Use a tape delay, or a plug-in that models one, when you want echoes that fade into the background and sound warm and a little loose: vocals, guitars, synth leads and dub. Use a clean digital delay when the repeats need to stay clear and sit exactly on the beat. It's also the one to use for wide, stereo echoes.
If you only have a digital delay, turning its high cut down to around 4 kHz gets you a good part of the way to tape.
At a glance
| Property | Tape delay | Digital delay |
|---|---|---|
| How it stores the sound | On a loop of magnetic tape | As numbers in memory |
| Each repeat | Darker and a little dirtier than the last | An exact copy, only quieter |
| Pitch of the repeats | Drifts with wow and flutter | Fixed |
| Turning the time knob | The echoes bend in pitch | The echoes fade or jump to the new time |
| Feedback past 100% | Builds up, then the tape holds it | Often capped, or a freeze mode |
| Noise | Tape hiss, which grows with feedback | None to speak of |
| Tempo sync and stereo | Not on the original machines; many plug-ins have both | Standard |
| Where it sits in a mix | Behind the dry sound | Beside it, unless you filter the repeats |
What is the difference between tape delay and digital delay?
Both hold on to a sound for a moment and play it back late, and with feedback some of that echo goes back in to make the next one. The delay lesson covers the controls they share: time, feedback and mix. The difference is in how the sound is held while it waits.
A tape delay records the sound onto a short loop of magnetic tape and reads it back from a playback head a few centimetres further along. The gap between the heads, divided by the tape speed, is the delay time. Every repeat is recorded and played back again, and every pass through the tape changes the sound a little. Some treble goes missing and the peaks get rounded off, while the motor's speed never quite holds still.
A digital delay turns the sound into a stream of numbers, tens of thousands of them a second, writes them into memory and reads them back later. Numbers don't wear out. As long as nothing else is in the loop, the hundredth repeat is the same as the first, only quieter, and because a plug-in keeps those numbers in the computer's RAM, its delay can be seconds long without losing any quality.
The first digital delays were studio rack units in the 1970s, such as the Eventide DDL 1745 and the Lexicon Prime Time, and Boss brought the idea to a guitar pedal with the DD-2 in 1983. Tape echo is older: the Echoplex was on sale in the early 1960s, and the Roland RE-201 Space Echo arrived in 1974, three years after Eventide's first digital unit. Plenty of producers kept using tape long after digital delays were cheap, for the sound described below.
Darker repeats
Tape can't hold the highest frequencies as well as the middle ones, and it loses a little more every time a repeat goes round. So the first echo is slightly duller than the original, the second duller again, and by the fifth or sixth it's a soft outline of the note. Your ears hear fading treble as distance, so a trail of darkening echoes seems to move away from you instead of stacking up on top of the mix.
A clean digital delay has none of that loss. In step 1 of the lab the digital repeats are at 375 ms with 45% feedback, each about 7 dB quieter than the last, and the teal top-end mark sits on the top of every bar: the tone never changes. That's why an unfiltered digital delay can sound harsh on a bright vocal. The echoes are as bright as the voice, so they compete with it.
This is the one tape trait a digital delay copies easily. Put a low-pass filter inside its feedback loop and every repeat passes through it again, so each one comes back darker than the last, in the same way. In the lab, with the Tone set to 3.5 kHz on both, repeat 4 has lost 7.6 dB of top end on the tape and 7.7 dB on the digital delay. Most digital delays have this filter, labelled high cut, damping or tone.
Saturation and harmonics
Record a loud sound onto tape and the tape can't follow the peaks all the way, so it rounds them off. That's saturation, and like any gentle distortion it adds harmonics, new frequencies at whole-number multiples of each note. On a tape echo it happens on every pass, because every repeat is recorded again, so the repeats get a little thicker and grittier the longer the trail goes on. The tape saturation lesson looks at the effect on its own.
The harmonics screen in the lab sends a 220 Hz note through both delays and measures the fourth repeat. With 10 dB of drive on the tape, it carries a 3rd harmonic at 660 Hz about 25 dB under the note. At 16 dB of drive the 3rd is at −17 dB and the 2nd at −20 dB. The digital delay's bars stay empty at any setting, because it stores the numbers it's given and does nothing to them.
On a busy mix a harmonic 25 dB down is too quiet to pick out by itself. What you hear is the echoes getting denser and softer at the edges, so they blend into the track and stop sounding like a pasted copy. Push the drive further and the repeats break up into fuzz, which dub and lo-fi producers use on purpose.
Wow, flutter and pitch
No motor and tape path runs at a perfectly even speed. The slow drift in speed is called wow and the fast ripple on top of it is flutter. When the tape speeds up, the playback head reads the sound slightly faster than it was recorded, so the pitch goes up; when it slows down, the pitch drops. Only the echoes are affected, because the dry sound never touches the tape.
Pitch changes are measured in cents, and 100 cents is a semitone. In the lab, 25% wow and flutter moves the tape repeats up to about 7 cents either way, which sounds like a slight looseness more than a wobble. At 60% it's about 17 cents, and on a sine wave you hear the echoes swirl against the dry tone. The digital delay reads its memory from a fixed point, so its pitch line stays flat at zero.
Changing the delay time
On a machine like the Space Echo the time knob changes the motor speed. Slow the motor down and the echoes come later, but everything already on the tape also plays back slower and lower while the speed is changing. That's why sweeping the time on a tape delay gives the swooping dives and rises you hear in dub. Step 6 of the lab drops the time from 375 to 250 ms and the tape echoes slide up in pitch before they settle.
A digital delay doesn't have to do this. The simplest ones jump straight to the new time, which can click; better ones crossfade from the old time to the new one, which is what the lab's digital delay does over 30 ms. Many plug-ins let you choose. Ableton Live's Delay has three modes for it, called Repitch, Fade and Jump, and Repitch is the tape behaviour.
Feedback past 100%
Above 100% feedback, each repeat comes back louder than the one before. On a tape echo the build-up runs into the tape's saturation, which rounds off the level so it can't grow for ever. That's self-oscillation: the echoes swell into a sustained, dark roar, and dub engineers play it like an instrument by riding the time and feedback knobs. In the lab, at 105% the tape repeats hold at about the level of the original.
A clean digital loop has nothing in it to stop the growth, so past 100% it would just get louder on every pass until something clipped. Many digital delays stop at or just under 100% for that reason, and many offer a freeze or hold switch instead, which keeps looping what's already in the memory while ignoring new sound. The lab's digital delay stops at 95%, where its repeats fade by about half a decibel each. The delay feedback lesson has more on how feedback sets the length of the trail.
Time, sync and stereo
This is where digital delay wins. Its time can be set to the sample, so a tempo-synced delay lands exactly on a 1/8 note at any BPM and stays there. Long times cost nothing, so a two-second echo sounds as clean as a 100 ms one. A digital delay can also run separate times on the left and right, or bounce each repeat from one side to the other as a ping-pong delay. A real tape machine has one tape loop, its times are set by the spacing of the heads and the range of the motor, and it has no idea what tempo your song is.
Tape also has running costs. Original machines need fresh tape, cleaned heads and servicing, and they hiss, even in silence. The hiss goes round the loop with everything else, so it grows as you turn up the feedback. None of this applies to a plug-in, which is a big part of why most people now get their tape delay from software.
Tape delay plug-ins are digital
Every plug-in runs on a computer, so a tape delay plug-in is a digital delay with tape's behaviour written into it: a filter in the loop for the darkening, saturation on every pass, a slow random wobble on the delay time for wow and flutter, and often hiss you can turn up or off. Universal Audio's Galaxy Tape Echo and Roland's own RE-201 plug-in model the Space Echo, and Soundtoys EchoBoy has tape styles among its echo types. The Strymon El Capistan and the Boss RE-20 are digital pedals that model tape echo.
In a DAW, then, you're choosing between a delay that leaves its repeats alone and one that changes them on every pass, and most delay plug-ins can do some of both. What a model adds over a filter is the saturation and the pitch drift, which are the two screens where the lab's digital delay stays blank.
When to use tape delay and when to use digital
| Job | Tape delay | Digital delay |
|---|---|---|
| Echoes behind a vocal | Good: they fade back on their own | Good with the high cut at 3 to 5 kHz |
| A rhythmic 1/8 or dotted 1/8 part | Fine, if the plug-in syncs | Best: every repeat on the grid |
| Slapback on a vocal or guitar | The original sound of it | Works, slightly cleaner |
| Wide stereo or ping-pong echoes | Only in plug-ins that add it | Best |
| Dub throws and runaway feedback | Best | Hard to get without saturation |
| Long, clear echoes on a sparse mix | Gets murky as it goes | Best |
For a vocal in a full mix, I'd start with a tape-style delay. The darkening and the slight drift keep the echoes behind the voice without much work, and a little saturation stops them sounding like a second singer. Reach for a clean digital delay when the echo is part of the rhythm, such as a synced 1/8 on a pluck or a guitar, or when it needs to be wide. Slapback was a tape sound first, and it still suits tape.
Whichever you use, put it on a send with the mix at 100%, so you can filter, saturate or automate the echoes without touching the dry part. The insert vs send lesson explains the routing.
How to make a digital delay sound like tape
Any DAW's stock delay can get most of the way there. These steps follow what the lab's tape echo does.
- Put it on a sendLoad the delay on a return track, set it 100% wet and send the part to it.
- Darken the loopSet the high cut, damping or tone control between 2.5 and 5 kHz. It needs to be inside the feedback loop so each repeat gets darker; a filter after the delay only darkens all the repeats by the same amount. If yours has a low cut in the loop too, 150 to 300 Hz keeps the echoes off the bass.
- Add saturation after itPut a tape or soft saturation plug-in after the delay on the return. It won't build up pass by pass the way real tape does unless your delay has a drive control inside its loop, but it gives the echoes the thicker edge.
- Add a slow wobbleIf the delay has modulation, set a slow rate, under 1 Hz, and a very small depth, so the echoes drift by a few cents at most. More than about 10 cents and it starts to sound like a chorus or a detuned tape.
- Set the feedback by earAround 30 to 40% gives three or four repeats you can hear. Darker repeats seem to die away sooner, so you can usually run a little more feedback than on a clean delay.
Common mistakes
Leaving a digital delay unfiltered on a vocal
Full-bright echoes sit right next to the voice and make the words harder to follow. Pull the high cut down until the echoes move behind the voice, then stop.
Too much wow and flutter
A few cents of drift sounds like tape. Twenty or more sounds like a tape that's being chewed, which is great as an effect and distracting on a lead vocal. If the echoes sound out of tune against the song, the wobble is too deep.
Filtering after the delay instead of inside it
An EQ after the delay darkens every repeat by the same amount, so the trail stays the same brightness all the way down. The tape sound comes from a filter that each repeat goes through again, so use the delay's own high cut if it has one.
Running feedback past 100% without a safety net
Self-oscillation gets loud fast. Turn your monitors down, put a limiter after the delay and automate the feedback back down once the moment is over.
Comparing them at different levels
A saturated tape echo can come out louder than a clean digital one at the same settings, and louder tends to win. The lab matches the two for loudness; in your DAW, match the return levels by ear before you decide.
Training your ears to tell them apart
The quiz under the lab plays one of three delays on a level-matched loop with the screens covered: a clean digital delay, a digital delay with a high cut in its loop, or a tape echo. The middle one is the trap, because it darkens the same way the tape does. Listen past the tone to the pitch of the third or fourth repeat and the grain on its edges.
Questions people ask
Is tape delay better than digital delay?
Neither is better. Tape delay is the better choice when you want the repeats to fade into the background and sound a little worn, and digital delay is better when you need long, precise, clean or stereo echoes. Many mixes use one of each, on different sends.
Is a tape delay plug-in digital?
Yes. Every plug-in is digital, so a tape delay plug-in is a digital delay with the tape's losses worked into its code. How close it gets to the real thing depends on how carefully the original machine was measured and modelled.
What is the difference between analogue delay and tape delay?
Both lose top end and distort a little on every repeat. Tape delay stores the sound on magnetic tape, so it also gets wow, flutter and tape hiss from the motor and the moving loop. Analogue delay pedals such as the Boss DM-2 pass the sound along a bucket-brigade chip instead, so there's no tape to wobble.
Why does digital delay sound harsh?
Usually because every repeat keeps all of its top end, so the echoes are as bright as the dry sound and compete with it. Turn the delay's high cut, or its tone or damping control, down to between 3 and 5 kHz and the repeats will sit behind the dry part instead.
Can you sync a tape delay to tempo?
A real tape machine can't sync itself, because its time comes from the motor speed. You set it by ear or by working out the time: at 120 BPM, a 1/4 note is 500 ms. Tape delay plug-ins almost always have a sync switch, so you get the tape sound locked to the grid.
Does tape delay add noise?
A real tape machine does, as a constant hiss that's there even when nothing is playing, and it grows as you turn up the feedback because the hiss goes round the loop too. Some plug-ins let you add it back. The lab leaves it out so the comparison is about the repeats.