For casual music listening at low volumes i’ve been using for a while an old Aiwa XR-M121EZ amplifier + my 90s Panasonic boombox speakers. The power consumption of this setup was approx. 10W (measured from the wall plug with a BroadLink SP3S).
After watching this yt video i discovered there are more efficient class-D amplifiers like this based on a PAM8403.
After searching a bit i was able to find a pre-assembled build here on Aliexpress for a very cheap price.
Reportedly it uses some Chinese clone of the PAM8403 chip which has similar specs (datasheet here).
After trying it i was so surprised how well it performs i’ve decided to use as a replacement for my old Aiwa amplifier.
Pros:
- power consumption @ 5V is less than 10 mA, below what my USB meter can measure
- it is able to auto-detect/sense headphone input and adjust the levels accondingly, so i can directly plug my smartphone and feed music to it.
- it does not get hot during use according to my finger thermometer 😊.
Cons:
- it has no power switch, to turn it off you just unplug the USB connector.
- it makes the speakers “pop” when turned off or when moving the audio jack.
To avoid damaging my old speakers i’ve built myself a very simple passive switching circuit with just a few components.
Pic:
