Yup, the problem is that a cab's "program power" rating is usually meaningless and usually just 2x its "rms or continuous power" rating - which is too much for long life on subs in particular. QSC is in the business of selling you bigger amps for more money, they don't really give a damn if you burn your shit up.
Re-read my post about overexcursion.
guitarman3001 wrote:
Re: "continuous power rating", isn't it very uncommon to run an amp or speaker at its sustained "rms" rating for a long period of time? Even a loud concert is a series of peaks and valleys volumewise and is not a consistent sustained continuous tone. If what you're running through the subs is primarily the frequencies coming from the kick drum, which is a very short attack, wouldn't you be more concerned with the peaks than with "continuous" power? Or am I looking at this wrong too?
guitarman3001 wrote:
Re: "continuous power rating", isn't it very uncommon to run an amp or speaker at its sustained "rms" rating for a long period of time? Even a loud concert is a series of peaks and valleys volumewise and is not a consistent sustained continuous tone. If what you're running through the subs is primarily the frequencies coming from the kick drum, which is a very short attack, wouldn't
You are simply delivering energy (power). You are always delivering peak and avarage at the same time. Those terms just denote the way you are looking at it. For example if you were using pink noise as a source and delivering continuous power "X" you would likely be also delivering somewhere between 50 and 200 peaks of "4X" every second. Typically your power amps will hit their internal limiters when you are putting out only 1/10th to 1/3rd of the rated continuous power. From this point you can't develop any more power. That's why manufacturer's have a program rating for speakers. Remember that continuous rating for a speaker is at least a 2 solid hour rating. That's a long song 
In big general terms peaks are not as damaging to speakers when they are above the tuning of the box. It all depends.
Again I'd recommend trying adding a comp/limiter to your kick channel and you will hear it get louder with no additional power.
dboomer wrote:
guitarman3001 wrote:
Re: "continuous power rating", isn't it very uncommon to run an amp or speaker at its sustained "rms" rating for a long period of time? Even a loud concert is a series of peaks and valleys volumewise and is not a consistent sustained continuous tone. If what you're running through the subs is primarily the frequencies coming from the kick drum, which is a very short attack, wouldn't
You are simply delivering energy (power). You are always delivering peak and avarage at the same time. Those terms just denote the way you are looking at it. For example if you were using pink noise as a source and delivering continuous power "X" you would likely be also delivering somewhere between 50 and 200 peaks of "4X" every second. Typically your power amps will hit their internal limiters when you are putting out only 1/10th to 1/3rd of the rated continuous power. From this point you can't develop any more power. That's why manufacturer's have a program rating for speakers. Remember that continuous rating for a speaker is at least a 2 solid hour rating. That's a long song
In big general terms peaks are not as damaging to speakers when they are above the tuning of the box. It all depends.
Again I'd recommend trying adding a comp/limiter to your kick channel and you will hear it get louder with no additional power.
Hrmm...I don't know anything at all about limiters. I understand the basics of compression when used on vocals but I'm not sure I understand how limiters work and precisely how they'd protect my speakers from being overloaded. Basically I don't know squat about limiters.
If it were me I'd sell those mismatch pair of entry level subs off and go with pair of Yorkville LS808 since the GX7 would match up perfect and out perform the entry level stuff by a 2 to 1 margin.
Plus if you get low end feedback with that amp it would be a matter of a seconds before you'd see a puff of smoke bellowing out of them.
If funds are low might look in the used market since a lot folks are dumping their older higher end PA gear to update to newer gear.
Well, I might be the only one here that's run cheap crap like that sucessfully so I'll describe a similar rig I've run:
- DBX 223 crossover with the 40 Hz HPF engaged.
- GX5 sub amp
- Pair of PV118 subs
To get any punch out of them the amp is run wide open and the low out knob on the crossover at +6db. I run the master of the mixer up as far as needed - sometimes as much as 3-6db past where the sub amp limit lights start flashing. You'll hear the subs start to sound compressed and not get louder past that. That's all those subs are good for - more power will just tear them up. DO NOT turn things up to the point where the bass guitar lights up the limit lights - they should only flash on the kicks! Beware of the kick mic feeding back - that can smoke those subs no prob. I usually use a gate on the kick mic to help with the low frequency feedback.
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