If you've ever played around with a biofeedback device, you may have noticed that the "tone" runs down to a tick-tick-tick sound as you relax. What this should tell you is that what is perceived as Tone and what is perceived as Beat are separated by only a few octaves. These timings will harmonize your BPM with your key chord. You don't have to use the root of the chord, but you may want to stay with the thirds, fifths etc. Say you're playing something in the key of G Major, and you want a fast dance tempo, about 140 BPM (beats per minute). Since D is the Fifth of G Major, go with 137.658 BPM, and your Beat is now tuned to an octave of D, and harmonizes as a Fifth of the key chord, G Major. The timings, in milliseconds, reading down the D column now form half notes, quarter notes, eighth notes, and so on. These are what you will want to dial in to your effects so that, for example, delays "repeat" with the beat, reverbs are "tuned" and harmonize, and things like phasers and chorus effects cycle on the measure. Alternatively, if you're playing in the key of A and want a common Rock tempo, since C is the Third of that chord and is close to 120 BPM, you might try the timings in that column.