Our step-downs have very minimal hum as we use toroidal stepdowns (not the EI square transformers that other use). Our cores are welded at start and finish they are tightly wound like a ribbon.

The laminations in our stepdown transformers are impregnanted with varnish. In most cases under vacuum. This means there is little vibration and this no audible hum. Finally the flux denisity of the core is set at avery conservative value (the induction in the magentics is low – hence noise is low).