The H9 basic configuration has a setting “Source Instrument” to optimize the “algorithms” for use with a bass guitar, standard guitar, etc. I just wondered if Eventide might indicate which is likely to be better suited for:
Alas, our bass player is out at the moment nursng his suffering wife, but will reply when he returns.
However, my guess is that he will suggest trial and error – see what works best.
Nick is right, see what works best for you. However, to my recollection, the "Guitar" setting should be fine for seven string and baritone guitars. I think this setting takes into account that low guitar B note. Obviously for a bass or 5 string bass, you'll need to use "Bass" mode. Note that this really only applies to PitchFactor algorithms, as its main purpose is to condition the pitch tracking for lower notes which need more time to determine the lower frequency (longer wavelength) before they decide on the proper harmonizing voice.