficult.

The signal chain is:

cdj1000 > djm8000 > driverack PA > TD controller > tecton > ps15

Last time I found the amp with red lights on signal and peak but there was only a low signal coming from the mixer and driverack. The amp wasn't running hot and there were no lights on the controller.

 

I'm at a loss

[i_hate_fisicks]

What's the driverack PA for? And which Tecton have you got?

[avdavesound]

I'm sure a few people will say its the driverack pa because of the switch-off thump. I've changed 5 drivers in ps15's a few weeks ago and they all had the same problem,the braided wires going to the voice coil where broken. I fixed 2 because I could see the break, on the other 3 the braided cable broke inside the cone just before the coil.

dj's most of the time try to push the system to the max and the crossover point on the td controller is two low so the ps15's are nearly full range and they get pushed 2 much. to solve it we put in a dx1 before the td controller to take care of the crossover points and limiting and use the td controller just to process the ps15's.

what known driver failures have you had so far?

 

Last time I found the amp with red lights on signal and peak but there was only a low signal coming from the mixer and driverack

thats not good. could be a short circuit somewhere. have you tested the cables or tried different ones?

 

I suspect you're all bored of reading about ps-15's but I am hoping for some help.

I love giving out about them!!

[upsuEnts]

Cheers guys,

 

On opening up the boxes (the part of the club we use them in closed early for obvious reasons) this time it turned out to only be the fuses.

We use the drive rack to take the crossover point of the ps15's up a little bit to about 140hz and it's a tecton 38.4 I believe.

 

I think it was a power surge because the fuse in the amp , but I've had the braids snap before and the coil getting too hot and dropping off before.

[fatfrog]

I think your whole problem is the Dj's - You really aught to set up a limiter somewhere in the system chain to take care of overdriven signals.

 

I would also suggest putting the limiter into the amp rack somewhere where it's existence isn't noticed to avoid people tampering with it.

[upsuEnts]

There's a compressor on the drive rack set to kick in when we reach our spl limit and the high/low limiters come in before the amps clip.

This is one of the reasons I'm surprised :s

[PoppaDom]

There's a compressor on the drive rack set to kick in when we reach our spl limit and the high/low limiters come in before the amps clip.

This is one of the reasons I'm surprised :s

 

 

Why are you suprised? Just because it starts to compress before the amps clip doesn't mean that the speakers themselves aren't being subjected to more than they would like. Also compression doesn't stop peak levels being reached it just squashes them beyond the preset limit. A limiter holds the levels below providing protection. (Of a sort)

 

Dom

[aidso]

I would say limiter in line. what you have to remember is that most DJ gear has a far higher output level than PA mixers. Also check your EQ. make sure you dont have the low end boosted.

[Shez]

the high/low limiters come in before the amps clip.

 

How about setting the limiters to come in before the speakers exceed their maximum level, rather than the amp. Assuming that the amp is specced sensibly, this will be below the amp's clip point in any case. Set it a couple of dB below that point if DJs are using the system as the crest factor of their music is far lower than live music.

 

A concurrent post has been automatically merged from this point on.

 

I would say limiter in line. what you have to remember is that most DJ gear has a far higher output level than PA mixers.

 

That's not been my experience - decent PA desks can manage up to about +28dBu; I don't think I've ever come across a DJ mixer that can manage that. The problem is often the DJs themselves - they push the desk far harder than it should be driven, so the signal that comes out is frequently clipped. Those mixers rarely have enough headroom to cope with all the gains & all the EQs being turned up to 11...

[Stuart91]

At the risk of asking the obvious, do you have the sense lines connected from the amp outputs back to the controller?

[tolley1466]

Surly there is a limiter built into the Driverack?

[csg]

This problem is a bit of a supprise to me - as an experienced nexo user who runs ps, msi, si and ls systems, ive never, never blown a driver or diaphram

These rigs spend most of their time in nightclubs / dance tents at festivals etc and get driven very hard for extended periods of time with very nasty music. The protection afforded by the processor should mean that it is impossible to blow anything providing that the input signal to the TD controller is clean and the amplifiers are fault free

 

so, at the risk of stating the obvious:

1) The sense lines are connected with correct polarity

2) The controller connects directly to the amplifier inputs, with all other processing before the td controller in the signal chain

3) The amplifer power is within the range recommended by nexo

4) All the equipment in the signal chain prior to the td controller is run underneath its clip point

 

It should also be noted that Nexo recommend that amplidier clip limiters are turned off as they can confuse the td protection circuits. No other limiting should be needed for system protection, so other limiters should only be used for volume restriction, and even then, such limiters should be placed prior ot the TD controller in the signal chain.

 

If all the above are true, then im at a bit of a loss, and would recommend having the TD controller looked at by Fuzion as it doesent seem to be performing its duties correctly.

[Shez]

Surly there is a limiter built into the Driverack?

 

There is indeed one in the driverack PA, but on the one occasion that I was unfortunate enough to have to use one of those, the limiters didn't seem to make a blind bit of difference. I'm used to the DR 260 where they definately work.

As with all limiters though, if they're not set up appropriately for that combination of amp & speakers, they're of no use whatsoever.

[alex_kyuss]

I would have a good look at the drive rack because at my old company we had a drive rack that broke 2 comp drivers on different days and with 2 different engineers. we found that the left channel high out put would square wave but it wasn't constant it was very random.

[smalljoshua]

That is a well documented problem on here. That. and the fact the DRPA does the same as a DCX2496 but for more money, is why they aren't recommended on here.

 

It may be worth replacing the DRPA just as a precaution.

 

Josh