There now follows a short delay-ay, a middle-sized delay-lay-ay, and a long delay-elay-lay-ay-y.
What can you do on the way to echo? Martin Sheehan looks at the tricks of the modern delay line.
INTERESTING things can happen when you play with time. It's not so much the way an aural event can be taken out of its 'real time' and replaced elsewhere, the interest lies more in putting the displaced events near each other. For example, when a sampled sound is triggered back it can be said to have been displaced from its real time. In a sense it has been delayed. But it's a whole new tangle of patch leads when a delayed sound is used in conjunction with its real time source.
Take flanging for example. The mere warping of a sound by moving it around in time (between six and 12 milliseconds of delay) is in itself staggeringly unremarkable. Add it to the original real time source, however, and presto!, the ear is excited. There is an interference caused by changes in the relative positions of the original and the delayed sound, and that's interesting to the ear. A comb filter effect is produced whereby some frequencies cancel out and others become reinforced in little stripes throughout the sound. As the delay time varies, so these little stripes go on the march and the ear can get quite involved in following their manoeuvres. This effect is heightened by the use of extra repeats of the delayed sound courtesy of the knob often labelled "Feedback" on your delay unit. The pattern of stripes now becomes bolder and more involved, and the characteristic sweeping sound of flanging will become obvious.
The changes in the delay times and hence the movement of the delayed sound back and forth in time is achieved by a Low Frequency Oscillator (LFO) which will normally boast two knobs likely to be called "Depth" and "Speed". Judicious use of these chaps, coupled with a low feedback and a bias toward the longer end of the flanging delays, will result in the much loved "Chorus" effect. A slow speed on the LFO is best to avoid the detuning effect that can occur when manipulating longer delays, and the feedback should be turned down to minimise the unsubtlety of the flanging sweep. At short delays of around two milliseconds (ms), buckets of speed and depth can be implemented without fear of detuning as only the highest frequencies of the sound are upset at these timings. The resulting effect heard in this delay vicinity is referred to as 'phasing'.
There is a point at approximately 30 ms of delay when the repeat of a sound is just beginning to become perceptible as an individual in its own right. Here we hit upon Automatic Double Tracking (ADT). It is used to thicken a sound without adding a discernible echo. Beyond this, at about 100 ms, comes the old rock 'n' roll 'slapback' echo - a repeat arriving rapidly after the original. They hadn't invented all singing, all dancing, DC to daylight digital doobrees in the days of drainpipes. It was all done with tape recorders reswallowing their own outputs, so the length of the delay was determined by the strict formula:
Distance between Record and Relay Heads / Tape Speed
Nearly all current delay units are now digitally based. Some, however, which deal only with shorter delays for effects such as flanging, are still produced using analogue delay techniques. These are still very valid and can offer some subjective advantages such as a thicker, warmer sound. They are impractical, however, for longer delays as noise can become a problem. Tape based delay units are also very effective but tend to suffer from the tendency towards the entropy of all mechanical systems. (They wear out - ed.)
The use of longer (over 100 ms) delays to enhance the sound of an instrument, track or mix is subject to an enormous number of variables. The length, level, and harmonic content of both the original sound and the delayed sound need to be taken into account.
The inevitable dryness of sound that is inherent with the close miking techniques can be greatly improved by the use of delay units. The aural interest is created by the interaction of the delayed sound with the dry sound, rather than the delay being an effect in itself. Consequently the scope for experimentation (ie playing about) is enormous. In order to produce a lot of the music we like to hear - delays will be unavoidable.
Feature by Martin Sheehan
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