I am currently running a Grado platinum reference on a stock Thorens TD150 mkII and Grado phono preamp. I like the the music it produces, but on my new Arcam - Monitor Audio - B&W based system I am noticing the hum a lot more. The hum increases as the cartridges swings towards the center of the platter, so I am assuming the unshielded cartridge is to blame.
With the b&w sub I am also now noticing more rumble, which may also indicate the cartridge is the wrong compliance? If I recall correctly, the tone arm is medium weight, something like 13 grams.
The phono stage has high and low level settings, but not sure it can effectively handle low very output MC.
It's been my experience that if you change something out and all of a sudden get 60 Hz hum, there is a ground fault somewhere. Before spending any money, start with the isolation drill. Disconnect the cartridge leads and move the arm across the platter at zero attenuation. Repeat with the headshell removed. Make sure to double-check the preamp / power amp combo by going to zero attenuation on a non-active input selection after the turntable leads have been disconnected. A final check (if feasible for you) is to test a totally different table.
The Grado Statement Platinum is a lower ouput [ 1.5 mV ] brother to Reference that was produced to combat your problem . It costs the same . Make sure your Phono Stage is up to the low output .
Thanks for the input. If I understand this correctly, I don't think I am having ground fault problems, because when the cartridge is swung away from the table (past it's rest), the hum essentially disappears. Thanks all for the cartridge suggestions. I was actually considering the Grado Sonata Statment, but was concerned about the hum on the Platinum Reference. So you are saying the low number of windings on the Statment cartridges reduces hum from the motor? Even with greater need for preamplification? I think the statements are 0.5 mV.
..sounds to me like your getting hum from the turntable itself. Grados are especially sensitive to hum like this. Call Grado for help..they have some things that may help.
The Sonata comes in three versions. I use the Sonata with 1.5 mv output which is known as the Sonata VPI version. Call Grado and they will give you the info on this.
BTW: I forgot to mention, it sounds like you have an arm and cartridge mismatch causing the cartridge to resonate. You can try adding some mass to the arm and see if that corrects the problem.
The Grado cartridges are a moving iron design and have always been notorious for hum problems with turntables/tonearms that have less than ideal shielding of the motor. This has been well documented. I was a Grado dealer for many, many years and know this first hand.
I'm not sure that even reducing the output voltage of the cartridge will work unless you want to shield the motor somehow on your Thorens.
IMHO, I would move to a different cartridge, (or spend the time and money to shield the motor).
What Mofi said. I would shield the motor. The cartridge is a good one. Shielding may take some time and effort to install but would be cheaper than spending on a new cartridge that will at best be as good as the one you've got. I suggest you get sheet of mu metal and cut it so as to fit under the platter mat. It needs to be grounded, but contact with the underlying platter would likely by itself be sufficient to do that, in that case. Otherwise, lift the platter off and see if you can affix some mu metal over the motor. Then ground the shield. You could even try just a thin sheet of ordinary copper from a hardware store.
That seems like a cheap solution, will try shielding and grounding motor. Even 50% reduction in noise would be a big deal. Thanks.
Yogiboy, assuming more weight is what's needed, your thoughts on adding weight to tone arm without changing character of the sound? I have fooled around with adding blutack to various places on a tone arm on adifferent table to reduce errant vibration and all that did was take the life out of the signal. Advantage was it sticks on its own! I suppose I would want to add weight roughly equally to both cartridge and counterweight ends? What are you suggesting I use, coins OK?
I was actually thinking that I needed a medium compliance cartridge for this medium weight arm - so adding weight for Grado seems counter to that? I think the arm weighs more like 15 grams fwiw. Again, your thoughts appreciated. I guess it doesn't hurt to try adding weight.
If you go on Ebay check out head shell weights. Technics has 3 gram weights for a couple of bucks. I would give that a try. The Sonata is a light cartridge (6 grams)so I use a weight on my SME 309. You will change the VTA when you do this so make sure that the arm you have can be adjusted for VTA.
Hello, Hum was significantly reduced by addition of Shunyata Venom Defender to AC line. Low frequency resonance still an issue on imperfect disks. Would like folks thoughts on these three low to medium compliance cartridges for the TD150mk2:
Update. Tried Shelter 201 cartridge. Improvement over Grado Platinum in terms rumble and a decent sounding cartridge but as soon as I tried with 45rpm recording it’s shortcomings in terms of arm match were laid bare. Subwoofer went wild to point I was worried it might be damaged.
Replaced Shelter 201 with Audio Technica AT150Sa (which has replaced the AT150MLX in their product line). Rumble problem fixed. Not as romantic in the mids as the Grado out of the box, but not sterile either with what sounds like ruler flat frequency response, fast and detailed with very good bass and exceptional tracking. I actually think this AT cartridge might be a giant bargain.
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