SME "Dynamic Balance Kit" - yahoo auctions japan

I'm also using google translate, so take dynamic with a grain of salt. Perfect example, "used" translates as "junk" — e.g. "SME tonearm beautiful junk goods."
 
It looks like a way to make a static balance tonearm a dynamic balanced one. The spring is there to keep VTF constant despite warps or even if played non-level.

My guess looking at the picture is it works like this: You set the weight on the wayrod to minimum (for zero balancing and to maintain lateral balance) then apply VTF via the knurled nut on the spring attachment until you reach wanted VTF as measured on a scale. Once adjusted you get the benefits of a dynamic balance tonearm. Meaning constant VTF pressure since VTF is set by the downward force set by the spring, not by gravity.
 
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The only problem I see with this device is that a truly dynamically balanced tonearm has it's VTF pressure spring around the vertical pivot point axis.
 
It looks like a way to make a static balance tonearm a dynamic balanced one.

Thanks for this. Makes sense. Did some digging around and it seems that dynamically balance tonearms were all the rage in Japan circa 1980. Most likely plays off that idea.
 
Once adjusted you get the benefits of a dynamic balance tonearm. Meaning constant VTF pressure since VTF is set by the downward force set by the spring, not by gravity.

except to ride a warp, as the arm climbs against the spring the spring compresses, thus the spring rate goes up, thus the downforce is increased. All springs have a resonate frequency. That frequency is determined by deflection, ie load. The more defection, resonate frequency goes down.

In other words, there is zero chance that thing would keep tracking weight equal at all times, and it most likely will add another arm resonate besides what the spring at the other end adds (cantilever)
 
yes, it does come to mind, but the fluid damping kit for SME relies on a paddle that impedes horizontal movements - right?

I was thinking this thing is more of a sophisticated 'penny on headshell' device. I think it's there to allow for the low mass SME to accommodate lower compliance MC carts. It seems that instead of applying mass to the headshell, this device applies pressure near the pivot. It may (I'm not sure about this) have a lesser effect on the overall effective mass - yet achieve the same result as the primitive penny solution...

or not... :)


The SME fluid damping kit applies damping in both planes. The spring can't "damp". A spring can only add restorative forces, and only at the resonate frequency of the spring.
 
I was thinking this thing is more of a sophisticated 'penny on headshell' device. I think it's there to allow for the low mass SME to accommodate lower compliance MC carts.
Dynamic balancing lowers effective mass, so I doubt it would increase the range into lower compliances.
 
except to ride a warp, as the arm climbs against the spring the spring compresses, thus the spring rate goes up, thus the downforce is increased. All springs have a resonate frequency. That frequency is determined by deflection, ie load. The more defection, resonate frequency goes down.

In other words, there is zero chance that thing would keep tracking weight equal at all times, and it most likely will add another arm resonate besides what the spring at the other end adds (cantilever)
Are you talking only about this application of the spring type downforce? (If so, I can see how you are right.) How about those that have the spring force centered around the vertical pivot like the old Empire and Dual arms?
 
Are you talking only about this application of the spring type downforce? (If so, I can see how you are right.) How about those that have the spring force centered around the vertical pivot like the old Empire and Dual arms?

Those were (flat wound) coil springs. They will still have a restorative force, but the resonate level of the spring can be taken to a very very low frequency. Here's how. The total length of the spring. Between its normal ride height(tracking weight on album) and maximum compression( peak warp) the percentage of spring compression of its total length is very small. The resonate frequency change of the spring is therefore extremely small. And, depending upon the central pivot height above stylus ride height, if lower than a corresponding static balance arm, will have lower restorative forces working against the stylus.
 
Back in the early/mid 80s many of us got wrapped around what percent VTF should be applied by weight versus spring.
 
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I had a Grado wooden tone arm that used used a spring for pressure. And it worked rather well. I updated mine with a version of SME anti skate compensation. But it wouldn't work well with V-15's and Stantons 681EEE so I up graded to an SME 3009. I also tried a 3012, but settled for a straight line tangential tone arm to rid myself from tracking problems from Ortofon MC cartridges at the time.
 
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