Noise when supplying S10 from amplifier

DIY Products&Projects
1

Hi everyone in the forum, this is my first message. Some weeks ago, after a long product selection work, I decided to purchase an S10. I’m really happy for the audio quality, knowing the limitations of native bitrate of the streaming services I’m using (Amazon Prime music + web radios), and for the product usage in general.

I order to cut off stand-by consumption from PSU and for a more comfortable “single button powering” of the system, I tried to supply the S10 from +5Vdc picked from the “dock” connector on my Yamaha R-S300 amplifier. I try to attach some photos.

Unfortunatly supplying the S10 from the amplifier dock connector I receive a noise floor, not so high but udible. This noise immediately disappear when I power using external PSU. It also seems to be not present if I power headphones at the S10 output, excluding the amplifier from the signal path.

I thought about a ground loop, or a difference between audio GND and 5Vcc GND.

What do you think about? do you thing the problem could be solved introducing an audio transformer on the output, whithout loosing on frequency response?

Really thanks,
bye Matteo

immagine
immagine1353×933 240 KB

2

Hi Matteo, this should be a ground loop issue. You need to use isolated power to avoid this.

3

Thank you for the reply! I also think this is a ground loop. Do you think an audio transformer on the RCA side could solve the problem without losing in frequency response?

immagine

The alternative could be a 5V relay, driven by the amplifier dock connector, which enables 230V to the Arylic power supply…but it seems a little complicated for the purpose

4

Need to check the specification of this device. Why not use the AC-DC adapter, just an extra power cord.

5

It’s true, your point of view is the smartest. I initially had thought to power the s10 from the amp principally for cutting off standby consumption.

But thinking that an usb supply rated “energy class 5” costs less than 1 euro per year in terms of standby energy wasted, it’s better I relax and think about listening to my music :slight_smile:

Thank you for your answers!