Current-Sensing Servo Feedback

BAM · 24th February 2004, 07:33 PM

Some of Velodyne's subwoofers, including the CT-15 and its successor, the CHT-15, use a means of servo feedback that analyzes the signal from the preamplifier board to the amplifier board and calculates the amount of power that will be needed to set the cone in motion into a waveform. Then it measures the current across the driver and any extra current that wasn't sent by the amplifier. Then the difference is inverted and sent back to the amplifier to get that cone back under control. This seems like it would be extremely easy to implement. how might we go about developing such a circuit?

Addendum: I'm talking about a single-voice-coil woofer.

EC8010 · 24th February 2004, 11:18 PM

Quote:

Originally posted by BAM
This seems like it would be extremely easy to implement.

Which is why the world is full of them? As you've guessed, current drive to a loudspeaker is easy enough. Making the bass response correct is far harder, requiring some form of motional feedback. The great thing about motional feedback is that it works well. Right up to the point where it suddenly destroys the driver. It's a bit like balancing a party balloon on a sharp pin.

24th February 2004, 07:33 PM	#1
BAM diyAudio Member Join Date: Sep 2001 Location: Carmel, IN; West Lafayette, IN	Current-Sensing Servo Feedback Some of Velodyne's subwoofers, including the CT-15 and its successor, the CHT-15, use a means of servo feedback that analyzes the signal from the preamplifier board to the amplifier board and calculates the amount of power that will be needed to set the cone in motion into a waveform. Then it measures the current across the driver and any extra current that wasn't sent by the amplifier. Then the difference is inverted and sent back to the amplifier to get that cone back under control. This seems like it would be extremely easy to implement. how might we go about developing such a circuit? Addendum: I'm talking about a single-voice-coil woofer. __________________ "He is no fool who gives what he cannot keep to gain what he cannot lose." - Jim Elliot Please, put some music in my ear-hole.

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