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Author Topic: Why is all active speakers underpowered???  (Read 20267 times)

Samuel Rees

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Re: Why is all active speakers underpowered???
« Reply #10 on: December 25, 2013, 09:17:03 PM »

What products is the OP even talking about? How often do we know the drivers and their ratings in powered speakers?
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Scott Bolt

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Re: Why is all active speakers underpowered???
« Reply #11 on: December 25, 2013, 10:28:25 PM »

The problem is that if a loudspeaker is rated for max of 130dB, then people expect to play music and put an SPL meter in front of it and read 130dB.

This sounds like a good idea-but 130dB is the peak.  If you say that "average" music has a 10dB crest factor (most has more than that) then the typical meter (that has a slow response time (even though it say "fast" will read around 120dB.    So they keep pushing it trying to get to the "rated" 130dB.  Higher dynamic range material would produce lower average readings.

With a meter that can actually respond to the peaks-they would read the rated 130dB peaks.

Things are not always as simple as people would like them to be.

+1,

Also, even if the speaker does make the continuous SPL rating listed, there is nothing that says it sounds good at that SPL.

IME, the big difference between less expensive speakers, and more pro level gear is that the more pro level gear sounds good all the way up to where it clips (and even then in most cases).

Less expensive boxes tend to sound good at lower volumes, but not so much when they are forced to get really loud.

.... and all that assumes that the SPL readings are actually done the same way.

To answer the OP's question.... active speakers are very likely powered perfectly for the amp and driver installed.  If anything, the amps installed are much bigger than they need to be (especially for the HF driver) and are digitally limited.  The larger amps are only used because it is less expensive to use the exact same amp for HF and LF on all their speaker lines.
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John Roberts {JR}

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Re: Why is all active speakers underpowered???
« Reply #12 on: December 25, 2013, 10:48:04 PM »




 If anything, the amps installed are much bigger than they need to be (especially for the HF driver) and are digitally limited.  The larger amps are only used because it is less expensive to use the exact same amp for HF and LF on all their speaker lines.

I wouldn't bet big money on that. powered speaker designers can use higher impedance drivers for high-mid and low impedance drivers for LF, so same voltage power amp makes more appropriate power for the passbands.

Talking about power in the context of loudspeakers is just a convenient hook that consumers think they understand.

JR
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Greg Rosic

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Re: Why is all active speakers underpowered???
« Reply #13 on: December 25, 2013, 11:52:38 PM »

hello
Manufacturers of the PA speakers in most cases spec amp to have 2x RMS speaker rating. So, if speaker have 500W amp need to have 1000W. I can confirm that this formula work fantastic and no speaker and amp ever overheating or work with clipping. In this way amp and spekaer work with 50% load. Even for bass you can use 4x RMS rating because peaks. But, 99% active speakers have amps 0.5-1x RMS rating. Why is that??? How large 1kw 18" driver can be driven with 500w-1000w amp? Cant be.
It's my understanding that an amp rated at 500 w RMS can put out more than that for short periods of time without clipping, and thus matches the speaker specs perfectly. In my mind the only reason for an amp 2xrms of speaker, is to make sure that it doesn't clip at maximum volume. I generally see amplifier manufacturers claim that a speaker needs an amplifier with 2-4xrms (wonder why? more sales). Where as a lot of speaker manufacturers say the amp can match rms. I'm sure that a powered speaker is about perfectly matched with it's amp. One thing I don't understand is for example the QSC K series, the amplifier supplies up to 500 watts to the woofer, and up to 500 watts to the horn. This seems like overkill for the horn, as I've never seen one that can handle that much power. And if it could it would be so much louder than the woofer...
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Tim Perry

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Re: Why is all active speakers underpowered???
« Reply #14 on: December 26, 2013, 01:42:22 AM »

It's my understanding that an amp rated at 500 w RMS can put out more than that for short periods of time without clipping, and thus matches the speaker specs perfectly.

not likely

Quote
In my mind the only reason for an amp 2xrms of speaker, is to make sure that it doesn't clip at maximum volume. I generally see amplifier manufacturers claim that a speaker needs an amplifier with 2-4xrms (wonder why? more sales). Where as a lot of speaker manufacturers say the amp can match rms. I'm sure that a powered speaker is about perfectly matched with it's amp. One thing I don't understand is for example the QSC K series, the amplifier supplies up to 500 watts to the woofer, and up to 500 watts to the horn. This seems like overkill for the horn, as I've never seen one that can handle that much power. And if it could it would be so much louder than the woofer...

Think about it: a speaker with two (presumably identical) 500W amplifiers (into 2 ohms)

woofer: 2 ohms

tweeter (horn)  8 ohms

net result: marketing voodoo
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Bob Leonard

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Re: Why is all active speakers underpowered???
« Reply #15 on: December 26, 2013, 01:56:01 AM »

And that's why you eliminate all the bullshit by 1) choosing a quality, known and respected brand of your choice, and then 2) listening to the cabinet under real life conditions before you buy it.

I've never placed much importance on numbers that relate to SPL unless I was looking at them myself. What concerns me more is the right cabinet doing the job I want it to do. don't care about anything else. If I size my amps in relation to the boxes I'm powering and they do the job without being damaged, then I'm happy, and the customer is happy. In the end I don't get paid to design and engineer the cabinet. I get paid to make it sound good. 
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Ivan Beaver

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Re: Why is all active speakers underpowered???
« Reply #16 on: December 26, 2013, 08:48:59 AM »

It's my understanding that an amp rated at 500 w RMS can put out more than that for short periods of time without clipping, and thus matches the speaker specs perfectly.
In the old days-when amps were measured using continuous sine waves- you could get "a tad" bit more power when measuring a short pulse.

But with todays amplifiers-(class D and others) they can only produce a short pulse-and that is the rating of the amplifier.

Why in the world would a manufacturer rate an amplifier for 500 watts when it can actually put out 1000 watts?  They would be shooting themselves in the foot.

I would argue that in most cases if an amplifier can deliver 500 watts-that is THE MOST it can do on a very short duration signal.  And depending on how things are "measured/calculated", 500 watts is probably VERY gracious.

I WOULD NOT expect or assume that the amp could produce any more power than that.

In most of todays amps the power the amp can produce continuously is around 6dB less than the peak power.  Yet you almost NEVER see the continuous rating-ONLY the peak rating.

And that will be my stance until somebody proves me wrong.
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Steve M Smith

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Re: Why is all active speakers underpowered???
« Reply #17 on: December 26, 2013, 09:20:09 AM »

Yet you almost NEVER see the continuous rating-ONLY the peak rating.

Because the sales department only want to see the highest number possible.


Steve.
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John Roberts {JR}

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Re: Why is all active speakers underpowered???
« Reply #18 on: December 26, 2013, 09:44:18 AM »


In most of todays amps the power the amp can produce continuously is around 6dB less than the peak power.  Yet you almost NEVER see the continuous rating-ONLY the peak rating.

And that will be my stance until somebody proves me wrong.

I have written about this before too... It cost more money "and" makes the amp a worse match for how speakers consume power to make amps full continuous power. For the last few decades amp makers backed off 24x7 power output because consumers were unwilling to pay for it, and spent their money buying reduced term output amps.

Now with class D efficiency the duty cycle calculus is a little different, but I prefer to leave amp/driver selection to the speaker engineers.  The market will work out what is a value or not.

"You can't fool all the people all the time."

JR
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Bob Leonard

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Re: Why is all active speakers underpowered???
« Reply #19 on: December 26, 2013, 11:02:42 AM »

I don't like powered speakers for a number of reasons John, but that's another discussion. Your last statement though is spot on and probably what I've been trying to say.

There are plenty of people being paid to design these boxes and I'll leave it up to them to match the components. If the design is good, then everyone's happy and the box sells. If the design is faulted then just like you said, it won't take long for the market to work it out.
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Re: Why is all active speakers underpowered???
« Reply #19 on: December 26, 2013, 11:02:42 AM »


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