Mysterious Subwoofer Thumping

My new Polk Audio sub woofer seems to have a life of its own. When everything is off (except the subwoofer), out of the blue, the unit begins to emit a series of thumping noises from the bottom, which resonate on the floor. Any ideas?

Comments

  • pkquatpkquat Posts: 494
    I don't know which model sub, but it do know some subs have an "auto" setting to turn the amp on and off. It is often triggered by the audio input connection to the sub. You could have some noise in that line that occasionally triggers the amp to turn on and later turn off, or if there is a sensitivity setting for the audio signal it is set to low. A piece of equipment upstream of the sub could be producing a slight hum or have a ground loop, even when "off" / standby. Some equipment even when off or in standby mode will pass through a signal.

    Without knowing more about your model sub and the rest of the system it is only guessing.
  • Gunther16Gunther16 Posts: 245
    Do you carry a cellphone when you getsomewhere around it? I noticed whenever I carry my phone and get within 5-6 feet of my sub it thumps even with the rest of the equipment off. The sub is on standby at the time. Just saying!
    Polk 3.1TL (Gimpods boards, Sonicaps, Mills Res., Dynamat, Sonic Barrier, Hurricane Nuts, Cabinet sealing, Glue of magnets,Cardas Binding Post upgrades) - to be relegated to my daughters system eventually as I permit or am ready to part with.
    Polk CS350 Center
    Polk FX500 Surround
    Definitive Powerfield Subwoofer
    B&W 803D2
    Krell Showcase Processor
    Krell KAV 3250 Amp
    Adcom 555II Amp
    Adcom 555II Amp
    Musical Fidelity A3CD
    Sony PS4300 Turntable
    Rotel RQ970BX Phono Preamp
    Adcom Ace-515 Line Conditioner
    Richard Grays Power Company Line Conditioner (2)
    Hitachi 60" Ultravision TV
    Oppo BDP-103 Blue Ray
  • mdaudioguymdaudioguy Posts: 3,974
    Gunther16 wrote: »
    Do you carry a cellphone when you getsomewhere around it? I noticed whenever I carry my phone and get within 5-6 feet of my sub it thumps even with the rest of the equipment off. The sub is on standby at the time. Just saying!
    I've had lots of subs and cell phones, but never had that happen!
    7.1 - polk RTi10 x 3 (LCR) : FXi3 x 2 : RTi4 x 4 : Sunfire SDS-12 : Yamaha Aventage RX-A2040 : Adcom GFA-7500 : Squeezebox Touch : DIRECTV : Roku SE : Panasonic PT-AX200U PJ @ 120"
    5.1 - Definitive Technology ProMonitor 800 x 4 : ProCenter 1000 : Klipsch Sub-10 : Pioneer Elite SC-91: DIRECTV : LG OLED55B6P : Roku Premiere+
    Garage Duty - polk Monitor 10s : Pioneer A-717 Integrated Amp : Squeezebox Classic
  • lightman1lightman1 Posts: 8,504
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    Gunther is still rockin' the brick. That's why.
  • VatoVato Posts: 2
    piquat: I have the PSW505 Sub-woofer. There is a single connection cable from the receiver to the subwoofer, as per manual instructions. The thumping comes on when everything is turned off (TV, DVD player, and Receiver.) Very strange and annoying. Thanks for your comment.
  • pkquatpkquat Posts: 494
    From your description I assume you connected similar to Figure 8 in the manual, either to the Line IN or LFE in with an RCA cable.

    Does it happen every few minutes, or every 15 mins or more? I would first try switching the sub to "ON" vs auto, and see if it goes away. If it goes away, it is likely there is some noise in your connection to the sub that is tripping the auto on feature. The thump is the amp turning on and off. Make sure the line to the sub is away from any power cords or cable / Sat TV cables. These can transfer noise into the cable.

    Even though everything is off, there can still be noise in the system or transferred into the cable. If you turn the the sub on with everything else off, see if you can hear a faint rumble or noise from the sub. You may have to get very close to it or put your ear up to it to hear it.

    If you have another amplifier connected to a speaker, or even a boom box that has RCA input jack, I would try connecting the RCA cable going to the Sub to the other system instead. With everything else off, slowly turn the volume on the amp and speaker or boom box and see if you can hear any noise. If you hear noise, turn the volume down by about half, and try moving the RCA cable location and see if it gets louder or quieter. Move it away from any thing that is making it louder. If you don't hear any change, turn the volume up a little more a try again. This may be easier with two people.

    If there is no noise, then there is another issue, and it would be best to contact Polk customer service 1-800-377-POLK (7655), or ask the question here http://www.polkaudio.com/psw505-black/d/1179
  • Gunther16Gunther16 Posts: 245
    Yup, brickin it, Is there any other way to go?
    Polk 3.1TL (Gimpods boards, Sonicaps, Mills Res., Dynamat, Sonic Barrier, Hurricane Nuts, Cabinet sealing, Glue of magnets,Cardas Binding Post upgrades) - to be relegated to my daughters system eventually as I permit or am ready to part with.
    Polk CS350 Center
    Polk FX500 Surround
    Definitive Powerfield Subwoofer
    B&W 803D2
    Krell Showcase Processor
    Krell KAV 3250 Amp
    Adcom 555II Amp
    Adcom 555II Amp
    Musical Fidelity A3CD
    Sony PS4300 Turntable
    Rotel RQ970BX Phono Preamp
    Adcom Ace-515 Line Conditioner
    Richard Grays Power Company Line Conditioner (2)
    Hitachi 60" Ultravision TV
    Oppo BDP-103 Blue Ray
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