Why Protect Amplifiers from Lightning Riding in on Outdoor Speaker Wires?

Outdoor speakers are typically isolated from ground therefore it is not common to surge protect that end of the line in most installations.  But, the amplifiers that power the outdoor speakers are another matter.  Running speaker wire out to numerous outdoor speakers is like putting up a giant copper antenna and asking for nearby lightning to “hit me.”  It does not take a direct strike to inject surge energy into the speaker wires.  Strikes as far as one quarter mile away generate enough EMP energy for the surge to travel thought the air and inductively couple onto the speaker wire and travel into the home or other structure.  And, once lightning finds itself inside the home it can easily destroy the amp and migrate to other equipment in the rack or home.


What is lightning trying to do?  It is trying to find the least resistive path to ground and its going through your electronic equipment to do it.  As the lightning energy passes through the power supplies and circuit boards, the resistance converts the excess energy to heat, and heat is what degrades and destroys sensitive electronics.  And, it is not just expensive electronics that are susceptible to damage from lightning.  Even the life of heavy duty electrical devices like compressors, pumps, and motors can be severely shortened by electrical surges.

When you have an outdoor speaker system you have the potential for lightning to enter the home on speaker wires.   Systems Integrators can easily understand and explain that once this unwanted energy gets on the line it is going to go directly through the amplifier on its way to the earth ground of your house unless we divert it around the amplifier.  See an example design diagram here.

An amplifier surge protector, such as the TPD AmpPro, intercepts the surge coming in on speaker wires and sends the energy to ground.  That is why each amplifier protector needs a good connection to the AC ground that is feeding the amplifier.


As entertainment moves from the family room and home theater to the back yard, different surge protection methods must be used.  While the power side of the equipment should always be surge protected the “back doors” such as speaker wires, Ethernet, RS485 communications etc. are also recommended to be surge protected if they leave the home or have longer runs than normal.  Protection from even one lightning strike will quickly pay for all surge protection equipment in the home or office. There is also added safety for shock potential in high exposure lightning areas when data wires are not grounded.   Less lockups, less glitches, and a better sounding and longer lasting system are long term benefits for the owner.   Those savings will continue for many, many years into the future and the customer will save on their investment in Transient Protection Design many times over.