remove hum from active subwoofer?

[BlaezaLite]

good advice. I just printed money and have to wait for the ink to dry. I like how people throw out advice like its no big deal for them. "yea, JUST get"....


ill try that. thanks


who says this is true?

Its advice, like you asked for?

Or Speedwoofer? Wharfedale? Monoprice? Quality at a budget. Better?

 

[AsRock]

when nothing is playing theres a hum. I usually ignore or dont notice it. but its something id like to lower it a bit. possible?

disconnected from avr, still hum, put it on same electrical line as the other components, hum.

Sounds like a bad ground, even when the cable is disconnected from the sub side ?.

 

[ty_ger]

It's a hard wired setup not one of those figure 8 plugs or did you not look at the picture the OP posted

I think he is talking about the plug you put in the wall; assuming that it is an ungrounded plug that can be flipped.... Swapping which side is hot and neutral. But, if the plug is symmetrical that the hot and neutral sides are the same size, one would assume that the manufacturer assured that it should work properly either way.






I think Vayra86 has this handled.

 

[Wirko]

I think he is talking about the plug you put in the wall; assuming that it is an ungrounded plug that can be flipped.... Swapping which side is hot and neutral.

Yes, that's it.

But, if the plug is symmetrical that the hot and neutral sides are the same size, one would assume that the manufacturer assured that it should work properly either way.

It's basically impossible to isolate the 50/60 Hz interference from audio signals once and for all. Yes, the amount of hum is often "low enough", and it's lower with balanced wiring, but sometimes it's unacceptable. Turning the wall plug 180° is a simple experiment and sometimes affects the hum (for better or for worse).

 

[Steve-007UK]

Could just be a bad cable. Try swapping. If not then it is something internal that you won't be able to fix easily.

This is a thing, i've had a few subs over the years some good some bad but depending on what cable i have used can make the sub hum when nothing is playing where as a cable that is well shielded works fine and i get no humming sounds so try to test some different cables first.

This is the cable i use atm but running it from my yamaha stereo amp as it has sub out.

Amazon.co.uk

If it still makes humming sounds when that cable is not plugged in then the sub is getting old and something inside is failing

 

[eidairaman1]

Sounds like a bad ground, even when the cable is disconnected from the sub side ?.

Possible transformer resonance being passed into the audio circuit

 

[AsRock]

Possible transformer resonance being passed into the audio circuit

Or even a dry joint who knows.

 

[unwind-protect]

If the thing hums when no input cable is connected you are basically screwed.

Wegschmeissen neu kaufen.

 

[Wirko]

Or even a dry joint who knows.

Or a dry capacitor. If monitors and mobos can have them, so can subwoofers.

 

[Courier 6]

or maybe the filter capacitor from the amps psu is going bad, only solution is to replace the capacitor

 

[damric]

It could be anything posted above. I/O jacks do wear out, some way faster than others. I've had a few cheap guitars that would hum once the jack socket started to disintegrate from plugging and unplugging. At least if it is the jack socket, you might be able to find replacement parts and repair it yourself. I'm an electronics technician and it wouldn't even be worth my time, so I'd buy a new sub. Time and frustration can be worth more than money.

 

[Harlow]

Although not really HiFi, you could try one of these hum isolators:-

https://www.amazon.com/Filter-Elimi...und+loop+isolator&qid=1740074491&sr=8-11&th=1

As others have said, if the sub woofer amp is getting old, the electrolytic capacitors may be drying out. The first caps I'd test with an ESR meter (or just change) would be the smoothing capacitors on the low voltage DC supply to the amp. These caps are probably several thousand microFarads and up to 63V DC. As these capacitors age, the capacitance drops and the Equivalent Series Resistance rises, both of which are bad for smoothing 50/60Hz ripple. When choosing PSU caps, look for "low ESR" components. They're designed to cope with high ripple currents found in rectified DC.

Back in the days when HiFi amps were fitted with sensitive RCA inputs for moving coil or moving magnet cartridges on record decks/turntables/transcription units, it was normal to disconnect the earth from the mains supply to the deck and instead use the mains earth from the amplifier to ground the metalwork in the deck, via the screening braids on the audio leads (or vice versa). When you had both devices earthed to the mains (amp and deck) you sometimes got a "hum loop" via the audio lead braids.

Finally, I'd work my way through all the electrolytics on the amplifier's printed circuit board, from input to output. A ESR meter will help avoid unnecessary replacements, but you may have to lift one leg of each capacitor off the board to check components in isolation. When all said and done, replacing the whole amplifier board (and PSU) might be less hassle. There are plenty of inexpensive prebuilt audio amps and PSUs which could be retro fitted inside the sub woofer, if you have basic soldering and home DIY skills.

 

[oinkypig]

get a amazon oscilloscope. you can find the clipping point of your rca output to sub. then because its a power sub, you need to remove the backplate and probe the power output wires(with sub discconected from amplifier) and find the clipping point of the amplifier to set the backplate gain knob. This is more oriented for proper signal and rms output playing to sub. Follow the others advice on getting rid of hum, although improper settings can lead to hum as well.