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Re: Input 60Hz hum
I had the same problem once and in my case i had accidentally used ground wire for signal. pls check ur connections again. one check u can do is set the high pass filter to 70Hz and see if that cuts out the low hum.
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Hum is tough. It is often caused by quite a variety of things. First, address the basics:
1. Make sure that none of your signal cables run near to power cabels.
2. If possible, feed all power from the same receptacle.
3. If your plugs are not polarized, try reversing one at a time.
If none of those basic checks uncovers your demon, verify the path of the noise by disconnecting the signal from the preamp at the input to the sub. If is still hums, then look closely at the power feed to the sub, More likely, the hum will stop (along with the music.) In this case, try breaking the shield ground at the sub input (e.g. with a ground isolation adapter.)
You should also confirm that the hum is limited to the sub. Subs tend to exaggerate hum because playing signals in the 60Hz is their forte. So with the sub turned off and bypassed, listen for the hum in your main speakers. If it is there, too, then start checking your sources. Remember, even a source device other than the one selected for play could be the source ... completely disconnect each source at the preamp to track it down.
If it is a 60Hz or 120 hz hum, the fault may be a bad solder connection to a filter capacitor in the power supply.
If it is a hum like a bad mic connection, you may have dirty contacts on an input, dirty tracks on a mixer control, even on the EQ portion.
It may also be a bad cable is connected, or a 1/4 inch jacked input may not be grounding out when the plug is removed. You may have a bad ground on the power feed and you have a ground loop as a result, or a cable is faulty and creating it's pwn ground loop to something else.
Contact cleaner is not a bad idea, slide pots are notorious for spurious noise over time. LPS1 is not bad, but it does use silicone as the dry lubricant portion.
If all of that is ruled out, look internally for bad solder joints- anything that looks crumbly is suspect, and also check for loose wires and jacks with bad solder connections. Also look for loose connectors too.
I'm thinking you have an open shield ground on the RCA input side. Connecting speaker inputs possibly restores the ground. Try connecting the high level inputs then disconnect the remote end of the cables (floating the grounds).
Then get out an ohmmeter and find that open circuitor or bad solder joint between RCA ground and real ground in the speaker's amplifier. Or.... if speaker ground kills the hum and you want to use RCA Line Level input to the sub, just connect one minus speaker output on your source amp to one minus on the sub's amp.
Turntables require a special input in the amp (usually marked PHONO) because they require high gain and different equalization - and yes, that ground wire has to go to ground unless you want to get a super annoying 60Hz hum from it! If your amp doesn't have a phono input, you're going to have to go out and get a phono pre-amp and connect it between the turntable and the amp. Best of luck!
This hum could be from a ground loop or a bad main board in your TV.
1. Try removing all the inputs from the back of the TV.
2. Unplug the TV for about 3 minutes and plug it back in.
3. Turn on the TV and go to HDMI1 input.
4. Turn the volume up to see if you hear the hum.
5. If you hear the hum without any inputs into the TV, then the problem is with your main board, or with the quality of power you have going to your TV (your wall outlet may have an open or bad ground).You can try plugging the TV into a different outlet across the other side of the house (to try a different circuit) to see if your power is the problem.
6. If you don’t hear a hum without any inputs into the TV, then the audio hum is caused from one or more of your inputs.
7. You will have to plug in one input at a time into the TV, and turn up the volume to see if that one input is creating the hum.If the TV hums, then you have a problem with that device and or the cable that connects it to the TV.
8. There is a chance the hum will occur when two or more devices are connected to the TV at the same time.So be careful of this issue. This issue is not the fault of the TV and is a grounding issue between the devices.
I hope this information has helped you.
The hum you hear from the speakers and from the unit itself originate with 60hz AC power. They may not actually be related. Sometimes a transformer will hum slightly and unnoticeably. That you're getting a loud speaker hum says there is an electrical leak or a grounding issue somewhere.
Do all sources produce the hum or, say, just the phono? How about on headphones? Try rotating the AC plug. In those days they weren't keyed with one large blade as they are now.