will shielded rca cables eliminate hum?

I just finished installing a system in a bus we are building. All of the amps/source are installed into a bar. The space is tight and there is very little room to separate power/ground/signal cables. We have led lighting under the seats and along the sides of the ceiling that change color with the music. When these lights are on, they create a hum in the system. I am sure, this is the source of the hum because: - it doesn't change with engine rpm or even if the engine is running or not - it stops with the lighting off - it changes as the leds change color. If I go to shielded rca's from the head unit to the amps, will that eliminate the hum?

So, are all shielded rca cables created equally? I used this amp install kit and now that I check it claims the rca cables are "2 16” Clear Twisted Pair with Wrap Double Shielding Signal Cable w Molding RCA Plug" http://www.lanzar.com/sku/OPTIKITCAP0/Optidrive-0-Gauge-Dual-Amplifier-Wire-Kit-and-30-Farad-Round-Capacitor-wLED-Display Do you think those are as good as the knu shielded cables?

i did a bus one time and had the same problem. it was flourecent lights.

never could totally get rid of it. of course there really werent very many options for re-routing and such.

ended up putting in a 12 volt home style lighting system that in a home, would have run from a transformer, but i just wired it directly to the aux batteries in the bus.

if its flourecents, good luck to ya.

balanced in and outputs would be nice but its hard to fulfill that spec on the whole system.

yuk

quiet rural missouri, near KC.

If your system moves you physically and not emotionally, you have wasted your money.

if you dont hae flourecents, maybe its a by product of a transformer in the led system.

also, if you have a dimmer on the system, see if you can bypass the dimmer ans see if it goes away.

yuk

quiet rural missouri, near KC.

If your system moves you physically and not emotionally, you have wasted your money.

Shielded cables may minimise electromagnetic interference (radiated) but not conducted electrical interference - eg, through the 12V supply. Have you tried small or (and) large caps at the amps/source? Ditto at the light's power source? (Input & output if it's power module.) An FYI ramble follows: Not that I've had to deal with modern noise makers, but things that cause noise can radiate it or send it out along their input (and output) power connections and other wires. Then it's Catch-22 - the noise-source's wires or circuit radiate, the receiver's (amp/audio source) power and other wires get induced noise or the noise goes through their cases. Caps can quench the conducted (wire) noise. Shielding quenches radiated noise. Shielding means grounding metal cases and maybe adding more metal - maybe wire mesh over ventilation and other "non-metal" holes (or behind plastic displays etc) - basically creating a Faraday cage. Caps were traditionally small and fast types (0.01uF - 0.1uF ceramic or greencaps), but as I found out recently, sometimes big caps help - eg, 100uF and higher electrolytics. Sometimes coaxial caps are needed - the cap case is soldered to the equipment case and wires "pass thru" the cap (break wire at the case and solder each end to the respective side - but that's in extreme circumstances like some (IMO poorly designed) 12V PSUs for PCs etc. And where cases are else need to be floating, small caps from case to GND (or even +V as well) if they can't be hard-grounded - but surely all 12V system cases can be? Sometimes a cap anywhere between the noise and the receiver is sufficient unless there is bad radiation. In that case, cap as close as possible to the source to quash leakage. Otherwise cap as close to the receiver to quash ingress. Sometimes both. And sometimes a large and small cap. (Although a large cap should quash the high frequencies done by small caps, due to the materials and construction used, that's usually not the case. EG, big filter caps (10,000uF) at PSU DC outputs with small caps (0.01uF) as well, though the small caps are usually placed near ICs/chips etc so they also quash chip generated noise before radiating from PCB tracks. There are so many possible sources and solutions. It is often a case of trying this or that and then making it permanent to eliminate the worst (ie, placing caps of different sizes between conductors and GND before soldering or permanently attaching). Just don't get fixated into one solution or frustrated that that doesn't work. Oh - I forgot to mention ground loops etc - typically overcome by "single point grounding". Alas I'm rusty and I hated that crap anyhow... And I didn't mention series chokes - the equivalent to (large) parallel capacitors. But why do people often connect radio and audio direct to the battery? Because the battery is a HUGE cap and is the cleanest DC available (exempting regulation or more caps elsewhere). Same for noise generators - straight to the battery to squash the noise. (But then noise and receiver conductors are close together, and here we go again - Catch 22.) Others are likely to have newer and specific solutions, or even correct if I'm wrong above. [ I remember tin cans over ignition coils and distributor caps soldered to shielding over the HT leads to splugs etc. Even steel wool under hubcaps (ie, bearing hubcaps; not wheel caps). LOL - we still have splus etc yet no longer need such measures... Then came GSM interference... And then Arabic numbering...) Maybe my best solution - use gas lighting.

The led's are 12 volt and run off of a controller. There are four ribbons running off one controller. There is a gel cell battery in the rear of the bus that all of the audio and lighting run from. It's connected to the main batteries with an isolator circuit to prevent running down the main batteries. The first point from the gel cell to all of the rest of the equipment is a 3 farad cap, but there is not a cap between the led controller and the rest of the equipment. I will try that next. I also ordered a set of quality knu shielded interconnects and I will try that as well. Wish me luck.

Maybe a simple test is moving the caps nearer the LED controller, or even the audio. The controller will use PWM which can generate noise at both ends. Is it non-shielded ribbon? Disconnect the ribbons at the controller end. If noise reduces, it could be radiated from the ribbon, or reflected out the power input (to the controller).

I finally got a chance to install some good quality Knuconceptz shielded rca cables tonight. That killed the buzz when the engine is running. However, if the bus engine is not running, it's still present. I'm going to install a choke on the head unit's power feed next to see if that takes care of the rest.