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Author Topic: Power amp specs and ratings....  (Read 11721 times)

Ivan Beaver

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Re: Power amp specs and ratings....
« Reply #20 on: August 04, 2015, 07:35:29 am »

Serious question, with so many speaker manufacturers ALSO making amps, would you still recommend their "opinion" on amp selection? IE, should I use a QSC amp that is slightly under the "program" rating for their own speaker rather than a powersoft amp that provides plenty (based on their own mystery tests). 

While I'm on that subject, anyone compare some of the powersoft m series with the newer QSC PLD, CXD amps?


It has less to do with the brand and the power and more to do with exactly how YOU are using it.

For some styles of music that have a limited dynamic crest fact (low dynamic range), a smaller amp (and not let it clip) is better.

FOr music with a wider dynamic range, a larger amp will allow you to get more "life" and impact out of the loudspeaker.

There is no "correct" answer.  Only answer that vary depending on the situation.

Just like setting limiters.  Different situations require different setups-in order to get "the most" out of a system without blowing it up.

One size DOES NOT fit all.
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Keith Broughton

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Re: Power amp specs and ratings....
« Reply #21 on: August 04, 2015, 08:39:23 am »

Quote
my primary advice to buy powered speakers because actual design engineers have already made the difficult decisions for you
Or systems that are speaker and amp packages.
As stated, the "hard" decisions are made for you with the added benefit of having a better chance of vendor support in the case of problems with the equipment.

Someone mentioned HP ratings for cars and as someone who has done a bit of racing and custom tuning of engines, I can say that the HP ratings can also be skewed in favour of a particular outcome.

That said, it would be reasonable to expect a manufacturer could tell you how long a "burst" recovery would take.
Consider the Behringer 12000 amp at 6000w/ch into 2 on a 15A plug. REALLY!?!?!?!
12000 watts for how long and what is the restore time?



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TJ (Tom) Cornish

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Re: Power amp specs and ratings....
« Reply #22 on: August 04, 2015, 09:32:54 am »

Serious question, with so many speaker manufacturers ALSO making amps, would you still recommend their "opinion" on amp selection? IE, should I use a QSC amp that is slightly under the "program" rating for their own speaker rather than a powersoft amp that provides plenty (based on their own mystery tests). 

While I'm on that subject, anyone compare some of the powersoft m series with the newer QSC PLD, CXD amps?

This is the ultimate decision I'm deciding between.  Well, those or just going with the Ashly nXp which includes an amp (was already going with an Ashly Protea processor).
Ross, my original reply stands.  If the manufacturer recommends or requires a specific amp for their product, you should use it.  More amp power is not necessarily a good thing - that just gives you the potential to kill your drivers faster.

If the model of speaker you are using doesn't come with tuning and limiting data for a recommended amp system, then you have more flexibility to use 3rd party amps, but that probably indicates you are using either an old design speaker or a low end speaker, and if it were me, I would pick a different product to get the benefit of the manufacturer doing the heavy lifting on the programming.
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John Roberts {JR}

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Re: Power amp specs and ratings....
« Reply #23 on: August 04, 2015, 09:49:54 am »

Serious question, with so many speaker manufacturers ALSO making amps, would you still recommend their "opinion" on amp selection? IE, should I use a QSC amp that is slightly under the "program" rating for their own speaker rather than a powersoft amp that provides plenty (based on their own mystery tests). 
Pretty much yes always take the manufacturer's advice, except with the caveat that you are using official published recommendations (approved by engineering) and not what some janitor who answered the phone at work told you (or worse, a salesman).

Back decades ago when I was working at Peavey I asked the speaker design engineers to fill out a matrix of which Peavey amps to pair with which Peavey speakers. That was a last century thing, now I say just use a powered cabinet.

JR
Quote
While I'm on that subject, anyone compare some of the powersoft m series with the newer QSC PLD, CXD amps?

This is the ultimate decision I'm deciding between.  Well, those or just going with the Ashly nXp which includes an amp (was already going with an Ashly Protea processor).
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Art Welter

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Re: Power amp specs and ratings....
« Reply #24 on: August 04, 2015, 12:29:43 pm »

That said, it would be reasonable to expect a manufacturer could tell you how long a "burst" recovery would take.
Consider the Behringer 12000 amp at 6000w/ch into 2 on a 15A plug. REALLY!?!?!?!
12000 watts for how long and what is the restore time?
Keith,

Just before the last Christmas holidays I conducted a battery of tests on some old amplifiers and a new Behringer NU4-6000 four channel amplifier. To my surprise, the  NU4-6000 performed as well on low frequencies as on mid/high frequencies, and is capable of near full power sine wave output with all four channels driven to rated output at two ohms, or two bridged mono pairs driving four ohm loads each. The  $350 NU4-6000 appears to be within 3 dB of the $5500 Powersoft K10 rating on sustained (more than 1 second) output.

The NU4-6000 with two bridged mono pairs each driving four ohm loads just below the illumination of the clip/limit light each put out 85.5 volts at 60 Hz (1828 watts), 84.6 volts at 30 Hz (1789 watts), dropping the mains voltage on a 100' 10AWG 120V line from 118.1 volts down to 107.2 volts, drawing 31 amperes.

Using just one bridged mono pair, the amp ran for 40+ seconds before I terminated the test, as the amp was drawing 19.8 amperes, and the "tired" 20 amp mains breaker had popped several times in various tests already. The amp would have put out more power given a full 120 volts, but the test represents "real world" situation, we don't generally plug our amplifiers in to an outlet two feet from the mains transformer.

I also tested my old "heavy iron"  bass favorite, a Crest CA9, bridged into a 4 ohm load it dropped the mains to 99.6 volts, drew 37.8 amps but only put out 80 volts (1600 watts). The NU4-6000 put out more power, and drew only 50% of the power from the mains compared to the CA9.

My back (and bank account) are very pleased with the NU4-6000, after the testing I purchased another pair. The amps have run with no shutdowns in direct sunlight at 100 F temperatures. With only two shows so far, don't have any long term experience, but as cool as they run I expect longevity.

Art
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Keith Broughton

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Re: Power amp specs and ratings....
« Reply #25 on: August 04, 2015, 12:53:02 pm »

Keith,

Just before the last Christmas holidays I conducted a battery of tests on some old amplifiers and a new Behringer NU4-6000 four channel amplifier. To my surprise, the  NU4-6000 performed as well on low frequencies as on mid/high frequencies, and is capable of near full power sine wave output with all four channels driven to rated output at two ohms, or two bridged mono pairs driving four ohm loads each. The  $350 NU4-6000 appears to be within 3 dB of the $5500 Powersoft K10 rating on sustained (more than 1 second) output.

The NU4-6000 with two bridged mono pairs each driving four ohm loads just below the illumination of the clip/limit light each put out 85.5 volts at 60 Hz (1828 watts), 84.6 volts at 30 Hz (1789 watts), dropping the mains voltage on a 100' 10AWG 120V line from 118.1 volts down to 107.2 volts, drawing 31 amperes.

Using just one bridged mono pair, the amp ran for 40+ seconds before I terminated the test, as the amp was drawing 19.8 amperes, and the "tired" 20 amp mains breaker had popped several times in various tests already. The amp would have put out more power given a full 120 volts, but the test represents "real world" situation, we don't generally plug our amplifiers in to an outlet two feet from the mains transformer.

I also tested my old "heavy iron"  bass favorite, a Crest CA9, bridged into a 4 ohm load it dropped the mains to 99.6 volts, drew 37.8 amps but only put out 80 volts (1600 watts). The NU4-6000 put out more power, and drew only 50% of the power from the mains compared to the CA9.

My back (and bank account) are very pleased with the NU4-6000, after the testing I purchased another pair. The amps have run with no shutdowns in direct sunlight at 100 F temperatures. With only two shows so far, don't have any long term experience, but as cool as they run I expect longevity.

Art
Now that you mention it, I seem to recal reading something about that.
Even though the Behringer amps don't quite put out the "advertised" power, the cost / watt ratio is still very good.
I suggested one of my equipment suppliers buy 4 DSP12000 amps and at $800 CDN/ea, a great deal.
So far, they seem to work just fine, although I did use a 2 pole 30 amp (L14/30) distro panel to power the rack.
As for the back, these 12000s are quite weighty so no benefit there. :(
This guy has been running a bunch of the first gen Powersoft Digam amps and we don't see all that much of a difference in average performance and for the lower cost, it's hard not to buy the Behringers.
Still, it would be nice to have some burst recovery specs.
As Ivan says, many times, it's the application that has to be the determining factor in amp choice.
I would probably not use Behringers for EDM but for straight up rock and roll, no problem!
« Last Edit: August 04, 2015, 12:56:04 pm by Keith Broughton »
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Scott Holtzman

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Re: Power amp specs and ratings....
« Reply #26 on: August 06, 2015, 04:36:09 pm »

Now that you mention it, I seem to recal reading something about that.
Even though the Behringer amps don't quite put out the "advertised" power, the cost / watt ratio is still very good.
I suggested one of my equipment suppliers buy 4 DSP12000 amps and at $800 CDN/ea, a great deal.
So far, they seem to work just fine, although I did use a 2 pole 30 amp (L14/30) distro panel to power the rack.
As for the back, these 12000s are quite weighty so no benefit there. :(
This guy has been running a bunch of the first gen Powersoft Digam amps and we don't see all that much of a difference in average performance and for the lower cost, it's hard not to buy the Behringers.
Still, it would be nice to have some burst recovery specs.
As Ivan says, many times, it's the application that has to be the determining factor in amp choice.
I would probably not use Behringers for EDM but for straight up rock and roll, no problem!

I have to agree, against everyone's advice I picked up one of the four channel 'nukes and put that ugly bitch in a rolling case with an x32 rack.  I got an open box on flea bay for $349 shipped and have had no complaints.

What I am still trying to quantify is the original assertion of the thread.  Even if you get down to a common denominator (power for x # minutes with x load from x to x @ x% THD) you still end up with some amps with balls and some amps with no balls.  I have not heard the iTech's but I can tell you that the Xti's don't have something that the Macro Tech's do.  It always leave you with something in your gut that you left something on the table and made the wrong compromise.

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John Roberts {JR}

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Re: Power amp specs and ratings....
« Reply #27 on: August 06, 2015, 06:40:11 pm »

I have to agree, against everyone's advice I picked up one of the four channel 'nukes and put that ugly bitch in a rolling case with an x32 rack.  I got an open box on flea bay for $349 shipped and have had no complaints.

What I am still trying to quantify is the original assertion of the thread.  Even if you get down to a common denominator (power for x # minutes with x load from x to x @ x% THD) you still end up with some amps with balls and some amps with no balls.  I have not heard the iTech's but I can tell you that the Xti's don't have something that the Macro Tech's do.  It always leave you with something in your gut that you left something on the table and made the wrong compromise.

Hello again Scott...  8)  "Balls" is not a technical term. You probably mean "duty-cycle". Amplifiers have not delivered 100% duty-cycle for a very long time, because customers decline to pay for 100% duty-cycle. 

Which leaves us with a fairly subjective, if the amp has enough duty cycle for your application it has balls, if not enough, no balls.  :P

As i said several months ago, listen to anecdotal posts from other professionals doing similar genres of music using similar speaker loads. First to identify weak sisters, and/or amps with "balls".  ;D ;D

I continue to be impressed with the modern generation(s)*** of light weight (light iron?) high power amps that  make decent power while wasting less as heat (yes even Behringer). The tree huggers have to love that.

I could have given you a duty-cycle spec back when I was still a power amp product manager (last century) but in my judgement you customers would have misused it, just like slew rate and damping factor before that.  (By "you" I don't mean you Scott, but you customers in general, while that probably includes Scott.).

JR 

*** We're probably at least two amp technology generations beyond what I had to work with. Peavey was pedaling as hard as they could to make class D kick class, but now it is delivering on those very old promises (light weight and lower cost). In my judgement the high voltage power switching devices just weren't up to the task back decades ago. 
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Scott Holtzman

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Re: Power amp specs and ratings....
« Reply #28 on: August 07, 2015, 05:27:18 pm »

Hello again Scott...  8)  "Balls" is not a technical term. You probably mean "duty-cycle". Amplifiers have not delivered 100% duty-cycle for a very long time, because customers decline to pay for 100% duty-cycle. 

Which leaves us with a fairly subjective, if the amp has enough duty cycle for your application it has balls, if not enough, no balls.  :P

As i said several months ago, listen to anecdotal posts from other professionals doing similar genres of music using similar speaker loads. First to identify weak sisters, and/or amps with "balls".  ;D ;D

I continue to be impressed with the modern generation(s)*** of light weight (light iron?) high power amps that  make decent power while wasting less as heat (yes even Behringer). The tree huggers have to love that.

I could have given you a duty-cycle spec back when I was still a power amp product manager (last century) but in my judgement you customers would have misused it, just like slew rate and damping factor before that.  (By "you" I don't mean you Scott, but you customers in general, while that probably includes Scott.).

JR 

*** We're probably at least two amp technology generations beyond what I had to work with. Peavey was pedaling as hard as they could to make class D kick class, but now it is delivering on those very old promises (light weight and lower cost). In my judgement the high voltage power switching devices just weren't up to the task back decades ago.

John, I think duty cycle is the missing variable, it goes hand in hand with crest factor.  The new PLD amps from QSC have a 20ms spec.  I find that useful.

I know older amps had more energy storage, if you unplugged them playing you could still listen for a minute at some volumes.  That is somewhat invalid as I am sure control circuitry when the +5 rail goes down mutes outputs.

I do like the Peavey Class D's.  The price is not too pad and they are very aesthetically pleasing. 

Lastly, your statement on subjective reviews is interesting.  I have had cases where someone reports that the xxx product blows away the yyy.  When I have both products side by side the delta is not that great.

I think quality equipment at various price points, none of it is going to be widely disparate in performance.  Case in point the QSC KW-181, the JBL PRX-718xlf, the EV ETX18p.  They can all be interchanged without any problem form a client perspective and very little change even with trained ears.  To get a better sub (or amp, processor, mixer etc) than any of these ~$1000 or so boxes requires you to at least double in price, maybe more.  It continues to rise logarythmically and places significant barriers for small operators to move up to the next level.  You have to either capatalize or finance the equipment and be ready for a lower ROI until you actually sell it. 

It gets worse because now that you have updated your amp as this thread is about, now you need to upgrade both tops and subs, more amps, then your board is no longer relevant at the new level, you may need new lifts, it never seems to stop. 

Thanks for distilling down my chaotic thoughts into something digestible.  Oh look squirrel...... ::)
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TJ (Tom) Cornish

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Re: Power amp specs and ratings....
« Reply #29 on: August 07, 2015, 06:17:11 pm »

It gets worse because now that you have updated your amp as this thread is about, now you need to upgrade both tops and subs, more amps, then your board is no longer relevant at the new level, you may need new lifts, it never seems to stop. 
Tim Mc's $3dB principle is an unfortunate reality of this industry.  The next stop after spending $10K is spending $20K, then $40K, then $80K...

I may sound like a broken record here, but I really wish people would stop caring about amps (and passive speakers in general), and start caring about systems - whether the amp is inside the speaker, or the amp is external, but a matched component with the speakers.  At this point in time, there's no benefit for consumers in having to care about all of this ridiculous minutae.

Step 1 - Buy a speaker system.  While shopping, evaluate the performance of the whole system, and make an appropriate purchasing decision. 

Step 2 - Do basic system alignment and room tuning to make the system fit the room. 

Step 3 - enjoy far better sound quality by leveraging the manufacturer's engineering efforts than what the average touring system tech is able to roll from a pile of mismatched bits and inadequate time and/or skill.

The only reason not to buy a matched system is maybe if you are trying to stretch old inventory as long as possible and want to reuse some old boxes, which is hopefully a temporary situation.  Other than that, a matched system is the way to go - both at the big-dog level and the lounge level.
« Last Edit: August 08, 2015, 07:01:40 am by TJ (Tom) Cornish »
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Re: Power amp specs and ratings....
« Reply #29 on: August 07, 2015, 06:17:11 pm »


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