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Thorens TD-124 Project Turntable

beatcomber said:
Really? You don't need to ground the SME 3009 to the chassis? That would certainly make armboard swaps quicker and easier.
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Glenn I just run a ground wire from the arm to the pre. And it is a lot easier changing arms. I don't think the arm has to be grounded to the chassis be cause it doesn't touch anything metal on the TT. But I do use a 3 prong power cord that is grounded to the TT. This is just something I discovered playing with it.:D
 
bob06 said:
Glenn I just run a ground wire from the arm to the pre. And it is a lot easier changing arms. I don't think the arm has to be grounded to the chassis be cause it doesn't touch anything metal on the TT. But I do use a 3 prong power cord that is grounded to the TT. This is just something I discovered playing with it.:D
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Very interesting... the SME original cable on my 3009 has ground leads at both ends - one for the preamp/amp and one for the chassis. Do you connect both leads to the preamp?
 
bob06 said:
Glenn I just run a ground wire from the arm to the pre. And it is a lot easier changing arms. I don't think the arm has to be grounded to the chassis be cause it doesn't touch anything metal on the TT. But I do use a 3 prong power cord that is grounded to the TT. This is just something I discovered playing with it.:D
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Bob06... You're confusing my techie side:-) A ground is a ground is a ground. Should not matter where it's attached as long as the pre-amp/amp is on the 3-prong grounded outlet. So you are saying that you do ground the tonearm to the pre-amp which is in turn grounded to the TT via the 3-prong outlet.... true?
 
AudioJag said:
Bob06... You're confusing my techie side:-) A ground is a ground is a ground. Should not matter where it's attached as long as the pre-amp/amp is on the 3-prong grounded outlet. So you are saying that you do ground the tonearm to the pre-amp which is in turn grounded to the TT via the 3-prong outlet.... true?
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Your confusing me now. :D Yes the way you described it. It will be all grounded together thru the ground from the outlet plug. But in your case I was trying to fix your problem. That's why I wanted you to disconnect the ground from the arm to the 124 to see what it does.
 
bob06 said:
Your confusing me now. :D Yes the way you described it. It will be all grounded together thru the ground from the outlet plug. But in your case I was trying to fix your problem. That's why I wanted you to disconnect the ground from the arm to the 124 to see what it does.
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Ok, misunderstood..... We're still on the same page ..... I'll remove the tonearm ground and see what we get. I'll let you know later today.

Thanks
 
beatcomber said:
Very interesting... the SME original cable on my 3009 has ground leads at both ends - one for the preamp/amp and one for the chassis. Do you connect both leads to the preamp?
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Glenn you don't need both wires as long as one end is to the arm and the other to the pre. I'm not an expert on this. This is just what I found on my 124 that I did not have to have my arm grounded to my 124.
 
I have 2 SME's on my 124 and neither one of them are grounded to the chassis. Both just go to the pre. And never ran into any problems.
 
bob06..... Do you think that the moving iron cartridges that I'm using as opposed to mc or mm might have something to do with it? I don't recall any problem when running the mi's on the 3009. And one other issue I ran across that your feedback would be appreciated...... TD124 sr#32694 ... I read somewhere that the motors were not shielded and could cause hum problems? True/False?
 
I don't ground any of the arms I have used to the 124 chassis either. Haven't had any hum issues.

As far as returning to stock, I meant the power cord configuration only.

Regards
Mister Pig
 
Mister Pig said:
I don't ground any of the arms I have used to the 124 chassis either. Haven't had any him issues either.

As far as returning to stock, I meant the power cord configuration only.

Regards
Mister Pig
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Thanks for getting in on this puzzling problem I have. Just to be clear, do you ground the tonearm to your pre-amp instead as bob06 does? Or not at all?

I'll be removing the ground later today. I have other commitments for the next few hours. I'll check back after I remove it.

Thanks All.
 
AudioJag said:
Thanks for getting in on this puzzling problem I have. Just to be clear, do you ground the tonearm to your pre-amp instead as bob06 does? Or not at all?

I'll be removing the ground later today. I have other commitments for the next few hours. I'll check back after I remove it.

Thanks All.
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FWIW, I had a similar problem after I mounted an SME 3009 on an Empire 208. I never could figure out what was causing the ground loop hum!
 
You have one of 3 problems that I can be an issue. The cartridge, the arm or a ground problem. You have to experiment and track down what the problem is. The easiest is to start with the ground. I have found that most hum problems are from not being grounded properly. As for as the motor not being shielded. Not sure on that one. My 124 is way older than yours and I have not had any problems.
 
bob06 said:
You have one of 3 problems that I can be an issue. The cartridge, the arm or a ground problem. You have to experiment and track down what the problem is. The easiest is to start with the ground. I have found that most hum problems are from not being grounded properly. As for as the motor not being shielded. Not sure on that one. My 124 is way older than yours and I have not had any problems.
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Ground on tonearm removed. Hum still the same. I'm going to try changing from one of the two MI's to a Denon DL160 MC cartridge as Bob06 suggests in order to track down the issue.

Thanks
 
Moving coil installed and actually I thought the hum increased. I then replaced the ground connection. No change. Put the moving iron cartridge back.

Unless there are any other thoughts, looks like the SME Series III that I have is not compatible with the TD-124. Not sure if I can live with the hum, might have to go back to the 3009. Nuts....... I won't make that decision yet.

I sure like the TD-160 w/SME SeriesIII that I use for my daily TT. Much easier to deal with and no problems at all. Can't get the courage to part with the 124 though!

Thanks bob06 and beatcomber for you help.........
 
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There is no such thing that an arm is not compatible with a TT. Did you check and see if it is just one channel that hums or both channels. Disconnect the left channel from the pre and see if it hums then disconnect just the right. Did you check under the cover of the TA to make sure all 5 wires are connected. I have seen many 124's with SME III's on them.
 
bob06 said:
There is no such thing that an arm is not compatible with a TT. Did you check and see if it is just one channel that hums or both channels. Disconnect the left channel from the pre and see if it hums then disconnect just the right. Did you check under the cover of the TA to make sure all 5 wires are connected. I have seen many 124's with SME III's on them.
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I believed the same thing. I believe it's from both channels, but I'll double check. Already checked wires and they are all connected.

There is only one more thing that I can think of doing..... don't really want to do it, but maybe just to see if it is the main section of the arm and not the cartridge carrying arm. I can swap the SME IIIs which is on the 124 with the SME III which is on the 160 to see if the hum goes away. (no rubber grommets on the 160 sme III ... not needed on the 160)

I don't remember if I mentioned that the hum is only there when the stylus in on the record..... when lifted -- no hum.

Your thoughts?
 
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When the stylus is on the record?
So am I to assume the clutch is engaged so the record isnt spinning (otherwise how would you hear the "hum")?
If so, you might not be hearing "hum" in the electrical sense but "hum" in the mechanical sense.
 
If it is electrical - and not caused by a specific cartridge, it would be good if you could draw at what places in your headshell, arm, tt and interconnects ground or or shielding wires are brought together.

In an ideal situation, shielding from left and right should not be connected to each other in the interconnects, tt, arm or headshell; and the ground wire should not be interconnected to anything other than the metal parts of your tt and the ground screw on your pre-amp.
If you unplug left and right TT interconnects from the pre-amp and also the ground wire, you should never measure closed circuit between any two of the ground wire, left channel shield and right channel shielding.
 
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