Question on the power supply connection to the pcb for etherwave

Thank you for posting this fine work, Gianluca. How is the grounding made here? Would you give us some sound examples? I wished my manual skills were almost as good... 

Hi JPascal I am glad you like it, I temporarily use the radiator as ground mass using a small non-amplified speaker but I purchased the ultratone kt108 amplifier that I am waiting for and I have yet to understand what type of support to buy and finally make the correct calibration.

when everything is ok post some audio files.

Good morning everyone, I received the new Behringer KT108 Ultratone, and I wanted to ask those in possession if using headphones to practice without disturbing anyone, you can hear a hum in the background giving a lot of annoyance, but also hearing from the amplifier case however, it feels this strange defect as if it were not well isolated from its internal power supply.
I state that I use quality cables and headphones and in any case even when the line input audio cable is not connected to the amplifier this noise remains the same.
Anyone have the same problem?
maybe the amplifier I purchased is defective.
Thanks for who can help me.

If I understand correctly you are hearing a hum even with no inputs connected to the amplifier?  If this is true there is almost certainly a problem with the amplifier.

Is the hum present on the headphones only or on the speakers too?
Does the hum level change when you adjust the channel volume(s) or is it a constant level? 

Since it appears that there is no headphone volume control, I'm guessing that you have to set your headphone volume by adjusting the channel volume, which is not a great arrangement if the hum is occurring in one of the later stages of amplification.  If the headphone is overwhelmingly loud when the channel volume is set high, you might be able to make a modification that would improve the signal-to-noise ratio by reducing the hum to the headphones at normal listening levels with the channel volume set near the top of the range.

But you shouldn't have to modify something that is new, and if it doesn't work as it should and you have the option to exchange you may want to look into that.

Hi pitts8rh, yes the buzzing is heard both in the headphones and on the speaker despite the theremin cable is disconnected from the amplifier and the buzzing increases by raising the volume. I tried to connect another type of amplifier and this does not happen so it is really the fault of the amplifier that I will have to change. Thanks for the reply.

Better luck on your next one!

Thanks so much

Ginaluca, for some reason I can't see your imageshack pictures?  For instance this one:

https://imagizer.imageshack.com/a/img922/7318/7qJcb3.jpg
https://imageshack.us/a/img922/7318/7qJcb3.jpg

redirects me to https://imageshack.com/ and seems to be wanting me to log in (I don't have an imageshack account).  I'm using Firefox 73.0.1.

There is photo album storage here at Theremin World (Media | Photo Albums) if you want to use that.  Then you can link from their location in the album to your post.

Hi Dewster I have created an album

Thanks!  Once your pics are in an album you can link to them like this:

And you can edit your old posts to do this if you like.

Looks like a nice clean build!