You need to list your entire system. |
My system:
Garrard 301 turntable
SME M2-12 tonearm
Audio Technica ART9 and Denon 103r cartridges
Naim Superline/Supercap phonostage
Lamm LL2 preamp
FM Acoustics F10 power amp
Tannoy Turnberry SE speakers
Cables are all Mogami 2803 with Auditorium 23 speaker cables |
Phonograph cartridges are a balanced source. That is why the ground wire is needed, as it is the ground of the balanced system. The thing is, when employed as a single-ended source, the capacitance of the interconnect plays a bigger role when the ground cable is connected.
By running a balanced preamp that ignores ground at its input, you get around this problem. Truly balanced systems tend to be very cable-immune.
If you don't want to replace your preamp, you might have to consider a lower capacitance cable between the arm and preamp. |
I'm wondering if the liveliness you describe is low level noise coming through the ground connection..... |
oops....you said less lively with ground....sorry. |
Never heard of this very strange |
try to look at the Garrard ground...it is usually just 2 prong cable. The ground should be from the motor bracket. That may help with the hum...the liveliness may be some combination between these two grounds.... |
What should I exactly do to the Garrard ground ?
Should I connect a cable from the motor bracket to the ground of the AC mains ? |
I tried borrowing a friend's pro-ject phono stage which has variable gain options. I noticed that with this phono there is no hum at 40 db and 50 db gain, however the moment I switch the gain to 60 db (that is the max gain on this phono) the hum is back. Can this be used as a clue ? |
Atmasphere, this hum issue is a recent one. It did not happen before. The cables were no different. Moreover the Mogami 2549 and 2534 cables that I use are extremely low capacitance cables. I also have a Van Den Hul D501 phono IC which also doesn't solve the problem. |
Another observation: I noticed that when I switch off the motor of my Garrard 301 the hum changes. It becomes thinner and slightly less prominent. Does that mean it is something to do with the Garrard motor grounding ? |
Do you have any sort of loading on the cartridge? |
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regarding the ground I would try both either ground the Garrard at the motor bracket and also on the cable or just the motor, or just the cable. You should find out which works better at your system. Also check if there is ground going from the arm.... |
What exactly does it mean by ground the Garrard motor ? Please advise since I am a total novice at DIY. |
do you have 3 wires on the Garrard power cord? Means is there ground wire attached at the motor bracket ? if not try to use separate wire to ground it there... |
The Garrard motor has only two wired terminals. But my upgraded pc has 3 wires. The ground wire is just left taped and loose on the motor end. Should I connect this ground wire to some area on the motor ? |
Pani
Congrats on your Garrard. Phono hum is a nasty. I have been pretty unsuccessful in removing mine. Hope you have better luck. Do share your experience.
Best
Pradeep |
Hi Pradeep,
You are using a SUT with a low gain MM stage, that should not cause a hum IMO. In my system when I use a lower gain stage the hum is gone. The hum is only there when I use the highest gain on the phono. Unfortunately my MC cart needs the highest gain so I have no choice.
Do you hear the hum with both your turntables ? |
Are the phono cables routed near any power cords, power supplies, or components that may be inducing hum in them? Did anything change in the system or its physical setup around the time the problem appeared?
Also, my suspicion would be that if connecting the ground wire makes the system sound "less lively," that having it not connected is somehow compensating for some other issue. If you haven't already tried this, see how the system sounds with the wire connected and with the resistive loading changed to a much higher value than the 100 ohms you have been using. The relatively heavy 100 ohm load may be adversely affecting dynamics. (I note, btw, that 100 ohms is the **minimum** load impedance recommended for the AT-ART9).
Regards,
-- Al |
Does the phono preamp have hum in the highest gain setting when there are no interconnect cables connected from the tone arm? If it does the arm and cartridge may be off the hook.
The loading resistors need only be used if your preamp is susceptible to Radio Frequency Interference (RFI). Ignore what the manufacturer recommends- if their preamp was susceptible then they will have a recommendation. Otherwise the stock 47K is sufficient.
I would certainly start by grounding the wire and removing the loading resistors- see how that works for you. |
