For a single or two repeats, this would likely be virtually unnoticeable, due to being less than half a percent difference. If perceivable at all, it would 'feel' a bit 'rushed' (as opposed to a 121BPM delay on a 120.5BPM tempo feeling 'laid back'). 'Feel' for timing, especially with percussive instruments, lives in these sub-millisecond time frames.
The percent difference between 60 and 60.5 BPM will, of course, be twice as large as the above.
THIS.
If you're playing at tempo 200 with a single-repeat eighth-note delay, the time between the note and the echo is 0.15 seconds. For tempo 200.5, the time would be 0.1496 seconds. That's 4/10ths of a millisecond's worth of difference. Maybe Steve Vai, with his, uh,
amusing sensitivity to modeler latency (* cough *), can hear that difference. But ain't nobody else who can!
But, if you're playing at tempo 50 with a four-repeat quarter-note delay, the time between the note and the first echo is 1.2 seconds. If it's tempo 50.5, the time would be 1.1881 seconds. That's a difference of 0.0119 seconds, or 11.9 milliseconds; and that's just the difference in where the echo will land on the
first repeat. The difference will increase by that amount on each repeat, so, by the fourth repeat, you'll be almost 50 milliseconds off. Anyone, from Lil' Wayne to your pitch-deaf uncle who claps on the 1 & 3, will feel
that as a "stumble in the beat."
A more moderate example, falling between these two, can be heard in the echo on Phil Collins' voice in his famous "In The Air Tonight," when he sings, "...the first time, the last time, we ever met .. met .. met .. met...." Having it out-of-synch on that vocal is a nifty effect. But imagine how distracting it'd be if you
didn't want it!
Consequently, there is a real use for fine-tuned tempos. The need for it is felt more...
- at slower tempos
- with longer delay note-values
- with more repeats
- when playing with loops and sequences, click-tracks, etc.
So, to make a long story short...
(too late!)
...we should really have the fine-tuning tempo option.