What is effective mass of Versa Dynamics 1.2 tonearm - diyAudio
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Old 29th January 2013, 03:34 PM   #1
D10 is offline D10
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Default What is effective mass of Versa Dynamics 1.2 tonearm

Hi,
I couldn't find this info. I am wondering if Miyajima Shilabe with its very low compliance would be good choice for this tonearm?
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Old 29th January 2013, 05:37 PM   #2
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Have you checked the library at Vinyl Engine | The Home of the Turntable They or one of their members may well know..
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Old 30th January 2013, 12:04 AM   #3
AVWERK is offline AVWERK  United States
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I think what you might need is a way to hook up a paddle in silicone type of damping system for low compliance cartridges with this arm
My ET 2 ( Eminent Technogoly) has such a system, but not needed at present.
You might even give them a call and buy the trough or build one.
Might not even need one, since I have never seen one with this table/ arm combination before
I,m still looking to buy one of these someday

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David
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Old 30th January 2013, 04:05 AM   #4
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It's very short. So I suspect the effective mass is low. I may be all wrong. But, if I am correct, nothing prevents you from adding real mass to both ends of the vestigial arm, increasing the effective mass...

I don't think it is possible to use a damping trough on this arm, possible, but difficult to install, since the arm swings...

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PS. I would be interested to know the real numbers... also how they are computed.
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Old 30th January 2013, 03:21 PM   #5
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Thank you guys. I put post on Vinyl Engine - no response so far..
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Old 30th January 2013, 10:28 PM   #6
AVWERK is offline AVWERK  United States
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The effective mass is from the pivot to needle with cartridge included. Then when you add your counterweight and balance it all out plus your tracking force, the moment of inertia comes into play.
Unless you know exactly what mass will make your cartridge work, you then change everything by changing how far the counterweight is from the pivot and so forth. Definately an interactive issue with no simple answer
Theres all kind of math you can get involved in with this if you search around and doubt if it will really do anything better than getting out your favorite bass albums and listen carefully for detail down low.
Varying different counter balance weights and distances from the pivot points will solve any issues and be less confusing in the long run.
Your vacuum platter rules out any problems with distance from pivot and the weight may be beneficial if placed further out with very low compliance MC,s
Its a 3 dimensional problem that careful listening will cure this side of test records and instrumentation.

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David
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Old 2nd February 2013, 01:09 AM   #7
AVWERK is offline AVWERK  United States
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I just read an old Stereophile back issue where Gordon Holt was testing an Mc3000 and a bottom note on the effective mass from Versa Dynamics was 20 grams

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David
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Old 2nd February 2013, 01:35 PM   #8
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But this mass is only valid for vertical, horizontal it will be a lot more and thus you have two low frequency resonance points.
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Old 4th February 2013, 01:17 PM   #9
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The higher mass horizontal point would be lower in frequency, and so somewhat irrelevant?

Is it a good assumption that the horizontal mass is any different than the vertical for this airbearing arm? One motion is rotational the other linear...

And is not the moving mass for most "long" arms going to be substantially higher than for the Versa's very short arm?
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Old 4th February 2013, 11:58 PM   #10
AVWERK is offline AVWERK  United States
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What groove t says is right. With straight line tracking air bearings you wind up with 2 small resonant bumps rather than one big one that occurs in regular arms

The horizontal mass is considerably higher and somewhat an advantage when you consider what the stylus is forced to do. The needle is carrying and responsible for movement in 2 planes instead of 1 fixed pivot point of regular arms and hence the 2 resonant points occur
The Dynavector 505/7 tried the same thing, with high horizontal mass and another shorter arm with similiar effects due to 2 different pivot points
They also used an internal spring bob and spring to cancel out resonance that worked well but the arm suffered from warp wow because of the short pivot arm transversing warps
The splitting of the pivot points gives you different motional impedences in comparison to one fixed mass over the stylus. You have a moveable weight carried and moved horizontal differently by the stylus compared to vertical.
You wind up with 2 effective masses instead of one
The goldmund would be still be a single fixed pivot point seen by the stylus since a sled is pulled and you still get one resonant point
I sure someone can explain it better

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David

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