Receiver Power Consumption vs Output Power

[VMPS-TIII]

Yeah these are stable at 4 Ohms. I guess my final question is it worth even getting an amp since they’re pretty good amps on their own even though they’re AVR’s?

What does your ear tell you? Do you hear distortion? Is your receiver running hot?

If you don't hear distortion and the receiver is running fine then why change it? Audiophiles have a tendency to continually upgrade and we don't always know when to simply appreciate what we have.

 

[ryanosaur]

What VMPS said.

The only time upgrading electronics will make a difference is if you are going from perhaps 10+ yr old equipment to new... or if the amps are truly underpowered to do the job required.

if your speakers were lower sensitivity with a 45° phase angle at the min impedance point of <4 Ohms at low frequency, you might have a case for an upgrade.

Per VMPS, if you aren’t hearing distortions and your equipment isn’t struggling... put your feet up and enjoy... and fantasize about the next real upgrade.

 

[Dan Maldonado]

What VMPS said.

The only time upgrading electronics will make a difference is if you are going from perhaps 10+ yr old equipment to new... or if the amps are truly underpowered to do the job required.

if your speakers were lower sensitivity with a 45° phase angle at the min impedance point of <4 Ohms at low frequency, you might have a case for an upgrade.

Per VMPS, if you aren’t hearing distortions and your equipment isn’t struggling... put your feet up and enjoy... and fantasize about the next real upgrade.

Thanks guys! I’m getting distortion free play all the way up to reference volume so I guess I’m good for now. Dual Svs pb 2000’s minidsp’d for bass.

 

[ParleyW]

The Monolith is an ATI amp and they are honest about power ratings. The 1800 watts is likely close to a max rating so if you factor 70% max efficiency, that's about 1250 watts available to the speakers / 7 = 180 watts/ch.

Interesting that my new Crestron CNAMPX-7x200 shows 2400 watts even though it’s a ATI clone.

 

[Loosescrew]

I am struggling with some of the information posted here, so allow me to offer an alternative explanation which was hinted by one of the editorial comments:
Steady state, thermal equilibrium.
Please allow me to elaborate:
Your average multi channel receiver will not have to output gobs (technical term) of power playing your usual schtick to all channels or do it in a prolonged fashion. If you doubt that please examine your front main speakers and your other speakers for size.
As such during NORMAL operation (how many times was that pointed to during the article?) the total power output will not exceed the rating of the receiver and everyone is happy (we will not even get into how a satellite speaker which will play higher frequencies will probably not dip into low impedances and become as difficult of a load as front speakers, we will leave that for the advanced reader).
Want to make your average receiver squeal like a pig without playing the theme to deliverance?
Hook up a challenging speaker load for the main pair choose a setting that will direct most of the power to the front pair and give it the beans for a couple of hours and wait for the thermal protection to kick in.
See when I went to school we talked about quiescent, steady state, instantaneous and maximum continuous conditions. When you built a separate two channel power amp you don’t have the luxury of knowing HOW it will be used and hence you have to derive all this crud AND built an amp that can handle it. All of it. All day long. And yes digital smps power supplies can do amazing things but again if you ever had to design a gold rated supply and look at the specs you will see we are chasing an asymptote.
For the thermal equilibrium conversation let’s take as an example the insulation on transformer windings. They have a certain temperature they can withstand before going bye bye and there are many ways you can send them on their way to pushing daisies. Output stages (also have a maximum rated junction temperature) can similarly be modeled as heat pumps going to ambient through thermally resistive paths starting all the way from the junction. They still use silicon on those jobbies don’t they?
Large heavy expensive heat sinks in class A/AB amplifiers (actively cooled in professional equipment) have lower thermal resistance. Have you guys checked out the price for aluminum cans lately?
And for those that will cry class D those amplifiers as pointed out in the graph above also have power losses as well (though granted smaller ones but all the arguments hold) Intel and AMD have not figured out how to eliminate those in their processors (or build a zero switching time transistor) so with all due respect I don’t think Sony is up to the task.
Long story short (I know I know too late) in my opinion they are gaming the system and the specs like every other mainstream amplifier/manufacturer before them and they can get away with it because they are following a SYSTEM approach.
And speaking of specs a professor a long time ago pointed out that the cornerstone spec of the audio industry (watts rms) does not really make much sense if you really think about it. Root mean square is ironically a term used to denote the equivalent direct current that will produce the same POWER as the alternating current that we are measuring. But that term is necessary as ALTERNATING current (and its associated voltage) will turn negative over half of a full period (please feel free to look at the simple area under the curve derivation for a sinusoid to see how that 0.707 comes up). And while speakers CAN under certain extreme circumstances “push back” (most of them ARE basically motors thereby inductive reactive loads) the power generated by an amplifier’s output transistors is always positive (please let’s skip the conversation over an amplifier’s output impedance and its damping factor). Think about that rms thing for a while…
Let the hate mail come in….

 

[PENG]

I am struggling with some of the information posted here, so allow me to offer an alternative explanation which was hinted by one of the editorial comments:
Steady state, thermal equilibrium.
Please allow me to elaborate:
Your average multi channel receiver will not have to output gobs (technical term) of power playing your usual schtick to all channels or do it in a prolonged fashion. If you doubt that please examine your front main speakers and your other speakers for size.
As such during NORMAL operation (how many times was that pointed to during the article?) the total power output will not exceed the rating of the receiver and everyone is happy (we will not even get into how a satellite speaker which will play higher frequencies will probably not dip into low impedances and become as difficult of a load as front speakers, we will leave that for the advanced reader).
Want to make your average receiver squeal like a pig without playing the theme to deliverance?
Hook up a challenging speaker load for the main pair choose a setting that will direct most of the power to the front pair and give it the beans for a couple of hours and wait for the thermal protection to kick in.
See when I went to school we talked about quiescent, steady state, instantaneous and maximum continuous conditions. When you built a separate two channel power amp you don’t have the luxury of knowing HOW it will be used and hence you have to derive all this crud AND built an amp that can handle it. All of it. All day long. And yes digital smps power supplies can do amazing things but again if you ever had to design a gold rated supply and look at the specs you will see we are chasing an asymptote.
For the thermal equilibrium conversation let’s take as an example the insulation on transformer windings. They have a certain temperature they can withstand before going bye bye and there are many ways you can send them on their way to pushing daisies. Output stages (also have a maximum rated junction temperature) can similarly be modeled as heat pumps going to ambient through thermally resistive paths starting all the way from the junction. They still use silicon on those jobbies don’t they?
Large heavy expensive heat sinks in class A/AB amplifiers (actively cooled in professional equipment) have lower thermal resistance. Have you guys checked out the price for aluminum cans lately?
And for those that will cry class D those amplifiers as pointed out in the graph above also have power losses as well (though granted smaller ones but all the arguments hold) Intel and AMD have not figured out how to eliminate those in their processors (or build a zero switching time transistor) so with all due respect I don’t think Sony is up to the task.
Long story short (I know I know too late) in my opinion they are gaming the system and the specs like every other mainstream amplifier/manufacturer before them and they can get away with it because they are following a SYSTEM approach.
And speaking of specs a professor a long time ago pointed out that the cornerstone spec of the audio industry (watts rms) does not really make much sense if you really think about it. Root mean square is ironically a term used to denote the equivalent direct current that will produce the same POWER as the alternating current that we are measuring. But that term is necessary as ALTERNATING current (and its associated voltage) will turn negative over half of a full period (please feel free to look at the simple area under the curve derivation for a sinusoid to see how that 0.707 comes up). And while speakers CAN under certain extreme circumstances “push back” (most of them ARE basically motors thereby inductive reactive loads) the power generated by an amplifier’s output transistors is always positive (please let’s skip the conversation over an amplifier’s output impedance and its damping factor). Think about that rms thing for a while…
Let the hate mail come in….

Very well written, nothing contradicts Gene's, but the additional information is very useful.

 

[highfigh]

Ever wonder how your favorite manufacturer rates power consumption on their AV receivers and how it relates to maximum available output power to your speakers? I can't tell you how many comments I've read on our forums or Youtube community alleging dishonest wattage claims based on the back panel power consumption of AV receivers. This article explores this topic to determine the truth. We give several product examples including power calculations which were vetted by the brands for accuracy.

If you think the back panel tells the whole story about the full capabilities of your AVR with respect to power, you need to read this article to see what's really up.

Read: Receiver Back Panel Power Consumption vs Max Output Power

View attachment 41487
The above example shows a 140wpc x 11 Pioneer receiver which is speced to output 880 watts max output power. So how can it only consume 340 watts? Did it break the laws of physics? Read the article.

This has caused confusion for well over 40 years- it goes along with "How many Watts does this receiver have?".

 

[lovinthehd]

This has caused confusion for well over 40 years- it goes along with "How many Watts does this receiver have?".

...or, worse, how many watts does this speaker have?

 

[highfigh]

Another annoying question was "How many Amps does this put out"?.

 

[Strong Eagle]

So... old thread... still very informative... and it leads to a couple of questions for me. My Sony STR-DN1080 appears to have fried itself, so time for a new AVR. The direct Sony replacement is the STR-AN1000. Its power ratings look like this.

Given that this is a class AB amp, how can this amp consume only 240 watts? Is this rating because of heating requirements?

On the other hand, the JBL MA710, a class D amplifier has the following specs.

Given that this is a class D with much higher efficiency, why would this amp have a maximum draw of 500 watts? Unless it really does put out more watts per channel, ACD?

Thank you.

 

[lovinthehd]

So... old thread... still very informative... and it leads to a couple of questions for me. My Sony STR-DN1080 appears to have fried itself, so time for a new AVR. The direct Sony replacement is the STR-AN1000. Its power ratings look like this.

View attachment 68744
View attachment 68745

Given that this is a class AB amp, how can this amp consume only 240 watts? Is this rating because of heating requirements?

On the other hand, the JBL MA710, a class D amplifier has the following specs.

View attachment 68746
View attachment 68747

Given that this is a class D with much higher efficiency, why would this amp have a maximum draw of 500 watts? Unless it really does put out more watts per channel, ACD?

Thank you.

Did you read the article linked in the first post of this thread? The Sony avr just says power consumption, not max, and can exceed 240W.

 

[Strong Eagle]

Did you read the article linked in the first post of this thread? The Sony avr just says power consumption, not max, and can exceed 240W.

That was a pretty useless response. Thanks. For example, why would Sony elect to mark it as a 240 watt device when it could potentially draw more, even when tested at 1/8 de-rated, unclipped power. Since Sony advertises 120 watts per channel at 1 kHz, it looks to me that the formula would work out to be:

Class AB: 0.125 * 120 = 15 watts / .20 (eff) = 75 watts x 7 = 525 watts

So again, why did Sony elect to mark this as a 240 watt input device. when, from a marketing perspective, a bigger number would look better, and from an electrical load perspective, at 1/8 load, ACD, this AVR would draw quite a lot more than 240 watts... unless there is some sort of thermal protection built in which limits the output power.

And again, for the JBL MA710, the formula looks like this:

Class D: 0.125*110 = 13.75 watts / .80 (eff) = 17.19 watts x 7 = 120.32 watts

So why did JBL mark the this as a 500 MAX watt device? Does this number suggest that as one approaches max power and 90 percent efficiency, this AVR could potentially (by the numbers given) put out as much as 55 percent of rated power, ACD, as in:

Class D: 0.55*110 = 60.5 watts / .90 (eff) = 67.2 watts x 7 = 470.6 watts

I doubt that's actually the case; nevertheless, the MAX input power of this device was derived from somewhere, and based upon the output power alone, 500 seems excessive.

Perhaps you could enlighten us?

 

[lovinthehd]

That was a pretty useless response. Thanks. For example, why would Sony elect to mark it as a 240 watt device when it could potentially draw more, even when tested at 1/8 de-rated, unclipped power. Since Sony advertises 120 watts per channel at 1 kHz, it looks to me that the formula would work out to be:

Class AB: 0.125 * 120 = 15 watts / .20 (eff) = 75 watts x 7 = 525 watts

So again, why did Sony elect to mark this as a 240 watt input device. when, from a marketing perspective, a bigger number would look better, and from an electrical load perspective, at 1/8 load, ACD, this AVR would draw quite a lot more than 240 watts... unless there is some sort of thermal protection built in which limits the output power.

And again, for the JBL MA710, the formula looks like this:

Class D: 0.125*110 = 13.75 watts / .80 (eff) = 17.19 watts x 7 = 120.32 watts

So why did JBL mark the this as a 500 MAX watt device? Does this number suggest that as one approaches max power and 90 percent efficiency, this AVR could potentially (by the numbers given) put out as much as 55 percent of rated power, ACD, as in:

Class D: 0.55*110 = 60.5 watts / .90 (eff) = 67.2 watts x 7 = 470.6 watts

I doubt that's actually the case; nevertheless, the MAX input power of this device was derived from somewhere, and based upon the output power alone, 500 seems excessive.

Perhaps you could enlighten us?

No I can't explain why the different types of ratings are being used in manuals or marked on the rear panels (outside of perhaps where required by regulation)....I also wish they'd be more specific about spec conditions. I'd also like to see beefier power supplies in avrs generally.

Goes not just for this spec but others as well (like pre-out output for example).

 

[Strong Eagle]

I agree on all points. I suppose it doesn't matter in a way but it does rather seems like the "horsepower" ratings of various electrical devices such as saws and shop vacs... a so called "2.5 HP" circular saw would have to draw more than 15 amps on a typical US household circuit... it just aint so.

It seems that the folks that test these things could put this issue to bed once and for all by using an ammeter on the input line and some sort of power measurement on each output amp.

 

[lovinthehd]

I agree on all points. I suppose it doesn't matter in a way but it does rather seems like the "horsepower" ratings of various electrical devices such as saws and shop vacs... a so called "2.5 HP" circular saw would have to draw more than 15 amps on a typical US household circuit... it just aint so.

It seems that the folks that test these things could put this issue to bed once and for all by using an ammeter on the input line and some sort of power measurement on each output amp.

I think it's just the nature of marketing and specifications coexisting to an extent. Sometimes ya just gotta do the math. With ACD testing of amps you do somewhat get an idea of max usable power, tho.

 

[Verdinut]

We can't ignore the fact that the maximum usable output power is definitely dependent on the capacity of the power supply circuit.

 

[Hobbit]

I am struggling with some of the information posted here, so allow me to offer an alternative explanation which was hinted by one of the editorial comments:
Steady state, thermal equilibrium.
Please allow me to elaborate:
Your average multi channel receiver will not have to output gobs (technical term) of power playing your usual schtick to all channels or do it in a prolonged fashion. If you doubt that please examine your front main speakers and your other speakers for size.
As such during NORMAL operation (how many times was that pointed to during the article?) the total power output will not exceed the rating of the receiver and everyone is happy (we will not even get into how a satellite speaker which will play higher frequencies will probably not dip into low impedances and become as difficult of a load as front speakers, we will leave that for the advanced reader).
Want to make your average receiver squeal like a pig without playing the theme to deliverance?
Hook up a challenging speaker load for the main pair choose a setting that will direct most of the power to the front pair and give it the beans for a couple of hours and wait for the thermal protection to kick in.
See when I went to school we talked about quiescent, steady state, instantaneous and maximum continuous conditions. When you built a separate two channel power amp you don’t have the luxury of knowing HOW it will be used and hence you have to derive all this crud AND built an amp that can handle it. All of it. All day long. And yes digital smps power supplies can do amazing things but again if you ever had to design a gold rated supply and look at the specs you will see we are chasing an asymptote.
For the thermal equilibrium conversation let’s take as an example the insulation on transformer windings. They have a certain temperature they can withstand before going bye bye and there are many ways you can send them on their way to pushing daisies. Output stages (also have a maximum rated junction temperature) can similarly be modeled as heat pumps going to ambient through thermally resistive paths starting all the way from the junction. They still use silicon on those jobbies don’t they?
Large heavy expensive heat sinks in class A/AB amplifiers (actively cooled in professional equipment) have lower thermal resistance. Have you guys checked out the price for aluminum cans lately?
And for those that will cry class D those amplifiers as pointed out in the graph above also have power losses as well (though granted smaller ones but all the arguments hold) Intel and AMD have not figured out how to eliminate those in their processors (or build a zero switching time transistor) so with all due respect I don’t think Sony is up to the task.
Long story short (I know I know too late) in my opinion they are gaming the system and the specs like every other mainstream amplifier/manufacturer before them and they can get away with it because they are following a SYSTEM approach.
And speaking of specs a professor a long time ago pointed out that the cornerstone spec of the audio industry (watts rms) does not really make much sense if you really think about it. Root mean square is ironically a term used to denote the equivalent direct current that will produce the same POWER as the alternating current that we are measuring. But that term is necessary as ALTERNATING current (and its associated voltage) will turn negative over half of a full period (please feel free to look at the simple area under the curve derivation for a sinusoid to see how that 0.707 comes up). And while speakers CAN under certain extreme circumstances “push back” (most of them ARE basically motors thereby inductive reactive loads) the power generated by an amplifier’s output transistors is always positive (please let’s skip the conversation over an amplifier’s output impedance and its damping factor). Think about that rms thing for a while…
Let the hate mail come in….

Very well written, nothing contradicts Gene's, but the additional information is very useful.

Agreed, I found myself writing a simpler version of this. Basically, a 150x11 AVR isn't designed deliver 1650W for long periods of time. It's not designed to be a continuous output bench PS and will fail if used as one. And just because no one mentioned it, there are also caps in the AVR amps that store energy for immediate short-term use. Of course, it's not designed to be a pulse PS either. The combination of what it can deliver continuously, and reserve power is generally sufficient for our home theaters.

The rms argument again .

 

[PENG]

I agree on all points. I suppose it doesn't matter in a way but it does rather seems like the "horsepower" ratings of various electrical devices such as saws and shop vacs... a so called "2.5 HP" circular saw would have to draw more than 15 amps on a typical US household circuit... it just aint so.

It seems that the folks that test these things could put this issue to bed once and for all by using an ammeter on the input line and some sort of power measurement on each output amp.

I have been saying this for a long time, that such power output ratings manufacturers have been using from day one are almost meaningless. Just about the only meaningful aspects is when you used them to compare in a like for like situation, example, comparing the same series of Sony AVRs, or same series such as the Denon AVR-X3800H through AVR-A1H and from Marantz Cinema 70 through Cinema 30 and then you can perhaps rank them based on the power output based on the same measurement conditions, such as at the same THD+N, 20-20000 Hz etc.

To have output power rating much more meaningful practically, as you alluded to, they would have to measure the current and voltage, not power, and plot it against the test frequency within the range 20-20000 Hz, and THD+N.

Gene of Audioholics and Amir of the Audiosciencereview are the better ones as they do provide graphs, not just single point numbers:

Example:

Gene's: nice, but could be better if he provide at least one for different test frequency such as 100 Hz and 5,000 Hz.

Amir's:

This one is probably currently the best, because he uses more test different test frequencies, so the more technically oriented users could be happier as they could see the results for different test frequencies, not that critical in most cases, but is nice to see/have.

Again, ideally, they should go with voltage and current, not "power" because then many semi technical people won't complain on forums about their concerns about current capabilities for their so called high to drive speakers that may have excessively large power angles, and impedance dips, power ratings do tell the story to a large extent but nowhere near as good if voltage and current are measured under various test conditions.

 

[PENG]

Given that this is a class AB amp, how can this amp consume only 240 watts? Is this rating because of heating requirements?

This simple questions have been asked on various forums on almost weekly basis lol..

Simplified answer:

Manufactures, including Sony, rarely provide the conditions under which the power consumption is measured. In some cases, when thanks to Gene who asked Sound Unite/now Masimo, so we know Denon and Marantz seem to use something close to one or two existing standards for multichannel amps:

Not sure if this is the one HD linked earlier, but if you really want to know more, you can read the fine print:
Receiver Power Consumption Rating vs Output Power Is Not Watt You Think! (audioholics.com)

The key take away from Gene's excellent article using the Marantz SR8015 as example is in the following section:

Marantz SR8015 Example:

The SR8015 rated power 140wpc x 11 channels but the back panel power consumption is only 780 watts.

Marantz de-rates 2CH power rating to drive ALL 11 channels for the IEC 62368 safety test. In this case, 90.4 watts for ALL 11CH driven.

1/8th power (90.4 watts) = 11.3wpc / 0.17 eff = 66.5 watts

66.5 watts x 11 = 731 watts + 35 watts from HDMI, DAC = 766.5 watts < 780 watts back panel rating

Note: Our bench tests of the SR8015 produced 100wpc x 7 ACD which would yield a power consumption of 700/0.55 (eff) 1272 watts + 35 watts = 1307 watts > 780 watts back panel power rating.

Someone on an audio forum is about to type "But wait, 1307 watts > 10% above 780 watts (858 watts). Yes they are correct, however, this is NOT a violation of the safety standard since the ACD test is NOT considered to be a "normal operating" condition as previously stated.

Does Sony follow the same standard, you would have to ask Sony, or may be one day, @gene would ask them too, and oh, may as well ask Yamaha as well lol.

 

[dcrandon]

So... old thread... still very informative... and it leads to a couple of questions for me. My Sony STR-DN1080 appears to have fried itself, so time for a new AVR. The direct Sony replacement is the STR-AN1000. Its power ratings look like this.

View attachment 68744
View attachment 68745

Given that this is a class AB amp, how can this amp consume only 240 watts? Is this rating because of heating requirements?

On the other hand, the JBL MA710, a class D amplifier has the following specs.

View attachment 68746
View attachment 68747

Given that this is a class D with much higher efficiency, why would this amp have a maximum draw of 500 watts? Unless it really does put out more watts per channel, ACD?

Thank you.

Wait unitl Monday, 8/12/24 when the new FTC power ratings take effect, then look at their specs again.

Federal Register :: Request Access