Pulsing/heartbeat

I have a new Polk PSW505. My receiver is an Onkyo tx-nr656.

There is a very annoying pulse sound from the subwoofer, almost like a rapid heartbeat. I thought it was the sub, so I exchanged it for a new one. Still, same exact problem. I bought two different high quality sub cables, both did the same thing. The LPF of LFE is set at 120Hz. As most suggest, the lowpass knob on the sub is turned all the way to 120Hz.

I have tried both sub outs on the receiver, two different cables, and two brand new PSW505 subs. I have adjusted/tried every input, every setting, and only one thing helps.

If I turn the lowpass knob down to around 80, maybe 90 it goes away. But then the bass isn't really adequate. Any ideas? If the sub is on, making the noise and I unplug the cable, it stops. So is it my receiver (also new), but then why does turning down the low pass on the sub help? I have had two other subs, a Klipsch and a smaller Polk hooked up previously and never had this issue with the same reciver which leads me to think it is the sub.

Comments

  • VR3VR3 Posts: 21,757
    Grab you a ground defeat for the power cable ie, going three prong to two prong, see if that solves your problem
  • dwilcox900dwilcox900 Posts: 7
    I did that, no help. Plus it's already just a 2 prong. I tried plugging it in to a different outlet across the room with an industrial gauge cord just to get it away from the other circuit but no change.

    Again, it seems related to the lowpass being turned up past 90.
  • msgmsg Posts: 2,897
    Do you have bass management enabled on your AVR, in other words, is your AVR controlling the LFE?

    If so, can you turn it off, or set to bypass or full range so that you get full range to the sub and use the sub's crossover? Just as a test.

    Be good to test it with a different receiver to rule that out, but not like everyone happens to have a spare one laying around.
  • dwilcox900dwilcox900 Posts: 7
    Pretty sure I fixed it! I tried turning off the receivers wi-fi, no luck. Tried hooking it up straight to a dvd player, no pulse noise. So, looking for a source of interference I remembered I had a Chromecast plugged into the back if the receiver. Took that out, noise seems to be gone! :)
  • Dennis GardnerDennis Gardner Posts: 4,594
    Glad you found it! Sometimes all the signals in the air cause issues that are hard to find.
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