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Cartridge Loading and Compliance Laws

After reading into various threads concerning cartridge/arm compatibility, then gathering information from various cartridge manufacturers I am left feeling confused with head spinning a bit.... Ok, cart compliance I get, arm and total mass I get, arm/cart compatibility and the whole 8-12 Hz ideal res. freq. range I get. But why on earth then do some phono cartridge mfgs claim their carts are ok to use with med. mass common modern arms when they are in the highish 20-35cu compliance range? Am I missing something??

Ie. Soundsmith, VanDenHul, Ortofon and who knows, maybe more??

From what I gather, below 8Hz is bad and above 12Hz is bad. If one is less ideal than the other, which is worse I wonder, too low res. freq. or too high?
jeremy72
fleib
1,124 posts
 
Jeremy,
Static compliance is always higher than dynamic. It's dynamic compliance that is used to estimate arm/cart resonance. The standard used in these calculations is measured at 10Hz. Some Japanese cart manufacturers measure dynamic at 100Hz. Those figures are not directly comparable to 10Hz figures.
Regards,
jeremy72 OP
97 posts
 
So, what you are saying is that most mfg.'s (Lyra, Shelter, Ortofon ect.) use dynamic compliance numbers on their spec sheets but for some reason VDH is using static compliance figures. Correct me if I am wrong here..

Is there a conversion calculator for converting static compliance to dynamic compliance?
jeremy72 OP
97 posts
 
Is this formula correct? If so, it would indicate that both are identical measurements only stated in different units.

1 cm / dyne = 1 g ^-1.s^2 = 10^3 kg^-1.s^2

thus 10^-6 cm/ dyne = 10^-3 kg^-1.s^2

1 um = 10^-6m

1 mN= 10^-3 kg.m.s^-2

therefore 1 um / mN = 10^-3 kg^-1.s^2

the two units are thus identical.

From what I gather on the Colibri test measurement sheet their testing is conducted at roughly 100Hz. (Similar to how Lyra tests)
jeremy72 OP
97 posts
 
All this together would seem to indicate that the stated VDH 35 Micron/mN compliance is the same as saying 35 x 10-6 cm/dyn only in different terms. If testing was done @ 100Hz. I think...

Its kinda like saying .5" is the same as 1/2" Right?

My math could be flawed though, so if that is the case anyone please feel free to correct these statements above.
fleib
1,124 posts
 
There is no formula to convert static compliance to dynamic. In fact dynamic cu can be different laterally than vertically. For resonance estimates vertical is normally used. Most specs are dynamic cu. For example, most Benz carts are 15cu (dynamic). VDH only gives static, but tells you eff mass range of arms for the cartridge.

The only examples of both static and dynamic I could find listed is AT. The 33EV has a static cu of 40. Dynamic is 10 @100Hz. That's equivalent to approx 17, 18 @10Hz. There is no reliable formula to convert 100Hz to 10Hz.
www.lpgear.com/product/AT33EV.html

IMO it's better to find out what makes a good match from other users. Resonance estimates are often wrong and great sounding combos can be outside of the recommended range. If you want to find out exactly what res freq is, get a test record. You're more likely to get bad results with a low cu cart on a light arm. When res is near the audible band it can impact on the music.
Regards,
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