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Ok, when I hook up my P3-24 and its supplied TT-PSU. I get a bit of residual buzz. I rewired the arm ground and the arm is 100% correct in wire, continuity and such. The P3-24 is connected through my Cambridge Audio 640p phono preamp and it's grounded to the preamp's ground post.
With my stereo switched to the input used to play LP's and volume turned up quite loud I only get a bit of the 640p's phono preamp hiss/noise. As typical as I always have with it and unobtrusive. Ok, now I go and turn on the TT-PSU and I get "buzz". The TT-PSU is properly connected, the wall wart power supply is connected to a good quality power strip, though it makes no difference even if I plug it directly into the wall outlet. The wires on it are clean, and visually undamaged. I decided to cut about 3ft of 18 gauge signal wire and ground it to one of the TT-PSU's back panel screws. I in turn connected it to the 640p ground terminal. The "Buzz" is greatly reduced say oh by 90%. It's hardly noticeable at low volumes but grows a bit more at higher volumes and if one listens for it, IT'S STILL THERE!
So now if I disconnect this ground wire I attached to a back screw of the TT-PSU the "Buzz" grows louder again. If I then physically hold the tip of the stripped ground wire in one hand and the I touch the top of the TT-PSU or even if I just touch one of the back screws the "Buzz" is oh 99.9% gone. But if I reconnect the ground wire and as such no longer touch the wire and TT-PSU cover the "Buzz" is louder again back to the say oh maybe 90% level not the 99.9% gone level. WHAT GIVES!?!
Why does the "Buzz" virtually goes completely away if I am a conduit between the tip of the ground wire and the top panel or even touching the screw in back of the TT-PSU?
It also make no difference if I choose other grounds, ie: my Onkyo receiver's ground post or even the screw on the wall outlet's decorator plate.
Any thoughts or advice?
Thanks in advance.
Follow Ups:
HiIMHO, this is most likely because the 640P's grounding post isn't a true ground; it just links to the ground side of the internal circuit. There is no connection between the 640P and the ground that connects to the wall sockets (i.e. via the house-wiring). You compensate for this 99.9% when you touch the case!
You could get round this by running an additional wire from the 640P to an item you KNOW is grounded at the wall (perhaps an amplifier), securing it under one of the case screws at the back (may need a small amount of paint removed from under the screw). If your amplifier happens to have a ground terminal, you could use that. Obviously, grounding to the TT-PSU works about 90%, by your account, so maybe that isn't grounded to the wall either (I'm not familiar with its design, though I have used a 640P, and didn't need to add further grounding).
The second, and probably easier, alternative is to run a wire from the 640P's terminal to a grounded object, such as a water pipe or radiator.
Finally, there's also the possibility that's just been suggested, that the problem is caused by the grounding strap on the 2M Blue, which could be creating a ground loop. Now, if this cartridge is like other Ortofon MM cartridges, there should be a strap linking one of the two ground connector pins (usually it's the green-coded one) to the cartridge body. This can be gently prised out of contact with the connector pin, or removed completely, breaking the ground loop. If other alternatives don't work, that could well be worth a go.
HTH anyhow,
Mark
Edits: 06/26/12 06/26/12 06/26/12 06/26/12 06/26/12
Not to worry about using a outlet ground pin.I know that taking only a ground prong, with no + and - prongs, attach an insulted wire to it and make sure the wire is clean with no frays on this ground prong end would create a ground to the house's grounding set up. I've tried this once to try to enhance a carbon fibre brush as a static remover (aka: much like Maple Shade's record cleaning brush) and I had no safety issues. It did not do much so I just stopped doing that.
I also take care to understand about electricity as such.
The 640p ground post is only a chassis ground like you said and as noted I can get the buzz out by say over 90% this way. I also tried the phono section ground lug on my Onkyo receiver and the same results, only say 90% buzz gone but the residual noise is still ever so noticeable.
As you read when I add myself to the ground wire I attached to the ground of the 640p and touch the TT-PSU the buzz basically goes away. But if I only attach the wire from a screw on the chassis of the TT-PSU without me being a part of this circuit it still remains at the lower level of 90% or so.
As to the Ortofon 2M Blue. Looking at its pins in back the GREEN pin has a clean metal section base. It's the only pin that has this unpainted metal base. The other pins do not have this, they have what appears to be intact black paint on the metal base. The RB301 copper lead is fully snug on these pins and is touching the cleaned off metal base of the GREEN PIN. It makes no difference though if the copper leads of the Rega arm touches all the way back to this clean off silver base or not.
I'll try a real known ground connection and yes we will see if the DL-110 results in a better situation.
Edits: 06/26/12
Hi
I think the metal base on the 2M's green pin is probably the visible part of the strap connecting it to the cartridge's metal screening can, which encloses the coils. That's how it is usually done, anyway (I've had other Ortofon MMs, and Goldring and Shure cartridges, with this system). This contacts the pin itself, so pulling the connecting lead slightly out won't make any difference: one has to pull the strap off (it is normally a sliding fit into the screening can). The disadvantage is that this is hard to reverse.
Of course, the can is rather deeply buried in the 2M's body structure, though it is actually the same shape as the corresponding part in the OM series (where the external shape follows its contours very closely) and 500 series cartridges.
Mark
I remember trying to talk someone through these issues with the same TT on another board. The OP eventually just stopped posting in the thread, so I never figured out if the issue was solved. I did notice he changed cartridges, so that may have fixed it and he didn't update the thread. What cart are you using? Also, he never answered this question I had: what happens if you unplug the TT from the PSU but keep the arm plugged into the phono stage? Also, your re-wire created a separate ground wire for the armtube (i.e. not Rega style), yes?
---
"In music, the only thing that matters is whether you feel it or not. You can't intellectualize music; to reduce it analytically often is to reduce it to nothing very important."
-Ornette Coleman
Cartridge is an Ortofon 2MBlue.
I have chosen to order/buy a Denon DL-110. as I want to try a new cartridge for the P3-24. The TT SOUNDS FABULOUS EVEN WITH THE 2MBLUE! I'm impressed by its fidelity but the residual buzz is an issue.
Yes, also I created a separated tonearm ground wire, in fact I chose while doing this to do a complete arm rewire. It went well and as such with continuity tests came out testing fine including the arm ground wire.
If I unplug the TT-PSU cord that runs from the TT-PSU into the motor of the P3-24 while keeping the tonearm RCA's connected to my 640p, the buzz remains.
As I noted I can 99.9% kill any residual buzz if I'm the conduit between the added ground wire I put between the 640p grounding post and to the TT-PSU by physically touching the TT-PSU chassis. (scratching my head as to why).
A-HA! It's all connecting. He was also using an Ortofon 2M (can't recall the color). When I looked around on other forums for answers, I saw other people having problems with the 2Ms in combo with this TT. My recollection is the carts have some kind of metal screw on the top that is supposed to connect the cartridge ground (for what purpose, I don't know), but it interacts poorly in this setup. You could try isolating that screw from the arm via something thin and non-conductive. Heck, just loosening it from the arm while still connected to the phonostage would let you know if this is the problem (also, if it doesn't fix it, it could be that the arm is isolating already and what you really want to do is connect that screw to ground). Alternately, you could just wait and see if your new cartridge fixes the problem.
I would like to state that all this is based on theories from second hand info, so I am both unsure of what exactly the root cause is, and therefore my strategies to fix it may not work.
---
"In music, the only thing that matters is whether you feel it or not. You can't intellectualize music; to reduce it analytically often is to reduce it to nothing very important."
-Ornette Coleman
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