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[John Roll]

I work in a club that shares its PA system between live bands and DJs. Since the DJs have been around, I've been replacing drivers, especially, the horns on a regular basis, despite setting limiters. The cabinets are old EV SH1810-ERs. The components which get taken out on a regular basis are the horns (DH-3). The owner has asked me to look into a solution. My solution is NOT to have DJs, but they make money for him, more so than the live stuff, so it's unlikely that my suggestion will be taken seriously. I was asked how other clubs do it. Are they replacing things as much or would newer cabs be more tolerant of DJ material? I've considered adding some tops somehow dedicated to the live stuff only, but since I would end up replacing the drivers in the old stuff anyway, that isn't an option. Can the horns be replaced with more durable, more forgiving components? My worry is that anything new I might suggest (Cabs or components)will meet the same fate, plus the drivers will cost more to replace/recone. I'm totally at a loss as to how to remedy this situation and make everybody happy. All suggestions welcome at this point.

John

[Phil LaDue]

I'm a bit curious as to how you have the limiters set up.
I wouldn't put it past some people to disable a limiter "to make the show better".

[Dick Rees]

John Roll wrote on Sun, 30 December 2007 16:23

I work in a club that shares its PA system between live bands and DJs. Since the DJs have been around, I've been replacing drivers, especially, the horns on a regular basis, despite setting limiters. The cabinets are old EV SH1810-ERs. The components which get taken out on a regular basis are the horns (DH-3). The owner has asked me to look into a solution. My solution is NOT to have DJs, but they make money for him, more so than the live stuff, so it's unlikely that my suggestion will be taken seriously. I was asked how other clubs do it. Are they replacing things as much or would newer cabs be more tolerant of DJ material? I've considered adding some tops somehow dedicated to the live stuff only, but since I would end up replacing the drivers in the old stuff anyway, that isn't an option. Can the horns be replaced with more durable, more forgiving components? My worry is that anything new I might suggest (Cabs or components)will meet the same fate, plus the drivers will cost more to replace/recone. I'm totally at a loss as to how to remedy this situation and make everybody happy. All suggestions welcome at this point. John

OK.  You need to find out what exactly is causing the driver failures.  Overdriving.....clipping (and if so clipping what/where)  Maybe your speaker repair guy can help.  

You might try charging the DJ's for any system damage.  Talk to the owner and see if he'll go for a policy of charging users for damage.  But try to find out what's causing the problem first.

[Dick Rees]

What amp(s) are you pushing these with?  A more detailed description of your entire signal path would be helpful.  How far are the amps from the speakers?  What gauge speaker cable and how long?

If you're running multi-amped, where are your X-over point?

[John Roll]

They can't get to the limiters in the Driverack. It's behind a security barrier. I used the procedure in the Driverack PA manual to set them. I don't have a better way to do it.

[John Roll]

Quote:

What amp(s) are you pushing these with? A more detailed description of your entire signal path would be helpful. How far are the amps from the speakers? What gauge speaker cable and how long?

?

The tops are being driven by a Crest CA12 @8ohms per side.

The path is GL2400>DBX1231>Driverack PA>Crest>cab

The amp rack is no more than 3ft from the stack with the repeated driver failures.

Not sure about gauge wire. It looks like 14 gauge,but don't quote me. The run looks to be about 10-15ft.

The problems started when the DJs arrived. I have never blown a driver in that system in t my 3+ years there doing live shows. My theory is that even though the overall level isn't enough to clip the amp, when they crank their EQs to get more highs and lows, it sending a clipped distorted signal to those drivers. Eventually they give up.

[Dick Rees]

That seems a reasonable evaluation..  Your cables should be fine in such a short run.  My guess would be that they're cranking the hi's on the channel strip (and everything else, probably).

As to the amp:  I think what may be happening is that you have a 1:1 relationship, ampW to speakerW and are running out of power.  When the lows hit hard, the top starves out and may be suffering from lack of power rather than too much.  I'm no expert on this, so you should get a second opinion, but I think something with more like 1200W/channel into 8 ohms would give you the headroom you need.  The amp may well be clipping.  You could eyeball it during a show.

Edit:

You can keep running full range with a larger amp or keep the one you have to run the lows and get another for the hi's.  You've already got your cross-over in the DriveRack.

[John Roll]

Sorry,I should've been more specific. The lows have their own amps, QSC3402 and are not in the loop as far as the tops go. I cross the them over at 200hz. The tops are 3way passive; 18-10-1.It was suggested I replace the DH3s with higher wattage horns, but if the DJs are distorting the highs, then the higher wattage won't matter, or will it be more forgiving?

John

[Andy Peters]

John Roll wrote on Sun, 30 December 2007 15:23

I work in a club that shares its PA system between live bands and DJs. Since the DJs have been around, I've been replacing drivers, especially, the horns on a regular basis, despite setting limiters.

You say you've "set limiters" but you don't say how.

Despite what most people believe, a limiter will not save your drivers, especially if it is not set properly. In fact, a limiter can actually increase the power dissipated by the driver.

How are the limiters set? Threshold, attack time, release time, etc.?

-a

[John Roll]

The limiters in the DriverackPA don't have any way to vary those parameters. Although, I've never thought to look beyond what was presented in those screens. There's a basic method in the manual regarding setting system gain structure and limiters. I used that because there was no other means at my disposal. Andy, do you agree with my theory about why the horns are being destroyed? I recall a thread over in the Lounge, though, where you replied something about running a square wave through a driver all day at low power and not destroying anything. Would adding current limiting to the horn circuit help? My opinion is that the distortion generated at the DJ's mixer,when they crank up the eqs (highs and lows)destroy the horns even though the amp is not clipping. If I had my way, there'd be no DJs through the system, but I don't have that option