For information: a capacitor in the 552 that must have been failing and finally failed completely was causing the buzz. Apparently unusual, but at least easy to fix.
Good to know, thanks. Another reason to add to the list of Hum causes
Was that in the head unit or PS ?
I had an Olive NAP140 and HiCap that was serviced by WH a couple of years ago, and when they came back they hummed so much more. Of course I had no proof, but perhaps it was caused by a capacitor issue.
The original thread was regarding mechanical hum from the boxes, Catlovers post further down was regarding hum through the speakers which seems to have been down to a faulty capacitor in the 552PS in this case.
Thanks - sorry missed that earlier
Just to say I just installed a Isol-8 minisub Axis, which has DC blocking. This replacing an Audiolab DC blocker and Wireworld Matrix power block. Amp definitely quieter, though not silent. Sound quality’s definitely stepped up noticeably though. Removed some digital artifacts and given a kind of analogue sweetness to the high end. Interested whether anyone else has noticed that kind of lift, or is using the Isol-8 minisubs.
I’ve owned a Uniti Atom HE who have in my opinion loud hum. My brand new NDX2 is completely silent, so is also my Uniti Nova. Love these two units.