The speaker is starting to buzz during the low

If the sound is a scratchy type of sound then the voice coil has been damaged and is rubbing up against the internal magnet producing the scratching and low sound since the cone is barely moving;.

Well yes your speaker is damaged, the cone actually has a tear, so audio that has low base or high pitch will cause distoration..

Simply remove it, take it with you and buy a similar one.. Same size, same watts, same ohms and just put the new one in.

speakers are standered only brand names are different..

BTW if you feel that you dont want to purchase a new one, simply stick the tear with duct tape, or you can hot glue it together.. If its plasctic, plastic weld works good(ask for it at a hardware)..

Probably, or the woofer coil itself is experiencing a heat, volume or motion related short. Clean any dust or debris from the heat sink fins in the back. Make sure it has lots of space for cooling ventilation.

This sounds like a power supply problem. If it works after is sits or cools, check at the power supply for bad or disturbed solder connections, a lot of time if you look at the circuit board where the component comes through you will see a small ring in the middle of the solder.

I have had the same problem with my Sony sub. It sounds like it is picking up electrical noise and would not go into standby when the reciever was off. I rerouted my wires and changed to a much higher quality wire. I was using a very low quality stranded copper with thin insulation to start with.

does this sub have an LFE output? if so, connect that to the LFE input on the reciever and make sure it is set up properly in the set up menu in speaker configuration. if the sub has speaker line input outputs, connect speakers to input of sub and out of sub to amp/recvr

It sounds like you're doing everything right. Did you define the sub to the Onkyo (Subwoofer = Yes, page 22)?

Let's prove the sub works. Set its volume about half-way, cutoff= 170Hz. Temporarily connect an RCA cable from its Line Input to one of the Tape Out connectors on the Onkyo and play some FM through it. If it's alive you'll hear the low end of the music.

Don't buy into the hype that there are different pedigrees of RCA (or speaker) cables that will make an audible difference. Save your money.

Sounds like you have an heat sensitive semi-conductor that might be connected to a relay (the clicking thing). As it warms up it acts up!
You can pin it down by spraying suspected parts (while under power and when it acts up) with Servisol Freezer Spray. Only spray one part at a time. The faulty part will return to normal, till it warms up again, or you force it to by touching it with a soldering iron.
If nothing happens to the part you spray, it's working and test the next. Don't bother to spray non semiconductor parts.

i have a sony subwoofer with no power. i found out that the voltage regulator (ic's)are bad. check that.

Is this buzz from the speakers?
Is this buzz from the set itself when the sound is turned down?
Is this buzz a low pitch sound?
Is this buzz a high pich sound?
Does this buzz vary in loudness with the volume control?
Does this buzz change in level from time to time?

You should post the details and the circumstances of use in order to give some idea of the conditions.

Jerry G.