Speaker Hum and cracking noise

[studiord]

Hello,

I am using a Nad C555i (Rega RP1 clone) with Marantz 7004 and B&W 685 speakers since more than a year. I have noticed that the speakers give out a continuous hum and crackling sound at loud volume (12 o clock and above) even when the TT is not playing. The amp is fine as there is no hum from other sources. Also, I don't think it has anything to do with the cartridge as I recently upgraded and therefore the leads are properly fitted. But when I touch the cylindrical part of the tonearm near the base, the crackling sound increases. Therefore, I suspect it's an internal wiring issue.

I would appreciate if you guys could help me identify whats the problem and possible solutions ? Thanks in advance.

PS: The turntable has no ground wire so probably it's not an earthing issue.

 

[Tanoj]

Did you connect the Earthing wire , from the tt to the amp ?

also check if the earthing of wall socket is working fine ?

Which TT are you using ?

Regards

Tanoj

 

[Shivam]

This seems like an earthing issue. Check that the amp, phono preamp and the turntable have a common earth.

 

[studiord]

Hi Tanoj,

As mentioned, there is no earthing wire supplied with the NAD C555i turntable. Also, I have not connected it directly to wall socket as I am using a power strip which has earthing I suppose.

Did you connect the Earthing wire , from the tt to the amp ?

also check if the earthing of wall socket is working fine ?

Which TT are you using ?

Regards

Tanoj

 

[studiord]

Thanks for your reply Shivam. There is no pre-amp as my Marantz 7004 amp has phono inputs. Also, TT does not have earthing wire. What are the other options ?

regards

RD

This seems like an earthing issue. Check that the amp, phono preamp and the turntable have a common earth.

 

[Shivam]

Try connecting a thin flexible wire to the body of the amplifier and another end to the metallic base of the tonearm mount. Make sure to connect where there is no overlying layer of paint. Let us know if it helps.

 

[jls001]

Earthing is MUST. The NAD would surely have some point from where you can connect an earthing wire, which in turn must be connected to your Marantz's earthing terminal (if your Marantz amp has a phono stage, it WILL also have a earthing terminal). Finally, please ensure that your amp's power supply has earthing terminal properly connected.

 

[studiord]

Thanks for your reply. I have examined the NAD TT and could not find any place where the earthing wire can be connected. Or maybe I am missing something? Also, this might sound dumb but how do I check if the main power supply has proper earthing or not?

Earthing is MUST. The NAD would surely have some point from where you can connect an earthing wire, which in turn must be connected to your Marantz's earthing terminal (if your Marantz amp has a phono stage, it WILL also have a earthing terminal). Finally, please ensure that your amp's power supply has earthing terminal properly connected.

 

[jls001]

but how do I check if the main power supply has proper earthing or not?

First, check that your amplifier uses a power cord that has a ground pin. Do not use a power cord that uses only two pins for an amplifier that has a phono stage.

Next, check that your power socket actually has earthing. To check this you will need a multimeter. A multimeter is very cheap nowadays (Rs 150-200) and useful so please buy one. When you look at a power socket, the large hole at the top is earth terminal. There are two holes below that - left is Neutral, right is Live.

Set your multimeter to measure AC line voltage of 230V (your meter may have setting for 700V AC). Measure the voltage between Live and Neutral -- it should be about 230V. Next, measure the voltage between Live and Earth - this should also be about 230 Volts. Next change the voltage range to lowest AC range and measure the voltage between earth and neutral - this should be 1.5V to 2 V AC. If it is higher than 2 to 3 Volts, then your earthing probably needs to be re-checked by a professional electrician.

 

[Hiten]

Was the problem solved ?

PS: The turntable has no ground wire so probably it's not an earthing issue.

In some turntables one channel ground wire (-ve) connects to TT/tonearm chassis so no separate ground wire is necessary.
Regards

 

[sachu888]

Can you share a pic of your setup.I think you are getting acoustic feedback,try placing TT in different location.

Regards,
Sachin