• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Strange varying AVR power usage.

Chr1

Addicted to Fun and Learning
Forum Donor
Joined
Jul 21, 2018
Messages
793
Likes
605
Wondering if anyone has any ideas as to why my AVR power consumption seems to be fluctuating...

I have been using a cheap plug in power meter to check the power consumption of my various bits of audio hardware, and my AVR consumption appears to have two different levels!
When I first plugged it into the power meter the consumption was generally between 76 and 82 Watts. I thought that this was rather high, at idle particularly, as it is a Pioneer SC-LX86 which utilises Class D amplification, and it is only powering the center, wide and surround back channels. (I am using additional power amps for the L/R and surround wide channels.)

Anyway, after a couple of weeks I moved the meter to check something else. When I reconnected the power meter to the AVR about a week later it was only using between 12 to 13 Watts! (This was actually what I had expected it to be using when playing stereo or 2.1.) Anyway, this was the average draw for several weeks of use. Then after using the meter to check something else for a while, when I reconnected it to the AVR it was back up to it's original draw of between ~76 - 82 Watts! I have been using it for about three weeks since and this appears to be the average draw again. This is when playing stereo or surround formats at various volumes. Volume level and channels used does not seem to affect the power use significantly. Very weird.

I am really confused by this as ~80 Watts seems like a very high draw at idle however I am not sure what it should be to be honest!

Anyway, any insights or advice most welcome...

Have attached the manual for the power meter.

Thanks in advance!
 
Last edited:

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,757
Likes
5,918
Location
PNW
Don't see an attachment....what's the make/model and you're sure it's okay? I just got one....haven't tried it on my audio gear. I wouldn't be particularly surprised that the draw would be higher than 12/13 watts even with class D.....now I'll have to try that on my avrs :)
 
OP
Chr1

Chr1

Addicted to Fun and Learning
Forum Donor
Joined
Jul 21, 2018
Messages
793
Likes
605
Sorry. For some reason I am being told that it's too large at 5MB. Ho hum.
Anyway it is one of these.
I have several and even tho they are cheap, they appear to be reliable...

Yes, I agree that 12-13 Watts seems rather low and I am wondering if I somehow managed to change the scale of the meter. I can't see anything in the manual that would suggest that this could be the case...but it just seems too weird that it could have been drawing at a completely different level for several weeks!
 
Last edited:
D

Deleted member 48726

Guest
80 watt sound really high for a class-d amp. I think that is around what i measured idle-power to be on my Yamaha A-S1000.
 
OP
Chr1

Chr1

Addicted to Fun and Learning
Forum Donor
Joined
Jul 21, 2018
Messages
793
Likes
605
Yes, this is why I am confused. I have been monitoring it for about a month and a half now and when initially switched on the power drawn rises to the level mentioned (~76-78W). This is the idle draw. It does not increase much even when playing multichannel at quite high volumes. It would be interesting to see what happens when the AVR is driving all of the channels without using the two external power amps but I am reluctant to do this due to the hassle involved as access is not easy. I am pretty sure that I did not change anything on the power meter when I was getting the lower readings previously, and it is obviously set to display Watts in all the aforementioned cases. Very strange indeed.
 
Last edited:

DVDdoug

Major Contributor
Joined
May 27, 2021
Messages
2,920
Likes
3,835
Do you EVER see readings in-between (like 40W) with something else plugged-in?

MAYBE the thing just has low-resolution at low power ratings....

Where I work we have an instrument that measures RF power and its internal calculations seem to limit the resolution. The display shows 0.01W resolution and at one point we are shooting-for 5W. But the display jumps from 4.89 to 5.01 to 5.19W. It will never show 5.00 or 5.10, etc. All of the power readings have the same "odd" resolution limitations and we never get the exact reading we are looking for. (Of course, there are tolerances so we CAN meet the specs.)

I don't think I've ever seen a digital instrument that skips certain numbers before, but since power is probably calculated by squaring a voltage reading, and the voltage reading has some (unknown) resolution limits with the voltage calculated from a binary-integer reading. The ADC will always have 1 bit (1-digit) resolution but Just the conversion to voltage can give "odd" quantization steps even before it's squared.

Other strange things can happen with digital readings... A long time ago I was working with something that measured pressure (PSI). It displayed the pressure digitally and it also put-out a voltage to a chart recorder. At a certain reading the chart reader would "go crazy" while the digital display was OK. I think there were some range/scaling options so it only happened occasionally. I didn't know anything about the software/firmware but it turned-out to be integer roll-over somewhere in the voltage conversion/calculation. For example with 8-bits you can count to 255 and if you try to count one-more the count rolls-over to zero. (It may not have been an 8-bit value but it was a rollover.) If I was seeing "255" or the actual-direct conversion from binary to decimal it would have been obvious. But it was a conversion from a binary reading to pressure and then another conversion to voltage and I was totally confused. I thought it was a hardware problem... Eventually, the programmer figured it out and fixed the bug.
 
Last edited:
OP
Chr1

Chr1

Addicted to Fun and Learning
Forum Donor
Joined
Jul 21, 2018
Messages
793
Likes
605
No, the meter seems fine otherwise. I have measured lots of things and the readings appear to be reliable. My Technics SE-A1000M2 draws ~40W at idle, so yes that range is covered. My Beelink AP34 Pro mini PCs draw up to around 7.5-8W running Foobar and MathAudio RoomEQ plus EQ, so I don't think it is simply low resolution or a fault with the meter. Thanks for the suggestions though.
I will try plugging in a different brand tomorrow as I have ordered another to check...
 
D

Deleted member 48726

Guest
Sorry, I thought for some reason is was an integrated or a power amp. It's an AVR. An AVR has a lot of processing and active circuits drawing power. Even idling. You can't compare the idling power with an integrated or power stereo amp.
 
OP
Chr1

Chr1

Addicted to Fun and Learning
Forum Donor
Joined
Jul 21, 2018
Messages
793
Likes
605
Yes, I realise that. I mentioned my amplifier drawing 40W as there was a question relating to the accuracy and resolution of the meter in that range. Anyway, I have just posted to find out what other people's AVRs use. Thanks.
 
Top Bottom