Sunfire sub true sub woofer EQ signature schematic /advice please

[zen]

Discovered that input to left or right channel will instigate a rumbling noise from sub , which is still present when signal removed.

Also discovered that if i monitor the plus 173V across one of the main smoothing caps, which is stable with no signal , but when input provided voltage can fluctuate 152V - 168V . Replaced the cap , which made no difference .

The minus 173V across the other cap is fine .

Could really do with some help trying to isolate this issue.

https://youtu.be/MSwIRZFfPc0

[jworthin]

If the rumbling is a 60hz hum you should replace all e-caps in the 13V supplies in the preamp and power boards.
The Sunfire sub standby circuit mutes the output until input charges the standby cap, maybe a half second. The cap will not re-mute after the input is removed until the cap discharges, maybe 10 seconds.