Compliance question

the thin end of the wedge
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arcamguy
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Compliance question

Post by arcamguy » 28 Oct 2019 14:49

Hello group,
I understand the basics of compliance: low mass arm, high compliance cart; high mass arm, low compliance cart etc.

But there are other basics I don't understand. For example, how do I read this formula: it's for the AT440MLA. (I'm picking this cartridge only as an example.)

10x10-6 cm/dyne: does this mean the compliance is 10?
40x10-6 cm/dyne: does this mean the compliance is 40?

The first example is dynamic compliance; the second is static. What's the difference between dynamic and static, and which one should I use when I choose a cartridge?

Also, other compliance measurements are expressed as um/mN. What does that mean?

Apologies for my ignorance. Your expertise will be appreciated,
Thanks

billshurv
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Re: Compliance question

Post by billshurv » 28 Oct 2019 15:10

This is confusing. Firstly a compliance unit (CU) is the same as um/mN is the same as cm/dyne x10-6. That's the easy bit.

Now the confusing bit. There are 3 unrelated compliance measurements.
1. Static. This is poking a blob of rubber and seeing how much it moves. No real use for vinyl replay
2. 10Hz dynamic. This is the one we need and is calculated backwards from the resonant frequency with a given effective mass.
3. 100Hz dynamic. This is used by japanese vendors and is in fact a measure of the VTF required to meet tracking spec.

You cannot convert between these three, even if some rules of thumb appear to work.

patient_ot
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Re: Compliance question

Post by patient_ot » 29 Oct 2019 15:55

The 440 and successor 540 cartridge (as well as the rest of the 500/700 series) are high compliance by today's standards (e.g. approximately 20-25 CU Western measurement) and will work best on tonearms that are 10g or less in effective mass. You may be able to make them work on a slightly heavier arm but your RF between the arm and cart will be quite low (e.g. lower than 8hz). Some arms have a damping feature which may help smooth things out a bit.

arcamguy
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Re: Compliance question

Post by arcamguy » 30 Oct 2019 14:04

Thank you very much for your responses. Appreciate the input.

Alec124c41
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Re: Compliance question

Post by Alec124c41 » 31 Oct 2019 01:58

At the other end, a cartridge on an arm that is too light will sound thin in the bass.
A cartridge that is on an arm that is too heavy will sound heavy in the bass.
Obviously, there are degrees of mismatch.
Weights can be added to a headshell, and usually, a lighter headshell can be found, for fine-tuning your set-up, if the mismatch is not too gross.

Cheers,
Alec

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