How to figure out amplifier class in my integrated amp?

[Eppie]

At two ch spec?

I would assume so. That's around 2 amperes. My 7 channel AVR is rated at 6 amperes with 7ch at 105W which is in the same ballpark as the 260W rating mentioned.

 

[lovinthehd]

I would assume so. That's around 2 amperes. My 7 channel AVR is rated at 6 amperes with 7ch at 105W which is in the same ballpark as the 260W rating mentioned.

Hard to know just what the "power consumption" specs mean over time as they aren't generally accompanied by the specifics of the spec....but mostly I'd look to other ways to figure out actual power consumption (let alone power supply spec) than an unspecified rating for whatever reason it's there for.

 

[PENG]

The 8/6/4/2 Ohm Dynamic power spec is widely used in Europe and other international markets...
Since the audio market is now global the respective brands still mention this spec on their websites..

Just my $0.02...

I know, and I have no issue with the dynamic ratings, in fact I wish they all provide this spec. In my opinion, they should provide details of the basis, or at least specify the standard they follow (NAD did specify IHF). To be fair, Yamaha did so too but you have to dig deeper, that mean download the owner's manual. At least in that case, some can argue, dismiss, or convince themselves whether the short duration rating helps enough to make an audible difference.

For those (pretty much everyone else beside NAD, Yamaha and Anthem) who don't specify dynamic ratings, we would have rely on test benches such as Audioholics.com and Audiosciencereview.com.

PE. W.. Mitchell, "A Musically Appropriate Dynamic Headroom Test for Power Amplifiers," Paper 2504, (1987 October.). doi:
AES E-Library » A Musically Appropriate Dynamic Headroom Test for Power Amplifiers
"The EIA RS-490 (former IHF A-202) amplifier test standard includes a "dynamic headroom" test employing a 20-mS tone-burst. In an informal survey of musical recordings, power bursts were found with durations from a few milliseconds up to several hundred milliseconds, with an apparent clustering in the 80-200-mS range. Since the practical value of an amplifier depends on its ability to reproduce musical dynamics, a more useful power rating would be obtained by amending the dynamic headroom test to employ a 200-millisecond (or similar) tone-burst."

 

[Eppie]

Hard to know just what the "power consumption" specs mean over time as they aren't generally accompanied by the specifics of the spec....but mostly I'd look to other ways to figure out actual power consumption (let alone power supply spec) than an unspecified rating for whatever reason it's there for.

Power consumption whether in watts or amperes is typically stated at max power levels. It's provided so that the consumer can safely estimate the max load on a typical 15 ampere house circuit. There isn't much else for the consumer to go by. The only way to figure out the actual power consumption is to drive the amp to its maximum rated RMS power under load with proper test equipment but that should be the number that is stated by the manufacturer any way. Most consumers won't care or understand the specifics of the spec.

It can get a bit confusing though since it's sometimes stated in watts, or amps or VA, and while Power = Volts x Amps the VA rating for AC devices does not necessarily match the stated wattage. I imagine that the American UL and Canadian CSA have a standard for how power consumption needs to be stated.

 

[M Code]

Do you know what the parameters are, tho?

I don't recall exactly...
But it was a short, peak tone burst like @ 1kHz..
When I get back to my office, I will try and dig out the specifics..
Essentially it was just another creative marketing ploy to show a higher output spec..

Just my $0.02...

 

[PENG]

Power consumption whether in watts or amperes is typically stated at max power levels.

I am not sure how "typical" that is. It would have been much more meaningful if they actually state the conditions for test in even just a little more detailed manner.

Take a look of Yamaha's and D+M's specs on this. One has multiple number/conditions, the other just 1.
Then look at Mc's NAD's, Outlaws and the meaning of "typical" being variable will be obvious.

For me, I would use that spec to compare models of the same brand, even then I would be careful...ymmv..

 

[PENG]

Do you know what the parameters are, tho?

Someone has done a pretty good job tabling the differences:
Comparison of Standards for Amplifier Power Ratings | CAF (prosoundtraining.com)

Yamaha's seem inline with CEA's:
What's the difference between Continuous RMS and Dynamic Power ? - Yamaha - United States
It is 20 ms full scale, then rest for 480 ms.
That would be similar to CEA-2006 (how gene's measurements based on, also Amir's), but not exactly the same.

NAD's IHF (an old standard) dynamic power into 8/4/2 Ohms would be similar to Yamaha's.

So basically, 1 kHz, 20 ms, that is 20 cycles, are the two important parameters.

 

[Eppie]

I am not sure how "typical" that is. It would have been much more meaningful if they actually state the conditions for test in even just a little more detailed manner.

Take a look of Yamaha's and D+M's specs on this. One has multiple number/conditions, the other just 1.
Then look at Mc's NAD's, Outlaws and the meaning of "typical" being variable will be obvious.

For me, I would use that spec to compare models of the same brand, even then I would be careful...ymmv..

Sorry, but are we talking about the same thing? The variable specs are usually stated for output power which depends on the load and whether RMS or peak. The stated consumption power rating should be about the same whether testing at 4 ohm or 8 ohm loads, etc. so they only give one value.

 

[PENG]

Sorry, but are we talking about the same thing? The variable specs are usually stated for output power which depends on the load and whether RMS or peak. The stated consumption power rating should be about the same whether testing at 4 ohm or 8 ohm loads, etc. so they only give one value.

We are talking about the power consumption spec given in manufacturers specs on websites, owner's manuals or datasheets. Take a look of some examples:

Yamaha RX-A3080:
Power Consumption........................................................................ 490 W wt. 39.9 lbs, rated output 150 W, 8 Ohms They also provide a "maximum power consumption" but again, without stating the test conditions.

Denon AVR-X2600H:
Power consumption:......................................................................... 500 W wt. 21 lbs, rated output 95 W, 8 Ohms

For power amp, again let's look at Yamaha's 11 channel MX-A5200:
• Power Consumption ....................................................................... 650 W wt. 58.2 lbs, rated 150 W, 8 Ohms
• Maximum Power Consumption (All Channel driven, 10% THD)... 1,500 W

So you can see that THD also affect the number, as expected.

This is just one comparison example, to show those numbers likely don't represent the power consumption when the amp is driven to its "maximum power levels".

And no, if the power consumption spec is what you think it is (which could be true in some cases but we really don't know), then the numbers will not be the same whether testing at 4 Ohm or 8 Ohm load, that is just not possible based on basic electrical theories. It will also be further complicated by the fact that it would depend on the duration of the test. For example, if it is a 1 minute test, the output will very likely be higher than if it is for 30 minutes (for AVRs anyway) so the consumption will also be higher during that 1 minute test.

This spec is just not very meaningful, it is of course meaningful and useful to a point. For the average consumers they may be misled, or confused no doubt about it. Just do a search even just on this forum and you will see how often people even assumed the power consumption specs = the amp's actual maximum output. For example, I have seen more than once, someone opined that there is no way a mid range Denon AVR can output 100 WPC, 5 channel driven because the power consumption is only 660 W, because class AB amp's efficiency is only 50-60% etc., blablabla...

When you see such claims or questions, you will know people in fact were confused, or misled.

The moral of the power consumption spec story is, take it with a grain of salt, it could mean differently depending on brands, models, conditions of test, use etc., that are not specified more often than not.

 

[Eppie]

Totally agree that those figures are confusing. If you plug equipment into a power bar, your only concern is not to exceed its rating. The max power consumption should be with all channels driven but the other power consumption value doesn't tell you much without the qualifiers. I prefer the ampere rating in my manual since it's easiest to try and stay within the 15 amp rating on a house circuit.

Whether 4 ohm or 8 ohm loads, though, it's still running off the same power supply which will have physical limits or will be designed to current limit for protection. That should be the limiting factor in the max current a piece of equipment can draw from the wall.

If only it were as simple as measuring a toaster.

 

[Pogre]

Should we merge this with the LPF/LFE thread..?

 

[PENG]

Should we merge this with the LPF/LFE thread..?

Clearly not, I am just going to say to Eppie, that unless we both have all day to discuss this on a separate thread, this is getting nowhere. Suffice to say for now, that the maximum capacity of the power supply in a power amp/AVRs that Eppie alluded to, is not the same as power consumption that is much more complicated to define, because it depends on so many other things.

A 1200 W maximum rated toaster will likely not draw more, but just about any mid range AVR's power amp can draw anywhere from next to nothing to >15A or more, in the duration is short enough, before the fuse would blow or the protective scheme would put a limit on it, or interrupt it, and all the time this would depend on the impedance characteristics of the load and many other factors.

So in addition to stating the number of channels driven, at certain level/% or rated output at stated THD, are we going to say power consumption means some sort of average, or "typical", when driving a "typical" loudspeaker load, or what...? Complicated!! Sorry this is for Eppie, but I am too lazy to do two separate posts.

I would just be as happy or happier, if manufacturers just provide the VA rated of the PS transformers.

 

[Pogre]

Clearly not, I am just going to say to Eppie, that unless we both have all day to discuss this on a separate thread, this is getting nowhere. Suffice to say for now, that the maximum capacity of the power supply in a power amp/AVRs that Eppie alluded to, is not the same as power consumption that is much more complicated to define, because it depends on so many other things.

A 1200 W maximum rated toaster will likely not draw more, but just about any mid range AVR's power amp can draw anywhere from next to nothing to >15A or more, in the duration is short enough, before the fuse would blow or the protective scheme would put a limit on it, or interrupt it, and all the time this would depend on the impedance characteristics of the load and many other factors.

So in addition to stating the number of channels driven, at certain level/% or rated output at stated THD, are we going to say power consumption means some sort of average, or "typical", when driving a "typical" loudspeaker load, or what...? Complicated!! Sorry this is for Eppie, but I am too lazy to do two separate posts.

I would just be as happy or happier, if manufacturers just provide the VA rated of the PS transformers.

I'm just kidding around Peng! I'm comparing the confusion of trying to explain these nebulous power ratings to explaining LPF for LFE. There's a lot more to it than appears on the surface. Just another facet of the industry that is often confused or misinterpreted. I'm paying attention and trying to learn from you guys. Just tryna inject a little levity...

 

[Eppie]

I hear ya Peng and your points are well taken. From a consumer standpoint, average max power levels are the most meaningful and having a standard for measurement is required to make an apples to apples comparison. If I had the time, I would go over the CSA web site to see what standards exist. I do know that receiving CSA certification is not that simple. I have friends at Quatum 5X who design and build wireless microphones and transmitters/receivers for the NBA, NHL, MLB and others and anything that plugs into an outlet has to go through strict design checks and certification. That includes complying with labeling requirements for power consumption or current draw, so there must be some kind of standard.

 

[M Code]

The Dynamic Power Output measurements were done under the test procedure defined by the JITA...
JITA stands for Japan Industrial Technology Association. I have not yet located the specific standards but as I mentioned previously it is based on a peak power tone burst for a short period...
Don't know exactly the time measurement period but probably no more than 20-30 milliseconds....

Just my $0.02...

 

[PENG]

I hear ya Peng and your points are well taken. From a consumer standpoint, average max power levels are the most meaningful and having a standard for measurement is required to make an apples to apples comparison. If I had the time, I would go over the CSA web site to see what standards exist. I do know that receiving CSA certification is not that simple. I have friends at Quatum 5X who design and build wireless microphones and transmitters/receivers for the NBA, NHL, MLB and others and anything that plugs into an outlet has to go through strict design checks and certification. That includes complying with labeling requirements for power consumption or current draw, so there must be some kind of standard.

I am very familiar with CSA's electrical standards and have copies of quite a few but I don't remember seeing anything related to audio power amplifier power consumption so I wish you luck finding one.

In my opinion as an EE specialized mainly in power and control systems, I feel the whole power consumption thing for audio amp is sort of a misnomer or even BS, meaningless if I choose to be blunt.

It would be a lot more useful for the consumers to know the power supply rating by transformer VA rating, maximum rail voltage, storage cap uf and voltage rating, and the output device collector current rating, and of course the number of output devices in parallel (For AVRs, usually just two, that is, one for each half of the push-pull). That way, at least we will have a good idea of the capability of the amp, instead of trying to figure out under what condition the amp will consume the specified X number of Watts. Think about it, we don't use amps to amplify single sine waves, but on music waves that vary continuously with time. Yes it would still be sine waves if do a Fourier transform, but the point is, the continuous time varying complex waveform (varying magnitude of V, I and the phase angle between them) of the loudspeaker's load current makes it impossible to have a meaningful static power consumption figure. As you mentioned, wish it was like a toaster, that would draw pretty constant current, or even an electric fan, heaters etc and will be simple to spec "power consumptions".

If it is a regulatory requirement to have this power consumption figure regardless, then they need to get their act together to at least have everybody follow the same rules, not like it is now, resulting in the huge difference brands/models as shown in the examples I cited using D and Y's.

Anyway we better move on before someone presses the thread hijack button.

 

[Eppie]

Thanks @PENG. I studied some EE in university so I appreciate the more detailed explanation. I'm glad that I have not needed to apply any Fourier transforms in years. I'm in IT now in the finance industry and while actuarial sciences can get complex it's nothing like wave theory. Yeah, time to move on but it was a fun discussion.

 

[PENG]

At two ch spec?

Thank you too, I do get passionate, overly sometimes, when I felt a need to reference EE theories. Actually we are only partially hijacking the OP' thread because he did ask about how to tell if the amp is class A, AB etc., so looking deeper into the power supply related specs (and that invariably would include the vague power consumption figures) is one way for the average consumer to tell. And yes, I can tell you have some EE background, it's obvious.

 

[Eppie]

I was wondering why the VA ratings were a lot higher than the wattage listed on some amps. Some useful formulas on RapidTables describe apparent power in VA vs real and reactive power. Interesting. If apparent power is what is supplied to the circuit, then the VA rating would be the most useful in determining circuit load. OK, I'm done now.

 

[PENG]

I was wondering why the VA ratings were a lot higher than the wattage listed on some amps. Some useful formulas on RapidTables describe apparent power in VA vs real and reactive power. Interesting. If apparent power is what is supplied to the circuit, then the VA rating would be the most useful in determining circuit load. OK, I'm done now.

Haha you are done alright but then you asked...

You already know the power formula is, P = V*I* Cos (Ø), Ø is the phase angle between the V and the I phasors (equivalent to "vector" on the mechanical side).

You also know Cos (Ø) = 1 and that would be for a resistor load when Ø, the phase angle is 0 degree, Cos (60°) is 0.5 and Cos (30°) is 0.866.

So it is obvious that the VA rating, where P = V*I is always > W except when the phase angle is 0°.

Keep in mind that the magnitude of the load current is not affected by the phase angle so whether the load is highly resistive, such as with phase angle less than 10° with the whole audio band, or frequently exceeds 30° within the band, the current can still be calculated by the formula V = I*|Z|, the symbol | | denotes the absolute value of Z. So I = V/|Z|

Example: V = 10V, Z = 3+j4, |Z| = square root (3²+4²) = 5
the phase angle is arctan (4/3) = 53°

How to Calculate Impedance: 10 Steps (with Pictures) - wikiHow

Utility companies do charge industrial customers on VA instead of W, for the obvious reason that you cited, but they typically allow for the power factor to be as low as 0.9, power factor = Cos (Ø)
If Cos (Ø) = 0.9, then the phase angle Cos (Ø) = arcCos = 25.85°, that is, industrial customers don't pay for VA unless there phase angle falls below 25.85° during their peak demand period that could vary from 5 minutes to an hour depending on the local utility company's policy.

Everything formula I cited above are Google, anyone can do it.

So short story long, yes VA is a better metric than Watts overall but both are needed in most cases for practical analysis and/or evaluation purposes.

Now we are done.