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Grado "wobble"...?

I've searched the archives for info about this problem, but haven't come up with much. Can anyone please explain what exactly is happening when Grado cartridges wobble, and why they do this?

I bought a Grado green some months back, mostly as an inexpensive way to teach myself how to install a cartridge. (I've been a vinyl fan all my life, but was for years listening to it on a bland B&O linear-tracker.) Since then, I've changed tonearms (from a Thorens TP-16 to an Origin Live RB-250). When I did so, I was finally able to properly align the cartridge using the tool from Turntable Basics--the Thorens arm's fixed mounting holes precluded getting a perfect alignment. But since the change, I've experienced wobbling for the first time. It seems to happen mostly on 12" 45 RPM UK pressings from the 1980s, for whatever strange reason. I can see the entire cartridge body shake laterally, and sometimes the stylus will actually skip out of a groove.

Since this cartridge was basically intended as a throwaway, this is probably a good kick in the pants to get the new one I've been planning on, but can anyone shed some light on this phenomenon? Do the wood-bodied Grados wobble as well?

Thanks in advance,
Joshua
am_dial
am_dial OP
35 posts
 
I should probably clarify a few things. First, the cartridge wobbles only rarely: three records so far, out of several thousand. On all the others it performs far better than a $40 cartridge has any right to.

Also, I've tried to find some common denominator regarding these 3 records but have come up with little so far. Each has a very slight bit of warp, but no more than many others in my collection. Two are 45 RPM, one is 33 RPM. None has vast dynamic shifts. But these 3, for whatever reason, all cause the cartridge to wobble every time I try to play them, while (so far) no other records in my collection seem to. And one of these records (I don't recall playing the other two) played fine, no wobble, when the cartridge was in the Thorens arm.

Thanks for the tip regarding this question at Vinyl Asylum.
dopogue
1,773 posts
 
I've experienced this phenomenon on several Grados, all the way up to a Reference/Reference model in a JMW 10.5 arm. It is consistent in the fact that the same records always induce the wobble and, yes, it seems to happen more often with 45 rpm records than with 33 1/3. It's something Grado owners simply have to learn to live with, apparently. At least I've never been able to stop it. And yes, it's annoying.
dweller's avatar
dweller
3,854 posts
 
For the record, it's the Grado "Wiggle".
And yes, mine did it too (I always thought the damn thing would bust loose and leave a huge scratch on my LP -it never did...)
raygunn
10 posts
 
The problem is one of improper cartridge/arm matching.
Grado cartidges will resonate visually and audibly (check out what your woofers are doing during the "dance"...).
Your amp is reproducing that stuff!

As "jlazart" accurately points out, you need a medium effective mass tonearm or a tonearm that utilizes dynamic damping to get the best out of the low compliant Grados. Arm/cartridge matching is critial to getting the best performance and sound out of an analog front-end.
am_dial OP
35 posts
 
Hmm. Though I know very little about this stuff and am highly math-phobic, I ran a calculation according to the figure on Galen Carol's "tonearm/cartridge capability" web page and came out with a resonant frequency of 8.635, which though lower than the recommended 9-11 range doesn't seem to miss by much. I didn't think the Grado's compliance of 20cu was considered "low." But admittedly I have a lot to learn in this regard. Thanks for all the help so far.
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