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PROCESSING – TIME-BASED EFFECTS Part 1

 

UAD plug-in model of the Roland RE-201 Space Echo

UAD plug-in model of the Roland RE-201 Space Echo

 

DELAYS

There are various types of time-based effects, also known as time domain effects.

The simplest types are called delay effects.

You may come across mono delays, stereo delays, tape delays, outboard delays, numerous flavours of plug-in delays, duplicated tracks offset in time, cross delays, multitap delays, ping-pong delays, and others in your travels.

There can be lots of parameters to choose from, and or they can be as simple as picking a subdivision of the tempo and setting a delay level and feedback.  They may have presets available to choose from.

They will often have a means of synchronising the echoes generated to the tempo of the song, either by locking to the host DAW with a button in a plug-in or by using MIDI system messages such as MIDI Clock.

With delays, you can typically enter a tempo to lock to in Beats Per Minute (BPM) or by the Tap Tempo method.  This is a name for playing in the tempo by tapping the beat on a MIDI drum pad or lkeyboard or even with in-tempo mouse clicks.

Most of the modern delays and many older MIDI-capable delays allow Tap Tempo data entry.

When you synchronise the delays to the tempo, it reinforces the rhythm.

Sometimes you will want to be slightly faster than the tempo by a single BPM or so, and sometimes you will want to have a lazier feel to the echoes, having them arrive slightly later than the real tempo subdivisions.

This is a matter of feel, of slotting into the pocket, of deepening the groove.  There is no right or wrong here.

EARLY ECHO EFFECTS

Waves Kramer Tape Delay

Waves Kramer Tape Delay

In the early days, tape heads were used to create delay effects, since it was the only way to shift the sounds in time relative to each other.  This had the advantage of being rather atmospheric, especially since there was always a loss of high end caused by the analog tape recording process, together with the off-tape compression effect, which dulled things further.

There was also the introduction of additional tape hiss and noise to consider, but it was a cool effect and playback equipment at the consumer level was really not so great.  It worked pretty well on numerous hit records.

The echoes would lose clarity as they repeated.  This was aesthetically pleasing and added an air of mystery to the proceedings for the most part.   They could also be used as musical effects, setting up rhythmic patterns more or less in tempo in a hit and miss way.

The big problem was that you had a fixed delay time determined by the position of the playback head(s).  Assuming that the tape machines were aligned correctly, the tape was new and of reasonable quality, and the positioning of the head was measured accurately, you could confidently set a delay time accurately to within roughly 5 milliseconds.  The main reason for the inaccuracies was the likelihood that the motor was a little unreliable and the tape recorder would not run at the speed it claimed to.

7.5 inches per second was not necessarily the actual speed even if the recorder was set to give you that.

It was also very unlikely to be precisely in sync with the tempo everywhere in a song, barring a miracle, and wow and flutter caused further issues with steady tempi.  Wow and flutter were different but related weaknesses of lesser quality or old and unmaintained analog tape machine transports.

All tape recording suffers from wow and flutter to some degree since it is a mechanical system that relies on dragging a bit of metal oxide-coated tape through the fluctuating magnetic field around a tape record head that is fed by the recorder’s input signal.  It seems like something from the Stone Age these days (that really should be Iron Oxide Age), but I’ve made a lot of records on 2″ tape machines and for the most part they sounded pretty good to me.

Neither flexible nor accurate, but still a great sound, primarily due to its complexity, relative to digital delays.

With the 1980’s, DDL (digital delay line) types of outboard delays appeared to replace the older tape-based systems like the Watkins Copycat and others.

USING SPECIFIC DELAY TIMES

The AMS delay units were all the rage in the mid-80’s, and these let you enter specific delay times with millisecond-accurate values.  These corresponded to BPM by a formula.  You would divide the BPM by 60,000 which gave you the number of milliseconds to enter for a quarter-note delay.

Naturally, the BPM (beats per minute) divided by 60 is equal to the number of beats per second.  For example, 120 BPM (a popular upbeat pop tempo) divided by 6o seconds gives a value of 2, meaning two beats occur per second.   That’s half a bar of 4/4.

At a 4/4 tempo, there will be four beats in one bar, which takes two seconds at 120BPM.  One bar of 120 BPM is exactly two seconds long.

UAD Cooper Time Cube

 

This relationship persists at all tempi, obviously, so that you can work out the delay times and express them in beats and bars that are in tempo with the song, if you know the time signature and the tempo.

60,000/BPM = 1/4 note in milliseconds.

At 120 BPM, doing an easy bit of math, you will see that one 1/4 note beat occurs every half a second, otherwise known as 500 milliseconds, so a bar in 4/4 will last for two seconds exactly at 120 BPM.

Delay times generally are expressed and numbers entered as millisecond values.   They rarely need to be more than a few seconds in length, so milliseconds are convenient and accurate.

There are delay time charts available on the internet you can download and print.  The values are simply shown in many plug-ins as musical note values of the host tempo anyway, meaning you don’t usually have to do the calculating any more these days.

DELAY PARAMETERS AND TYPES

Most delay units or plug-ins feature a control called Feedback.  This makes a copy of the output and feeds it back into the input of the delay.  You will have a level control for the feedback to control how severe the effect is.  You can hurt your speakers very quickly by letting echoes build up rapidly under the influence of the feedback control.  It’s a hit and miss affair to pick a setting for feedback, and you will find that the higher it is the more repeats build up.  This can be a problem, clouding things in the mix quickly, but it’s a great special effect.

It’s popular to let things get out of control for a beat or two then turn the feedback down again.  This happened regularly on early rock’n’roll records from the 1950’s, with tape delay experiments, and especially in Jamaica on reggae and dub mixes, where the effect was first explored in a serious way.  Lee ‘Scratch’ Perry was a pioneer of this musical application of delayed signals.

Normally you’ll find simple filters or tone controls.  These are helpful in making the echoes darker, which makes the spatial illusion of depth that echoes provide all the more convincing.  In real life, highs have less energy than lower frequencies, so they die away sooner when sound travels over a distance.  Our brains expect to hear this in the sound’s innate tonal qualities when sound bounces off distant surfaces and returns to our ears.

The copies (i.e. the separate echoes) are different in many subtle ways from the original with tape delays, and that is not the case with digital duplication of tracks.

The sum of those differences makes for a compelling sound, that engages the listener well.  This partly accounts for the enduring popularity of the Roland RE-201 Space Echo, a device I once loved and now miss.  Ah well.  Where would I buy quarter-inch tape anyway?

Cross-delays are a type of stereo delay where the feedback control feeds the left delays back to the right input and the right delays back to the left input.  This makes for some cool rhythmic effects, but don’t overdo the feedback or it will all boil over into mayhem very quickly.

Sometimes with a modern plug-in, you can modulate the delay times with an LFO, or use wow and flutter controls to emulate the performance of a genuine old analog tape delay.  These are pretty cool features, but don’t go too crazy.  Check on the headphones that you aren’t overdoing this, as it disturbs listeners easily.

Ping-pong delay is found on mono/stereo plugins (mono input, stereo output).  They are a mono input delay that pans the delays it generates  into alternately left and then right sides of it’s stereo output.  Ping-ponging back and forth, as it were.

PSP 608

PSP 608

 

The ping-pong delay adds width, as does any stereo delay.  You can duplicate tracks in the DAW, pan them differently, and delay them in time slightly to the original and other duplicates, and you will get a primitive but precisely controllable delay as a result.  Width is great, and headphones are a good way to check how things sound.

Multi-tap delays are complex beasts with many delay repeats that can be individually panned and configured.  Experiment  with these and have fun!  Presets will save you time, being locked to tempo and covering most popular bases.  Don’t forget to high-pass and low-pass filter the repeats for maximum grooviness.  You can get more than twenty taps (distinct repeats) on some multi-tap delays.  Chaotic at the best of times!

Wet/Dry controls are very useful.  Setting the balance of wet to dry to about 20% or less of wet signal (and that means about 80% or more is unaffected, dry, original signal) seems to be about right most of the time to my ears, but it’s all a matter of taste.

Some delays include fancy additional features like pitch-shifting the delays, sot hat they are more like chordal arpeggiation effects than delay effects.

Swing triplet feels are popular, as well as the more common subdivisions of the tempo into square note values like straight eighth-notes.

Tempo affects the type of delay you are likely to prefer.  The slower the song, the longer and louder your delays can be, in general.  Ballads like long delays much more than uptempo songs.  This is a functional difference..

Uptempo music really loves slapback delays (single repeats close to tempo) and rhythmic sixteenth or eighth note patterns.

If there is no mix control allowing you to set the amount of dry to wet (effected) signal, it will normally be a 100% wet model by default, but these are very rare.   It might be called either MIX or WET/DRY, and is usually marked from 0% to 100%.

The 0% mark represents dry sound (no repeats are at the output, just the original).

The 100% mark represents completely WET sound (only the delay is at the output, and not the original).

Using delays you can set up cross-rhythms in your music that do not otherwise exist.  This is a very musical area to explore.  Many songs use delays to create hooks in the vocal line, where the repeat is a major part of the hook, or is the hook itself.

Eventide Factory

Eventide Factory

 

A GOOD REVERB SUBSTITUTE

Finally, delays are a great substitute for small room reverbs.

They can do a good job of simulating natural space, but take up less room in the mix than the phenomenally complex web of echoing acoustic reflections that you hear with a sound occurring in a real-world reverberant space.

This is helpful for several reasons, but increased intelligibility and decreased frequency masking (obscuring other sounds in the mix) relative to reverb effects are probably the main benefits.

In my next blog, I’ll deal with the modulation processing effects, which include chorusing, flanging, phasing and several others.  The following blog after that will cover the other major time-based effect, reverb, in a two-part blogpost.   See you then.

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3 Responses to PROCESSING – TIME-BASED EFFECTS Part 1

  1. Prince Charles Alexander June 29, 2014 at 9:37 pm #

    Sorry, your formula is backwards. It’s 60,000/BPM = 1/4 not in ms.

    • admin June 29, 2014 at 11:02 pm #

      Thanks Prince Charles Alexander, you are absolutely right. That’s my mistake, writing a bit too quickly and I missed it in my haste. I will correct the post shortly. Thanks again for catching that.

    • admin June 29, 2014 at 11:07 pm #

      Thanks again Prince Charles Alexander, I have now corrected my typo. Eagle eyes! Can’t say math has ever been a strong point!

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