Got them for a fair price. I'll post impressions compared to the Mullard M8100's and the WE403B's when I get them.
post #1351 of 1888
5/6/08 at 5:07pm
It's actually quite normal for inexpensive transformers to hum like this. These are mechanical vibrations of the transformer laminations, and to a certain extent, transformer windings. Transformers are still manually impregnated even with larger/reputable manufacturers -- so they are subject to sample variation. It's easy to fix, though... bake the transformer for 1 hour at 120 degrees Celcius, while hot, dip the entire transformer to a varnish material like Dolphon AC-43 (about 40 bucks per gallon) and air cure for 24 hours.