I'm running into a problem with one of my QS4s, and before bothering the service dept., I wonder if anybody has any ideas. Sometimes there is audible interference that as best as I can tell is localized to the down-firing woofer. It's not always there, only about 50% of the time. I've double-checked the channel from the receiver with another speaker, and changed the speaker wire (plus the obvious stuff like tightening binding posts).

Anybody have an idea as to what's causing this, and what I can do short of sending the unit in?

Have you tried switching the QS4's around, swap the left and right one and see if the problem follows the speaker. This will tell you if it is in the speaker or originates in your amp. If it follows the speaker I think that your best plan of action would be to contact the service department to have this taken care of.

Ya, that's what Joe in service suggested i do with my m60s awhile back to be sure the problem was in the speaker and not from the source. Swapping the left and rights ought to give a good indication of driver issues or source issues.
Its good advice for starting the troubleshoot process.

Hi fhw,

Usually "interference" implies some type of outside source, like radio frequencies (RF) leaking into the amp or cables. Or do you mean audible distortion of either a mechanical or electrical nature?

Regards,

Hi, Alan.

The interference sounds essentially like the static you would hear on a car radio about 1 hour outside of town, but intermittently and seemingly localized to the down-firing woofer. I'll certainly recheck things as per other people's suggestions.

A concern I have that may have been my own doing: how thick is the MDF used to build the QS4s? I've stand-mounted mine using 1/2 inch screws, and am worried I may have caused mechanical damage to the internal wiring (thereby putting me on the hook).

If you are brave, you could open the speaker and see if a wire might be touching the driver. Joe at the service center can tell you if this is wise or not, and good ways to go about it.

Hi fhw,

You've got to swap the speakers first to see if the static-like sound stays with the speaker or remains in the original channel. The way you describe the sound, it might be a noisy channel or intermittent connection in your amp's left-channel circuitry. It's not RF and I'm fairly certain it isn't a bent or warped voice-coil former, because that produces a mechanical scraping sound. Switch the surrounds and then call Joe if you're still getting the problem.

Regards,