> On 06.05.2020, at 21:39, Richie Burnett <rburnett at richieburnett.co.uk> wrote: > >> >> Well, sure, so there would be an emphasis on the second harmonic in that >> hum? ;) > > Usually mains hum on supply rails Oh, I totally misunderstood that! :/ I was referring to mechanical hum, from the transformer. Hence my question and confusion. Sorry! Michael.