a question on power...

I tried desperately to find this out without asking the group, for fear of revealing my ignorance on the subject, but I wasn't able to do it... so I know someone here can answer it and I'll swallow some pride.

Typically 7.1, 6.1, etc Receivers will list their RMS power output per channel in the optimal speaker setting, i.e. 110wper channel X 7 for a 7.1 receiver. Okay, cool... (and yes, I did read the article on this site about this being somewhat less than ideal way to measure it.... ). But, what if you are planning on using it only with 5.1 channels (at least for the time being). Does the power redistribute itself? In other words for this same receiver would it be 154w X 5?

In case the answer to the question is vendor-specific, I'm looking at the Yamaha HTR 5860. Thanks again!

No, the power won't redistrobute, but with less power demand than if all speakers were running, you will have cleaner power to your speakers.

Paul

No, it would still be 110 wpc.

Most receivers use a single power supply shared by all channels. Each channel is capable of 110 watts. Play them all simultaneously ("all channels driven") and the amount of power for each channel will drop. Manufacturers like H/K rate their receivers when all channels are driven while most others (Yamaha, Denon, Onkyo, etc) rate it when only 2 channels are driven. So, when only two channels are driven at the same time, you will get their stated power output of 110 watts; when more than two are driven at the same time, the power to each channel will drop.

The watts aren't redistrubuted but there will be more power available at clipping with less channels driven. Please see this from Sound and Visions lab tests on the Denon 3805. I think this is what you were driving at:

http://www.soundandvisionmag.com/assets/download/DenonAVR-3805lab.pdf

msmith855 said:

I tried desperately to find this out without asking the group, for fear of revealing my ignorance on the subject, but I wasn't able to do it... so I know someone here can answer it and I'll swallow some pride.

Typically 7.1, 6.1, etc Receivers will list their RMS power output per channel in the optimal speaker setting, i.e. 110wper channel X 7 for a 7.1 receiver. Okay, cool... (and yes, I did read the article on this site about this being somewhat less than ideal way to measure it.... ). But, what if you are planning on using it only with 5.1 channels (at least for the time being). Does the power redistribute itself? In other words for this same receiver would it be 154w X 5?

In case the answer to the question is vendor-specific, I'm looking at the Yamaha HTR 5860. Thanks again!

Click to expand...

It's an excellent question. Manufacturer's try to hide the real guts of receivers - the power supply, the transformer, and power consumption numbers. On pg. 94 of the Yamaha 5860, you can see the power consumption of the unit is 400 watts and weighs a little over 27lbs. By comparison, the Pioneer 1015 is 480 watts and almost 34lbs - pg 75 of their manual. You're getting a much beefier power supply, better transformer, and larger heat sinks. The 5890 would be a closer comparison of the two. The wattage ratings are overbloated and should be ignored. They don't tell you the milliseconds each unit can hold that output power before distortion is audible. Same reason you can buy a $130 Insignia 100x6 watt receiver at Best Buy - 19lbs, no mention of power consumption (try to find the manual on the website or even any indication they sell receivers). Distortion is rated at 1.0% at 1kHz instead of .05% at full bandwidth (20-20,000Hz) to pad the numbers (and most likely tested at 6 ohms instead of 8!). Take a good look at Harman Kardon's 235 - the second lowest offering of their surround sound receivers. It has a power consumption of 890 watts, weighs 33lbs, and is rated at a measly 50 watts per channel. Again, this is the 235, not the 435, 635, or massive 7300. If all these mid level receivers were tested on the same professional equipment, you'd find power ratings between 30 and possibly 60 watts per channel.


http://www.yamaha.com/yec/customer/manuals/PDFs/HTR-5860.pdf

http://www.pioneerelectronics.com/pio/pe/images/portal/cit_11221/218219130VSX1015TXOperatingInstructions.pdf

http://www.bestbuy.com/site/olspage.jsp?skuId=7016463&productCategoryId=cat03031&type=product&tab=1&id=1099394773266

http://www.harmankardon.com/specifications.aspx?Region=USA&Country=US&Language=ENG&cat=REC&ser=&prod=AVR 235&sType=C

msmith855 said:

I tried desperately to find this out without asking the group, for fear of revealing my ignorance on the subject, but I wasn't able to do it... so I know someone here can answer it and I'll swallow some pride.

Typically 7.1, 6.1, etc Receivers will list their RMS power output per channel in the optimal speaker setting, i.e. 110wper channel X 7 for a 7.1 receiver. Okay, cool... (and yes, I did read the article on this site about this being somewhat less than ideal way to measure it.... ). But, what if you are planning on using it only with 5.1 channels (at least for the time being). Does the power redistribute itself? In other words for this same receiver would it be 154w X 5?

In case the answer to the question is vendor-specific, I'm looking at the Yamaha HTR 5860. Thanks again!

Click to expand...

As opposed to others here, I'd say there's a chance of some power redistributing.

The reason is simple enough. Practically all HT receivers are fed power from a single source, i.e. the central power supply. When you ask that power supply to feed full rated power into all seven channels, it will do so and if the receiver is any good, it will fulfill its specs.

If you use five rather than all seven channels, the demands on the power supply will be smaller, because you will have two channels working at idling power. This will in all probability allow the power supply to deliver a little bit more voltage to the rails, given that it is not at all likely to be regulated, and that it will rely on electrolytic caps for its reserves and filtering.

You will, in fact, be given that little bit extra of the difference in power supply rail voltages between load off and full load on conditions; it ALWAYS exists, and the difference depends on the overall quality of the power supply. Typically, it's 2,5-3,5V between full on and load off.

Ultimately, you can find out by attaching a voltmeter and measuring the supply rail voltages in its load off state, i.e. with the volume pot turned to its minimum. Then you can risk your life by throwing everyting into high gear (but NEVER turn the pot to its max, half way worst case, you don't want clipping!) for several seconds, and watch your voltmeter needle or display go down somewhat.

Obviously, the actual differences are very small, in the order of say 2...4 watts per channel, no more. As others have pointed out, your bigger benefit will be cleaner power.

Only switching to classic two channel stereo could bring such significant offloading of the power supply that you could record larger power gains, but even then, they wouldn't be anything to write home about.

Cheers,
DVV

Buckeyefan 1 said:

It's an excellent question. Manufacturer's try to hide the real guts of receivers - the power supply, the transformer, and power consumption numbers. On pg. 94 of the Yamaha 5860, you can see the power consumption of the unit is 400 watts and weighs a little over 27lbs. By comparison, the Pioneer 1015 is 480 watts and almost 34lbs - pg 75 of their manual. You're getting a much beefier power supply, better transformer, and larger heat sinks. The 5890 would be a closer comparison of the two. The wattage ratings are overbloated and should be ignored. They don't tell you the milliseconds each unit can hold that output power before distortion is audible. Same reason you can buy a $130 Insignia 100x6 watt receiver at Best Buy - 19lbs, no mention of power consumption (try to find the manual on the website or even any indication they sell receivers). Distortion is rated at 1.0% at 1kHz instead of .05% at full bandwidth (20-20,000Hz) to pad the numbers (and most likely tested at 6 ohms instead of 8!).


http://www.yamaha.com/yec/customer/manuals/PDFs/HTR-5860.pdf

http://www.pioneerelectronics.com/pio/pe/images/portal/cit_11221/218219130VSX1015TXOperatingInstructions.pdf

http://www.bestbuy.com/site/olspage.jsp?skuId=7016463&productCategoryId=cat03031&type=product&tab=1&id=1099394773266

Click to expand...

Buckeye, there are other factors you have to include in your reasoning.

One, the quality of materials and manufacture of the power transformers. This is a hornet's nest all by itself, because it has many variables, all of which influence both the quantity and quality of what you hear VERY directly. For example, use OFC high purity copper wiring instead of the usual standard fare, and your overload characteristics and tranformation factor go up significantly, you hear cleaner and clearer sound. Then there's the core - type, quality, construction. Then the insulation. Then the design. You get the idea.

Two, don't forget the transformation factor. Your transformer may take your 120 VAC and turn it to say 35-0-35V. However, after the bridge rectifiers, this will become 49-0-49V, and since the current drawn is still the same, while power is still defined as AxV, your actual power factor is changed. Working in the opposite direction is the transformer quality, which may sag this down to say 42-0-42V - I have actually seen this happen, and not once. I start cutting my veins open when my transformer sags by more than 3V AFTER the rectifiers, not to mention the fact that if I needed 49-0-49V, I'd specify thebtransformer to be able to deliver its 35-0-35V at full load on conditions, not idle.

Then come the rectifier(s) and filter caps. God alone, if even He, knows what you'll find, I've seen it from really bad to quite deecent. But in general, ANY receiver is a load of compromises, and power supplies are bulky and expensive, so manufacturers tend to "save" on them, the price being sound quality.

To the best of my knowledge, the only worthwhile way to tune up your HT receiver is to buy a decent power line filter. This will offload the power supply so that the electrolytic caps will act more as power reserves and less as filters, since they being fed cleaner power.

Cheers,
DVV

DVV said:

As opposed to others here, I'd say there's a chance of some power redistributing.

The reason is simple enough. Practically all HT receivers are fed power from a single source, i.e. the central power supply. When you ask that power supply to feed full rated power into all seven channels, it will do so and if the receiver is any good, it will fulfill its specs.

If you use five rather than all seven channels, the demands on the power supply will be smaller, because you will have two channels working at idling power. This will in all probability allow the power supply to deliver a little bit more voltage to the rails, given that it is not at all likely to be regulated, and that it will rely on electrolytic caps for its reserves and filtering.

You will, in fact, be given that little bit extra of the difference in power supply rail voltages between load off and full load on conditions; it ALWAYS exists, and the difference depends on the overall quality of the power supply. Typically, it's 2,5-3,5V between full on and load off.

Ultimately, you can find out by attaching a voltmeter and measuring the supply rail voltages in its load off state, i.e. with the volume pot turned to its minimum. Then you can risk your life by throwing everyting into high gear (but NEVER turn the pot to its max, half way worst case, you don't want clipping!) for several seconds, and watch your voltmeter needle or display go down somewhat.

Obviously, the actual differences are very small, in the order of say 2...4 watts per channel, no more. As others have pointed out, your bigger benefit will be cleaner power.

Only switching to classic two channel stereo could bring such significant offloading of the power supply that you could record larger power gains, but even then, they wouldn't be anything to write home about.

Cheers,
DVV

Click to expand...

Maybe this is just an exercise in semantics but I think of redistribute as taking something from one place and moving it to another. Verses generating more power due to a smaller load from the power supply. I'm not an EE but I agree with your analysis.

DVV said:

Buckeye, there are other factors you have to include in your reasoning.

One, the quality of materials and manufacture of the power transformers. This is a hornet's nest all by itself, because it has many variables, all of which influence both the quantity and quality of what you hear VERY directly. For example, use OFC high purity copper wiring instead of the usual standard fare, and your overload characteristics and tranformation factor go up significantly, you hear cleaner and clearer sound. Then there's the core - type, quality, construction. Then the insulation. Then the design. You get the idea.

Two, don't forget the transformation factor. Your transformer may take your 120 VAC and turn it to say 35-0-35V. However, after the bridge rectifiers, this will become 49-0-49V, and since the current drawn is still the same, while power is still defined as AxV, your actual power factor is changed. Working in the opposite direction is the transformer quality, which may sag this down to say 42-0-42V - I have actually seen this happen, and not once. I start cutting my veins open when my transformer sags by more than 3V AFTER the rectifiers, not to mention the fact that if I needed 49-0-49V, I'd specify thebtransformer to be able to deliver its 35-0-35V at full load on conditions, not idle.

Then come the rectifier(s) and filter caps. God alone, if even He, knows what you'll find, I've seen it from really bad to quite deecent. But in general, ANY receiver is a load of compromises, and power supplies are bulky and expensive, so manufacturers tend to "save" on them, the price being sound quality.

To the best of my knowledge, the only worthwhile way to tune up your HT receiver is to buy a decent power line filter. This will offload the power supply so that the electrolytic caps will act more as power reserves and less as filters, since they being fed cleaner power.

Cheers,
DVV

Click to expand...

DVV,

Good points, but for the laymen here with a $500 budget, they aren't looking at class A amps with balanced topology, push-pull designs with 200 amperes of output current, and metal film resistors and film capacitors. It just won't happen with these Yamaha's, Pioneers, and HK's.

Some very interesting discussion, and it's even making me lean more towards Pioneer after all (maybe... if I can tear away from my Yamaha bias)....

I've heard the term "cleaner power" before... but what does that REALLY mean to me? is there a real discernable difference?

msmith855 said:

Some very interesting discussion, and it's even making me lean more towards Pioneer after all (maybe... if I can tear away from my Yamaha bias)....

I've heard the term "cleaner power" before... but what does that REALLY mean to me? is there a real discernable difference?

Click to expand...

In a nutshell, it just means at higher volumes, you'll have less audible distortion. Distortion can color sound, something you want to avoid. Better power supplies, transformers, and large heat sinks will help ensure this doesn't happen. You still need to utilize your ears when driving speakers at high levels.

DVV said:

But in general, ANY receiver is a load of compromises, and power supplies are bulky and expensive, so manufacturers tend to "save" on them, the price being sound quality.

Click to expand...

Just to point out an issue to general readers: be weary of such claims as sound quality difference as made in the above quote. Such claims need to be substantiated via measurements that directly coorelate with auditory perceptual research, or alternatively, proper double-blinded listening experiments that test only the variable(s) under claim. In lack of such supporting data to accompany these previously unfounded claim(s), one can only assume that such statement(s)[in regards to ANY reciever paying the price of sound quality or any such previously unfounded claim] is a subjective opinion[based on sighted or other flawed listening tests) as opposed to a verified fact.

-Chris

I would suggest reading up on the subject of power ratings on this site Here:

http://www.audioholics.com/techtips/audioprinciples/amplifiers/receiverpower.php

http://www.audioholics.com/techtips/audioprinciples/amplifiers/allchannelsdriven.php

As others have pointed out, many/most receivers are not able to put out their rated power into all channels simultaneously. Each channel is individually capable of providing the rated power, and typically the rated power is also available from two channels simultaneously (sort of a holdover from the stereo-only days). But, with all channels driven, you start running into the limitations of the power supply that is providing the voltage rails (and sourcing the current) for all of the amplifier channels.

The Yamaha model you are interested in has basically the same power supply and amplifier design as my receiver, the Yamaha RX-V750. The two are rated a little differently, but the two sets of specs apply to either unit. The individual amplifier channel design of this receiver is pretty robust, and does a decent job with low impedance speakers (as long as you keep the impedance switch in its 8 ohm setting, regardless of the actual speaker impedance). By this I mean that each channel's circuitry can source enough current so that the power delivered into 4 ohms is (more or less) twice what the power delivered into 8 ohms is.

However, the stated power consumption of the unit is only 400W or so. When you de-rate this to reflect the efficiency of the power supply, you can guesstimate that the total power delivered to all channels probably can't get too much above 300W, at least not steady-state. Sure enough, in a Sound and Vision test of my RX-V750 receivera year or so ago, the measured power into 5 channels simultaneously was 61 W (i.e., 305W total).

Is this a problem in real use? Almost certainly not, for the following "qualitative" reasons:

1. The signal being fed to the 5 or 7 channels isn't the same, so power peaks will not occur at the same time.
2. The signal is not a steady-state signal, so that peak power is only demanded for short intervals (and, the short-term peak power capacity of the receiver is higher than both the rated per-channel power rating, AND also the power-supply limit.
3. Average power being delivered to each channel, even when listening at loud volume levels is probably only a couple of watts.
4. The volume difference between 60 wpc and 100 wpc (assuming you were listening to identical steady-state signals on 5 channels) is not all that much - about 2 dB

In short, I wouldn't be too concerned about the power-supply robustness of the Yamaha. That said, it does sound as if the Pioneer may have a slightly more robust power supply, given the indirect evidence that its stated "from the wall" power consumption is a bit higher, and that it weighs more (which is often an indicator of a beefier power supply transformer, as well as possibly more, and larger, capacitors. Whether this makes more difference to you than sonic differences and/or feature differences between the two units, only you can say. If it were me, I would put more weight on any sonic and feature differences. It might also be worthwhile to see which unit runs hotter, when driving the same set of speakers at the same perceived volume level.

rschleicher said:

As others have pointed out, many/most receivers are not able to put out their rated power into all channels simultaneously.
...
Is this a problem in real use? Almost certainly not, for the following "qualitative" reasons:

1. The signal being fed to the 5 or 7 channels isn't the same, so power peaks will not occur at the same time.
2. The signal is not a steady-state signal, so that peak power is only demanded for short intervals (and, the short-term peak power capacity of the receiver is higher than both the rated per-channel power rating, AND also the power-supply limit.
3. Average power being delivered to each channel, even when listening at loud volume levels is probably only a couple of watts.
4. The volume difference between 60 wpc and 100 wpc (assuming you were listening to identical steady-state signals on 5 channels) is not all that much - about 2 dB

Click to expand...

I think that is an excellent summary of the relevant issues. I was going to mention some of those things but thought, nope, better not...it will just start another round of the all channels driven vs 2 channel driven power rating controversy.

I think someone has posted something similar before, but for convenience let me do it again anyway.

The following information are from H.T. mag Dec 2004 (Pioneer), Aug 2004 (HK & Denon, same reviewer). Some of the published results are quite consistent with those published by other British AV magazines.

Pioneer 52TX, consumption=630 VA, or 480W (implying power factor=480/630=0.762)
Note that neither Pioneer nor Denon explicity tell us their power consumption numbers are maximum, typical, average, continuous, short time rated, or whatever. We can make all kinds of assumption but strictly speaking we do not know for sure what the basis are.

5X115.3 @ 0.1%, 5X129.7 @ 1% into 8 ohms
2X121.2 @ 0.1%, 2X143.1 @ 1% into 8 ohms
2X197.0 @ 0.1%, 2X231.4 @ 1% into 4 ohms

Denon 3805, consumption=852 VA (7.1AX120V)
Assuming power factor=0.8, consumption=680W approx.

5X114.9 @ 0.1%, 5X125.0 @ 1% into 8 ohms
2X132.2 @ 0.1%, 2X162.3 @ 1% into 8 ohms
2X218.4 @ 0.1%, 2X243.0 @ 1% into 4 ohms

HK 630, consumption=1040W (specified as maximum)
Note that Denon/Pioneer does not state their consumption as maximum explicitly.

5X79.7 @ 0.1%, 5X93.3.0 @ 1% into 8 ohms
2X84.6 @ 0.1%, 2X100.6 @ 1% into 8 ohms
2X146.9 @ 0.1%, 2X170.8 @ 1% into 4 ohms


HK330, consumption=890W (same as the 230, 235 and is specified as maximum)
No H.T. mag test data for the HKAVR330, but according to S&V Mar 2004
http://www.soundandvisionmag.com/assets/download/322004163324.pdf

1X95W @ clipping, 1 KHz into 8 ohms
1X148W @ clipping, 1 kHz into 4 ohms
2X86W @ clipping, 1 kHz into 8 ohms
2X25W @ clipping, 1 kHz into 4 ohms
Note that when both channel driven into 4 ohms, the 330 activated its protection mode after 0.5 sec if it was asked to produce more than 25W.

So based on the HT mag/S&V lab measurements, you can guess whether you can get more power if you run less channels. To me, you can't just take those power consumption numbers to the bank. Also, it would appear that the HK receivers may have higher losses, e.g., the AVR330 consumes 118W even at idle. No doubt their power consumption numbers are impressively high as pointed out by Buckeyefan1

BuckeyeFan1,

The HKAVR235's 890W power consumption may or may not be a continuous rating. They call it "maximum". And aren't you happy to see that despite HK's often emphasized "high current capability" (they do specify it as an "instantaneous" rating only), the Denon actually does better than the AVR630 in power into both 8 ohms and 4 ohms.

The only HK models the 3805 cannot beat are the 7200/7300. Those are just monsters, and there is nothing our 3805s can do about it.

BuckeyeFan1,

The HKAVR235's 890W power consumption may or may not be a continuous rating. They call it "maximum". And aren't you happy to see that despite HK's often emphasized "high current capability" (they do specify it as an "instantaneous" rating only), the Denon actually does better than the AVR630 in power into both 8 ohms and 4 ohms.

The only HK models the 3805 cannot beat are the 7200/7300. Those are just monsters, and there is nothing our 3805s can do about it.

Click to expand...

I am happy. Thanks for asking. But part of that is I just got back from a nice ride on the Road Star Warrior and I have bugs in my teeth. I'm also on my third St. Pauli Girl. The happiness continues!

A lot of you may not remember one of my very early posts, but my Denon 3805 was getting so hot inside my entertainment center, I installed a CPU fan directly over the heat sink that kicks on with the receiver. I've heard the HK's run just as hot. I don't know that excess heat is an issue when these heatsinks are as large as a 15lb dumbell, but they sure create a small furnace around them.

I am extremely impressed with the Denon 3805. It's just a little out of reach for most of the newbies here, so it's hard to justify when there is such a great selection for almost half the asking price. If these newbies shop hard for speakers with higher spl ratings, the entire powersupply issue is out the window. Wouldn't it be wonderful if all future speakers came with a 94dB or higher spl rating?

One other reason why you are happier if I remember correctly you didn't pay as much as some of us did. I paid C$1680 or US$1350 incl tax. You are absolutely right, my Veritas are 87 dB. If they were only 90 dB, I would not have bothered hooking up the 3805 with the amp. I wish there are more high quality speakers out there that are more efficient than 90 dB.

Duffinator said:

The watts aren't redistrubuted but there will be more power available at clipping with less channels driven. Please see this from Sound and Visions lab tests on the Denon 3805. I think this is what you were driving at:

http://www.soundandvisionmag.com/assets/download/DenonAVR-3805lab.pdf

Click to expand...

I still own a working Pioneer vsx-903s. It's a Dolby Pro Logic unit that has two amps, one for the front lcr at 100 watts for each channel and the second for the rear surrounds at 100 watts for each of the two speakers. When you switch this receiver to 2 channel stereo mode its rating is 130 watts per channel.

Really quite an odd piece of gear I believe.

DVV said:

For example, use OFC high purity copper wiring instead of the usual standard fare,

Click to expand...

DVV said:

What may be your evidence for this claims? Any worthwhile resistance change?

Then the design. You get the idea.


I am trying but my reading tells me otherwise

"Topological Analysis of Consumer Audio Electronics: Another Approach to Show that Modern Audio Electronics are Acoustically Transparent", Rich, David and Aczel, Peter, 99 AES Convention, 1995, Print #4053.


To the best of my knowledge, the only worthwhile way to tune up your HT receiver is to buy a decent power line filter.


Maybe an expansion of this knowledge is in order?

This will offload the power supply so that the electrolytic caps will act more as power reserves and less as filters, since they being fed cleaner power.

You think?

Click to expand...