Hi Jim, I was implying common-mode crosstalk, which these particular ones seem to h= ave a lot of. The weird part is that there appears to be a large difference= between these two, even though they are identical. Best regards, Bob ________________________________________ From: piclist-bounces@mit.edu on behalf of Jim Sent: Monday, July 1, 2019 10:19 AM To: Microcontroller discussion list - Public. Subject: RE: [EE]: Audio amplifier power supply problem Bob, I have a comment, but I don't want you to think i'm be a smart a**. I'm just stating basic fundamentals. You mention "Feed through from primary to secondary". Isn't that the whole principle of a transformer? A transformer is supposed to transfer, or actually, transform the activity on the primary into a somehow different form of itself onto the secondary. So, it seems to me feed through would be expected. Regards, Jim --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .