> I live above a subway line here in the city of Toronto.
> I get a lot of line noise and there is know way for them to fix it,
> they just laugh.
A Notch filter will NOT fix this problem.
Save your time and dough.
Spark noise is broad band,
so is anything radiated from devices using square waves.
(well! pink noise:)
Have you considered moving?
73 de Gary7SLL