Delay and distance calculation?

Hi there,

does anybody know of a mathematical formula to calculate delays and distances?
Here´s what I´m looking for:

Let´s say I record my guitar amp with a mic placed directly in front of the speaker, another mic will be placed farther away in the room.

Now the sound will hit the "room mic" later than the close mic, right?

I need to know how far I must move the room mic away from the speaker (or from the close mic) so the delay of the sound that gets caught by the room mic will be in time with the song (say it should be delayed for a 16th note...).

So there must be some formula that considers time (seconds or milliseconds), distance (meters or centimeters), tempo (bpm) and their interrelation...

Does anyone know it?

Thanxx and cheerz

Julian Angel