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hypex power ratings

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March Audio

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@davidr3032 Power is proportional do heat dissipation. Short bursts of a few seconds is known peak power. Continuos power of 5 minutes (which follows FTC rules) still is the full 500W RMS rating. Only if it you leave the amplifier on full power for hours than maybe the amp overheats and starts limiting its power output. That is, if you don't add extra heatsinks or fans.

This applies for all amplifiers by the way, class A and AB as well. It's just that these usually have large heatsinks because they are inefficient, and class D avoids it for short burst and continuos few minutes of power, which are regular use cases for music or movies, and not hours on max power which is an unrealistic test use.
This.

The FTC rules/tests are completely unrepresentative of real world usage.
 

March Audio

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Few would disagree. However the answer for amp manufacturers to this is to petition the powers that be that govern standardised methods of testing and to get them to change it. While still letting everyone know the power rating of your amp meantime. You can also include all the extra specs you like in the datasheets stating how great it performs with other parameters. Without a standardised ratings people like me wont know if they are buying a more power amp than what they have or if its safe to use it with their speakers
As mentioned there is no standard.

The FTC governs advertising information in the US only. Thats all. It's not a technical standard. The tests they stipulate to conform with advertising rules in the US have little relevance to real world usage (ie playing music) so in my opinion give a false basis for comparison. Maybe better than nothing, it helps to minimise some of the ridiculous inflations of power output that used to be seen in marketing marketing material, but still.....

If you see "RMS" power quoted anywhere it really means average. It's just calculated from rms voltage/current.

However the number will remain the same so you can safely compare.
 
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Matias

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Here are the specifications from the ICEpower 300AS1 datasheet. I know it is not Hypex NCore as this thread says, but I can assume the same applies to all class D boards.

Power delivery depends on the module heating. And it heats a lot faster both with lower AC input and high power in low impedance loads. Still considering the rated 300W in 115Vac results in 30 second, which is longer than any real music content would use.

I had the wiring in my home set up so that my amps run in 230Vac phase+phase. It noticeably heats a few degrees less than the 127Vac phase+neutral.

power over time.jpg
 

pma

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This.

The FTC rules/tests are completely unrepresentative of real world usage.

No. This is only an excuse, usual excuse. Modern popular or electronic music is often so highly compressed that it requests high average power when playing loud. And undersized heatsinks go hot very quickly.
 
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davidr3032

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I dont think I've really got an answer to my question. I haven't got much in the way of actual numbers. So I will try again being very specific -

Does anyone know what the power rating would be of a Nord nc500dm into 8 ohm (0.01% THD, 20Hz-20 kHz) ?
Continuous power

If not an exact figure, an estimate please. But some sort of number would be good
 

March Audio

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No. This is only an excuse, usual excuse. Modern popular or electronic music is often so highly compressed that it requests high average power when playing loud. And undersized heatsinks go hot very quickly.
That's simply not true.

I will demonstrate the RMS signal levels of a range of music tracks later.
 

March Audio

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Daft Punk Get Lucky. Highly compressed modern popular music.

RMS amplitude level over the track is -12dB.

Capture.PNG


So if your peak output voltage was 20 volts (100 watts peak into 4 ohms, thats 50 watts average with a sine wave) the the rms voltage is -12dB which is only 5 volts. Thats 6.25 watts.
 
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March Audio

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I dont think I've really got an answer to my question. I haven't got much in the way of actual numbers. So I will try again being very specific -

Does anyone know what the power rating would be of a Nord nc500dm into 8 ohm (0.01% THD, 20Hz-20 kHz) ?
Continuous power

If not an exact figure, an estimate please. But some sort of number would be good
I cant tell you how the Nord implementation performs but this is the performance of the NC500 module. At 0.01% THD+N you are in the region of 330 watts.

Capture.PNG
 
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davidr3032

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I can
I cant tell you how the Nord implementation performs but this is the performance of the NC500 module. At 0.01% THD+N you are in the region of 330 watts.

View attachment 106473

Thanks. I can't make out the graphs too well on my phone currently. Is that 330w for 20Hz-20 kHz? I can only make out lines for individual frequencies. And this is continous power?
 

March Audio

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Thanks. I can't make out the graphs too well on my phone currently. Is that 330w for 20Hz-20 kHz? I can only make out lines for individual frequencies. And this is continous power?
It's but there is another thing to bear in mind. Music simply doesn't have high energy at 20 kHz. You will never need 330 watts at 20kHz, it will literally be only a few watts.

Touch the graph picture and it will reopen and you can zoom in.
 
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anchan

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I'm no expert but I have built a few amps myself now, including a few tube amps, a First Watt, and two Ncore amps so I have a better understanding of the power rating situation than I did previously.

As stated, Hypex actually gives more information than others, and if you know how to read it, it gives a much better picture of the capabilities of the amp. Why should they quantize their information to fit only the RMS slot just because that's what consumers mostly kind of understand? Their modules are also geared towards integrators so the information is helpful, not misleading.

Let's take an example, the First Watt amplifiers. These are rated in the most straightforward way, and it's easy to understand. The rails on these amps run at 24V. Therefore, there is no way to ever exceed a little bit less than 24V output signal to your speakers. Taking into account losses due to source resistors and R(on) of the transistors let's say it can swing 20V (hard ceiling, absolutely no more).

Into 8 ohms, given V^2/R you have 20^2/8 = 50w peak. Peak does not mean peak as in short bursts like others have said. It's a mathematical reference. Now to get RMS you can work out the actually formula, but it actually turns out to be peak/2 so you have 25W RMS.

Now imagine an amp that is similar to the First Watt above but the rails are 50V and not capped at 24V. But it can"t swing up to 50V all the time continuously because of thermal reasons, but it still can swing into the 40V range for seconds at a time delivering your bass notes and loud passages and peaks and such undistorted even. This amp perceptibly would be a much more capable and powerful amplifier even though it couldn't sustain a 40V / 1kHz test signal on the bench for an hour while you go and make a bacon lettuce and tomato sandwich. So it fails the RMS continuous lab test, but it still can get louder than a rail limited amplifier like the First Watt or other similar topology.

Considering the quasi-sinusoidal nature of music, this gives you a hell of a lot more power than the continuous RMS criteria can show. Some amplifier topologies can take advantage of this, while fixed rail limited amps cannot. That's why RMS continuous ratings are not quite everything and we need a few other parameters to tell the story.
 
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davidr3032

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I cant tell you how the Nord implementation performs but this is the performance of the NC500 module. At 0.01% THD+N you are in the region of 330 watts.

View attachment 106473


These graphs seem to show the power rating for the module driven at individual frequencies, not 20hz - 20kHz Presumably if it puts out say 330w at 1kHz, it will put out less than that when all frequencies are driven?
 

Inner Space

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I bought the quad years ago for some quad electrostatic speakers and it sounded wonderful with them. I'm not enjoying the magnepans as much.

Some interesting discussion in this thread, but it misses the point, surely. The OP doesn't like the Magnepans. Simple as that. Imagining a change of amp will solve the problem is to disappear down a fruitless rabbit hole. Far better to bite the bullet and change the speakers.
 
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davidr3032

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Some interesting discussion in this thread, but it misses the point, surely. The OP doesn't like the Magnepans. Simple as that. Imagining a change of amp will solve the problem is to disappear down a fruitless rabbit hole. Far better to bite the bullet and change the speakers.

Is that the logical thing to do? Try one amp with your speakers. If you're not happy, then you have to get rid of the speakers. So people should just hold on to their old amplifiers and don't change them no matter what speakers they buy

You could be right of course. But I thought it would make sense to try another amp. Which I would certainly sell on if I didn't notice an improvement

Especially since the magnepans are 6 foot high and I had to hire an estate car, take a ferry and drive a couple of hundred miles to pick them up
 
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NTK

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These graphs seem to show the power rating for the module driven at individual frequencies, not 20hz - 20kHz Presumably if it puts out say 330w at 1kHz, it will put out less than that when all frequencies are driven?
The amplifier will certainly not be able to output its "rated" power when all frequencies are driven. This has to do with the crest factor of the waveform.

The effect is illustrated in this QuantAsylum blog post (read the section on the Multitone test):
https://quantasylum.com/blogs/news/ti-tpa3255-evm
With 12 tones, the TI TPA3255 EVM amplifier clipped at 22 W, and the amplifier is rated at ~150 W (8 ohms)!

Per current standards, amplifier power are tested using a single tone sine wave. This means the peak voltage of the signal is 1.41 times (3 dB) higher than the RMS voltage. This ratio of peak to RMS voltage is the crest factor. Therefore, if your amp can output a maximum voltage swing of +/-50 volts, its "power rating" at 8 ohm would be: (50/1.41)^2 / 8 = 157 W. (The 1.41 number in the calculation is the crest factor.)
[Note that the multi-tone is a steady signal, i.e. crest factor is different and separate from the dynamic range of the signal.]

However, music (and multi-tones) is not a single tone sinewave, and has a much higher crest factor. If we choose a more realistic value of 12 dB (= 4x), the power at which clipping starts will be: (50/4)^2 / 8 = 20 W.

I agree with @March Audio that the FTC test method is nowhere representative of the 99.9% use case. Nobody (sane and with intact hearing) drives their amplifer continuously to their max power and listen to single tone sine waves. Why should amplifiers be designed to this requirement?
 

Inner Space

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Is that the logical thing to do? Try one amp with your speakers. If you're not happy, then you have to get rid of the speakers. So people should just hold on to their old amplifiers and don't change them no matter what speakers they buy

You could be right of course. But I thought it would make sense to try another amp.

Honestly, I think it's exactly the logical thing to do. Poll the folks here: has swapping a competent amp for another competent amp of similar output ever rendered an unenjoyable speaker enjoyable? That's audiophile thinking. It will lead to a year or two of dissatisfaction, and then you'll change the speakers anyway.
 
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davidr3032

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Honestly, I think it's exactly the logical thing to do. Poll the folks here: has swapping a competent amp for another competent amp of similar output ever rendered an unenjoyable speaker enjoyable? That's audiophile thinking. It will lead to a year or two of dissatisfaction, and then you'll change the speakers anyway.

Of similar output? My plan was to try an amp with more output

I think youre taking things to the extreme here. Its an exaggeration to say magnepans are unenjoyable speakers.
Its also pretty far fetched to suggest I may be spending years trying different amps with them. And then sell them anyway. My plan was to try an amp with more power and better specs. If the quad amp sounds as good or the same I would hold on to it. There ain't no "audiophile thinking" going on here.

I take your point that another amp may not sound any better. But I already said that I'm aware that that may be the case. In fact I wouldn't be too disappointed if the quad 909 was just as good as a hypex based amp. As that would save me a lot of money ( I need the money to buy some cyogenetically treated unicorn hair fuses )
 

Matias

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@davidr3032 just try an NC502MP based amp from Buckeye or VTV and trial for 30 days. That's it.
 
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