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Calculation of effective mass of JMW10 tonearm?

Does anyone know how to calculate the "effective mass" of the JMW10 tonearm? Or better yet, can someone just tell me the number in grams? I am reading "How to Set Up and Tune Your Turntable and Tonearm" by George Merrill. In the booklet he recommends a tonearm resonance frequency between 8 and 16 Hz, 11 being ideal. I have already been told my just purchased ZYX R100FS (Fuji Silver high output) is a good match for the tonearm. But in trying to optimize the sound I need to know the tonearm resonance frequency which requires knowing the effective mass of the tonearm.

Help please. Thanks,
Jon
jonathanochi
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Why not ask VPI? I've always found they offer very good customer support.

VPI Contact info

Cheers,
John
kehut's avatar
kehut
668 posts
 
Jon-

I seem to remember asking that same question to Mike at VPI several years back. Now, I cant remember what the number was off hand. Unfortunately, the JMW 10 manual doesn't specify as you are likely aware. As Jmcgrogan2 suggests..place a call or email to Mike @VPI for that info to help you. At times..Harry will be on the other end to chat.

As an owner of the Aries 2-JMW10 with a ZYX R-100 Fuji Silver H..I can unequivically say that this cart is MARVELOUS with that arm!

BTW...one thing that you may have already noticed is that due to the light 5g weight of that cart..you will need either a lightweight counterweight for the 10 arm or use the VPI supplied 3g headshell weights. Mike at VPI actually suggest using both together, even knowing that it will put the CW a little further back on the arm. I use only the new dropped lightweight CW and that works great. The Fuji is not avail as you know with the SB option as on the Airy models..otherwise that would have done it.

Happy listening! ;) ...Ken
dougdeacon
3,338 posts
 
Kehut nailed it.

I haven't used a ZYX on a JMW, but VPI/Mike's suggestion to use both their 3g headshell weight and a lighter c/w mounted further aft sounds right to me. I have this vague recollection that the eff. mass of a JMW-10 is around 11g. If that's so then Mike's advice is spot on.

If you want to measure your resonance frequency, the HFN&RR test record has tracks specifically for that purpose. You'll be able to confirm resonance in both vertical and lateral modes to the nearest 1 Hz or so. A ZYX has different vertical and lateral compliance, so the resonance frequency will be slightly different in each mode.
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