What is ping-pong delay?

Ping-pong delay in plain English

A normal delay plays each echo back from the same place as the original. If the vocal is in the middle, its echoes are in the middle too, stacked on top of it. A ping-pong delay sends the first echo to the left speaker, the second to the right, the third back to the left, and so on until the trail fades. The name comes from table tennis, with the echoes going back and forth like the ball.

The dry sound doesn't move. A centred vocal stays centred and only its echoes travel, so the space around a part gets wider while the part itself stays where you put it. That's the main reason to use one.

On most delays ping-pong is a switch or a mode, and the time, feedback, mix and filter controls work the same as on any other delay. The delay lesson covers those. This page is about what changes once the echoes start bouncing.

How does a ping-pong delay work?

A stereo delay has two delay lines inside it, one for each side. In a normal stereo delay each line feeds back into itself, so the left echo makes the next left echo and the right echo makes the next right echo. Ping-pong crosses those wires: the output of the left line feeds the right line, and the right feeds the left.

Crossing the wires isn't enough by itself. If the same sound goes into both lines, both sides echo the same thing at the same moment, and swapping them changes nothing you can hear. A ping-pong delay also has to start the sound on one side. A common way is to sum the input to mono and send it into one line only, and that's what the lab does: the input goes into the left line, its first echo comes out on the left, and from there it crosses to the right for the second echo and back to the left for the third.

Some delays let you choose which side starts. Others keep the input in stereo, so a sound panned left starts its bounce on the left and a sound panned right starts on the right. A sound panned dead centre into that kind of delay won't bounce at all, which catches people out when they build a ping-pong from a delay's crossfeed controls.

Reading the lab

The lab is the delay from the main delay lesson, with ping-pong on from the second step. The echo timeline at the top has a lane for each speaker, left on top in pink and right underneath in violet, and every bar is one repeat at the moment it arrives, as tall as it is loud. With ping-pong off the two lanes match. With it on they take turns. The one-bar grid shows the same bounces against the beat at 120 BPM, and the panel on the right gives the delay time, how many repeats are louder than −40 dB and how long the echoes take to fall below −60 dB, all measured from the sound. The Mono switch beside Ping-pong adds the two sides together, which the mono section further down puts to use.

Use headphones if you can. On speakers each ear hears both speakers, so the bounce sounds narrower, and on a laptop the two speakers are so close together that the effect almost disappears. The lead, drums and chords loops are at 120 BPM, so the note values line up with them. Load a file with + Your sound, or press Record, and your own sound loops through the lab instead; it never leaves your browser.

Ping-pong delay timing

The delay time on a ping-pong delay is the gap between bounces, from one side to the other. Each side then has to wait for the other side's turn, so on its own each speaker repeats at twice the delay time. A 1/8 note ping-pong at 120 BPM bounces every 250 ms, and each speaker gets an echo every 500 ms, which is a 1/4 note.

Keep that in mind when you pick a note value. If you want each speaker to answer once a beat, set a 1/8. A 1/4 would give each speaker one echo every two beats, which can sound slow and sparse on a busy part.

At any other tempo the gap between bounces comes from the usual sum, 60,000 ÷ BPM for one beat, and the delay times and note values lesson works through it for every common value.

The dotted 1/8 suits ping-pong well on leads and guitars. The bounces fall between the notes of a straight eighth-note line, and the two sides end up with different relationships to the beat. In one bar at 120 BPM the left side's echoes arrive at 375, 1,125 and 1,875 ms, none of which is on a beat, while the right side's land at 750 and 1,500 ms, and 1,500 ms is beat 4. You can watch that on the beat grid in the lab.

At a 1/16 the bounces come every 125 ms, too fast to follow one by one. What you hear is a stereo shimmer or rattle behind each note, which works on hi-hats and short percussion and gets messy on anything that sustains.

Feedback and the lopsided bounce

Feedback decides how many times the echoes cross. At 0% you get one echo on the starting side and the other side stays silent, because the second line only ever hears what the first one sends it. So a ping-pong delay needs some feedback before it does anything. Around 30 to 50% gives several clear bounces, and past 60% they carry on long after the phrase has ended.

Each bounce is quieter than the one before by the same amount, which you can work out as 20 × log10 of the feedback. At 50% that's 6 dB a bounce, at 40% it's 8 dB, and at 70% it's 3.1 dB. The delay feedback lesson goes further into how that sets the length of the tail.

This design has a side effect. The starting side always gets the first and loudest echo, and every echo on the other side is one bounce quieter than the echo just before it. Add up all the echoes on each side and the starting side wins by exactly one bounce's worth of level: 6 dB at 50% feedback, 8 dB at 40%. Lower feedback means a bigger lean.

You'll hear that as a delay that tips towards one speaker. If it bothers you, pan the dry part a little towards the side that answers second, so the loud first echo sits opposite it. Panning the delay's return slightly towards the quieter side works too. So does more feedback, since that narrows the gap. On a delay that lets you pick the starting side, start it on whichever side has less going on in the arrangement.

Ping-pong vs stereo delay

A stereo delay with ping-pong off keeps the two sides separate. Each side echoes itself, so a sound panned left echoes on the left and a centred sound echoes in the centre. That's the first step in the lab, where the two lanes of the timeline match bar for bar.

Many stereo delays also let you set a different time on each side, say a 1/8 on the left and a dotted 1/8 on the right. The echoes spread out across the speakers without ever crossing, and the two rhythms play against each other. People call that a dual delay. It sounds busier than ping-pong, because both sides start echoing at once.

Very short times are a different effect. Delay one side by under about 30 ms and you stop hearing an echo; the sound itself seems wider and pulled towards the side that arrives first. That's the Haas effect. It doesn't survive mono the way ping-pong does, because the two copies are close enough together to cause comb filtering when they're summed.

Ping-pong delay in Ableton, Logic and other DAWs

Ableton Live's Delay has a Ping Pong switch. Older versions of Live had a separate Ping Pong Delay device, which Live 10.1 folded into Delay along with Simple Delay. Logic Pro's Stereo Delay has a crossfeed control on each side that sends its echoes into the other side, and it lets you pick each side's input. Set the left input to L + R and the right input to Off, turn the crossfeed up and the feedback down, and the bounce starts on the left. Soundtoys EchoBoy has a Ping-Pong mode alongside its single, dual and rhythm echo modes.

If your delay has no ping-pong switch, look for anything labelled crossfeed, cross feedback or stereo mode. The delay also needs a stereo output: a mono-only instance of the plug-in has one output, so there's nowhere for the echoes to bounce to. A stereo return is the simplest place for it.

Ping-pong delay on vocals, synths and drums

Vocals

Ping-pong suits vocal throws, where one word at the end of a line gets sent to a delay and bounces away across the speakers. Put the delay on a send and turn the send up only for that word. For the delay that sits under the whole vocal, a plain stereo delay often works better, since the bounce gets distracting once it's on every word. Ducking helps either way, and the ducked delay lesson shows how.

Synths, plucks and guitars

This is where ping-pong is at its best. A plucked synth line or a picked guitar part through a 1/8 or dotted 1/8 ping-pong fills both speakers with notes that fall between the ones played, while the part itself stays put. Keep the feedback moderate so you can still hear what was played.

Drums and percussion

A whole drum loop through a ping-pong delay gets cluttered quickly. Single elements work better: a 1/16 on a shaker or the hi-hats adds movement, and a ping-pong on the last snare hit of a fill sends it flying across the speakers into the next section.

Bass and kick

Leave them out. Most mixes keep the low end in the middle, where both speakers share it, and a bouncing bass echo puts a heavy low note in one speaker and then the other. If you want some of the bass in the delay, put a low cut of 200 to 300 Hz on the delay so only the upper part bounces.

Is ping-pong delay mono compatible?

Yes. Sum the two sides to mono and every echo is still there, because the left and right echoes are separate repeats at different times, and added together they make the same trail a normal delay would. You lose the bounce and get an ordinary delay at the bounce time, so a 1/8 ping-pong becomes a plain 1/8 delay.

What does change is how loud the echoes seem. In stereo they sit away from a centred part, which makes them easy to hear at a low level. Folded into the middle they land right on top of it, and a delay that sounded just right in stereo can crowd the part in mono. Switch your master to mono and check the send level before you commit. The mono compatibility lesson has more on testing a mix that way.

The Mono button in the lab adds the two sides and halves the sum, so a centred part stays as loud as it was and each echo comes out 6 dB lower than it was on its own side. What you lose is the space between the part and its echoes, so a level that felt right in stereo can still feel crowded.

On a correlation meter, ping-pong echoes on drums and short notes read close to zero, since the two sides are playing different repeats at any moment. On a held note the needle can wander either side of zero as the echoes overlap. That doesn't mean the delay will vanish in mono, because summed it's still an ordinary delay; and with a centred dry part mixed in, the reading usually stays above zero.

How to set up a ping-pong delay

This is the setup for a ping-pong on a send, which is how you'll use it most. On an insert, skip the send and use the delay's mix knob in its place.

1. Put the delay on a stereo returnSet its mix to 100% wet and turn up the send from the part until you can clearly hear the echoes. The insert vs send lesson explains why.
2. Switch on ping-pong and syncStart with a 1/8 or a dotted 1/8. Each speaker repeats at twice the time you set.
3. Set the feedbackRaise it until you hear three or four clear bounces after a phrase, usually somewhere between 30 and 50%.
4. Filter the repeatsBring the low cut up to 200 or 300 Hz so no low end bounces, and pull the high cut down to 3 to 6 kHz so the echoes sit behind the dry part.
5. Check the balanceListen for which side the delay leans towards. Pan the dry part or the return slightly to even it out.
6. Duck it if the part blursDuck the echoes by 6 to 12 dB so they bounce in the gaps.
7. Check it in mono and in the full mixPull the send down until you'd only miss the bounce if it were muted.

Ping-pong delay settings for common sounds

These are starting points that make the bounce easy to hear. Once the rest of the track is playing you'll usually bring the level down.

Common ping-pong delay mistakes

Bouncing the low end

A full-range ping-pong on a bass, a kick or a whole mix moves heavy low notes from speaker to speaker, and the mix feels unsteady. A low cut on the delay fixes it.

Setting the note value as if it were per side

A 1/4 ping-pong gives each speaker an echo every two beats. If you wanted an echo on every beat on each side, you needed a 1/8.

No feedback, or the wrong input

At 0% feedback a ping-pong delay gives one echo on one side and nothing else. And a delay built from crossfeed that gets the same signal on both inputs won't bounce either. If you hear no movement, check both.

Ignoring the lean

With low feedback the starting side gets most of the echo level, and over a whole song that can make a mix feel heavier on one side. Listen for it, and balance it with panning.

Judging it only on headphones

On headphones the bounce is as wide as it can be. On speakers it narrows, and in mono it's gone. Set the level on speakers and check it in mono, or the delay will be too loud for most of the people who hear it.

Ping-pong on everything

When several parts bounce at once, none of them has a place in the stereo picture and the movement stops meaning anything. Pick one or two parts to bounce and give the rest a plain stereo delay or none.

Training your ears for the bounce

The quiz under the lab mixes two kinds of round. In one, ping-pong is switched on or off at random and you say which; in the other it is on and you say which side the first echo comes from, because the lab can start the bounce on the right as well as the left. Every round is level-matched with the controls covered. Headphones make both much easier, since on speakers each ear hears both sides and the bounce narrows.

Questions people ask

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