apparant pitch instability

Hey,

So maybe it's me, maybe it's my records, maybe it's my power, maybe it's my new cartridge. But, having just mounted a new Dynavector 10x5 on my Rega Planar 2 and replaced the belt as well, I am of course now listening more often, and more attentively to my 'table to get the know the cartridge, than I have in quite a while. And I am noticing, on certain records, some apparent pitch instability -- a sort of warble of relatively high pure notes. I hear it particularly on piano and organ. At times it doesn't seem to be there at all, at other times it seems quite subtle, so that I think maybe it is just the natural envelope -- attack, sustain and decay -- of the note, and at other times it sounds obvious and very distracting. It seems worse on inner grooves, which is the opposite of what I would expect if the turntable motor is not running at a perfectly regular rotational rate. The cartridge sounds otherwise great -- detaied but warm, firm full bass, considereably fuller and deeper than on the Super Bias it replaced, with comparatively very quiet tracking (though the Super Bias was pretty old, so the comparison may not be fair.)

The records on which I've noticed the problem most are Arrau's Chopin Preludes on Phillips (the London Ashkenazy was better, but there the relavant preludes are on the outer grooves), a Stavinski Concerto for two pianos solo, and a Mercury Living Presence record of Marcel Dupre playing his own music on the St. Sulpice Organ. Organs are famously always struggling to stay in tune, so that one may be the instrument. I suppose the others may be as well, and that I may just be suffering from overly analytical listening. But I don't think so. None of these records is significantly warped, by the way. And the turntable is tolerably level, according to a bubble level.

I am certain that I have very poor power here -- running on a 1964 fuse box, with any number of other items serviced by the line, including computer. I have no easy way to control for that, as the whole house is similar. I am unfortunately not in a position to do much about this as I am temporarily renting. And anyway, I haven't heard this problem on digital sources or radio (though maybe I'm just not listening hard enough). But if it is the power, perhaps cutting on and off of varying in voltage , then I wonder if I'm not also ruining my amplification and power supplies.

Could I have put the belt on wrong? Could it be the cartridge breaking in (seems unlikely, but so does general relativity:))? A defect I should compain about? Some subtle mounting error?

Suggestions?

I don't want to make this sound worse than it is, the system sounds really very good -- the problem is not one that compromises all listening, at least not in a way one can isolate on most material. Assuming the problem, if I'm not imagining it, is not the cartridge, then I recommend the Dynavector highly. Bit of a pain to mount (ok, big pain) but lovely lovely sound.

Anyway, any wisdom or hypotheses would be welcome and appreciated.

Thanks,

RNM