Grab - Good point.

Most of the cheaper electronic tuners do have "slow down" in the display to counter (hide) the decay in pitch. Some of the better ones allow you to select one or two different "speeds." With the CA-30, I wouldn't expect the pitch decay to be too noticeable, but if you try to read the "whole thing" you could see it. It seems also to be more apparent if you're using a "slack" tuning. If the strings are at lower than normal tension, the pitch decay is greater than if they're at a high tension. The answer to this one is to try to get the tuning done before the sound decays, or pluck more often, maybe.

Since lap dulcimists often retune by as much as a fourth or so, the "slack string" effect gets very apparent for some tunings. I'm not sure what strings you would pick for a bass dulcimer (it is a lap dulci?) but it's possible that they're not getting up to tension, which would make tuning more difficult. A different choice of strings might help. If that's the problem, it's really not the tuner, it's the instrument that's "untunable," perhaps.

John