This time, trimming of the split wedge felts was needed because of excessive lift noise: when 20+ wedges are lifted together (using the pedal) quite a “zing” or “ghost” noise can be heard as the felts effectively collectively (and then effectively annoyingly) brush & strum the strings. This can amount to quite a loud and unwanted sound – especially in a recording studio where close mics are being used.
(The damper to the right has been trimmed – it’s important to round the ends of each wedge, not just shorten them)
The end result:
(In studio extremes, very precise trimming is required: the wedges almost rest ON the strings, protruding only very little between them – thus minimising lift noise).