Problem with new LEDs creating hum in speakers

[JC80]

Hey folks. About a month or two ago we had a marien electronics professional come in and redo all our audio (fusion, new speakers, new sub, new amp). We also had him add 4 Lumitec Rail2 LED lights under some seats in the back of the cockpit.

If you're not familiar with the lumitecs, they're really cool - they are running to our "courtesy lights" switch on the helm and they change from red to dimmable white to blue every time you toggle the switch on then off then on again.

The weirdest thing is that they create a hum in our new speakers but ONLY when the white light is on. Also interesting is that if we remove two of the four lights (though it doesn't seem to matter which two), the hum will go away, even when on white light.

The guy has been to the boat like 4 times to try and fix this by using audio filters etc. (which seemed to only slightly decrease it). He called lumitec and they told him to try some capacitor of some sort. I'm only concerned about the final cost of this installation and so I'm doing my own research. Does anyone have any ideas? I know this is an oddball question but I figured some electrical wiz on this site may be able to tell me something. Thanks!

 

[gerryb]

One possible problem especially since you have a new installation situation. You have improperly shielded power wire used to feed the LED lights running close to one of the wires used by the new audio system. When the wattage increases to a certain point, it is interfering with the audio system. Could be either a speaker wire or one of the head unit power wires. The white colored LED uses the most juice on those lights. Check where the wires run back to the breaker.

 

[JC80]

Gerry, thank you so much for your response! I believe we used the old (26 years old) speaker wire on the existing speakers and ran new wire for the arch speakers. The lights' wiring is old as well. Both sets of wires run together from the aft of the boat up to the dash (lights to the courtesy lights switch and speaker wires to where we bypassed a speaker transfer switch under the dash).

From what little I know about electrical components, it makes a lot of sense that maybe the older wires aren't properly shielded and, when we are running all four of the whites together, it's bleeding out. This is a great thought, thank you!

 

[tc410]

I find this very interesting. I installed the Lumitec rail lights under the gunwales on my Regulator and they cause humming through my Fusion sound system - but only in BLUE mode! Still chasing down a solution. Hmmm....

 

[JC80]

I find this very interesting. I installed the Lumitec rail lights under the gunwales on my Regulator and they cause humming through my Fusion sound system - but only in BLUE mode! Still chasing down a solution. Hmmm....

Interesting indeed because the system we installed was a fusion head unit as well... I'm going to try calling lumitec myself...

EDIT: Just spoke to them and they sent me some information on using a capacitor to cut out the noise. Unfortunately I believe my audio guy already tried that and it didn't work for us, though maybe a bigger capacitor is in order. If you want me to forward you the email send me a PM with your address.

 

[Wylie_Tunes]

What type of controller is in use? Ive seen this issue with some RGB controllers. its the PWM frequency created by the controller in order to create certain colors. On some, we've cured by wiring a CAP in and others, weve just changed controllers, If the LEDs are RGB, look into the new Wet Sounds V2 controller. Done a handful of them lately with no noise.

 

[tc410]

I'm not sure I understand what you mean by controller? The Lumitec lights are white/red/blue and the color is changed by a quick toggle off then on of the dash switch. As far as the Fusion controller, I have the Simrad Sonic Hub (by Fusion) which is all run through the touchscreens on my Simrad NSS 16's.

 

[JC80]

For anyone researching this issue in the future, this annoying hum is an issue known to the Lumitec people. Not sure how often it happens, but they actually have a precanned email discussing using capacitors to eliminate the noise. Through trial and error we were able to find the right capacitor that matched the frequency interference and that eliminated the problem. This was an annoying issue since it ran the bill up on our installation - in fact, I paid more in labor fixing the hum than I did on the lights itself. Cautionary tale to consider for anyone considering the Lumitec Rail2 lights.

 

[fc3]

LEDs use constant current drivers, which are basically square wave oscillators with a feedback loop. The feedback loop measures current flow through the LEDs and adjusts the ratio of current flowing vs not flowing to set the proper illumination level. Usually the power supply runs at a very high frequency so as to not generate audio frequency noise.

Sounds like they designed a very noisy power supply probably with a number of harmonics. They're slapping a Band Aid on the problem by adding capacitors, which are one type of AF filter. Personally I'd be raising holy heck over their sloppy engineering that significantly raises the installation cost to get them to pay for their mistakes.