I used to owned a high end home theater amplifier which consumes 100W in idle or low volume, 5W in standby, 700W in full power. It is top of the class Denon AVR unit, which can play sharp and loud in 7 channels speaker system. It satisfied all my music and movies need. Most amplifier last for a long time, including mine, so I am keeping it until it not cost justify to repair.
I didn't realized the power consumption of the unit as 10 years ago, most of the manufacturer will not tell you the idle power, or standby power consumption. It always plug-in and in standby mode, or on for 8-12 hrs daily for TV, satellite, radio, or any connected audio devices. One day, I initiated power energy audio of every components in my house to reduce my $100 - $200 electric bill charges. I obtained a power meter, and able to measure its power usage. At 1kWh rate of $0.25 with the unit idle (assume don't listen anything at all) at 100W, 1 month used 74kWh, and cost $18. Even putting the unit on standby for entire month also used $1, or 4kWh. This is the usage of a 30" refrigerator.
$18-$25 of electric usage based on $100 bill (18% - 25%) is motivating me to review my audio listening need. I don't listen loud volume due to close proximity to next door, as well as poor insulation in modern home. So I never hit 700W, and spend all of the time in low volume, which consumes 100W. It doesn't justify to use the Denon HiFi anymore for day to day leisure purpose.
This turn me into research what exactly is Denon's amplifier class in order to look for lowest power consumption amplifier. It turns out all home theater system are class AB amplifier, including mine. The latest Denon system still consumes 60W at idle, while I'm looking for something that only consume electric power energy based on the volume adjusted to. The end result is that I found class D 15Wx2 amplifier on eBay for $1.40.
I spent 2 weeks of research on pre-made class D amplifier board, as those are few dollars, and giving great sound quality. After filtering many review on good quality board, I placed an order on several 3Wx2 to 50Wx2 amplifiers that cost $0.25 - $2.70. I also ordered a 100Wx1 for $6 to replace the 1000W active subwoofer, which again consumes lots of power at idle. My low energy HiFi system needs to have subwoofer to enjoy the previous experience, yet to cut 25% electric bill.
The first board arrived, and tested great by connecting to my phone, and TV. I have to DIY a 3.5mm audio jack for smart TV, android phone, and laptop in order to test out the board. I have plenty of TRRS 4 conductors 3.5mm audio jack with mic, and needs to figure out where to connect the GROUND wire. After experienced AHJ and OMTP standard, it turned out to follow AHJ (right), which means the conductor closest to the top is not connected (used for microphone, but unused).
The board I tested is PAM8610 2x15Wrms class D amplifier with mute and standby pin. It is able to drive 4-16 ohm speakers, or 2 sets of 4 and 8 ohm combination speakers without getting too warm at regular listening. Sad that it doesn't work with 5V USB power source, and need 7-16V power supply. I used the power supply for WiFi router to power it (12V 2A DC), and it is working great. The sound is as good as Denon for the system I owned, even technically on paper, Denon THD is < 0.1%, while PAM8610 is 10%. My speaker and 500sf room arrangement can't feel the noise level this cheap class D amplifier generating.
PAM8610 board used 0.3W on idle, and 15W at full load, but I adjust the volume to 60% so should be using 10W. Idle used 0.223kWh vs 4kWh (Denon standby), 24 hr usage used 7.44kWh vs 74kWh. The cost is $0.06 for idle, and $1.86 24 hr usage. My usage is typically 4 hr/day, 1.24kWh/month, $0.31/month.
I am very satisfy with the HiFi downgrade with $1 - $3. I am going to get some bluetooth transmitter/receiver board and make the system easier to connect with various devices.
Waiting for 100W TDA7293 class AB amplifier board to arrive and get the sub-woofer up.
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