Thanks, nezbleu. I've also read that multiple ground paths can cause an AC ground loop, so I'll look into this more before soldering the RCA plugs. I'd have more options, at any rate, with a separate ground wire/lug.
Does anyone know what the metal tab is on the right channel ground (green) of this Ortofon OM5E? Is it a chassis ground for the cart?
IMG_4864 by jeffdrouin, on Flickr
If so, and if I were to ground the tonearm through the phono cable shield, should I solder the shield to the right channel RCA ground so that arm and cart grounds go out through the same path?
Does anyone know what the metal tab is on the right channel ground (green) of this Ortofon OM5E? Is it a chassis ground for the cart?
IMG_4864 by jeffdrouin, on FlickrIf so, and if I were to ground the tonearm through the phono cable shield, should I solder the shield to the right channel RCA ground so that arm and cart grounds go out through the same path?
Well, it's done and I'm listening to Loretta Lynn as I write this. There is a little background noise (I'm guessing AC hum) when the TT is idle, though I don't hear it when music is playing. And the music sounds even better than before.
The hum got slightly louder when I turned on the motor, and louder again when I touched the arm to put it on the record, getting quieter when I let go. So I'm guessing the arm needs to be grounded better.
The hum got slightly louder when I turned on the motor, and louder again when I touched the arm to put it on the record, getting quieter when I let go. So I'm guessing the arm needs to be grounded better.
there are two ground points on the Rega arms, one should be for the main arm tube and the other for the arm base, the ground for the armtube is behind the counterweight stub and if you wire the ground elsewhere you must remove the stub ground or it will act as an antenna.
the second ground is on the base plug which is a small copper tab coming off the pcb and sits against the plug wall, when you insert the plug into the base it makes contact.
both the armtube and the base plug must be connected by 'one cable'. if you use the pcb then either drill a hole in the base plug and pcb or cut a slot in the side of the base plug to accept the new ground wire. the ground out wire gets soldered to the ground pad on the pcb along with the armtube and base plug copper tab and the original ground via the 'cold' phono gets removed.
do not under any circumstances solder the original 'cold' ground and the new ground together.
the second ground is on the base plug which is a small copper tab coming off the pcb and sits against the plug wall, when you insert the plug into the base it makes contact.
both the armtube and the base plug must be connected by 'one cable'. if you use the pcb then either drill a hole in the base plug and pcb or cut a slot in the side of the base plug to accept the new ground wire. the ground out wire gets soldered to the ground pad on the pcb along with the armtube and base plug copper tab and the original ground via the 'cold' phono gets removed.
do not under any circumstances solder the original 'cold' ground and the new ground together.
If you are hearing an audible change in hum when you touch the tonearm then you have a grounding problem. You might want to grab your multimeter and check continuity across the various bits that should be "grounded", including tonearm tube,btonearm base, TT chassis, phono pre input jackk ground, phono pre chassis ground, PSU ground, etc.
I have a 40 year old Thorens turntable, an RB300,and a low output moving coil cart, and I don't hear hum through my speakers, and touching the tonearm makes no difference.
Chasing ground issues can be very difficult and time consuming.
I have a 40 year old Thorens turntable, an RB300,and a low output moving coil cart, and I don't hear hum through my speakers, and touching the tonearm makes no difference.
Chasing ground issues can be very difficult and time consuming.
Thanks to everyone who has chimed in to this thread.
I had some free time this morning and managed to fix the ground issue. I simply took a piece of spare tonearm wire, tinned one end and soldered the other to the existing joint for the tonearm and phono cable ground wires. The tinned end is held in contact with the base by means of the base plug, essentially replacing the metal tab in the original setup. The new joint is covered with electrical tape since I had to cut off some shrink wrap to get to it.
Not my prettiest work but it's dead quiet now.
IMG_5299 by jeffdrouin, on Flickr
IMG_5300 by jeffdrouin, on Flickr
IMG_5302 by jeffdrouin, on Flickr
I had some free time this morning and managed to fix the ground issue. I simply took a piece of spare tonearm wire, tinned one end and soldered the other to the existing joint for the tonearm and phono cable ground wires. The tinned end is held in contact with the base by means of the base plug, essentially replacing the metal tab in the original setup. The new joint is covered with electrical tape since I had to cut off some shrink wrap to get to it.
Not my prettiest work but it's dead quiet now.
IMG_5299 by jeffdrouin, on Flickr
IMG_5300 by jeffdrouin, on Flickr
IMG_5302 by jeffdrouin, on Flickr- Status
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