Audiotechnica OC9MLII High, Low or Med Compliance?

Thanks everyone. I've been looking at options for my VPI Scout and that has necessitated a focus on compliance matching. After establishing the effective mass (medium/low) of the JMW9 arm I wanted to make sure I was pairing it with a fairly high compliance cartridge. Very few people seem to run the ATOC9MLII with the Scout, preferring instead the Dynavectors for example. I've used the Dyna 20X (both low and medium output versions) series in the past but after a recommendation from Keith Herron for a lower cost alternative (the OC9MLII) I decided to give it a try without really looking into whether it was a good compliance match or not. It seems like the excellent performance I am getting from this relatively inexpensive cartridge may, in part, be due to it being a good match for the JMW9. Thanks for helping to sort this out since the spec sheet for the OC9MLII provides the two different compliance figures.

I replaced my Linn Arkiv with an OC9II on a Linn Ekos (a medium mass arm), and an interesting thing happened. On any album with even the slightest warp (most), the woofers on my Linn Keltiks pulse in and out wildly which severely saps amplifier power. I asked my dealer why and he said it was a compliance incompatibility between the Ekos and OC9.

"Would it be accurate to conclude that the OC9MLII is a medium to high compliance based on the above"?

Yes.

Thanks all. Would it be accurate to conclude that the OC9MLII is a medium to high compliance based on the above?

Audio Technica, like several other Japanese manufacturers, specify the dynamic compliance at 100HZ. As your link above suggests, of most interest is the compliance at resonance (around 10Hz) which will be somewhat higher.

For instance Denon state the compliance of the 103 is 5x10-6cm/dyne which seems quite low. However practical resonance tests suggest the compliance is closer to 10cm/dyne(10-6)around resonance. The graph of compliance vs frequency published in Denons manual confirms this.

I'd expect the dynamic compliance of the OC9 to be more like 16-18cm/dyne(10-6) at resonance (ie around 10Hz).

As far as I can tell, when the units are crunched out, 1µm/mN equals 1cm/dyne(10-6) - ie those two terms are interchangeable. I've also seem cm/dyne(10-6) expressed as CU.

I've had good results hanging an OC9ml/1 on medium mass arms including a Linn Basik LVX, a Premier FT-3 and also a higher mass VPI JMW-12.

I found this also:

http://www.diyaudio.com/forums/analogue-source/88268-dynamic-vs-static-compliance.html

From the Galen Carol Website:

A phono cartridge whose compliance is rated at 12 x l0ˉ6 or below, is considered low compliance. A cartridge whose compliance is rated between 13 x l0ˉ6 and 25 x l0ˉ6 is considered high to very high.

Note: Another way of expressing compliance is um/mN. Here a rating of 5 to 10 is considered very low, 10 to 20 is moderate and above 35 is very high.

Low mass arms mate well with both moderately high and very high compliance phono cartridges.

Moderate mass tonearms are good companions for moderate to low compliance cartridges.

If a low compliance cartridge is used with a low mass tonearm, undesirable resonances can occur in the audible range. Mistracking may also be a problem.

When a high compliance cartridge is mated with a moderate mass tonearm, resonances in the infrasonic range may occur in addition to some unwanted high frequency damping.