Deep hum on CDs made from vinyl

[snowysix]

The music tracks recorded from vinyl sound fine on the computer. I use Audacity to remove hiss, normalize, and am satisfied. This is just for family use. But a CD burned with these excellent tracks has a deep hum, electric-sounding, too loud to enjoy the music.

My turntable is new, has a little built-in amp for use when recording into a computer, and the vinyl records are in good shape.

When I record from cassette tape to computer, there is no resulting hum.

I got the hum in past years with a PC, and now the same with my new iMac.

Does anybody know the cause? And how could I prevent it or remove it?

 

[noisewreck]

Sounds like a ground loop issue maybe?

 

[moresound]

Yup. Is your turn table grounded?

 

[rayc]

I record & restore a lot of vinyl so I think there could be a couple of issues;
1. noise from the turntable that is an earthing/grounding issue
2. a level of noise from the vinyl that the ttable picks up
3. CD offset. This often happens & can be addressed by the recording/restoration software you're using.
I use Waverepair - but it isn't a Mac compatible prog. It has, within it's arsenal, a CD offset application that works a treat.
IF your recording/restoration software gives you a view of the file once recorded yopu might be able to see theDC issue. In waverepair - which sets up the wav file as a stereo wave it manifests as the signal beginning & ending below the centre line (see attached image - it's of the last few secoonds of a the left channel of a wave file) - in essence the whole file is centred below true centre.
This can often also be address by running a filter or EQ pass that eliminates signal below 50hz or similar - you'd have to experiment to set it accurately - before you burn it as a CD audio file.
Suffice to say the DC offset tweak is easier & more accurate.

 

[snowysix]

Thank you for responding.

DC Offset I am familiar with. Back in PC days I used Sound Forge to get rid of this. I am not seeing any DC Offset in the tracks which have this hum.

Since all three of you mention the grounding problem, I suspect this is probably my problem.

"Is your turntable grounded?" No it is not -- or, how should I know? PLEASE TELL ME how to ground my turntable. It's these practical details which are never actually described by the experts. What do I attach where, and to what?

 

[SouthSIDE Glen]

"Is your turntable grounded?" No it is not -- or, how should I know? PLEASE TELL ME how to ground my turntable. It's these practical details which are never actually described by the experts. What do I attach where, and to what?

Well, with good old-fashioned analog turntables, they usually have a separate ground wire coming out of them that hooked up to a ground screw on the preamp or receiver to which the turntable wa plugged into. But if you're running a USB turntable directly to your PC, it probably does not have a separate ground like that.

I'd first make sure you're not picking up RF or other EM interference from another source. Make sure the audio and or USB cabling is not running parallel for any length to any of the electrical cords powering any of the equipment. Also make sure none of that cabling or the turntable itself is running too near a CRT monitor, TV, refrigerator or neon or florescent light. Move the 'table and turn off tose lind of lights and see what happens.

If after all that - perhaps even trying the turntable in another room just to see if the hum follows - you suspect that maybe you have a ground loop problem in your current room, read up on ground loops here.

If after all that you can't budge the problem, you might have a defective turntable that is introducing the hum itself. Have a repair tech check it out, especially if it's still under warranty.

HTH,

G.