Yamaha Power consumption clarification help

[dees]

Please help me out.
I've noticed everyone here is very knowledgable about Yamaha receivers and was hoping someone could clear this up.

I recently purchased an htr-5760 and read the power consumption is 400 watts. Through all the posts I've read, I understand output power can't be higher than input power. So, I thought for a 7 channel receiver 400 watts doesn't leave much room for output power after you take into acount innefficiency.

I then checked the power consumption for high end Yamaha receivers and realized that except for their highest end model, they are all around 500 or less watts.

This doesn't add up to me. I can't believe that a $2500 receiver (the rx-z1) has so little output power. There's got to be something else coming into play.

similarly priced Onkyo, Denon, HK receivers all have higher consumption/input power. Yamaha is renowned for great audio, this can't be right. Can someone tell me what's going on.

 

[Buckeyefan 1]

The Denon 3805 puts out about 77 watts into 7 channels at rms, or 539 total watts. It's only slightly stronger than the Yamaha 2500. It can obtain 160 watts into two channels at 6 ohms at .1% THD, or 320 watts. Only when you get up into the flagship receivers, is there more output. The HK7300 puts out 139 watts into 7 channels, or 973 watts. You'll never realize this much power as a sine wave, or constant noise. Your 5760 is probably putting out somewhere in the neighborhood of 35-40 watts per channel if all 7 channels are driven at full frequency at .05 thd.

 

[Yamahaluver]

Thats nominal rating, check the manual for the max rating, in case of my Yamaha MX-1 power amp, the nominal is 550W and max is 1500W, the Z9 comes in at 1450Wmax.

 

[dees]

buckeye fan-
If you look at the receivers that are around the same price as the Yamaha 5760, the Onkyo 602 has 800 watts power consumption, the HK 235 has 895 watts max, even the denon 1905 has 600 watts consumption. And these are only the brands I looked up. Compared to the 400 watts of my receiver, these should blow it away through sheer power and dynamic headroom. But, Yamaha isn't known as a slouch compared to any brand. ???

Yamahaluver- If it doesn't say in the manual, how can I determine what the max power consumption is? How do I know that 400watts isn't already max power?

Whats the deal?

 

[Buckeyefan 1]

Go by amps, not watts.

See if you can find out how many amps the power consumption is. My Denon 3805 is 7.1 amps, while the Denon 5805 monster is 13 amps. I would go by amps over watts. The Denon 1705 is 4 amps, and the 1905 is 4.5 amps. There are no variables with amps like there are watts.

 

[dees]

aren't watts equal to amps times 120?

or amps equal to watts divided by 120?

 

[soniceuphoria]

Your method is correct.
Watts / amps = volts
amps x volts = watts
watts / volts = amps
volts / amps = ohms
amps x ohms = volts
volts / ohms = amps

the measurement of watts is standard and as long as the device used to measure is calibrated and/or the persons math skills are sharp a watt is a watt. Why do you think the speaker industry standard for testing for sensitivity is 1watt/1meter, if a watt varied then these specs would be meaningless. I think that a few people need to look further into ohms law. Happy Listening.
Greg

 

[Buckeyefan 1]

Sonic - you are correct. I should have said power output specs. Output power specs vary on receivers based on the total harmonic distortion used in testing. Watts are watts, but will vary according to the level of accepted distortion. The entry level Japanese receivers are known for rating their units at higher distortion levels and 6 ohms instead of 8. They play with numbers to sell their product. My guess is that Yamaha may be using an average figure of power consumption, while the others use a maximum figure. It doesn't make sense Yamaha is that much lower than the others, especially considering the weight of their 5890 and 2500 models. They are beefy, and have very similar specs to their Denon, Onkyo and Pioneer counterparts.

 

[DVV]

Sonic - you are correct. I should have said power output specs. Output power specs vary on receivers based on the total harmonic distortion used in testing. Watts are watts, but will vary according to the level of accepted distortion. The entry level Japanese receivers are known for rating their units at higher distortion levels and 6 ohms instead of 8. They play with numbers to sell their product.

Not strictly true.

ANY amp will have higher distortion into 6 ohms than it has into 8 ohms simply because it is required to deliver more current into 6 ohms for the same nominal voltage. This in turn means it's dissipating more power - and more power by default means higher distortion.

In real life, however, the difference can be effectively meaningless. It's generally accepted that only an odd piano meister can hear THD at 2%, most of us are sentenced to around 3% THD (however, with intermodulation distortion - IM - and transient intermodulation distortion - TIM or TID - that drops down to just 0.3%). Therefore, to most of us, it's all the same thing whether it's producing 0,000000001% or 1% of THD, we can't hear it anyway.

It could also be argued that lower THD specs also mean higher NFB levels, which is NOT good for TIM; this is not necessarily so, but you'll find that in real life (or economics of mass manufacture, if you like) that's all too often quite true.

My guess is that Yamaha may be using an average figure of power consumption, while the others use a maximum figure. It doesn't make sense Yamaha is that much lower than the others, especially considering the weight of their 5890 and 2500 models. They are beefy, and have very similar specs to their Denon, Onkyo and Pioneer counterparts.

On the other hand, it could well be so. Perhaps Yamaha opted for lower supply rails, but added extra muscle on current delivery in terms of lower load impedance tolerance.

The only sure-fire way to KNOW if this is so is to test them.

Cheers,
DVV

 

[dees]

either way, would it be safe to assume that the low power consumption for these receivers is not a fair indicator of actual output power?

 

[DVV]

either way, would it be safe to assume that the low power consumption for these receivers is not a fair indicator of actual output power?

Not fair, no. It is an indicator, definitely, but it doesn't show up the quality and quantity of the power supply, which always plays a big role in everything.

For example, two products, both rated the same, one has say two 12,000uF caps for all of it, while the other has say 18,000 uF caps - guess which one will deliver higher peaks?

Furthermore, it's quite possible that one product could have a significantly better QUALITY power transformer than the other; in that case, its better quality tranformer will definitely deliver more peak power than others.

Lastly, since there are no hard wired standards, one is always left to guess whether what he's seeing is the average or peak power requirement. And this is no small thing, because a say 400 VA toroid, if well made, will be capable of delivering no less than twice its rated power in short term peaks before it starts to seriously saturate, whereas run-off-the-mill stuff will saturate at 500 VA peak. And that's 300 VA of a difference we're talkning about.

By way of illustration, Krell's integrated amp, now some years ago, rated at 2x150/300W into 8/4 ohms, used a 400 VA toroid. Defies logic, at first glance, doesn't it? How can you have 600 watts of output power from a 400 VA transformer? Well, if it's really well made, and that one was really well made, it could pump out no less than 800 VA, I will guarantee it.

Don't forget that power, as defined by watts, is volts times amps. A 100 VA toroid, delivering say 2x25V, will by that reasoning be delivering 2x2 amps to qualify as 100 VA. But, after full bridge rectification, those 2x25V become (25 times sq. rt of 2, or 1.41) 2x35V, while the current stays the same. That's the conversion factor which is all too often just forgotten. The difference between peak and RMS.

Cheers,
DVV

 

[dees]

DVV,
Thank you. That clears up much of my confusion.
I'm sure Yamaha employs quality transformers that even things out.

Although I'm not quite sure what the difference between VA Watts and regular watts is. I noticed that the yamaha 5760 power consumption says 400 watts/ 500 VA. Is VA max power?

 

[MacManNM]

On the other hand, it could well be so. Perhaps Yamaha opted for lower supply rails, but added extra muscle on current delivery in terms of lower load impedance tolerance.

The only sure-fire way to KNOW if this is so is to test them.

Cheers,
DVV

If the supply rails are lower voltage, the output rating must go down, unless they are changing the impedance of the system. 20 Volts on the rails into an 8 ohm speaker is 50 watts. It doesnt matter how much current is behind it.

 

[PENG]

DVV,
Thank you. That clears up much of my confusion.
I'm sure Yamaha employs quality transformers that even things out.

Although I'm not quite sure what the difference between VA Watts and regular watts is. I noticed that the yamaha 5760 power consumption says 400 watts/ 500 VA. Is VA max power?

You keep asking the right questions, sound like you are an EE yourself, are you testing us here?

Just in case, Power (in Watts) = Power (in VA) X power factor. VA being VoltsXAmps. This is applicable on the supply (a.c.) side. Power factor is the consine of the phase angle between the voltage and current phasor (or, vector, if you prefer to call it that). For pure resistive load, power factor = 1, inductive load will get you a power factor of less than 1, in the extreme case, 0, as cosine 90 degree is 0, for a pure inductive or pure capacitive load (that hardly exists). If the 5760 specifies 400W/500VA, the power factor at the 400W point would be 400/500=0.8.

Some manufacturers, e.g., Harman Kardon, provides figures specifically for idling and maximum. The catch is, still, they do not tell you whether that "maximum" is a continuous rating or O/L rating. As others had pointed out, a well make power transformer has excellent short term overload capacity.

I really hope one of these days, some audio design engineer at Yamaha or Denon would comment on whether their "power consumption" figures at the back of their receivers are "nominal", under "typical" listening conditions, "maximum", or whatever. Until then, this debate, or guessing game will go on.

Whether all this matter or not, ask Gene, I think he probably won't be getting tired of telling us just one more time,... yet.

 

[Yamahaluver]

If the manual for Yamaha does not indicate Max power for your unit, try and check out the Yamaha Japan site, they will probably have the max consumption for your unit listed.

 

[dees]

This is what I understand so far, please correct me if I'm wrong: AV power is a form of power consumption that can potentially be doubled depending on the speaker impedance and quality of the transformer? And can be used to determine output power?

 

[DVV]

If the supply rails are lower voltage, the output rating must go down, unless they are changing the impedance of the system. 20 Volts on the rails into an 8 ohm speaker is 50 watts. It doesnt matter how much current is behind it.

Not quite so, you overlook voltage drops across active devices (0,65V for NPN and 0.7V for PNP transistors). To have 20V rms leaving your amp, and this is 28,3V peak, you need a power supply with about +/-35V rails.

As for the current, all you need is what the load requires. For 8 ohm speakers, this will be 3.53 amps peak; bit if that's what you have, and the load impedance drops to 4 ohms, you won't get over half the rated power, 25W. In other words, your current capability will determine how load tolerant your amp is, plus of course the amp's design.

In fact, talking about volts and amps is wrong, we should be talking about joules, or energy.

Cheers,
DVV

 

[BJP]

The Denon 3805 puts out about 77 watts into 7 channels at rms, or 539 total watts. It's only slightly stronger than the Yamaha 2500. It can obtain 160 watts into two channels at 6 ohms at .1% THD, or 320 watts. Only when you get up into the flagship receivers, is there more output. The HK7300 puts out 139 watts into 7 channels, or 973 watts. You'll never realize this much power as a sine wave, or constant noise. Your 5760 is probably putting out somewhere in the neighborhood of 35-40 watts per channel if all 7 channels are driven at full frequency at .05 thd.

Buckeyefan1, how did you determine how much watts the 3805 and 7300 puts out? I thought the 3805 puts out 120 watts into 7 channels.

Thanks,
BJP

 

[Buckeyefan 1]

Buckeyefan1, how did you determine how much watts the 3805 and 7300 puts out? I thought the 3805 puts out 120 watts into 7 channels.

Thanks,
BJP

Sound and Vision Magazine reviews. Check the archives. Their "In the lab" tests are on the last page. Click on the PDF file. The HK was reviewed last November. The Denon may have been July/Aug? I think their figure was a little higher than some other reviews for the Denon, but still under 100 watts.
www.soundandvisionmag.com

The 77 watts rating is right here in the Audioholics review under "build quality."
http://www.audioholics.com/productreviews/avhardware/Denon-AVR3805_review10.php
This goes along with what DVV is trying to tell us in laymans terms.
Based on the fuse rating of 7.1 amps, we can deduce that the power transformer is around 850VA (7.1A x 120V). Taking into account amplifier and power supply efficiency and processor overhead, true output power in 7-channels all-channels-driven would be about 850 x 0.7 – 50 = 545 Watts / 7 = 77 watts per channel assuming the receiver doesn’t have built-in current limiting.

 

[MacManNM]

Not quite so, you overlook voltage drops across active devices (0,65V for NPN and 0.7V for PNP transistors). To have 20V rms leaving your amp, and this is 28,3V peak, you need a power supply with about +/-35V rails.

As for the current, all you need is what the load requires. For 8 ohm speakers, this will be 3.53 amps peak; bit if that's what you have, and the load impedance drops to 4 ohms, you won't get over half the rated power, 25W. In other words, your current capability will determine how load tolerant your amp is, plus of course the amp's design.

In fact, talking about volts and amps is wrong, we should be talking about joules, or energy.

Cheers,
DVV

Are you clueless or do you just like to show that you have some engineering knowledge? 20 volts into 8 ohms is 50 watts. Period. Loss inherent to internal devices is irrelevant.

Are we timing our audio equipment now? Joules= Watts X Seconds.

Watts in the case of audio is RMS; a 50-watt amp has an infinite amount of Joules output?


So we rate the amp at 1 KHz?

50 Watts sounds much better than 50 mJ