Blowing up Event RCFs, how do not?

Lisa Lane-Collins

Lisa Lane-Collins

Sophomore
Dec 9, 2012
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Adelaide, Australia
Well, very likely over-excursed (I haven't had a chance to inspect them yet but they make sounds no longer and the same speaker cable run drives the one survivor fine so the sub is the break in the signal chain).

The set up is two in series running off of a single channel of a Crown Macrotech 3600. That's a collective 1200w RMS being delivered 1565w (Is this actually a bit underpowered?), which is a step up from what was driving them previously (single amp, single channel of a Yamaha P7000S, about 700W). Using a DBX Driverack to limit at around unity (0), gain structure on venue mixer was good, although the master was past unity. And I noticed the DJs were maxing out their console.

Wondering how/why they blew and how to better protect them?

 
The best way to protect the rig is to make sure that the rig is adequately sized for the expected use. Barring that, there are a few other things you can do.

Adjusting the limiter settings can improve the protection if the failures are thermal in nature (burned voice coils, cones don't move). Setting the long-term limiter to 3dB below the RMS power of the speakers will protect against whatever abuses may happen upstream, at the expense of output. And make sure that the limter is the *last* thing in the signal chain before the amplifiers.

If the failures are excursion-related (torn cones or surrounds, broken voice coil wires), you'll need to make sure that your HPF is set above the box tuning frequency, and is sufficiently steep. The manufacturer-supplied settings should meet these requirements.

What gain structure exists prior to your system shouldn't matter if your system is configured properly, and while DJs have a bad reputation, there are plenty of band engineers that have blown up rigs as well.
 
I pretty much set a cut around 40hz on all my subs if Im not there to babysit. You might be missing some of the low end content but it really helps with the driver over excursion. If they are using vinyl the low end rumble from tracking can make the low end flap around quite a bit. The 40hz hpf cleans that up nicely.
I do have a couple of guys I work with that seem to just slam it. Im not sure what for sometimes as its often way overkill for the crowd.
 
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