Speaker DC protection

DC signals also affect the movement of the speaker cone which may result in a reduction of audio quality, although low level DC doesn’t damage the speaker. If you were to apply more than a little DC power to speakers, this will cause the voice coil to heat up significantly, which would likely cause damage. A considerable DC through the speaker element can quite quickly fry the speakers.

The basic requirement of a speaker protector requires that any potentially dangerous DC flow to the speakers should be interrupted as quickly as possible. 

Many hi-fi amplifiers and professional power amps (and loudspeaker systems) provide some of protection, either to protect the speakers from an amp fault, and/or vice versa. Some of these are implemented at a very basic level and some are better. In hi-fi amplifiers typical circuit has a relay with a delay that turns on few seconds after amplifier is powered up to to stop any popping when the amp is turned on and with a detection circuit that disengages a relay if the amplifier goes wrong and sends DC current to the speaker. DC protection uses a relay to disconnect the speakers if any appreciable DC appears at the amplifier output. Typically that is in the range -/+ 1.5 to 3 volts.

Here are some links to speaker DC protection circuit designs I found on-line:








Be the first to post a comment.

Leave a Comment

Your email address will not be published. Required fields are marked *