Turntable hum

[jlovda]

I am restoring a Mcintosh MA6200 amplifier and am using it with my Dual 721 and Shure M91ED. If I do NOT attach the turntable ground wire to the amp I get a loud buzzing hum even when the turntable is not turned on. With the ground wire attached, everything is quiet and sounds fine. Is there I can do to either the amp or turntable to remove this noise?

Thanks

 

[wasclywabbit]

I'm assuming you only get the buzz when Phono is selected on your receiver. On most turntables if the ground is disconnected your going to get buzzing regardless as to whether or not the turntable is powered on or off. The cartridge leads and the ground lead are most likely connected directly to your receiver and are not switched. So if you've selected Phono on the receiver and no ground is attached, it's going to buzz. So best to just keep the ground wire connected to the receiver. There's no work around that I'm aware of.

 

[jlovda]

I'm assuming you only get the buzz when Phono is selected on your receiver. On most turntables if the ground is disconnected your going to get buzzing regardless as to whether or not the turntable is powered on or off. The cartridge leads and the ground lead are most likely connected directly to your receiver and are not switched. So if you've selected Phono on the receiver and no ground is attached, it's going to buzz. So best to just keep the ground wire connected to the receiver. There's no work around that I'm aware of.

Thanks for the reply. You are correct regarding the input selector position.

 

[gadget73]

Just connect the wire, thats what its there for.

 

[tabarddn51]

Yep, that's why we have them.

 

[rothwellaudio]

Just connect the wire, thats what its there for.

Yep,

 

[WaynerN]

The phono preamp section in your McIntosh has tremendous gain and your phono cartridge is kind of like a microphone. Unless the ground wire is connected to some metal (typically ground screw located next to phono input), it will hum. The ground wire in this case is a noise drain as all of the metal and wiring of the turntable is like an antenna. It can capture all of the magnetic stray magnetic fields that abound in many listening rooms. There are noise makers as well, like wall warts, some lighting (LED, fluorescent) and bad cable management. Sometimes the transformer in the amplifier can cause problems if the table is close to it. I try to keep all of my amps as far away from tables as possible.

 

[CastleMagner]

Need help with hum that started when I changed receiver from Sansui 9090db to Onkyo TX 8500 (not Mark II). Turntable is Sansui SR 929. Ground wire attached to the receiver, noise only when switched to phono.

I made the temporary switch to the Onkyo when the 9090 dropped the right channel. Read that sometimes hum is due to close proximity to transformer. The Oknkyo has a big one, and it sits to the left of the turntable. Don’t have room to move it more than 4 inches away from the turntable.

I’m stumped. Any thoughts?

 

[mrwood200]

Any thoughts?

Assuming the only change was the receiver switch, consider:
#1 Fixing the sweet Sansui receiver to pair with sweet Sansui TT..............
#2 Inches can matter. Scoot stuff around to see if you can reduce hum. Sometimes a slight angle may help.
#3 Maybe some cables got moved? Fluff the cables to try & reduce hum. Stay away from power cords.

.......when is the last time you used the Onkyo? Maybe the Onkyo (phono) has the hum?
Could be some work, but maybe set your Onkyo system up on the floor w/plenty of space.......see if you can get playback hum free. If yes, hum is probably from your physical layout....
If the hum is layout related & you are stuck with the layout & Onkyo, I might try some shielding with available sheet metal. Again, experimentation, trial & error.

 

[CastleMagner]

Assuming the only change was the receiver switch, consider:
#1 Fixing the sweet Sansui receiver to pair with sweet Sansui TT..............
#2 Inches can matter. Scoot stuff around to see if you can reduce hum. Sometimes a slight angle may help.
#3 Maybe some cables got moved? Fluff the cables to try & reduce hum. Stay away from power cords.

.......when is the last time you used the Onkyo? Maybe the Onkyo (phono) has the hum?
Could be some work, but maybe set your Onkyo system up on the floor w/plenty of space.......see if you can get playback hum free. If yes, hum is probably from your physical layout....
If the hum is layout related & you are stuck with the layout & Onkyo, I might try some shielding with available sheet metal. Again, experimentation, trial & error.

Th

 

[CastleMagner]

Thank you for the quick reply! Indeed fixing the 9090 is #1 on my to do list.

Hadn’t put the old Onkyo into service for 5?Years… I will try some of your suggestions. It may be a while before the 9090 is again ready for duty. Take care!