Vinyl Asylum

Suspicious calculation for arm/cart compatibility

67.101.125.244

For years, I've been trying to discover the effective mass of the Audioquest PT-5 tonearm. No luck. Then I realized I could find it using the calculators at the Cartridge Database. The arm's effective mass was the only variable I didn't know, so I tried to solve for that. (I determined the cartridge resonance frequency at 10 Hz using the old Sure tracking-test record; it's a Grado Gold.) So here's what I plugged into the calculator:

Resonance freq.: 10 Hz
Cart. mass: 5.5g
Fastener mass: .5g (estimated)
Compliance: 20 (listed by Grado as "cu")
Arm effective mass: X

Using those figures, the PT-5 effective mass was calculated at 6.6 grams.

Kinda low, huh? The only info I've been able to find on the effective mass of the PT-5 was from an old "Stereophile" review that listed it as "medium mass." I don't think 6.6g would fit into the medium category.

Is something wrong here? THANKS
-Bob

Follow Ups:

Dynamic or static compliance? - Mark Kelly 21:49:02 06/25/09 (7)
- Another variable: at what freq is the measured compliance reported? - charlies824 11:22:12 06/26/09 (0)
- Grado doesn't specify - hesson11 04:59:20 06/26/09 (1)
  - All units are equal - Mark Kelly 05:13:02 06/26/09 (0)
- RE: Dynamic or static compliance? - lovetube 04:24:42 06/26/09 (3)
  - Measuring effective mass - Mark Kelly 04:57:24 06/26/09 (2)
    - RE: Measuring effective mass - Old nuff 2 no better 10:40:40 06/27/09 (0)
    - RE: Measuring effective mass - lovetube 06:22:16 06/26/09 (0)

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