My colleague Sandy got a new subwoofer last month. It was working absolutely fine until last week it started to hum every time he connects with an RCA cable.
Since I am pretty confident with electronics, he asked for my help. I went and checked the subwoofer and guess what! I could fix it in an instant.
So this article is all about diagnosing and fixing the subwoofer hum problem. If you are also facing this problem and are clueless as to where to start, stop wasting your time and read on!
Probable Reasons Why Subwoofer Hums
Let’s start with addressing the main 3 reasons why your subwoofer hums. Because I believe that it is important to know where the problem actually takes place, before moving forward to solutions. So here are the top reasons why this kinda problem happens:
- Ground loop problem: One of the most common causes for which the hum originates is a ground loop error. This actually means that all the equipment/connections are having different ground potential. That interrupts the even flow of current among the lines. And thereby, you get this humming sound.
- If the head unit turns faulty: In most cases, the problem starts with a malfunction in the head unit. If there is anything broken inside the head unit, it doesn’t get amplified. So it transmits to the main amplifier which also fails to get amplified. Therefore you receive the humming sound.
- Faulty amplifier: The amplifier could also get defective. To detect if the amplifier is bad, you got to connect it to your phone or any source and check if that humming noise starts or not. Also, if you keep the amplifier on a hard surface and place some tiny stuff on its top, try touching the surface with your finger. You will notice that the hum sound increases and the amplifier vibrates.
A Quick Fix Method To Solve This Problem In An Instant
Presenting to you a Quick Fix trick that will alleviate your problem instantly. If you are in a hurry or cannot afford to miss your favorite show, this instant solution will change your game!
- Start off with checking if any wire is damaged or broken. Make sure that all the connections are secure.
- Now try removing the black wire from your connection method/amplifier/AV receiver. You gotta avoid its shortening. So cover the end of this bare wire with a piece of electrical tape.
- After removing the black wire, check whether your subwoofer stops humming. If it stops, get back to enjoying your show!
N: B However, if the humming still continues, stick the black wire to the chassis ground of your amplifier. If there is no chassis ground point, loosen a chassis screw and wrap the black wire around the screw, and now retighten it.
Troubleshooting Steps to Fix The Humming Sound Problem
So here comes the main part- I am gonna share the top 7 fixing methods that will help you to eradicate the humming sound for good. Without any further talk, let’s get to this!
1. Inspect The Head Unit
In most cases, the humming sound comes from a bad head unit. The head unit also acts as a small amplifier.
To diagnose it, get yourself an RCA cable and plug one end into your source and the other end into the amplifier. Now check if there is any humming sound or not. If not, then your head unit might turn defective.
If the problem lies in the head unit:
- Take a random wire and strip quite a large amount of it from the outer binding.
- Reach to the RCA ports that you have at the back of your head unit.
- Twist the stripped wire a little and place it around the port. So now when you plug your RCA, it will clamp to the shielding.
- And connect the other end to the head unit.
- Finally, check if there is any more hum.
Exactly the same way, you can connect it to the ground terminal of your amplifier. If the hum is gone, you are good!
2. Faulty Capacitor
The capacitors are responsible for filtering the humming sound out. So if you hear the hum, the capacitors are to blame. In that case:
- Open up your amplifier carefully and check whether the capacitors are burnt (due to electrolysis) or damaged.
- Apparently, they might look fine but if the surface on top is black and plain, then that means they are damaged and needs replacement.
3. Remove The Black Wire
Disconnect the black wire from your amplifier. Connect an RCA cable to the RCA connector on the rear of your amplifier and the LFE rails on point one input. Make sure that the volume is completely down. Now check whether that stops the humming.
4. Get Rid Of Cheap Unshielded RCA Cables
Well, you do not put much emphasis but it is important that you use a shielded RCA Cable. This was the problem of my colleague who was using a cheap and open RCA cable.
These cables are usually of poor quality and they tend to go bad within a few days.
So I would recommend using a good quality RCA cable that must be shielded. Also, make sure that the RCA connection soldering of your amplifier is secure.
5. Check Different Outlets
To eradicate the humming sound, firstly plug the subwoofer/receiver/amplifier into the same outlet. If there is a humming sound, try switching them to a different outlet. This is just to confirm if the outlet itself is faulty.
Now plug the sub and the other unit (receiver/amplifier) in separate outlets and check which one is defective. If anyone among these turns out to be faulty, look for replacement options.
6. Faulty Subwoofer
You might end up with a defective subwoofer! Yes, your subwoofer might fail to get rid of the 60-Hertz noise cycle, that you are calling a hum.
Other than that, there could be internal problems, for instance- faulty capacitors, circuitry issues, and so on. To diagnose the cause of humming, you need to:
- Remove all the external connections from your subwoofer.
- Unplug and plug the power back on.
- Now check whether there is any humming sound.
- If so, then your subwoofer is most likely to turn bad. In that case, you gotta replace it with a new one.
7. An Audio Isolation Transformer Helps!
If your subwoofer is facing ground loop issues, you could check and make sure that all the ground connections have the same potential. You can also try plugging all the connections into the same outlet.
If that doesn’t help, there is something that could fix this problem in an instant. You can install a low-level Audio isolation transformer on the subwoofer’s cable that would help fix the ground loop easily!
With an audio isolation transformer, the wire-inducing current remains in full effect. And thereby the signal remains unaltered. Besides, it can isolate the signal ground from the AC power ground.
Frequently Asked Questions
So here I will be covering some FAQs related to the subwoofer hum issue. If you think that you gotta learn more about this common yet annoying problem, then you gotta read on!
Can RCA cables cause hum?
Unfortunately, yes! When you use cheap quality open RCA cables in the parallel power cord, it leads to a humming noise. And that eventually increases to an annoying level. In that case, I’d recommend using shielded and good-quality RCA Cables.
What causes a 60Hz hum?
In most cases, poor RCA cables, loose connections, and powerful magnetic fields cause a 60Hz hum.
How do you test to see if a ground is good?
Use a voltmeter to measure the resistance value on the ground/terminal connection of your amplifier/receiver. If the reading goes beyond five ohms, then your ground might turn bad. Less than that, all good!
Hope these mind-blowing tricks will help you get rid of the humming noise of your subwoofer. These tricks are easy so trying them at home wouldn’t cost you a thing.
However, there always remains a chance that these tricks wouldn’t help fix the problem. Or it might temporarily alleviate the problem. In that case, you gotta deal with it again in the long run.
So if these tricks don’t help, I’d suggest you consult a technician to diagnose the issue and resolve it at once.