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Why do subwoofers thump when turning on power amp?


What would cause my powered subwoofers to "thump" when the power amp comes out of standby mode?

To clarify:

I first turn on my tube preamplifier and let it power up, stabilize, and come out of mute mode.

I then bring the power amp out of standby mode and it stabilizes and powers up.

The powered subwoofers (one for each channel) are connected to the preamplifier's RCA pre-out terminals. The subs are left in standby mode and use RCA interconnect signals to trigger to power up.

The thump happens when the power amp "clicks" on from standby mode and it only happens to the subwoofers, not the main speakers.

To make things complicated, the thump doesn't happen every time; occasionally there is no thump. I haven't been able to come up with any cause-and-effect relationship though.

I know I could just turn the subwoofers completely off each time and then turn them back on after the power amp comes out of standby mode but I like the convenience of using the DC trigger feature.

Any ideas?


Edits: 04/13/17

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Topic - Why do subwoofers thump when turning on power amp? - tketcham 09:17:51 04/11/17 (28)


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