Landl.livesound wrote:
The reason I used "should" is because it is almost impossible to guarantee that you will never destroy a driver. There is always the chance you will get a nice long blast of LF feedback that last for several seconds that will take out a driver, but as long as you have some crest factor you are fine.
Not if the voltage limiter is set up properly to ensure that that much voltage never reaches the driver. Voltage is an absolute. If you limit to X Volts, and you're well into your limiter trying to get more volume, you don't have enough rig.
Just realize that for you to make it *almost* entirely foolproof is to set a limiter for less than 1/2 the thermal value of your driver which can cut down a lot on performance.
Yup. That's when you add cabs.
-Have enough rig for the gig so you don't have to worry about even getting close to the limits of your rig
-The best thing is to know the limits of your rig, and if you use it enough you will know when you are running out of gas without seeing the clip lights.
Horns don't sound like they're running out of gas.
I would never expect everyone to be able to position there amp rack so they can see it from FOH, but surprisingly I always seem to be able to position the Amp rack where I can see it from FOH.
Clipping amps sound bad, and near-clipping amps sound bad. In portable land sometimes you can position an amp rack so you can see it, but that's an almost-never in install land, and sometimes you're too far away to be able to see it anyway.
If I was using a brickwall limiter I would put it somewhere way out of the way (At least 2x-3x the continuous rating of the driver.) And since most people won't use an amp larger than 2x the continuous rating of the amp you will be into super hard clipping in the amp before the limiter even kicks on.
And that would be the wrong way to deploy a brickwall limiter. Again, these limiters are there to protect the drivers, and they're not supposed to sound good. If you're hitting the limiter, you need to turn down, or add cabs.
Much of this comes from just my basic trying them on systems.
Learning the math goes a long way. Reading is beneficial too.
For example, the PL380 I use on subs puts out up to 1500 watts. The driver it is powering has no problem taking much more than 1500 watt kick hits. The crest factor on my low end stays around 10dB. So when that PL380 starts to clip the average power is in the 150-250 watt range which is way under the continuous rating of the driver, so I am in no way close to burning out the VC. (Even if the crest factor goes down to 6dB the driver will only get around 400 watts which is still much less than the continuous rating.
If your nice 1500 watt amp hits 1500 watts, then you're in distortion territory, not to mention way into the power compression range of the driver. Bad news all the way around. Again, bigger amps also help with heat, longevity, and distortion. Clipping an amp may not damage a speaker, but it sure doesn't sound any better than going into a limiter, and then you're in an uncontrolled environment. The system will sound better overall with an amp that is not clipping, or anywhere close to it.
I have tried out basic peak limiters just to see what they do, like the ones included on the DCX2496, BBE DS24, DR PA and they just sound really bad when you when even not that far into them. So I just said to get the darn things out of the way.
3rd time, limiters aren't to be hit, they're to be protection. If you're hitting the limiter, not enough rig.
*Now, what I wouldn't mind employing is a limiter with a very slow attack and release, like the thermal limiters in the iTech amps. I considered switching my rack from QSC to iTech just for this reason but decided against it so far. Maybe when the iTech HD's start hitting the used market for cheaper like the last iTech's are now doing.
Actually for protection I would much rather take a limiter like the one I described above since the amps most of us are using won't get close to the mechanical limits of the drivers. What I would want it to do would be to protect against the random long feedback, or LF keyboard/synth lines. Something like if X voltage is crossed for more than 3 seconds it will turn it down X dB/second. This then will let the peaks go through so as not to take away from the dynamics and lower the crest factor at the same time.
Not necessary if the system is deployed properly. Nifty, but not necessary. A far better way is to mix with tasteful compression and deploy the rig with proper lmiting. The compression will control the dynamics in a way that doesn't sound like the whole system getting turned down, and the overall mix comes together better. I'm spoiled with SAC though, because its compressors are completely transparent, as is the Levelizer plug, which allows for brickwall limiting without flat-topping the signal. I have a feed going into a nursery that smashes against a brick wall about 95% of the time to keep the volume very stable (sleeping babies and all) and it's perfectly listenable. You'd never know it was hitting a brickwall except for the fact that the volume is very constant.
Hope this makes some sense. Again nothing is foolproof, unless you take away a good amount of performance from the cabinet. But again the biggest protection is enough rig for the gig.
Not really. Do you redline your car? Most people don't. This is Tim Allen syndrome - more power does not fix problems. Doubling cab count is far more effective than doubling power.
Having enough rig is not protection, it's smart business sense. Knowing what gigs to take and not to take based on your rig is smart business sense. Knowing when to stop (turn down) is also smart business sense, as your investment is protected and so is your paycheck, and your customer base.
And don't worry this isn't some Banjo Center voodoo magic matching amps to speakers stuff. This is about that the music we put through is usually not sine waves.
Sine waves are horrible on the ears, great for calibration. If one is to get the most out of a system, one had better be calibrating that system with math and science, not "This amp is this much and this driver can handle about this much so we'll probably be OK." At that point, you are relying on marketing specs and figurin'. That's just as much voodoo as the knowledge cheerfully dispensed by the salesman at *pick your music emporium*. I'll take my multimeter and calculator any day of the week.
). It's what they teach the Guitard Center and Sam Rash people too. It's bad advice based on what looks right, kind of like trap arrays.