# Wattage as the wrong way to find an AVR



## Ringstone (Jun 23, 2013)

I have had some pretty serious discussions with various vendors about real power for an AVR.

When a new customer looks at a receiver with 100 watts per channel for $400 and then sees another receiver advertising 75 watts per channel for $1000, both with similar connections and features, the obvious question is, "Why is one twice as expensive as the other and not as powerful?" (The example was comparing Sony STRDE series to the HK AVR series.) 
I posed this question to a buddy who pointed out that HK advertises their Amperage, which was 40 amps, vs. the Sony's 1 amp. Of course the types of materials and processors contribute greatly, but I had to admit that the Toroidal Transformer was significantly bigger on the HK.

Apparently the industry has never really settled on the correct way to "honestly" list the true power of an Amplifier. From what I understand, some companies apply a test tone of 1khz to the amplifier and turn it up until it clips......they call this the max output in Watts. 
Other companies use a sweep tone from 20hz to 20khz and find an average where the amplifier clips. 
Those amplifiers with more Amperage are able to more than triple their rated output, for brief periods and thus have a more "effortless" sound with less distortion. 

It was also explained to me, without breaking out formula's, that the Amperage is what allows an Amplifier to really get the work done, hence provide those peaks of power for high volume, accurate moments. 
I laugh when I realized that they are called Amplifiers and not Wattifiers. 

As I begin my search for a replacement to my HK 510 (75 per channel, at 40 amps) I am disappointed that most of the literature found online for AVR's doesn't clearly list Amperage. 

Any thoughts or suggestions for an AVR in the 1k range....one that has good true output? Or am I just obsessing on something that is no longer really considered?

Spence


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## rab-byte (Feb 1, 2011)

You are correct amplifiers are not wattifiers and power does not actually dictate performance. 

You're looking for all channels driven, RMS rated at 20khz to 20hz. Most receivers do not come close to their advertised power handling. 

If you find reviews from AV magazines or sites they'll often measure the power output and include that in the review. 

Let us know what speakers you have or want and everyone here will be happy to offer opinions as to matching equipment. 

Welcome to the shack.


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## tonyvdb (Sep 5, 2007)

I can tell you that Sony receivers preform very poorly as far as actual output per channel. Finding a receiver for $400 that will actually do true 100watts per channel you need to go a little higher. This Onkyo 809http://www.accessories4less.com/make-a-store/item/ONKTXNR809/Onkyo-TX-NR809-7.2-Channel-Network-A/V-Receiver/1.html is about the best you will do and is capable of doing 100watts per channel all channels driven.

The challenge is most receivers are not given a large enough power supply to drive all the amplifiers to there full output. They tend to distort long before they get near the rated levels.
Weight of the receiver is a good indication of how large the power supply is.


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## lcaillo (May 2, 2006)

While a typical Sony receiver will not deliver the current of a typical HK, the 40 to 1 comparison in amps is misleading. Please publish the whole specification. No AVR can deliver a continuous 40 amps. Most can deliver more than 1 for short periods of time.


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## scrarfussi (Nov 15, 2012)

i think some amps . are highly overated . like the anthem Mrx700
40amps is a lot of current is that divided by 7


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## primetimeguy (Jun 3, 2006)

Something that would draw 40 amps could not be plugged into a standard wall receptacle so I doubt that number is correct.


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## OZZIERP (Feb 19, 2012)

For most of the current crop of AVR's (Flagship) with A/B amps they seem to top out at 12.8 amps.
That number is far lower on the ones using digital amps since they use a switching power supply.


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## lcaillo (May 2, 2006)

primetimeguy said:


> Something that would draw 40 amps could not be plugged into a standard wall receptacle so I doubt that number is correct.


 Correct. A claim of 40 amps is meaningless without some qualification of how that is measured.


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## jon96789 (Mar 21, 2013)

You can usually go by the weight of the receiver for the power capability. In order to have high power reserves, the AVR must have a larger power supply (i.e. transformer and capacitors). AVRs can vary in weight from 20-60 lbs.

Sony's higher priced models (ES line) have beefier power supplies and can supply more power with all channels than their Best Buy models.

The only exception to the "poundage" rule would be AVRs with digital amps (class D, some Pioneer, B&O, Rotel). Digital amps are more efficient and weigh less than their Class AB brethren.


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## tba (Jun 10, 2013)

I am using a simple calculation for a RMS output power of an AVR. Start from mains consumption, e.g 1000 watt. Then divide to the no of channels, let's say 5, so 200 Watt/ channel. Multiply this with 0,7, so 140 Watt/ channel. All these considering the nominal load (Ohms) recommended by the producer.
This is a rudimentary method but not too far from reality, for the standard amps. Also, considers that all channels are driven in full which is valid only on a SACD or DVD Audio.
tba


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## tonyvdb (Sep 5, 2007)

tba said:


> I am using a simple calculation for a RMS output power of an AVR. Start from mains consumption, e.g 1000 watt. Then divide to the no of channels, let's say 5, so 200 Watt/ channel. Multiply this with 0,7, so 140 Watt/ channel. All these considering the nominal load (Ohms) recommended by the producer.
> This is a rudimentary method but not too far from reality, for the standard amps. Also, considers that all channels are driven in full which is valid only on a SACD or DVD Audio.
> tba


Mains consumption has nothing to do with the output. You can not go by the specifications on the back or in the manual. There is not one receiver out there that can output its rated watts level all channels driven. The entire calculation is flawed and very far away from reality.
Any input source can drive the receivers amps to full if using All channel stereo or even BluRay uncompressed audio and simply running the volume past what the amps can handle depending on the speaker load.
Way to many things to factor into the equation.


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## tba (Jun 10, 2013)

I was expecting for such reactions. The method I have given is based on a 30 years of amp manufacturing experience, considering an average efficiency of amps. I have mentioned standard amps like A or A/B class. When a switching power supply is used, is something else but is not the case in most AVRs. I will not go in this debate further but I kindly ask you to use an oscilloscope together with a signal generator and a fake load and you will see. You can not defy the relation between the mains consumption and the output of an amp simply by thinking that the energy used is transformed in useful audio power and the rest is going in heat. The ratio depends on the efficiency of the amp. 
Ok, finally is about to not fall in a the trap by believing the specs of lets say 7X100 watt with a 400 VA consumed from the mains.

tba


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## lcaillo (May 2, 2006)

tonyvdb said:


> Mains consumption has nothing to do with the output. You can not go by the specifications on the back or in the manual. There is not one receiver out there that can output its rated watts level all channels driven. The entire calculation is flawed and very far away from reality.
> Any input source can drive the receivers amps to full if using All channel stereo or even BluRay uncompressed audio and simply running the volume past what the amps can handle depending on the speaker load.
> Way to many things to factor into the equation.


Actually it has a great deal to do with output. It correlates with it very closely after correcting for amplifier efficiency and standby power. The problem is that you have to measure actual power consumption at idle and at full power, then know or calculate the efficiency of the amp. You are correct that specifications are not particularly reliable for power consumption. The problem is that output specs are often manipulated cleverly and are often misleading.


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## tonyvdb (Sep 5, 2007)

But the tests they use are even flawed, They use a 1k test tone on all channels to get the readings. it is very possible that a receiver could even peak momentarily above the rated wattage draw if being used under high demanding movies and such. 
My Onkyo 805 does not even have a "max watts draw" on the back it only states 9.5amps max. and Ive never seen it draw more than 3.2amps on my Eathereal power conditioner digital readout.


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## lcaillo (May 2, 2006)

I agree. But suggestions of using weight or power consumption are no better.


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## rab-byte (Feb 1, 2011)

Has anyone noticed that the person the started this thread hasn't posted back yet?


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## lcaillo (May 2, 2006)

That happens all the time. People sign up, post a bit, then don't come back, sometimes for a while, sometimes never.


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## 3dbinCanada (Sep 13, 2012)

NAD is the only receiver manufacturer I know off that rates all channels driven at full bandwidth. However, that alone is not a very useful measurement as I'm not aware of any where of any film sound tracks that runs full bandwidth across all 7 channels simultaneously. The other spec I do find useful is the 2 channel test running full bandwidth into 8 and 4 ohms respectively. An AVR should be able to approach twice the rated power into 8 ohms when delivering into 4 ohms. 

One aspect that limits all channel power delivery is the built in protection mechanism. Yamaha scores low on the all channel driven tests despite having robust power supplies and amplifier circuits because its protection mechanism is slightly agressive and engages much to early. However, it scores very well in the 2 channel test which indicates that it has good dynamic capability.


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## tonyvdb (Sep 5, 2007)

3dbinCanada said:


> I'm not aware of any where of any film sound tracks that runs full bandwidth across all 7 channels simultaneously.


I know that Transformers DOTM, 8mm (train wreck) and a couple others will use much of the surround channels simultaneously with the mains at the same level as the mains. I have confirmed this as I have a 8 channel level meter array that shows all the levels as they happen in my rack.


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## 3dbinCanada (Sep 13, 2012)

tonyvdb said:


> I know that Transformers DOTM, 8mm (train wreck) and a couple others will use much of the surround channels simultaneously with the mains at the same level as the mains. I have confirmed this as I have a 8 channel level meter array that shows all the levels as they happen in my rack.


Have you confirmed full bandwidth across all channels? These films are very much a minority. Furthermore, most people run their systems with a sub or two offloading all the bass to the sub therefore substantially reducing the load on the AVR. All channels driven is not a very useful or practical specification.


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## tonyvdb (Sep 5, 2007)

not confirmed full bandwidth however I do have an unusual setup in that all my surround speakers are capable of playing down to 40Hz and I run them at 60hz and Ive seen at reference level the surround channels peak at +8db on the meters (the meters go up to +15db) yes I have them calibrated.


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## 3dbinCanada (Sep 13, 2012)

tonyvdb said:


> not confirmed full bandwidth however I do have an unusual setup in that all my surround speakers are capable of playing down to 40Hz and I run them at 60hz and Ive seen at reference level the surround channels peak at +8db on the meters (the meters go up to +15db) yes I have them calibrated.


Nice setup.  

Are running seperates or arew you pwering them through the Onkyo. Like I said most people off load the bass to their subs which eases the burden on the AVR. I rather have my AVR perform well on the 2 channel test than the all channel test.


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## tonyvdb (Sep 5, 2007)

I have only my mains on a separate amp. everything else is through the 805. I have run it in the past with everything through the 805 and no issues.
Ive said it before that the 805 is a rare receiver in that bench tested it actually exceeded it output two channels driven and was able to do better than 110watts all channels driven. Not many if any receivers can boast those numbers.


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## 3dbinCanada (Sep 13, 2012)

tonyvdb said:


> I have only my mains on a separate amp. everything else is through the 805. I have run it in the past with everything through the 805 and no issues.
> Ive said it before that the 805 is a rare receiver in that bench tested it actually exceeded it output two channels driven and was able to do better than 110watts all channels driven. Not many if any receivers can boast those numbers.


NAD is the only other manufacturer that meets its all channels driven specs. Don't forget that protection circuits have a huge role in what a receiver will do with all channels driven.


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