PSW 303 Hum

[mvsainsbury]

Just bought a new surround system:
Polk RM 20
Polk PSW 303 sub
Onkyo TX-SR674

I'm expierencing a hum on some of the different surround settings. I purchased the ground loop isolator, suggested in the manual, but it doesn't seem to do anything. Any other suggestions -- I'm guessing this is not that uncommon, there must be a better solution.

[zingo]

Check for loose connections or redundant connections (if you happened to wire two things into the same input). That is where I would start.

[appadv]

Check if "Double Bass" or something like that in your Onkyo's settings is set to "on". It bridges the front's low frequency portion + all other speakers set to small + the LFE to the sub. Sometimes the front channels fed to the sub on my Onkyo cause the sub to hum.

This setting creates a redundant connection, i.e. it is like connecting both speaker-level and line-level inputs to the sub.