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Looper's Delight
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I've been thinking about this alot.
There are enough big differences between "sequencer looping" and "delay
looping" to make them significantly different. Technologically, the former
requires much less memory. Audially, the decay of past generations is
somewhat more interesting with the later, although this is a purely
subjective judgement.
When you play a note into a MIDI sequencer loop, what is typically recorded
is 1) what note you played and 2) how hard you played it ("velocity").
This takes somewhere around five bytes to represent in your sequencer
(three for the actual MIDI data, a couple of bytes overhead for timing
data) regardless of how long your loop is. Now say you want this to
feedback at a nice robust 95%; enough to keep the beat around, but also to
let old material leave as you evolve the loop. What this means in MIDI is
that the note is played a second time without you doing anything at 95% of
its original velocity, and then the third time at 95% of 95% of the
original velocity, and so on.
When you play a note into a digital delay loop, you're essentially
recording digital audio. Just for the sake of comparison, let us say
that's 44100 2-byte samples every second of loop (that's somewhere near
CD-quality in mono). This means 88200 bytes per second of loop for our
delay buffer! Now say you want this to feedback at a nice robust 95%; blah
blah blah. What this means to a digital delay is that the relative
amplitude of each sample is reduced 95% each time it goes through the delay
buffer.
That's the kicker.
When you reduce the velocity of a MIDI note-on message, you are not
necessarily reducing the amplitude of the sound. In fact, in most cases,
you're changing the sound in very many more ways than amplitude. The
effect is far different than if you had used a digital delay for the same
purpose. The selection of what modulations occur in response to velocity
is critical in this sort of technique. Also, most MIDI synthesizers can
only play so many sustained notes at the same time; with a digital delay
there is no such limitation. This is part of what makes MIDI loop
sequencing attractive for percussion tracks; percussion sounds don't
usually sustain for very long, so you don't run out of "voices" in your
synth. Also, in usual styles of percussion track evolution (I'm thinking
of the x0xes), the "delay feedback" is 100%; to evolve the track you build
a completely new one and cut or xfade to it, or play with outboard effects.
In sum; you can't easily sound like a Frippertroid with just MIDI sequencer
looping.
Finally, at the risk of being a horrid A/D troll, I believe that analog
tape delays are likely to have a significantly different sound than digital
delays, due to the audio characteristics of tape saturation. I wouldn't be
sure though, I've never played through an analog tape delay before.
(Y 'jfm3)
P.S. Interesting... It was certainly once the case that good recording
tape was less expensive than computer memory. Nowadays, I'm not so sure
that's the case anymore.