Confused about compliance matching with airbearing

It just occurred to me that Fremer cites the large differential between mass in the vertical and lateral planes as being likely to cause vertical and lateral resonance to occur at two very different frequencies. I am not sure that's a bad thing, if the two frequencies are favorably related to each other so as to broaden and flatten the net resonance. Nor do I know how the formula for resonance in the lateral plane compares to the one for vertical and how it takes compliance into account, if it does.

The horizontal resonance will be considerably lower, because of the higher mass. The ET-2 specs are 7g vertical, 25-35g horizontal effective mass(in horizontal plane, effective is actual, given lack of a pivot). This has a fortunate effect,in that horizontal is mono info, and deep bass is mixed to mono; the greater inertia enables higher output(the cartridge is shifted less, thus greater displacement of cantilever with respect to the cartridge windings). And, since warps are vertical, there's no penalty in that regard. Off center spindle holes, however..

In practice, I've found the loading of the cantilever suspension by horizontal mass does effect the over-all sound- too high, and it's like being off level(the stage in one channel collapses-same effect as with maladjusted anti-skate) in both channels. This is obviously cartridge compliance dependent. I use an ATOC-9 in an ET-2, and minimize the horizontal mass by putting the counterweight at the extreme end of the beam, thus using as little mass as possible. Using the Shure test record, I noted resonance at 9HZ only(range on the record is 5-14 HZ). If I use the dynamic compliance spec for the cartridge(9 cu), I calculate close to that for horizontal resonance(9.235 HZ @33g,25g plus 8g cartridge ). Vertical resonance calculates as 14.71HZ with 5g effective mass vertically(this is suggested by ET-2 manual as value, not 7g, why I don't know). I have no tracking issues, even with off center lps, stage is huge, but I do note tight coupling of lp to platter is needed to produce satisfactory dynamics; greater mass would yield more, but at a price I don't want to pay.

The ET2 is quite low mass then. I'm at about 60grams with cart, counterweight, and entire arm assembly on the MG1.

Rcthweatt, The ET manual is a well-spring of technical information, but I am confused on the subject of horizontal mass. If I understand correctly, moving horizontal mass is 25-35gm wand+manifold, plus up to 40gms counterweights, plus optional 18gm damping trough.

Yeah, I do think the counterweight was overlooked. The damping trough is attached to the horizontal moving mass asemmbly....interesting.