How does delay work? Listen and try it

How delay and feedback work

A delay line holds audio briefly before sending it onward. With feedback, part of the delayed signal goes around the delay line again, producing further repeats. At a fixed feedback gain below one, each pass is reduced: at 50% feedback, successive repeat gains follow 0.5, 0.25, 0.125 and so on relative to the first delayed pass. Filtering and the source affect what you actually hear.

At zero feedback the delayed path produces one repeat. Above zero, repeats continue to diminish in this stable feedback range, although later ones can become inaudible. Reverb similarly uses sound arriving over time, but its many blended reflections usually form a tail rather than distinct rhythmic copies. Distortion changes waveform shape and harmonic content.

Delay controls compared

Time sets the interval between repeats from 80 to 900 ms, initially 375 ms. Shorter values place echoes close together; longer values leave more space. A straight quarter note lasts 60,000 divided by the tempo in beats per minute, so 375 ms corresponds to a quarter note at 160 BPM. At 80 BPM it is an eighth note. Musical subdivisions and feel matter as much as the number.

Feedback runs from 0 to 80%, initially 35%. Increase it to hear more repetitions fade into the arrangement. Tone ranges from 800 to 14,000 Hz, initially 6,000 Hz: a lower setting makes repeats darker, while a higher one retains more brightness. Mix runs from 0 to 100%, initially 30%, balancing the dry source against the delayed path.

Time places the repeats; feedback determines their decay across passes. Tone changes their frequency balance; mix changes how prominent the delayed signal is against the original. Adjust one, then listen before moving another.

Four listening exercises

Restore the initial settings between exercises and leave the source and volume unchanged. A short impulse exposes the repeats; a loop shows whether they fit a phrase.

• Time: compare 120 ms with 750 ms. Count the gap after a hit and notice when the repeat becomes a distinct rhythmic event.
• Feedback: compare 0% with 70%. Listen for one repeat versus a series that fades across the gaps.
• Tone: compare 800 Hz with 14,000 Hz. Focus on how successive echoes darken as the feedback path filters them, rather than on the dry attack.
• Mix: compare 10% with 60%. Listen for the point at which the repeats compete with the original phrase.

Read the meters and waveform

Watch the waveform after an impulse to relate the spacing of visible events to the time control. The RMS meter gives a measure of signal level over time, not a verdict on rhythm or clarity. Source material, feedback and mix all affect the displayed result.

The RMS and sample-peak readouts use a mono downmix, even when you listen to stereo audio. The sample peak is the largest sampled level in that downmix; it is not true peak. Stereo signals can combine or cancel in the downmix, so these readings do not describe each channel separately.

Equal perceived level makes a fairer comparison: louder repeats can attract attention even when they clutter the phrase. The level display is not a LUFS target and does not guarantee a true-peak ceiling. Listen for clipping or uncomfortable level changes and reduce playback volume if needed.

Fit echoes around the arrangement

Pick a phrase with room after it. Start with one repeat and set time by ear, or calculate a straight beat using 60,000 divided by BPM. A dotted or triplet subdivision requires a different interval; use your DAW grid or calculate the subdivision rather than assuming every delay is a quarter note.

Bring feedback up until the tail supports the rhythm, then back it off if repeats cover the next line. Darken the repeats if they fight the dry source. Finally adjust mix while the other parts play. A send and return can give multiple sources the same echo, while an insert can keep the effect specific to one track.

Try each of the three presets as a starting point and open the expanded view to inspect the signal. You can load a local mono or stereo file up to 25 MB and 120 seconds. Audio stays in the browser; this listening demo does not promise a mastered or exported file.

Use the impulse again after setting the loop. You can hear the repeat spacing without other notes filling the gaps, then return to the loop to hear the musical result. If the echoes are difficult to distinguish, lower the original playback level only as needed and avoid turning the monitors up to follow a fading tail.

Start with a single echo

Choose a short spoken word or percussion hit with silence after it. Set feedback to zero and listen for one repeat. Change the time until you can hear how the copy relates to the original. Then introduce feedback gradually. This sequence separates the timing decision from the decision about how long the echoes should continue.

Use the gaps in a phrase

An echo can fill the space after a line without covering the next one. Listen to the end of a vocal phrase and count the repeats until the next phrase begins. If the echo lands on a consonant, lower the mix, shorten the feedback or choose another interval. A different setting may be needed when the arrangement becomes busier.

Compare rhythm at a steady level

Use the same loop and playback level for each comparison. Tap along with the original beat, then listen for whether the repeat reinforces it or pulls attention away. A delay can deliberately create tension, so a repeat between beats is not inherently wrong. Choose the placement that supports the part you are making.

Common delay mistakes

A tempo calculation can be correct but still sound wrong for the part: a repeat landing on the next consonant may obscure the lyric. Change the interval or leave a longer gap in the performance. Excess feedback can turn a clear phrase into overlapping repeats; reduce it before reaching for another effect.

Do not judge only on headphones or with the track soloed. Listen at a moderate level in the full arrangement, and compare another playback system. A darker echo can make room for the original, but too much filtering may make the rhythm difficult to hear.

Delay questions

What is the difference between delay time and feedback?

Time sets the interval between passes. Feedback sets how much delayed signal returns for another pass, affecting how quickly the repeats fade.

Why does 375 ms not always mean the same note value?

The note value depends on tempo. At 160 BPM, 375 ms is one quarter note; at 80 BPM it is one eighth note. A dotted or triplet note uses a different duration.

Is delay the same as reverb?

Both involve sound arriving later. Delay often exposes discrete repeats, while a reverb tail usually combines many reflections into a denser impression of space.

Why can I hear only one repeat with feedback above zero?

Later repeats can fall below the level of the source, background noise or your hearing threshold. Increase feedback within the available range and use an impulse with space after it to compare.