this was driving me nuts with a bass guitar in a mix. test it for yourself. send A440 to the schope. it reads 453hz or so. seems to get worse (more than a whole step) as you get more towards the really low end.
Is this possibly down to the FFT size setting you're using? I get this result when I maximise the FFT setting. I should know this, but it's late so my maths might be a bit wrong. I think the frequency resolution is given by the sampling rate divided by the number of samples or something like that. I'm sure someone will correct me on this. Pete
This is the first time I've seen this plugin. I normally use Voxengo's Span or whatever it's called for the analysis task, but this overlay thing of 4 channels looks cool!