Ideal QSC PLX amp for Ampeg SVT-410HLF?

[AlexanderB]

I am curious about what would be the ideal QSC PLX amp (current series) for powering Ampeg SVT-410HLF.
For PA usage it is more or less standard to use amps about 1.5 times the continuous power rating of the speaker.
However, people seem to be more conservative for bass rigs, especially with this Ampeg since it is not as forgiving to over powering as some other designs.

Right now I run a SVT-410HLF from one channel of an PLX 3602. (Why that powerful amp? I just took one of the 3602s from my PA and put it in my bass rig. )
Great sound and performance but I am constantly worried to damage the woofers.

Please do not suggest to add another cab! I actually have a second, identical box but I do not need more volume. I just need less headroom...
I am also not interested in other brands since I already own some QSC amps and I really like them.

[runmikeyrun]

I have a QSC RMX 2450. It may seem like overkill, but real world i'm only getting about 500w/channel at 8 ohms and 700w/channel at 4 ohms. Remember you don't HAVE to crank it all the way up. Use good judgement. Also it's better to underdrive a SS amp than overdrive it- that's where you'll blow speakers. If you're really worried get a compressor/limiter. You may get a higher power rated cab later and need the extra juice, this way you don't have to buy a bigger amp too.

[lowphatbass]

I use a 3102 to power various cabs, sometimes a single cab rated as low as 250w. I personally don't see any problem going big on power amps, although others may not concure. I've used one channel to power mains or monitors in emergency situations, not a common occurance but certainly handy.

[Gearhead17]

Don't waste your money on something smaller. Just listen to the speakers for signs of distress and you should be alright. Is there a low frequency filter on that model? Set it on the 30hz setting if so and sleep a little better tonight.

[Bob Lee (QSC)]

Originally Posted by runmikeyrun

Also it's better to underdrive a SS amp than overdrive it

Since "underdrive" and "overdrive" don't have agreed-upon definitions, it's best to omit advice that uses those words.

[Bob Lee (QSC)]

Originally Posted by AlexanderB

I am curious about what would be the ideal QSC PLX amp (current series) for powering Ampeg SVT-410HLF.
For PA usage it is more or less standard to use amps about 1.5 times the continuous power rating of the speaker.
However, people seem to be more conservative for bass rigs, especially with this Ampeg since it is not as forgiving to over powering as some other designs.

Right now I run a SVT-410HLF from one channel of an PLX 3602. (Why that powerful amp? I just took one of the 3602s from my PA and put it in my bass rig. )
Great sound and performance but I am constantly worried to damage the woofers.

Please do not suggest to add another cab! I actually have a second, identical box but I do not need more volume. I just need less headroom...
I am also not interested in other brands since I already own some QSC amps and I really like them.

How much power are you looking for and into what impedance?

[JimmyM]

410hlf is 4 ohms, and handles 500w...an honest real world 500w, not an inflated thermal 500w. It also goes super low.

[Bob Lee (QSC)]

So that's 500 watts continuous average (i.e., thermal)?

[AlexanderB]

Yes, Bob. (Btw, Your support is much appreciated!) Ampeg refer to it as "RMS" so it is not "peak".
The cabinet is designed to go deep and loud with the right amp, just like Jimmy says.

[JimmyM]

Originally Posted by Bob Lee (QSC)

So that's 500 watts continuous average (i.e., thermal)?

Not thermal. Displacement limited. Couldn't think of the word Bill FM uses before, but that's it.

[Bob Lee (QSC)]

That would depend on frequency, then, and would be better expressed in terms of voltage.

[AlexanderB]

Thanks Jimmy. I guess one could say it is both thermally and excursion limited to 500 watts. If you exceed that level you risk over excursion in the lowest notes while a long term power in excess of 500 will risk to over heat the voice coils.

[JimmyM]

I don't think he's all that concerned about it, Bob. I think he just wants to know which amp you make would optimally best suit it withough danger of blowing it up. My answer would be that any of them would work as long you're careful with the volume knob.

Also, Alexander, that cab is a lot more forgiving to overpowering than you think. As I said before, the 500w of power handling Ampeg gives it is based on displacement, not when the voice coils burn up. So if you hear it distorting, you have more leeway than you think not to blow it up, and of course, turning your amp down below that point will fix it. If it was rated according to when the voice coils burn up, it would actually be closer to the 800-1000w range.

EDIT: Just looked it up. Its peak power handling (thermal) is 1000w.

[Bob Lee (QSC)]

So does that mean you want nothing significantly more than 500 watts into 4 ohms?

[Bob Lee (QSC)]

Jimmy, at what frequency would 500 watts cause displacement concerns?

[JimmyM]

Originally Posted by Bob Lee (QSC)

Jimmy, at what frequency would 500 watts cause displacement concerns?

Bob, got to admit that I haven't got that far in the class but I imagine the low lows are the most susceptible to it All I know is that Bill uses the term "displacement limited power handling" in rather general terms on here, more as a overall ballpark of what cabs handle in the real world based on their woofers' xmax, tuning and cone area. Ampeg is one of the very few who quotes both thermal and displacement limited. They call it peak and RMS, but same thing.

I still say any amp will work as long as you exercise common sense.

[projectMalamute]

Originally Posted by JimmyM

Bob, got to admit that I haven't got that far in the class but I imagine the low lows are the most susceptible to it All I know is that Bill uses the term "displacement limited power handling" in rather general terms on here, more as a overall ballpark of what cabs handle in the real world based on their woofers' xmax, tuning and cone area. Ampeg is one of the very few who quotes both thermal and displacement limited. They call it peak and RMS, but same thing.

I still say any amp will work as long as you exercise common sense.

On what basis do you conclude that the 'peak' and 'RMS' figures correspond to thermal and displacement limited power handling figures?

[greenboy]

Hey Jimmy,

Mechanical/xmax/dispacement-limited figures and thermal figures aren't the same as continous and program or peak figures. Mechanical is based on the driver in a specific enclosure alignment (tuning and internal space) swept sine as signal.

450-500 watts is a good figure for those drivers at a likely tuning in that enclosure size. You can bring more but at that point the thermal compression is likely to not let much more SPL result anyway.

[JimmyM]

Hmmm, did I get busted for extrapolating? Well I did mention that I hadn't got that far in class But since the numbers quoted fall in line with reality, I figured they were interchangeable. Here have been my definitions for them up until now:

Continuous: marketing term
Program: marketing term
Peak: marketing term that should mean when they fry voice coils, but often doesn't
RMS: marketing term that should mean displacement limited handling, but often doesn't

Guess I better hop on over to eminence.com and bone up. Hey, you guys are good!

[Bob Lee (QSC)]

"RMS" power is the misnomer for "continuous average" power, which is the thermal rating.