Solved! can't get sub rumble fixed

[samrozzi]

Ive been trying to dial in my tv/receiver and sub and the surround sound on the speakers is now great thanks to you all. The sub is pretty much the only issue with it not putting out the correct bass.

I've attached links to the equipment and a quick audio recording of the hum -

https/clyp.it/cjgqzrwp


The sub gives out a weird vibrating/rumble sound regardless of how I turn up the gain or anything on it. Assuming it has to be a setting on the sub/receiver?

How its currently wired is the sub has a left and right connection on the back and that is wired to the receiver which only has one sub input. Ive tried connecting just the left and just the right to see if any difference like I read in the manual but don't see any difference.

The sub I have is
https/www.amazon.com/Klipsch-Sub-12HG-Synergy-300-Watt-Subwoofer/dp/B003VIWK0G/ref=sr_1_6?s=aht&ie=UTF8&qid=1485670571&sr=1-6&refinements=p_4%3AKlipsch

this is the receiver
https/www.amazon.com/Onkyo-TX-SR505-Receiver-Discontinued-Manufacturer/dp/B000OBOGEG

 

[BFG-9000]

You should be using the line-level RCA rather than the speaker-level inputs, as then you can turn on the high-pass crossover in the receiver to avoid overloading the main speakers with bass. That particular sub does not have a passive high-pass crossover as it has no speaker-outs.

Sometimes this sort of thing can be caused by a ground loop which is easily fixed with a ground loop isolator on the RCA, but for this to be the case the sub should make no noise if the RCA isn't connected, and you aren't using the RCA.

The last time I had this sort of thing happen, it turned out to be a bad diode on the power supply board for the internal amp. The powered sub rumbled even with no connection to anything so I opened it up and noticed funny voltages around the rectifying diodes when plugged in. Sure enough, when unplugged I tested each of the 4 diodes for continuity and one of those showed continuity in both directions with a simple ohmmeter. Replacing it completely fixed the sub.

 

[samrozzi]

Sorry what do you mean by the line level rca instead of the speaker level inputs?

You should be using the line-level RCA rather than the speaker-level inputs, as then you can turn on the high-pass crossover in the receiver to avoid overloading the main speakers with bass. That particular sub does not have a passive high-pass crossover as it has no speaker-outs.

Sometimes this sort of thing can be caused by a ground loop which is easily fixed with a ground loop isolator on the RCA, but for this to be the case the sub should make no noise if the RCA isn't connected, and you aren't using the RCA.

The last time I had this sort of thing happen, it turned out to be a bad diode on the power supply board for the internal amp. The powered sub rumbled even with no connection to anything so I opened it up and noticed funny voltages around the rectifying diodes when plugged in. Sure enough, when unplugged I tested each of the 4 diodes for continuity and one of those showed continuity in both directions with a simple ohmmeter. Replacing it completely fixed the sub.

 

[BFG-9000]

Sorry what do you mean by the line level rca instead of the speaker level inputs?

You said the Receiver has only one sub out. It's the connection that uses that, with an rca cable:

 

[samrozzi]

This is the sub and receiver

http/m.imgur.com/a/dFAml

2 outputs in the sub and 1 in the receiver end

 

[BFG-9000]

Looks like you are already using the line level sub output from the receiver to the LFE input of the sub which is correct (if it's the same beige/gray RCA cable to both), but WTH is that red cable plugged into on the receiver? You shouldn't have anything plugged into that jack at all unless the receiver doesn't have a sub output.

If this means you get no sound at all then you'll have to enable the sub output on the receiver.

BTW you've got it backwards as a sub with line outputs to a receiver's inputs would only be logical for recording from the sub...