RFI/EMI is a tricky beast to handle.
It is nearly impossible to make an enclosure 'tight'. As a former designer of military electronics that were required to survive EMP, it's quite a challenge even at much smaller audio scales.
Thing about EMI/RFI susceptibility re: audio is all electronics - tube or SS - can convert very high frequency noise right down into the audio band via diode demodulation. And the higher the frequency, (like the microwave from cell phone systems) the harder it is to deal with.
Top issue for EMI entry is cabling to/fro the chassis - these are the real problem children. RFI walks along the cable skin and enters easily to your gear's nice metal box via audio connectors never designed for susceptibility control. Once inside, the RFI radiates all over using internal wiring. Even shielded cables, - although better than open wire - are nearly transparent to RFI at very high frequencies.
Re-engineering existing equipment is virtually impossible as to get real, testable results.
It is nearly impossible to make an enclosure 'tight'. As a former designer of military electronics that were required to survive EMP, it's quite a challenge even at much smaller audio scales.
Thing about EMI/RFI susceptibility re: audio is all electronics - tube or SS - can convert very high frequency noise right down into the audio band via diode demodulation. And the higher the frequency, (like the microwave from cell phone systems) the harder it is to deal with.
Top issue for EMI entry is cabling to/fro the chassis - these are the real problem children. RFI walks along the cable skin and enters easily to your gear's nice metal box via audio connectors never designed for susceptibility control. Once inside, the RFI radiates all over using internal wiring. Even shielded cables, - although better than open wire - are nearly transparent to RFI at very high frequencies.
Re-engineering existing equipment is virtually impossible as to get real, testable results.