Quote Originally Posted by dthp View Post

It's the case since I made a -15V/0V/15V linear regulated power supply, and the cord is 20 cm long.

The reg was actually ringing! As soon I put a 330µf cap between V input and ground, the noise stopped. I've not detected any troubles with the 7812SR-C yet, but if any, the fix would probably be the same.

I'm not sure it is the same issue, but I hope this will help you.

Anthony

Hi Anthony, thanks for your answer in 1st place.
I would like to clarify few details - in Murata 7805 datasheet they say more than 60cm and you have only 20cm long cable so I'm quite surprised this was the case.
On other hand when i was trying to touch different parts on PCB it was exactly the muratas which changed a bit a pitch of background tone so it would make sense that they are responsible for the tone as such. I'm using standard PSU which came with Caiman.

May I ask what 330µf cap have you used (max voltage / temperature) and how did you soldered it? Like directly soldering it to Muratas pin, or some other way? Maybe you have photo saved somewhere?

And my last question - how would you describe benefit of having Burson's hd audio discrete opamp instead of originally fitted opamp for headphone stage? I was thinking about exactly the same but Stan did not reccomended that BTW i believe that you was not able to fit Burson into Caiman so you left upper lid of Caiman open?

Thanks, maniac