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Thorens TD-124 Project Turntable

classicform said:
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.
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As usual, I haven't been clear enough. Thanks for bringing that up.

I can clearly hear the hum when the record is spinning with the stylus playing on a record. It's hum that shouldn't be there. I also can hear the hum when the clutch is engaged and the stylus is on the record (plus the platter turning below and other issues we don't need to worry about now :-))
 
What if the stylus is not on the record?

(hum when the clutch is engaged and the stylus is on the record is normal. That is mentioned in the TD-124 user manual. Other hum is not normal)

(and edit: I did not catch your :'I don't remember if I mentioned that the hum is only there when the stylus in on the record..... when lifted -- no hum.')
 
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Here's a question, and pardon me if this sounds dumb...

Is the hum you're hearing actual electrical hum, or is it merely motor or idler rumble being transmitted to the cartridge?
 
jancumps said:
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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Thanks.... I'll do some tests on this later and see what I come up with. The ground is via 3-prong grounded system. BTW... no hum when using SME 3009 on this same table with same config and cartridges. Only diff is the tonearm.
 
beatcomber said:
Here's a question, and pardon me if this sounds dumb...
Is the hum you're hearing actual electrical hum, or is it merely motor or idler rumble being transmitted to the cartridge?
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Nothing is "Dumb" beatcomber! Sounds like electical motor hum to me. And it is not normal to be there as the SME 3009 did not have any even with the notorious Grado (hum) cartridge. Believe me if I did I would have been all over the forum to get it resolved.

I understand that this is confusing dealing with essentially texting over in some cases thousands of miles. Please note that I'm not a novice to audio. I've been involved in analogue hifi/audio since I was a teenager in SF in the 60's and use to work with and sell these tables and other hi-end equipment.

This one just stumps me and I really appreciate the terrific help I'm getting. As I said earlier ....... sometimes you need more eyes on an issue to see something that is very obvious. Learned that in computer networking many years ago.
 
Hum is in both channels. Grounding measurements are as "jancumps" suggests.
If I get the time tomorrow I'll switch the III with the IIIs and see what happens.
 
Sounds to me like this is mechanical noise from the motor being transmitted to the cart via the platter. I'd look at your motor isolation.
 
Lapslah said:
Sounds to me like this is mechanical noise from the motor being transmitted to the cart via the platter. I'd look at your motor isolation.
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Thanks.... That would be true for the slight rumble, but not for the hum. New motor grommets were installed about a year ago. I'm not all that confident that the new grommets are all that good for rumble isolation. There may be better products out there. This forum would help with that if I think that is a problem to work on. For now the hum is the important issue if I want to retain the Ser III arm on the 124*.

*There was no extraneous hum with the SME 3009.
 
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Did you check continuity for all the wiring in your series III tonearm? A broken tonearm wiring can cause hum. If the 3009 didn't do that, I'd look at the grounding/wiring of the series III.
 
Well I owe a "mea culpa"..... The SME 3009 does it too!
Yesterday on the 124 I changed from the IIIs to the III then to the 3009.... and all had the same issue. That leaves it back to the table. When I was using the 3009 before I probably didn't pay much attention to the slight hum.... I was probably expecting it.

So.... I am inclined to believe as 'classicform' hinted on a previous post that this hum is actually a mechanical hum from the turntable motor being picked up by the cartridge when on the record.

That would mean that the new motor rubber mounts (thought they were oem) that I put on last year are not adequate for the turntable.

Looks like the next step would be to get from any TD124 owners that may have found a site that offers some really good isolation motor mounts give me some locations so that I can purchase them and install them.

Thanks to all members for the help in trying to get this beautiful table back to 100%
On a side note: This table sat covered and forgotten up in my closet for almost 30 years before I decided that maybe I should get it down, fix it up and start using it again :-)
 
AudioJag said:
Nothing is "Dumb" beatcomber! Sounds like electical motor hum to me. And it is not normal to be there as the SME 3009 did not have any even with the notorious Grado (hum) cartridge. Believe me if I did I would have been all over the forum to get it resolved.

I understand that this is confusing dealing with essentially texting over in some cases thousands of miles. Please note that I'm not a novice to audio. I've been involved in analogue hifi/audio since I was a teenager in SF in the 60's and use to work with and sell these tables and other hi-end equipment.
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Cool!

BTW, where in the Bay Area are you? I lived in SF for 17 years, from 1988-2005, and still have regrets about leaving.

AudioJag said:
Well I owe a "mea culpa"..... The SME 3009 does it too!
Yesterday on the 124 I changed from the IIIs to the III then to the 3009.... and all had the same issue. That leaves it back to the table. When I was using the 3009 before I probably didn't pay much attention to the slight hum.... I was probably expecting it.

So.... I am inclined to believe as 'classicform' hinted on a previous post that this hum is actually a mechanical hum from the turntable motor being picked up by the cartridge when on the record.
Click to expand...

Hold on a sec... Do you only get the hum when the stylus is the record groove or is it constant?
 
beatcomber.... Born and raised in SF.... Live in Vallejo for the past 30 years.

As previously stated .... only get the hum when the stylus is on the record.

I'm not the only one that has had this problem. Found an interesting fix on another forum.......... I'll let you know what it is and if it works later.
 
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By the way, you can hear the difference between mechanical and electrical buzzing.

If you hear a grumble (imagine that you hear an earthquake 3 kilometres below the surface where you live - don't ask why I know how that sounds :) ) ; it's mechanical.
That kind of noise is mostly also slightly dynamic - it has a rhythm.
If you hear a constant hummmm, it's electrical. this noise typically is constant, without any modulation.
 
AudioJag said:
beatcomber.... Born and raised in SF.... Live in Vallejo for the past 30 years.
Click to expand...

I used to drive out to Vallejo all the time to hit the thrift stores, looking for records! They were less picked over than the stores closer to the city. I always made a point of stopping off at the Nation's Burger on Sonoma Blvd. for a piece of cherry pie!

It must have been a blast growing up in SF during the '60s... did you ever spend any time at Big Al's Gas House, down on the peninsula?

(Sorry for going off topic.)
 
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