Periodic clicks or ticks are usually clock related leakage from the digital side to the analog side of the machine. Tascam incorporates shielding between these boards on even their most inexpensive recorder, so it could be a matter of a simple production fix if there’s a leak somewhere. This can hopefully be applied to existing machines if it’s deemed to be serious enough.
It is 100% this.
I can hear it shifting as I adjust the "DELAY" setting.
Tested all the ideas posted (24 bit, 96/192khz, PIP off with 3.5mm MIC plugged in), still present in all cases, only change was that the levels showed a bit higher with each tick @ 192 khz.
Curious how TASCAM will respond, I will attempt to clarify with them to see if this is expected from their end. So far they told me to update the firmware, and when I replied that I already did, they sent a link to update the firmware haha.
Again, just to clarify, I am no longer worried about this for real world applications -- I was far more concerned when I thought it started up out of nowhere, since it seemed like there was risk of it worsening.
At these levels, should never hear the internal clock on an actual tape.
Oh and @ rastasean, sorry for late response, yes, can independently adjust channel levels at all formats / bit depths.