I have the Mesa F-30 combo, I haven't really experienced humming and weirdo sounds with this amp. Its really a superbly versatile amplifier. I didn't get the F-50 as it uses 6L6 tubes and the cleans on the EL84 equipped F-30 are much better IMO and it saturates much easier for gain. It can do any style, blues to jazz to metal. Really a monster amp... I much prefer the Vintage 30s speakers to the normal Mesa Blackshadow speakers used...