a long answer trying to be as informative as possible

Posted by stark (A) on December 18, 2005 at 18:23:12

In Reply to: High compliance -- low mass posted by OLLY on December 18, 2005 at 16:51:31:

The reason that matching carts and arms is that like any mechanical system, they have resonant frequencies. If the fundamental resonant frequency is too close to audio frequencies (let alone actually audible), it will interfere with playing records (to put it mildly). Also, you want neither the turning of the turntable nor footfalls to interfere with it either.

There is a formula to calculate the (approximate) resonance frequency of a tonearm-cartridge combination:

a/sqrt(CM)

a = 500/pi approximately 159

C is the cartridge's compliance. The units are called CU's which are equivalent to 10^-6cm/dyne or 10^-6m/10^-3N

M is the combined mass of the cartridge (including affixing bolts etc) and the effective mass of the arm in grams
(Reference: Van Den Hul FAQ Appendix 2.)

This formula gives a frequency in Hz which ideally is between 9 and 11, but is OK between 8 and 12 and people have been known to live with those as low as 7 or as high as 13.

Now that you're sorry you asked, I can give you the good news that even if you're able to find out the specs for your equipment, they are not always measured in the same way (eg compliance can be static or dynamic and the latter measured at different frequencies; standards changed over the years).

I just go by the tracking force: under 1.6g is high compliance, between 1.7g and 2.3g is medium and 2.4g and above high compliance. YMMV.

Today, most cartridges are designed to be used with medium mass arms. If you have a low or high mass arm your cartridge selection will be more limited.

If you really want to know the resonance frequency of an arm/cartridge combination you can buy a test record with a frequency sweep and find out.

-stark

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Follow Ups Full Thread

Topic - High compliance -- low mass - OLLY 16:51:31 12/18/05 (13)

Re: High compliance -- low mass - HenryH 18:29:22 12/18/05 (0)

a long answer trying to be as informative as possible - stark 18:23:12 12/18/05 (10)

A small clarification - Mark Kelly 03:02:49 12/19/05 (5)

and an important clarification! - stark 08:30:34 12/19/05 (1)

Re: and an important clarification! - John Elison 13:07:05 12/19/05 (0)

Re: A small clarification - John Elison 07:15:17 12/19/05 (2)

Torsion pendulum - Mark Kelly 15:39:03 12/19/05 (1)

Thanks.... - John Elison 16:12:03 12/19/05 (0)

Re: a long answer trying to be as informative as possible - valvesonly 19:53:00 12/18/05 (1)

well... - stark 22:27:00 12/18/05 (0)

Re: a long answer trying to be as informative as possible - OLLY 18:56:27 12/18/05 (1)

all three are fine - stark 22:20:58 12/18/05 (0)

try www.vinylengine.com - tubesforever 17:02:27 12/18/05 (0)

Follow Ups

a long answer trying to be as informative as possible - stark 18:23:12 12/18/05 (10)

A small clarification - Mark Kelly 03:02:49 12/19/05 (5)

and an important clarification! - stark 08:30:34 12/19/05 (1)

Re: and an important clarification! - John Elison 13:07:05 12/19/05 (0)

Re: A small clarification - John Elison 07:15:17 12/19/05 (2)

Torsion pendulum - Mark Kelly 15:39:03 12/19/05 (1)

Thanks.... - John Elison 16:12:03 12/19/05 (0)

Re: a long answer trying to be as informative as possible - valvesonly 19:53:00 12/18/05 (1)

well... - stark 22:27:00 12/18/05 (0)

Re: a long answer trying to be as informative as possible - OLLY 18:56:27 12/18/05 (1)

all three are fine - stark 22:20:58 12/18/05 (0)

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