Kalcium wrote:
My guess is that if you're using the delay in a way where you clearly hear the repeats you would need the tempo to be set to the song tempo but if you're just using it for an echoy sort of sound where the repeats aren't heard clearly (Ie it doesnt sound like you picked the note twice with the second time being softer but more like 1 note with almost a reverby echo) then its not as important...
That's it in a nutshell. In brief, keep the delay out of the way of the original sound. You do this mainly by keeping it down in volume, darker in tone and the delay times short to medium.
The darker in tone thing is one of the most effective ways of doing it - which is why analog and tape delay are still very popular. These delays are also less precise, tending to soften the attack of the delay sound which help it to mask (blend/hide) behind the original sound. So if your digital delay has analog or tape emulations, try use those. Otherwise just keep the mix level down.
Very short delays below about 15ms, you don't hear as repeats, but rather as a tone shift from phase cancellations. Short "Slapback" delays (single repeat, 50 -150ms) like those so beloved of the Rockabilly players like Brian Setzer are less intrusive too. 200-300ms is more or less the range you want to live in for a few repeats though, longer than that and the first repeat starts taking on it's own discrete identity in the mix, regardless of the tonality.
You will also find that most stuff you write is within your natural tempo range - we all have a tempo that we default to (mine is 120 BPM), almost like we each have an internal fixed tempo metronome. You'll find that even if you start a song at a few beats a minute faster or slower, you will naturally speed up or slow down to bring the tempo in to line with our internal clock. If you set your delay to a value based on your natural tempo, you'll find longer delay times become more viable live. Importantly, if you play in a band, you need to figure out what your drummer's natural tempo is (my current guy is 128 BPM), because he's controling the band's overall tempo.