John Phillips
pfm Member
I guess that's right. A humming transformer is probably not a safety failure in kit designed for the entire "230 V" region (as was the 1995 free market objective). So we are left with having to fix something that isn't considered a "real" problem. The last time I designed and built a power amplifier was in the early 1980s and IIRC a good transformer was a simpler task to select then.For many applications the humming doesn't do any harm. For us, the golden ear crowd, any extraneous noise is regarded as interference and definitely not welcome.
You may get problems if the downstream components or SMPS has been designed without sufficient tolerance for possibility of incoming 253V AC.
So if your application demands quiet transformers, get it specced with a larger core and more turns to lower the flux density.