amplifier longevity

Re: the comment on Counterpoint Mosfets and heat It’s common practice for TO3 devices, mosfet or bipolar, to be covered by plastic covers.  They are there to prevent law suits when people get zapped by the + - rails voltages.  The heat of these devices are dissipated by conduction to the aluminum chassis via the silicone pad.  There’s absolutely no issues with that approach to mounting and using QCovers. 

@bigkidz I beg to differ. Keystone makes those white Q Covers with 4 holes, 1 hole, and no hole. The holes are not for ventilation but for a tech to use a probe to check rails voltage. There is no difference in temp disspation between the convention black Q Covers and the Keystone nylon ones. Any amp with a design where there’s more than 10-15V on the TO3 case should have Q covers covering the whole component for safety reason. The SA220s have 65+/- rails and they give the curious owners a good zap once in a while if not covered. The nylon keystone covers expose 2 screws... I honestly would not recommend unless you are using them to cover filament regs like 7806 or 7812s.  There is a reason why the black ones are still being used and sold for output devices.