I got a humming sound on my subwoofers it is connected to my car pioneer tuner. How can I fix this? Is it a defective capacitor on the amp?

The first thing I would check is your receiver/tuner and all connected components. Make sure all the settings are correct if it's not getting the correct signal they will not communicate to the subwoofer. The second thing I would check are the wires, even if they looked as if they're hooked up correctly they could be damaged in some way not receiving the signal to the other end check this with an ohmmeter and you can do this by putting it on the sound setting check one end of The Wire to the other and make sure it makes a beep or a humming noise, this means you have signal through the complete distance of the wire. If all that is correct then I would connect your subwoofer to another receiver/tuner. And if still no signal maybe the subwoofer is defective.

I would check the caps on the power supply. They are rather large electrolytic capacitors that will look like they burst and/or leaking. When these die, the caps ground and the sub will make a loud buzzing sound. If you are handy with a soldering iron you can replace them yourself. Replace them with the same voltage or a little bigger and same with the size.

If the cap. says 16v 4700pF on it, for example, a 20v 5300pF or a 16v 6200mF cap. will work for this application.

Humming noise on your sound is not due to your speaker but it is come from the amplifier. I've encountered a lot of this problem that is caused by the electrolytic capacitor. If you are a technician first locate for a dry joints on the board and then resolder it using your soldering iron and a high quality soldering lead. Resolder not only the capacitor but also around the output I.C.
If nothing happen then it is coming from your output I.C. sometimes it was leaky/shorted which produces a humming noise but first do the the above mentioned instructions before isolating the defective output i.c.

Actually I"m having the same problem. It is most probably the capacitors on the power supply internally. they are known to dry out and go back. cheap easy fix by a competent electronics repair facility. Also Cambridge will fix it for $75 plus shipping

U need to install a alternator noise filter in the power supply line, Radio Shack can supply the one you need, it goes by how many Amps of power the system uses.

jd40,
Sounds like a grounding issue. The first two places to look into is the powered subwoofer and antenna. During your last test, did you leave the FM antenna and subwoofer connected? Many times the hum is directly related to the antenna and/or the subwoofer and to how they are grounded; creating a ground loop through the receivers ground on the outlet. If the antenna is grounded to the dwellings wiring, hum is inevitable and sometime you can get a ground loop hum from how or how & where the subwoofer is grounded. Try taking them completely out of the loop.

Also try taking it further back to the basics, start with the receiver plugged into a known good grounded outlet with no surge or line conditioner in the loop and nothing connected to the receiver, nothing. Use one speaker and different wire to test each speaker output while in tuner and any other mode but phono. With no signal, you will either get nothing (no hum or static) or just static in the tuner mode. No hum is a good sign. Some systems will mute the speakers if no signal is connected to eliminate the static from being produced through the speakers but a ground loop hum will most likely still be produced even in mute. If you get a hum when nothing is connected to the receiver, try looking into getting a better grounded outlet, even maybe to a different dwelling.

-Chris

It sounds like you are describing an earth loop problem. I won't go into detail in this post, but try an isolation test first. disconnect everything from the reciever except the sub and try connecting say a BATTERY powered mp3 player or cd player to minimise connections to the electrical mains earth. you could also isolate things by taking your sub to a friend's house and trying it on their system.
If it is an earth loop use a process of elimination to find out which two pieces of equipment causes the earth loop. then apply filtering.
you can buy earth loop isolation transformers for about AU$26 and I've used one on my sub myself. Theyhave RCA (phono)plugs on each end and they connect inline with the signal cable to the sub amp.

as for the thumping sound it might be the speaker protection circuitry cutting off the amp to protect the subwoofer speaker from damaged. This might be triggered if the earth loop sound is causing the sub amp to overload and clip.

Failing this there might be a dried out overheated electro capacitor in the amp circuit causing the hum. Hav a chat to your local electronics person, who should be able to spot it!
Hope this puts you on the right track
Happy Hunting!

I use the sg 540 equalizer for cd and tuner. (I have two of them) I also use the sa 940 to power my sound. On the tuner input of the amp, i used standerd rca cables and connected it to the output of the equalizer. then i connected rca cables from the input of the equalizer to the output of the tuner. this only works when the top equalizer button is pushed on. hope it works for you.

This may or may not apply to your particular problem. On similar humming sound problems, I normally would look for either a fault in the input side and/or a leaky/defective capacitor in the power supply. On the input side, this may be a frayed shielded wire, loose connector (esp. the outer which is normally the ground). Try completely removing the connecting/input cable that goes into the subwoofer. If that doesn't work, then it you may want to check the big capacitor in the power supply section of the subwoofer. If you are not that familiar in working with power supplies, may I suggest that you ask any electronic technician to have a look at it since capacitors store a rather hefty voltage. Better be on the safe side. Hope this works out ok with you

here is a short test you can try, remove the rca audio cable from the amp & connect a diskman or toher audio o/p device that you can hook up with the same rca wires, turn on the amp & see if you have sound. you can also remove the speaker wires from the sub & using multi meter read the ohm's of the sub, most subs are 4 ohm. Hope this help locate your problem