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I'm not sure if this is the correct place to post a question like this, but here we go.

I recently purchased some LED strips for some backlight on my TV. Admittedly, these backlights are of the "cheap Amazon purchase" variety (although not the absolute cheapest out there). The LED lights are powered by USB, which I have plugged in to the back of the television.

I also had some old-ish Klipsch speakers (two satellites and a subwoofer) that I decided to try to hook up to the TV as well. The speakers connect to the TV through an 3.5 mm AUX cord. However when the speakers are powered on and connected to the TV, I noticed that there is a high pitched buzzing coming from both satellite speakers. I can make the buzzing stop if I disconnect the LED lights from their USB power. Also, If I connect the LED strips to some USB power source other than the TV, I can have the lights on with no speaker interference. The problem with that however is that then the LED lights are always on - as opposed to when they are powered by the TV USB outlet, in which case the lights only turn on when the TV is powered on. Obviously the latter is much preferable.

And I'm not sure if this is relevant, but the TV and speakers are currently powered by different wall outlets.

Here is the spec sheet for the speakers

Any suggestions?

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  • Did you install the LED's and the speakers at the same time or the speakers were working fine but the problem started with the addition of the LED's? Are your speaker powered, if not there should be an amp between the TV and the speakers? More details on your set up is needed. Are your speakers shielded?
    – Alaska Man
    Feb 10, 2021 at 18:52
  • I installed them at the same time, but the speakers work fine if the LED lights are unplugged. I'm not sure what you mean by "Are your speaker powered"...there is a power cord connected the subwoofer to a wall outlet, and then red/black wires running from the subwoofer to each satellite.
    – hm8
    Feb 10, 2021 at 18:58
  • You are saying the aux cable goes to the sub first and then the speakers are wired from the sub? Not knowing what sub you have i can not say if it powers the speakers as well, probably not, just passing the signal on. The Tv will not have the proper amplification (power) for the speakers, The sub has its own amp (i assume). Passive speaker need a power source, an amp or A/V receiver, Powered speakers have amp built in you plug them into a power source, wall outlet, like the sub. We can avoid assumptions if you post the make/model numbers of all the equipment and provide more details.
    – Alaska Man
    Feb 10, 2021 at 19:06
  • The usual (proper for passive speakers) set up is to send audio out from the TV to an Audio/Video (A/V) unit, OR Integrated amplifier. Then the audio is sent from the A/V - AMP to the speakers/sub. BUT, that is not to say that a proper set up will eliminate interference from cheap Chinese LED's. I have I have an A/V set up and cheep LED's from the USB on the TV and no buzz. I suspect the low power signal from the tv is an issue.
    – Alaska Man
    Feb 10, 2021 at 19:13
  • Added the speaker spec sheet to the question. As you said, aux goes from TV to sub, and then sub passes signal onto speakers.
    – hm8
    Feb 10, 2021 at 19:54

1 Answer 1

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Chances are that the the USB power and the AUX output of your TV share the same 5V power rail. When you connect the LEDs, you either overwork the power supply or some power modulation from the LEDs makes it's way through the power rails into your audio output.

One thing you could try to decouple the audio output by using a isolation transformer. Something like this perhaps https://www.amazon.com/C2G-40000-Extension-Isolation-Transformer/dp/B0047AKVYO (no endorsement intended, illustration only) .

You should check that LEDs don't draw more power than what your TV USB output is rated for. That would be 2.5W for "old" USB and 4.5W for USB 3.0 and up. If your handy with electronic stuff, there are few things with capacitors and resistors you can try, but that would probably be a better fit for https://electronics.stackexchange.com/

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  • Good answer. IMO a TV USB port probably had little to no design thought given to its use as a power supply. If it's so important to have TV back lighting synchronized with the TV I suggest you get a smart programmable remote or a wifi controller for the lights. Then you can have them even better synced, like disco effect for Jersey Shore, throbbing red for Housewives of Cleveland, and so on.
    – jay613
    Mar 13, 2021 at 14:23

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