MikeL-Pivoted arms only have perfect geometry at the two null points. But, how does that fact relate to phase? With the tiny error that 10" and longer arms have across the record, you are saying that they are not in phase except for the two null points? I have never heard that before and I have been to 3 county fairs and 2 goat breedings. Do you really mean phase?
Mark
the stylus is either perfectly aligned to the groove or it's not. phase is simply the relationship of one sound in time to another. when the stylus is aligned perfectly then the phase can be absolutely spot on. when it's not in alignment there will be a degree of mis-alignment. a pivoted arm only has the potential for spot on alignment at two points.
our ears are extremely sensitive to tiny changes in phase, much more than tiny changes in gain. that's because phase determines where things are in space. close your eyes and you can easily track the direction of sounds....and how far away they might seem. how real they sound. it's why digital seems flat. correct phase gets thrown out with all the math. DSD/SACD does space better than PCM because there is much less math involved.
there is a reason that linear trackers do space better than pivoted arms. it's because of perfect (potentially) time alignment.
at RMAF Fremer did a workshop on cartridge setup. he discussed a computer program developed by Fiekert which allows for phase alignment while adjusting azimith. he showed us how getting phase as close as possible was more important than balancing channel output. it's the phase alignment that 'snaps in' when everything is right. i'll caution that Fremer did not connect the dots here, i did.
i have three tt's; one with a linear tracker and 2 with pivoted arms. it's easy to hear what i'm talking about.
can a pivoted arm sound great? sure. can it do phase very very well? sure. can it do it as good as a linear tracker? no.