Something odd happened today when I swapped the original SMPS from my Lenovo T440s laptop with an after market one (plug issue). An odd electronic noise comes up to my tweeter, something similar with the noise that RAM and VRAM does it on your computer speakers if your microphone cable is routed inside your computer's case. I repaired the original's PSU's plug and noise disappeared.
There's a .ZIP file attached containing an .M4A audio file inside (it should play with any modern media player). The first 15 sec. is the noise of the after-market SMPS PSU, the next about 10 sec. is with the original Lenovo PSU, the next about 5 sec. is again with the after-market PSU.
This is most likely to a badly design and cheap components inside the after-market PSU. A power-line filter will not improve anything here, although I wasn't tested yet.
The noise travels through the USB cable into the DAC (the XMOS transport inside is not isolated from the USB port). I haven't tried any workaround yet, but worth mentioning that if using a crappy power supply to your audio player (a laptop in my case) some noise might get injected into your amplifier/speakers/headphones and the final THD+N and SINAD will definitely get affected.
I'll probably try soon an isolation transformer to see if the noise drops, but I doubt it will do anything good. A mains filter will be tested as too, so in case it will do, I'll also update https://www.audiosciencereview.com/...rline-noise-on-hifi-linear-power-supply.7955/. and https://www.audiosciencereview.com/...o-use-how-to-choose-a-power-conditioner.9629/ as well.
There's a .ZIP file attached containing an .M4A audio file inside (it should play with any modern media player). The first 15 sec. is the noise of the after-market SMPS PSU, the next about 10 sec. is with the original Lenovo PSU, the next about 5 sec. is again with the after-market PSU.
This is most likely to a badly design and cheap components inside the after-market PSU. A power-line filter will not improve anything here, although I wasn't tested yet.
The noise travels through the USB cable into the DAC (the XMOS transport inside is not isolated from the USB port). I haven't tried any workaround yet, but worth mentioning that if using a crappy power supply to your audio player (a laptop in my case) some noise might get injected into your amplifier/speakers/headphones and the final THD+N and SINAD will definitely get affected.
I'll probably try soon an isolation transformer to see if the noise drops, but I doubt it will do anything good. A mains filter will be tested as too, so in case it will do, I'll also update https://www.audiosciencereview.com/...rline-noise-on-hifi-linear-power-supply.7955/. and https://www.audiosciencereview.com/...o-use-how-to-choose-a-power-conditioner.9629/ as well.