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Need help with a grounding issue

K-Shaps

K-Shaps

New Member
Been awhile since I’ve posted here but I’m trying to solve for a grounding issue in my setup. I have electrical hum/feedback at higher volumes whether I’m using my turntable or an aux cable to an iphone/CD/etc.

My turntable (Denon DP-300F) does not have an external ground post and the grounds are in the head shell carried over the RCA cable plugged into my receiver.

My receiver (Pioneer SX-750) does have a ground post connection that is currently not being used.

the power cables from my turntable and from my receiver are plugged into the same power strip going into my wall socket.

Can I/should I attach a ground wire to my receiver’s ground and wrap it around a nail to eliminate the hum/feedback?

If I touch the metal on my receiver the hum does pretty much go away fully so I’m thinking I could do this but want to know best practices. Thanks in advance!
 
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K, doesn't your receiver have an outlet on it? Did you try plugging the Denon into there?
 
The receiver has two inputs for power however the plug from the turntable doesn’t fit in either one due to one of the prongs on the turntable power cord being bigger than the other.
 
A quick google/Amazon search I was not able to find a cheater plug that has equal sized male prongs. Do you have a reco on where I could find one?

Wouldn’t the hum still occur with my aux input though? Trying to solve for both
 
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try H/d- Lowes.
"Wouldn’t the hum still occur with my aux input though"? That I cant tell you. I have the 1250 & 1280, & that's how I have my TT connected, & have no issues.
 
Just went to my local Home Depot and they didn’t have this type of cheater plug. I’ll keep looking online and see if I can source one somewhere. I was honestly shocked they didn’t have one.
 
If you disconnect the tt, does the aux input still hum..?
Plug the rcvr into the wall, eliminate the power strip.. as a test..
Rotate the rcvrs plug in the outlet.. another test..
 
Turn table chassis are isolated from electrical service ground normally. So go from a chassis screw on the TT to a chassis screw on the receivers to a electrical ground if you have a 3 wire electrical system. If not then you need to run a #10 or 8 awg wire to a lightning rod copper stake driven at least 4ft into the ground, or a copper water pipe that descends in to the earth. If you are using a cable TV signal for the tuner or for a TV connected to the sound system you may have a real can of worms you may not be able to correct and that could also be the situation by having a computer audio out let connected to the sound system. Thats why I use Apple TV to connect the computer to the sound system wirelessly and use direct TV so as not be connected to AT&T or Spectrum cable services. Using optical and HDMI connections further reduces hum issues to nothing when connecting the TV to the HT sound system. Also keeping all electrical connections on the same circuit breaker helps, too. If you need more outlets use one that are fed from the same row of circuit breakers. Don't pick one on one side of the box and another from the other side. If you have aluminum wiring for electrical service in your house good luck!
And all it takes is one compromised connection in an electrical junction box to cause your issues, too. Thats why I have home runs between the circuit breaker cabinet and the stereo , HT and TV display.. 3 20 amp circuits and one 15 amp circuit. No junction boxes or splices.
 
K-Shaps said:
I have electrical hum/feedback at higher volumes whether I’m using my turntable or an aux cable to an iphone/CD/etc.
Click to expand...
ie, hum also occurs for AUX connected CDP

K-Shaps said:
electrical hum/feedback at higher volumes
Click to expand...
Why occuring at higher volumes rather than all/no volume?

Hum present in both channels would point to power supply.
Possibly hum is introduced into audio path and only becomes noticeable at higher volumes
Is hum mains 50/60Hz or rectified 100/120Hz, mobile phone app or tools like audacity to check/measure.
 
mbz said:
ie, hum also occurs for AUX connected CDP


Why occuring at higher volumes rather than all/no volume?

Hum present in both channels would point to power supply.
Possibly hum is introduced into audio path and only becomes noticeable at higher volumes
Is hum mains 50/60Hz or rectified 100/120Hz, mobile phone app or tools like audacity to check/measure.
Click to expand...
I agree, this is a confused (confusing?) thread started by a confused question. Acoustic feedback has nothing to do with grounding and a feedback issue isn't going to be cured by grounding anything. Also, how do you get feedback when using a CD player?
A proper description of the problem is needed before solutions can be offered.
 
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Do you use a subwoofer?
I would check your RCA cables. If you have long rca runs or unshielded rca's it could be that.
3.5mm to rca can be problematic sometimes
 
The hum is there even at low volumes, you just can't hear it at lower volumes. I wonder how close the TT is to the receiver and since the receiver is old, it has a non-polarized plug, which if I were you, would try rotating the plug into the outlet. You have a 50% chance that its plugged in the wrong way. The 120 volt fuse should be on the hot side (narrow slot in outlet).

'ner
 
This morning I unplugged everything from my receiver and plugged the receiver directly into my power outlet (flipped the plug in both orientations) and I’m getting the electrical hum on all inputs. So I think it’s safe to assume it’s something in the receiver? Or the power from my shitty old apartment? I also tried the receiver through my surge protector (plug in both orientations) and the same thing.

the electrical hum is there at all volumes. I used headphones to confirm.
 
Can you get a hold of a different receiver or amplifier to test with? That way you could isolate the receiver as the possible source of the hum. Also, that could tell you if it is something like bad filter caps on the SX-750 instead of a ground hum.
 
K-Shaps said:
If I touch the metal on my receiver the hum does pretty much go away
Click to expand...
Possibly a bad GND wire or burnt GND track. Suggest work through the GND connections in the "front end", ie from AUX RCA's to volumer pot, use multimeter to check GND continuity from RCA's (outer) to other GND points eg, black spkr post, chassis,,,
 
Try a different outlet on a different ckt. Just a thought. Do you have any dimmer switches on lighting ckts? Some solid state dimmers are notorious noise makers.
 
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