The grooves and flow of a song are reinforced by syncing compressors, delays, and reverbs to the tempo of the song. But what happens if your delays, reverbs, or compressors don’t have a tempo sync feature?
Below, I will show you how to calculate the note length in milliseconds like a nerd. How to convert a tempo from beats-per-minute (BPM) to time in milliseconds (ms) to free you from this limitation and enhance your music productions.
You will learn how to calculate delay and reverb timing to enhance the groove of a song!
Without getting too technical, all you need to know is the tempo of the song in beats-per-minute and the length of the note we want. For quarter note synced reverbs and delays, our desired note length would be (1/4). For a whole note, you would use (1/1) or just (1). An eighth note would be (1/8).
Got it? Good, let’s get to the math!
Below is the equation to calculate the note length in milliseconds:
“240,000 ms” /”[Tempo in BPM]” “× [Desired Note Length]”
Pretty simple right? Let’s say you want your reverb to be as long as a 1/4 note and the tempo of the song is 123 BPM. You would enter:
“240,000 ms” /”123 BPM” “× [1/4 Beat] = 487.80 ms”
Or entered into a calculator: 240,000 ÷ 123 ÷ 4
To calculate the note length for triplet notes, you multiply the above note length by (2/3) or use the equation below:
*A triplet is a rhythm playing three notes in the space of two.
“160,000 ms” /”[Tempo in BPM]” “× [Desired Triplet Note Length]”
Why do you multiply by 2/3?
The time it takes to play 3 triplet quarter notes (or any note like 1/8, 1/16, etc.) is the same amount of time as it takes to play 2 regular quarter notes. So much like converting between inches and centimeters, you multiply by (2/3) to convert from standard to triplet notes. Lastly, for dotted notes, you multiply the first equation by (3/2) or use the equation below:
*A dotted note is equivalent to writing the basic note tied to a note of half the value.
“360,000 ms” /”[Tempo in BPM]” “× [Desired Dotted Note Length]”
The time it takes to count 3 quarter notes (or 1/8, 1/16, etc.) is the same amount of time to count 2 dotted quarter notes. Mathematically speaking, this tells you that the dotted notes are the inverse of a triplet note!
How to Use This to Your Advantage
Syncing your song to the tempo is a great way force your delays, reverbs, and compressors to rhythmically enhance the groove of the song. This works especially well for reverb length and my personal favorite, pre-delay on reverbs.
You can also apply these concepts to attack and release settings on compressors to add a nice tempo-timed pumping effect to your songs. Remember, there are no rules so make sure to experiment!