60Hz hum from turntable

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bemo

New member
Just got a brand new turntable that I am running into my PC in order to convert some old vinyl to MP# and/or CD.

I have this 60Hz hum that I cannot get rid of. the plug is not grounded and there is a grounding block on the back of the TT. When I touch the grounding block, the hum lessens and if I touch the mixer, it disappears almost completely. I have run a wire from the block to the chassis of the mixer and it got rid of some of it but not all and presently the recordings i am making are unusable. Even noise reduction on AA doesn't work.

What can I do to get rid of this hum? Do I need to ground it directly to the power outlet, or is there another solution?
 
Well there is a terminal next to the TT output. I am using the preamp in my mixing console and there is no grounding terminal there. The console doesn't have a grounding prong on it's plug either.
 
What console is this? Does it have a dedicated phono pre? You'll need one for its RIAA eq, otherwise the turntable won't sound right anyway. The console doesn't necessarily need a chassis connection to safety ground, instead try terminating the turntable ground to pin 1 of an XLR and plug that into a mic input channel, or the sleeve of a TS cable plugged into a line input. Since your mixer doesn't have a safety ground, the chassis might be isolated or lifted from audio ground--you need to connect to audio ground.

If your mixer doesn't have a phono preamp, get something like the little ART phono preamp--which has a ground terminal and will solve your problem.
 
mshilarious said:
What console is this? Does it have a dedicated phono pre? You'll need one for its RIAA eq, otherwise the turntable won't sound right anyway. The console doesn't necessarily need a chassis connection to safety ground, instead try terminating the turntable ground to pin 1 of an XLR and plug that into a mic input channel, or the sleeve of a TS cable plugged into a line input. Since your mixer doesn't have a safety ground, the chassis might be isolated or lifted from audio ground--you need to connect to audio ground.

If your mixer doesn't have a phono preamp, get something like the little ART phono preamp--which has a ground terminal and will solve your problem.
Click to expand...
Ditto ...... you simply HAVE to have a phone preamp. There are plenty of cheap ones ...... that Art would do fine.
 
mshilarious said:
What console is this? Does it have a dedicated phono pre? You'll need one for its RIAA eq, otherwise the turntable won't sound right anyway. The console doesn't necessarily need a chassis connection to safety ground, instead try terminating the turntable ground to pin 1 of an XLR and plug that into a mic input channel, or the sleeve of a TS cable plugged into a line input. Since your mixer doesn't have a safety ground, the chassis might be isolated or lifted from audio ground--you need to connect to audio ground.

If your mixer doesn't have a phono preamp, get something like the little ART phono preamp--which has a ground terminal and will solve your problem.
Click to expand...

I was just thinking today about the XLR solution you mentioned. My console has tape in/out with RCA inputs. Would that work for the necessary phono pre?
 
bemo said:
I was just thinking today about the XLR solution you mentioned. My console has tape in/out with RCA inputs. Would that work for the necessary phono pre?
Click to expand...

No. I mean theoretically you could apply the RIAA eq with a plugin, but that's a less than ideal solution. You will still have impedance matching and probably signal-to-noise issues. So as Lt. Bob said, you need a phono preamp.
 
mshilarious said:
No. I mean theoretically you could apply the RIAA eq with a plugin, but that's a less than ideal solution. You will still have impedance matching and probably signal-to-noise issues. So as Lt. Bob said, you need a phono preamp.
Click to expand...
yep ...... the problem is that when they 'cut' a record, they roll off the bass a specific amount at an increasing rate as you go down in frequency so that the grooves won't have such large modulations; because they take up more room and thus, reduce the time you can get on a side and also the stylus will mistrack if the grooves swing too much.

They also boost the treble freqs to make those modulations larger because otherwise they're so tiny a needle won't pick them up.

So you have to have a circuit that correctly reverses those EQ changes.
The current standard is RIAA equalization but there have actually been many different ones thru the years ...... especially in the earlier days of records.

And, as mshilarious pointed out ...... the phono-pre is an impedance matching device. I actually have a couple of phono-pres that I can set different loads from maybe 80 ohm up to the ubiquitous 47k and you can set different capacitances too. All these things will change the sound and work differently with different carts. ( obviously I'm a collector)
Lastly, many carts put out extremely low voltages and you're liable to end up with the gain and channel volume cranked to the max.
A phono-pre is a gain device too.
You don't need to worry about all the stuff I mentioned about loading or capacitance or any of that.
But if you want to get good sound out of your vinyl, you really should pick up a phono-pre. I've seen 'em for as low as $30 or so.
You can spend thousands.
 
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