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Author Topic: Why is all active speakers underpowered???  (Read 2989 times)

John Roberts {JR}

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Re: Why is all active speakers underpowered???
« Reply #20 on: December 26, 2013, 11:53:09 am »

I don't like powered speakers for a number of reasons John, but that's another discussion.
After 15 years at Peavey and getting to know several excellent loudspeaker and amp designers (and many consumers). i really like the opportunity to have that decision made by people who understand more about the drivers and amps than simple rules of thumb.

The potential today with cheap DSP and Class D amps, makes the potential for even higher performance and reliability available. I know more than average about the technology and know that I can't do a better job than these engineers that do it for a living.
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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.
Rather than good design or bad, I suspect this comes down to expensive vs cheap boxes  designed to meet a lower price point using cheaper components and construction methods. That said even with sharp pencil design I suspect powered cabinets to spank non-powered systems all else equal because of the design engineer involvement.

JR
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Greg Rosic

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Re: Why is all active speakers underpowered???
« Reply #21 on: December 26, 2013, 12:19:05 pm »

I'm confused, I though amps gave RMS rating not peak power ratings. When I read the specs it says RMS or sometimes continuous. For example the QSC powered speakers say 1000W continous. I thought it was only car amplifiers which boasted their max transient output.
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Tim McCulloch

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Re: Why is all active speakers underpowered???
« Reply #22 on: December 26, 2013, 12:33:16 pm »

I'm confused, I though amps gave RMS rating not peak power ratings. When I read the specs it says RMS or sometimes continuous. For example the QSC powered speakers say 1000W continous. I thought it was only car amplifiers which boasted their max transient output.

Back in the Ye Olde Dayz, there was this thing called "dynamic headroom".  It was the ability to squeeze the last bit of current from the PSU filter caps and apply it to the output transistors.  How much more you could get for a few milliseconds (before you ran out of either current or output stage gain) varied from around 1.0dB or so to as little as zero.

These days, there is almost no such thing due to value engineering.
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Paul G. OBrien

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Re: Why is all active speakers underpowered???
« Reply #23 on: December 26, 2013, 12:39:02 pm »

I'm confused, I though amps gave RMS rating not peak power ratings. I thought it was only car amplifiers which boasted their max transient output.

Times have changed and amp designs have changed with it. IMO the "RMS" amplifier design was never a very efficient use of resources as music was always a much more dynamic signal than a pure sinewave. But it's also ironic that while current amplifier designs have moved towards a more dynamic output with less constant current capacity popular music recordings are more compressed than ever before and there are now music types with sustained synth notes that require an amplifier be capable of sustaining high currents and voltages. So maybe we will see the market segmenting into two types with heavy iron sub amps built like they were in the old days and lightweight digital amps for everything else.
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John Roberts {JR}

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Re: Why is all active speakers underpowered???
« Reply #24 on: December 26, 2013, 01:06:38 pm »

Back in the Ye Olde Dayz, there was this thing called "dynamic headroom".  It was the ability to squeeze the last bit of current from the PSU filter caps and apply it to the output transistors.  How much more you could get for a few milliseconds (before you ran out of either current or output stage gain) varied from around 1.0dB or so to as little as zero.

These days, there is almost no such thing due to value engineering.

Not to confuse the OP even more, back in the '70s there was consideration (by the IHF IIRC) of a dynamic headroom spec, mostly in the context of reproducing wide dynamic range classical music (Like 1812 overture with cannon or mortar explosions). This was before the trick amp topologies like Class G/H were popular so peak vs continuos sine wave power was mostly a matter of transformer/power supply "regulation" ( regulation means how much the voltage sags under continuous current vs. no load voltage due to winding resistance) and power supply reservoir cap sizing that affects ripple voltage and clipping under power. The FTC even got involved with voltage sag after the transformer gets hot (temperature coefficient of copper wire increases resistance with increased temp causing more internal losses) adding a thermal preconditioning step before measuring rated output power.

These metrics like dynamic headroom and overly dynamic recordings did not gain much currency with consumers so faded away. FWIW modern amps with PFC and regulated supplies will not suffer regulation or temperature sag while a smart amp may reduce voltage in response to difficult local conditions.

Back in the late '80s I designed a small bedroom studio monitor amp for Peavey (AMR) that was a nominal 35W amp, but was capable of 2x the voltage output transiently, so 4x the peak output power... In practice that 4x power deteriorated quickly, so i specified it as something like 100W for X mSec, 60W for 15 seconds (limited on purpose to not overheat the amp), then 35W for 24x7.   This was a kick-ass little amp, but the technology did not scale up to higher power points cost effectively, so that was the first and last model in that series.

This is an interesting (perhaps) diversion, but loudspeaker design and mating with appropriate amplification involves multiple variables beyond this simple discussion.

   JR
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dick rees

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Re: Why is all active speakers underpowered???
« Reply #25 on: December 26, 2013, 01:27:21 pm »

Regarding your thread topic:

They isn't...
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Tim McCulloch

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Re: Why is all active speakers underpowered???
« Reply #26 on: December 26, 2013, 01:51:45 pm »


This is an interesting (perhaps) diversion, but loudspeaker design and mating with appropriate amplification involves multiple variables beyond this simple discussion.

   JR

"The truth is rarely pure and never simple.  Life would be tedious if it were either, and modern audio systems a complete impossibility."  - Oscar "not a sound guy" Wilde, with topical satire
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Steve M Smith

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Re: Why is all active speakers underpowered???
« Reply #27 on: December 26, 2013, 02:40:45 pm »

Regarding your thread topic:

They isn't...

He means them's not.


Steve.
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Tom Roche

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Re: Why is all active speakers underpowered???
« Reply #28 on: December 26, 2013, 03:58:18 pm »

Regarding your thread topic:

They isn't...
Ha!  ;D   An alternative answer is "it aren't."
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Tim Perry

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Re: Why is all active speakers underpowered???
« Reply #29 on: December 26, 2013, 09:23:53 pm »

 Danijel Foler, please excuse these guys. They probably don't realize you are in Croatia.

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