The All Channels Driven Amplifier Controversy

[Votrax]

Sorry to be a stickler, but no where on the back panel does it say power consumption on ANY Haman Kardon receivers. I did check the .pdf file and it does not state power consumption. Here is the only power consumption spec offered on the AVR-330: http://www.harmankardon.com/specifications.aspx?Region=USA&Country=US&Language=ENG&cat=REC&ser=&prod=AVR 330&sType=S Scroll down to the bottom of the page.

It's just left of the power cord. It says Input 120V/60Hz 350W

http://www.harmankardon.com/back.aspx?prod=AVR 330&cat=REC&sType=S&Region=USA&Country=US&Language=ENG&ImgName=AVR330B.jpg

 

[Votrax]

On another note the rated power consumption on the rear of receivers is not always the maximum. The rear my receiver says the power consumption is 420W. The internal fuse is rated at 10 amps so technically my power supply could deliver 1200 watts before blowing. So it's a mystery how they come up with the power consumption ratings.

 

[MarkOcena]

Power rating on rear

Wow, I didn't know that the power rating on the back of the receiver was consumption at a specific power level. I thought it was just the maximum constant draw from the wall by the power supply. I didn't know that the amp are capable of more.

Thanks for the correction.

 

[keenan]

On another note the rated power consumption on the rear of receivers is not always the maximum. The rear my receiver says the power consumption is 420W. The internal fuse is rated at 10 amps so technically my power supply could deliver 1200 watts before blowing. So it's a mystery how they come up with the power consumption ratings.

That's only if the power supply/amplifier sections were 100% efficient and almost all are not. Digital amplifiers come the closet to converting what they draw into what they output.

Jim

 

[annunaki]

As the guest user posted on the previous page the consumption spec on the back of some receivers is under typical load (UL/CSA) or specified power level. The total power consumption of that H/K model is 890 watts 7 channels driven to rated power. Unless you missed that part in the link I posted. Figuring 55 watts x 7=385; 385/.50 (50% eff. average for class a/b)=770; 770 watts + 120 watts (processors, lights, ect.) = 890 watts. that seems fairly accurate. Using the same criterion, for the typical use power consumtion: 350 watts-120watts (for processors, ect.)=230 watts; 230/2 (50% eff.)=115 watts typical use 57.5 watts x 2 stereo or 16 watts x 7

Say one has reasonably efficent speakers 89db 1w/1m. With 16 watts on said speaker it could reach 101db (3db gain every time power doubles realistic output gains are 2-2.5db). Worse case we would see 97db per speaker. Every time one doubles surface area there is also a 3db increase. With 7 speakers at 16 watts we would roughly see an 8.5db increase. So now we have a system capable of 105.5db 1w/1m with 16 watts per channel. At the listening position one would most likely experience (guestimate) about 100-102db. (This is assuming one would use all the same size drivers, and the same amount of drivers per speaker. Doing it any other way would be a disgrace, right. )

I would say that that would be a fairly TYPICAL reference level movie experience with 350 watts of power consumtion. That leaves plenty of output power available for dynamics if the average power for each channel during a movie was around 16 watts. Nearly 6db of dynamics. That would be a earsplittling listening experience.

It's just left of the power cord. It says Input 120V/60Hz 350W

http://www.harmankardon.com/back.aspx?prod=AVR 330&cat=REC&sType=S&Region=USA&Country=US&Language=ENG&ImgName=AVR330B.jpg

 

[aarond]

Say one has reasonably efficent speakers 89db 1w/1m. With 16 watts on said speaker it could reach 101db (3db gain every time power doubles realistic output gains are 2-2.5db). Worse case we would see 97db per speaker.

If I'm not mistaken you double your spl (3db gain) when you multiply the power by 10. ie; 1 watt=89db, 10 watts=92db , 100 watts=95db , 1k watt=98db. That is the reason that 100 watts per ch is the norm because 1k watt would be the next level that you would notice.

 

[Unregistered]

If I'm not mistaken you double your spl (3db gain) when you multiply the power by 10. ie; 1 watt=89db, 10 watts=92db , 100 watts=95db , 1k watt=98db. That is the reason that 100 watts per ch is the norm because 1k watt would be the next level that you would notice.

You are mistaken but only because you are mixing power ratings (watts) and SPL (sound pressure level). Annunaki's example is correct.

If your speakers are 89dB sensitive, then 1 watt of power yields 89db SPL (1 meter from the speaker), 2 watts=92db, 4 watts=95, etc. Every time you double the power(watts) you get a 3dB increase in SPL. The just noticeable difference (JND) actually varies with frequency, but 3dB is taken as the average level increase required to notice an increase.

What you are talking about is the fact that it takes a 10dB increase for the SPL to perceived as 'twice as loud' - again it actually varies with frequency but 10dB is the accepted rule of thumb. So in order to make the sound twice as loud, you need a 10dB increase, which requires 10x as much power; in your example, it would take 1000watts (10x100) in order for you to perceive the SPL of the 1000watt amp as twice as loud as the 100watt amp.

Simply doubling the power from 100watts to 200 watts results in the 3dB increase which is the JND as mentioned above.

 

[Rob Babcock]

This is very informative, but I disagree that 3dB is a JND. It's widely known that in DBTs, level imbalances of less than 1dB will skew tests in favor of the louder component. JND will depend on the frequency/material being played, but thru the bulk of the main musical range the threshold is less than 3 dB.

 

[MarkOcena]

Distance from speaker

Don't forget to factor in distance from speakers, room boundaries effects (or lack thereof), etc before determining the actual SPL levels and comparing them to a particular reference level. From what I remember, sound intensity follows the inverse square law like other forms of energy, and decreases by the distance squared. Most listening distances are at least twice as distant from the speakers as where sensitivity is measured from.

 

[mtrycrafts]

This is very informative, but I disagree that 3dB is a JND. It's widely known that in DBTs, level imbalances of less than 1dB will skew tests in favor of the louder component. JND will depend on the frequency/material being played, but thru the bulk of the main musical range the threshold is less than 3 dB.

The JND also depends on the the bredth of the level differences, how many octaves or fractions. The wider the badwidth of level differences, the easier it is to detect

http://www.pcavtech.com/abx/abx_crit.htm

 

[WmAx]

This is very informative, but I disagree that 3dB is a JND. It's widely known that in DBTs, level imbalances of less than 1dB will skew tests in favor of the louder component. JND will depend on the frequency/material being played, but thru the bulk of the main musical range the threshold is less than 3 dB.

A reference to back you up:

The Subjective Loudness of Typical Program Material
Gilbert A. Soulodre, Michel C. Lavoie, and Scott *. Norcross
AES Preprint: 5892

-Chris