hypex power ratings

[March Audio]

After some research on linear power supplies I can accept that the ATI hypex amplifiers that use them would result in their amps being less powerful than other nc500 based amps. This makes sense to me. So it would seem that although the nord nc500dm I was asking about is less powerful than the 400w power rating its given. The figure of 250w can't be used to speculate as to the power rating of the Nord nc500 amps for example. Two different power supplies. Two different power outputs

So ive learned something at least
As to the power rating of the nord nc500dm I know its not 400w. But I also know its very powerful. 330w seems high to me as according to Amirs measurements i estimate it would be clipping. So I'm just going to tell myself its somewhere near 300 watts or so. I've bought a nord nc500dm now so I will just try it and see how it sounds. And not turn things up too much

That conclusion entirely depends on what distortion level you choose to measure at.

Just for info you speakers will be the dominant source of distortion, could easily be 5 to 10% at 330 watts.

 

[RayDunzl]

True but as the previous examples showed this might only be fractions of a watt.

Yes, but it still can occur at the limits of the amplifier's output power.

 

[sigbergaudio]

Yes well exactly. Therefore the correct power rating is not 700w into 4ohm. Thats one thing we can say for sure. And its wrong for manufacturers to quote it as so. If it is 445w then surely manufacturers who quote 700w are misleading people. By a significant amount

But Amir isn't specifically trying to find the amps overall power rating here. He's merely simply stating the amp power before clipping is 445w. Which is great info to know

Having followed the discussion I think you may be missing the fact that these Class D amplifiers works a bit differently than a traditional AB amplifier, and thus the current FTC requirements just don't give a good picture of their real world performance. You don't want misleading measurements. Following them would be misleading, just the wrong way, as it would rate them too conservatively.

 

[March Audio]

Yes, but it still can occur at the limits of the amplifier's output power.

Yes, but would it significantly change the effective power rating (real world music signals)?

 

[March Audio]

Having followed the discussion I think you may be missing the fact that these Class D amplifiers works a bit differently than a traditional AB amplifier, and thus the current FTC requirements just don't give a good picture of their real world performance. You don't want misleading measurements. Following them would be misleading, just the wrong way, as it would rate them too conservatively.

I think the limitations of the FTC test are equally applicable to A or A/B amps.

 

[davidr3032]

That conclusion entirely depends on what distortion level you choose to measure at.

Just for info you speakers will be the dominant source of distortion, could easily be 5 to 10% at 330 watts.

I understand that. The graphs have a very steep rise at the end. So slight variations on distortion levels will make a big difference to output power.

However if we don't listen to Amir then where are we

 

[March Audio]

I understand that. The graphs have a very steep rise at the end. So slight variations on distortion levels will make a big difference to output power.

However if we don't listen to Amir then where are we

Well I would ask you if you think you will hear a difference between 0.003% thd and say 0.02% or even 0.1% thd, especially when your speaker is producing 5% thd ?

It isn't a case of not listening to Amir. However I don't really see a reason to choose 0.003% as the figure to rate the power at. This is especially the case as the distortion level he chooses does vary from test to test.

 

[davidr3032]

Well I would ask you if you think you will hear a difference between 0.003% thd and say 0.02% or even 0.1% thd, especially when your speaker is producing 5% distortion ?

It isn't a case of not listening to Amir. However I don't really see a reason to choose 0.003% as the figure to rate the power at. This is especially the case as the distortion level he chooses does vary from test to test.

OK. I guess you should contact him and tell him whats watt

 

[March Audio]

OK. I guess you should contact him and tell him whats watt

Oh this has been discussed before. IiRC I actually advocated a 0.1% thd level, however a number of members thought it should be higher. Amir chose to carry on eyeballing the knee and reading at a variable value.

 

[davidr3032]

Having followed the discussion I think you may be missing the fact that these Class D amplifiers works a bit differently than a traditional AB amplifier, and thus the current FTC requirements just don't give a good picture of their real world performance. You don't want misleading measurements. Following them would be misleading, just the wrong way, as it would rate them too conservatively.

Yes though I'm sure there's many a AB amplifier that doesn't test too well by the FTC standard. Whose specs could greatly benefit from a different system of measurement

 

[March Audio]

Yes though I'm sure there's many a AB amplifier that doesn't test too well by the FTC standard. Whose specs could greatly benefit from a different system of measurement

It's actually consumers that would benefit.

As an example, not one that is relevant to to class d due to its high efficiency, but to pass the FTC 5 minute full power test class A or A/B amps require far larger heatsinks than are necessary for playing music. This increases component cost. It increases size and weight which in turn increases shipping costs. This gets passed on to the consumer.

Some form of burst power rating will give a better indication how loud an amp will go with music which is what the consumer is actually interested in.

 

[pma]

You are only playing your marketing business games, @March Audio . Talking about “explained” etc. You just do not like to admit any measurement method that would not bring numbers nice enough to your products, even if there is a method that is acknowledged. You will be finding and arguing with anecdotal stories about “music”. That’s a problem with manufacturers, they will be protecting their products. Should they post in marketing threads only, as their posts are not independent at all. No science, but marketing only.

 

[DonH56]

Far as I can tell Alan is debating using science-based principles to argue against the FTC's power ratings' applicability to the real world citing actual musical crest factors and such. And all this in response to the OP who questioning Hypex' power ratings. From my vantage point, the OP could have simply not bought Hypex anything and saved pages of debate on a subject covered extensively already, but compared to many examples of subjective marketing having no (or even countering) any sort of science/engineering-based explanation I think Alan is doing OK.

Not my forum, just my opinion...

As for defining clipping, meh. I was one of the ones arguing for 1% since that has been so widely used for so many years, but Amir countered with valid arguments for a new standard. As long as it is known and consistent then relative comparisons are possible within test groups so it does not matter that much to me. It is harder to compare between say Amir's measurements and that of someone using 1% and perhaps that needs more emphasis. Most amplifiers, especially SS amps, use feedback and distortion rapidly rises as you approach clipping. A small change in power thus leads to a large change in distortion. Manufacturers are all over the map in terms of how much margin they allocate to the power spec so comparing product spec sheets can often be misleading. At least Hypex does a good job of explaining exactly their test conditions and so forth. As pointed out endless before, it is up to the manufacturer to determine how they spec the final product.

Regarding burst or transient power, AFAIK the FTC does not define it, but the IHF defined a 20 ms burst test for dynamic headroom (or some such term) long ago.

The FTC power spec has been modified a few times over the years to reduce (water down for some, make more realistic for real-world conditions to others) the continuous-power requirements. I had hoped decades ago the FC would adopt, define, and include additional power testing specs and measurements but that never really happened (again AFIK -- I most certainly have NOT kept up with FTC specs!) Things like specific dynamic power tests, absolute units for noise floor (e.g. uVrms rather than dB relative full power), additional reactive load tests, etc.

Whatever - Don

 

[hyfynut]

With respect the power ratings of the amps are perfectly correct and normal. The issue here is that you have a mis understanding of those specs and how to interpret them.

I disagree. Digital amps have since their inception provided misleading and useless specs. The FTC amplifier rule was created for a reason. It’s the most universally accepted way to compare one amp to another on paper. This has nothing to do with interpretation, in fact that’s exactly what the amplifier rule was intending to do away with.

 

[NTK]

I'll use a car analogy here. (Yes, I know it is considered bad form here.)

If I am considering buying a new car, should I be impressed by one that says it will go 200k miles on first gear at redline? The answer is I probably will NOT buy that car because of that. It is something I don't need, and I know it doesn't come free. The car manufacturer has to take cost from something else to put into beefing up the gearbox and engine. I'd much rather that cost be placed into areas that actually give me something tangible.

It has already be shown (post #56) that with signals more resembling music, an amplifier can already clip at less than 1/5 of its "FTC output rating". Why would I need, and pay for, massive heat sinks and power supplies to satisfy some nonmeaningful FTC rules?

 

[hyfynut]

How is it irrelevant if when used to do what it is designed to do, ie play MUSIC, only a tiny fraction of power needed at 1kHz is required at 20kHz?

Its the FTC tests that are irrelevant because they dont actually provide a relevant basis for comparison.

How is it "unlevelling the playing field" when say a 100 watt (at 1kHz) amplifier will never ever be required to output 100 watts at 20kHz? The FTC have a fundamental lack of understanding if the think that it is required and is useful information for a consumer.

You are really missing the point of the FTC rule. Picking and choosing which frequencies your amplifier can reach it’s rated power is ridiculous. They picked all the frequencies and to keep the field level everyone should spec their product using the same parameters. They can easily add their preferred specs according to their preferred measurement criteria and an explanation for why they prefer them.

 

[hyfynut]

I'll use a car analogy here. (Yes, I know it is considered bad form here.)

If I am considering buying a new car, should I be impressed by one that says it will go 200k miles on first gear at redline? The answer is I probably will NOT buy that car because of that. It is something I don't need, and I know it doesn't come free. The car manufacturer has to take cost from something else to put into beefing up the gearbox and engine. I'd much rather that cost be placed into areas that actually give me something tangible.

It has already be shown (post #56) that with signals more resembling music, an amplifier can already clip at less than 1/5 of its "FTC output rating". Why would I need, and pay for, massive heat sinks and power supplies to satisfy some nonmeaningful FTC rules?

That analogy doesn’t quite work. Perhaps instead of 200k you meant 200mph. And the whole idea of the FTC specs are for all amplifiers to be measured with the same parameters.

 

[maverickronin]

The FTC rules might be overkill, but I think that's a good thing.

Anyway, here's the most ridiculous thing I can think of in my library at the moment...

 

[NTK]

That analogy doesn’t quite work. Perhaps instead of 200k you meant 200mph. And the whole idea of the FTC specs are for all amplifiers to be measured with the same parameters.

The FTC says the amplifier has to run continuously at its full power rating with a single tone sine wave. I agree that standardizing the test conditions is necessary, but those conditions need to be meaningful. IMO, designing to the FTC specs results in a poorer product because the specs do not represent real life conditions.

 

[hyfynut]

The FTC says the amplifier has to run continuously at its full power rating with a single tone sine wave. I agree that standardizing the test conditions is necessary, but those conditions need to be meaningful. IMO, designing to the FTC specs results in a poorer product because the specs do not represent real life conditions.

Again I have to disagree. Every reputable amplifier manufacturer since I’ve been lusting after great amplifiers has had no problems adhering to the FTC regulations. The only amplifiers that I’ve ever seen use that as reason for not looking good were usually noisy “audiophile” designs and now inexpensive digital amps.