Delay times and note values

Delay times in plain English

Music counts time in beats, and the tempo, in beats per minute, says how long each beat lasts. Note values divide the beat up. In 4/4 a 1/4 note is one beat, a 1/8 is half a beat and a 1/16 is a quarter of one. A delay counts in milliseconds instead, so to make its echoes land on the beat you have to translate one into the other.

Tempo sync does that translation for you. You pick a note value, the delay reads the tempo from your DAW and sets the milliseconds, and if you change the tempo the time follows. With sync off you type the time in yourself, which works fine once you know the number that matches the note you want.

If you're new to delay, the delay lesson covers feedback, mix, filters and the rest of the controls. This page stays on timing.

Reading the lab

Every loop in this lab is at 120 BPM, so a beat is 500 ms. The panel headed One bar at 120 BPM is a bar of 4/4 split into sixteenths, with a note on beat 1 drawn as the white dot and each dot after it a repeat, bigger when it's louder. When a repeat lands on a grid line it's on the beat; when it sits between lines it isn't.

The wide screen at the top places every repeat in time and shows how loud it is, and the panel on the right gives the delay time in milliseconds next to the note value it matches. Turn sync off and drag the time knob, and that panel tells you which note you're closest to and whether you're on it. The filters are fixed at a 150 Hz low cut and an 8 kHz high cut so the repeats stay clear, and ducking is off, because this page is about where the echoes land.

Press A/B to hear the dry loop at the same loudness. You can also upload a sound or record one, but the grid assumes 120 BPM, so your own loop will only line up if it's at that tempo.

How to calculate delay time from BPM

A minute has 60,000 milliseconds. Divide that by the tempo and you have the length of one beat, which in 4/4 is a 1/4 note:

1/4 note in ms = 60,000 ÷ BPM

Every other note value is a fraction of that. Here it is worked through at 128 BPM, a common house tempo:

1. Find one beat60,000 ÷ 128 = 468.75 ms. That's the 1/4 note.
2. Halve it for the shorter notesThe 1/8 is 234.38 ms and the 1/16, half again, is 117.19 ms.
3. Multiply by 1.5 for a dotted noteThe dotted 1/8 is 234.375 × 1.5 = 351.56 ms.
4. Take two thirds for a tripletThe 1/8 triplet is a third of the beat: 468.75 ÷ 3 = 156.25 ms.

Most delays let you type two decimal places, and plenty round to the nearest millisecond. Rounding 351.56 up to 352 makes each repeat 0.44 ms late, so after ten repeats the echo is about 4 ms off. That's too small to hear, so whole milliseconds are fine.

Some useful shortcuts drop out of the maths. A dotted 1/8 is three quarters of a beat, so it's 45,000 ÷ BPM in one go, and a 1/8 triplet is 20,000 ÷ BPM. At 90 BPM a dotted 1/8 is exactly 500 ms, the same as a 1/4 note at 120.

Note values and what they mean

Straight notes

Each straight note is half as long as the one above it. A whole note lasts four beats, a 1/2 two, a 1/4 one, and from there down through the 1/8, the 1/16 and the 1/32. Every step down halves the delay time and doubles how often the repeats come, which is why a 1/16 delay sounds more like a texture than an echo.

In British English the same notes are the semibreve (whole note), minim (1/2), crotchet (1/4), quaver (1/8), semiquaver (1/16) and demisemiquaver (1/32). Delay plug-ins nearly always use the fractions.

Dotted notes

A dotted note is the plain note plus half again. A dotted 1/8 is three sixteenths long and a dotted 1/4 is three eighths, which comes to 750 ms at 120 BPM. On a delay you'll see it marked with a dot or a D after the note value.

Triplets

A triplet fits three notes into the space of two, so each one is two thirds of the plain note. Three 1/8 triplets fill one beat, about 167 ms each at 120 BPM, and three 1/4 triplets fill two beats, about 333 ms each. Delays usually mark them with a T. Ableton Live's Delay puts them in their own Triplet sync mode, with Dotted as another, alongside the straight notes.

The two ideas pull in opposite directions. A dot makes a note half as long again, and a triplet makes it a third shorter, so a dotted 1/8 (375 ms at 120) is longer than a plain 1/8 (250 ms), which is longer than a 1/8 triplet (167 ms).

The dotted 1/8 delay

The dotted 1/8 is the note value beginners find hardest to picture. Count the bar in sixteenths, 16 to a bar. A dotted 1/8 is three of them, so the repeats of a note on beat 1 arrive three, six, nine and twelve sixteenths after it. Counted the way drummers count sixteenths, “1 e & a, 2 e & a”, that's the “a” of 1, the “&” of 2, the “e” of 3 and then beat 4 itself.

So a single note's echoes visit a different part of the beat every time and only come back to a beat after three beats, 1.5 seconds at 120 BPM. On the lab's beat grid that's the four dots after the white one, three of them off the beat lines and the fourth on beat 4.

Now play a line of straight eighth notes into it. The first echo of every note lands on an odd sixteenth, which is exactly where the gaps between your eighths are, so eight notes a bar sound like sixteen. The second echoes fall back on the eighths, on top of notes you played. That's how a simple picked part through a dotted 1/8 turns into a constant flowing pattern, and it works best when the notes are short and evenly spaced, so the echoes have room to sit between them.

The same trick works one size up. A dotted 1/4 is three eighths, so its echoes fill the gaps in a part played in quarter notes. It suits slower parts, pads and chords, where a dotted 1/8 would be too busy.

Triplet delays and swing

A 1/8 triplet delay repeats three times a beat. Every third repeat lands on a beat, and the two in between fall a third and two thirds of the way through it, places the straight sixteenth grid never reaches. Against a straight loop that makes the echoes swing, which you can hear on the lead in the lab, and the beat grid draws extra dotted lines to show where the triplet positions are.

On a track that already has a triplet feel, like a shuffle or a song in 12/8, a triplet delay sits inside the groove where a straight 1/8 would sound stiff. On a straight track, use it when you want the echoes to pull against the beat. Picked by accident, it sounds like the timing is loose.

Synced or free: when to use milliseconds

A free delay time that's a few milliseconds off a note value doesn't stay a few milliseconds off. The error adds up with every repeat, because each echo is a copy of the last one. Set 360 ms at 120 BPM, where a dotted 1/8 should be 375, and the first repeat is 15 ms early, the second 30 ms and the fourth 60 ms, by which point it's landing nearly half a sixteenth before beat 4. With low feedback you'd barely notice; with high feedback the tail audibly rushes.

Type in the right number and the echoes go straight back on the grid. A synced note value and the matching milliseconds sound identical, so when a delay has no sync switch, like a lot of older hardware, the maths above gets you the same result.

Use sync for any delay whose echoes are part of the rhythm. Use a free time when the delay is too short to hear as rhythm: a slapback between about 80 and 150 ms, or a doubling delay under 30 ms, where the Haas effect makes the repeat blend into the original. Those sound right by feel more than by note value, which the slapback delay lesson goes into.

You can also set milliseconds on purpose to change the feel. Shortening a synced time by a few milliseconds makes the echoes sit slightly ahead of the beat, and lengthening it makes them drag, so you can nudge how pushed or laid back a vocal delay feels. Keep the change small, under about 10 ms on a 1/4 note, because the error adds up down the tail the same way as above.

Working out the tempo from a delay time

The formula works backwards too: BPM = 60,000 ÷ the length of one beat in milliseconds. That helps with a sample that has no tempo marked. Zoom in on two kick drums a beat apart, read the gap off your DAW's timeline, and divide. A gap of 469 ms gives 127.9, which is a track at 128 BPM.

Guitar pedals and hardware delays often have a tap tempo button instead of a sync switch. You tap it in time with the music and the delay sets its time to the gap between your taps, usually as a 1/4 note. Some also have a switch that turns the tapped beat into a dotted 1/8 or a triplet, so you can tap quarter notes and get the subdivision you want. The calculator above has a tap button that works the same way.

The same maths for pre-delay and LFOs

Anything measured in time can be set to a note value. Reverb pre-delay, the gap before a reverb starts, sounds tidier on a note value once it's longer than about 50 ms: a 1/32 at 120 BPM is 62.5 ms, and the pre-delay lesson has a table of them. Compressor release times can be set the same way so the pumping breathes with the beat.

An LFO on a tremolo, auto-pan or filter is usually set in hertz, cycles per second, so convert by dividing 1,000 by the time in milliseconds. A 1/4 note at 120 BPM is 500 ms, which is 1,000 ÷ 500 = 2 Hz, and a 1/8 is 4 Hz. Most synths and modulation plug-ins have their own sync switch that does this for you, which the LFO lesson covers.

How to sync a delay to the tempo, step by step

1. Set the project tempo firstA synced delay reads the tempo from your DAW, so if the tempo is wrong, every note value will be too. Make sure your loops and recordings play in time with the click.
2. Switch on syncIt might be called Sync, Tempo or BPM, or shown as a note symbol. With it on, the time control changes from milliseconds to note values.
3. Start with a 1/4 or a 1/8These keep every repeat on the beat, so they're the easiest to fit under a part. Try a dotted 1/8 on short picked or plucked notes and a triplet on anything that swings.
4. Set the feedback for the note valueShorter notes need more feedback for the same length of tail, and longer ones need less. The delay feedback lesson has the numbers.
5. Check the echoes against the gridBounce a few bars to audio and look at where the repeats fall in the waveform. If they're off the grid and sync is on, the project tempo is probably wrong for the material.
6. Recheck any free times after a tempo changeSynced delays follow the tempo. Anything typed in milliseconds stays put and needs working out again.

Common mistakes with delay times

Leaving a free time after the tempo changes

Say you set a delay to 375 ms at 120 BPM, then speed the track up to 124. The right dotted 1/8 is now 362.9 ms, so the first repeat lands 12 ms late, the second 24 ms late, and the error keeps growing down the tail. Use sync, or redo the maths whenever the tempo moves.

Mixing up the dotted 1/8 and the 1/8 triplet

Both put echoes between the beats, so they're easy to confuse on a busy track. The dotted 1/8 lands on the sixteenth grid and makes a straight part denser; the triplet lands off it and makes a straight part swing. If a delay makes your tight part feel loose, check which one is selected.

Short note values with lots of feedback

A 1/16 at 70% feedback puts a dozen repeats into three beats, and on anything but short, sparse notes they pile up into mush. Short note values want low feedback, usually under 30%.

Reaching for the dotted 1/8 by habit

It suits short, evenly spaced notes. On a vocal, a sustained pad or a busy line, it often just fills every gap there is. Try a 1/4 or a 1/8 first and only move to the dotted value when the part has room for it.

Training your ears to hear note values

The quiz under the lab plays a 120 BPM loop through a delay set to a hidden note value, covers the controls and screens, and asks which one it is from three choices. Every round is level-matched, so timing is the only clue. Tap your foot to the loop while you listen. A 1/4 puts one echo on each tap and a 1/8 adds one exactly halfway between taps. Three even echoes per tap that swing against the loop are the triplet, a blur is the 1/16, and echoes that tumble across the beat and only meet your foot every third tap are the dotted 1/8. There are eight rounds, and your best score is saved in your browser.

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