Interesting that the topic of software looping emerged. I wanted to sync looped material with accompianment and was having some problems doing it with the RC50 and I have turned to VST plugins to solve the problem.
I have been heads-down in my studio creating new works that utilize looping techiques. This post is to share some of my observations over the last month of work.
[b]The old days[/b]
Years ago I had access to one of the original Echoplex tape loop machines. It consisted of a tape loop that ran past three tape heads: 1) an erase head, 2) a record head, 3) a playback head.
The playback head was movable from the top panel. Thus, the delay time depended on the distance between the record and playback heads. With this arrangement, the tape was freshly erased on every pass, the primary signal would be sent to the record head, and the delayed signal would be reproduced by the playback head. In order to produce multiple delays, a feedback control mixed the signal from the playback head with the primary signal (thus sending a portion of the playback signal back to the record head).
However, to produce an infinite loop (i.e., 100% feedback)was complicated due to the buildup of noise on each iteration.
[b]The digital domain[/b]
Digital delays and echos keep the signal in the digital domain, thus one can utilize 100% feedback without a degradation of the signal.
[b]Overdub vs. feedback[/b]
Overdub mode (such as on the RC50) functions as an internal 100% feedback path and, since it stays in the digital domain, exhibits no degradation. However, overdub is "all or nothing" ... you either have 100% feedback when overdub is "on" or no feedback when it is off.
At 0% feedback the primary signal will repeat one time only. At 50% feedback the primary signal will be cut in half on each pass -- it will echo at full volume the first time, then half volume, then half of that, and so on until it is no longer audible. Higher feedback percentages will cause a slower decrease with each pass. Feedback higher than 100% will cause each echo to get louder (although this will quickly max out/clip, etc.).
[b]Long Loops and live multi-tracking[/b]
When the delay time is relatively long, say twelve or more bars, then a loop's buildup is somewhat akin to multi-track recording -- except of course that when looping one builds up the tracks in real time.
This is popular with guitarists -- they will lay down a rhythm track on the loop then improvise a melody over it.
A long loop can contain involved chord progressions however takes longer to build up.
The Theremin, of course, is monophonic and is more melodic than rhythmic. Thus, with a Theremin, one must balance the complexity of the music with the time to build up the effect.
[b]Very short loops[/b]
What I am calling "very short loops" are one bar or less in length. The advantage of such loops is that they can be built up very quickly. They work well for repeated block chords.
They also work well for sustained notes... almost like a sostenuto pedal.
[b]Short loops[/b]
Short loops are longer than one bar yet short enough that the listener picks up on the repeats.
I have had success with such loops at 0% feedback. In one composition (which isn't quite finished) I send the theremin to two loops -- one that repeats at 2 bars and the other at 4 bars to produce a three-voice canon.
My latest work is in 5.1 sound and to send these loops to different positions in the sound field is quite effective.
[b]Software looping and automation[/b]
One of the considerations when looping is that to hold a pitch on the Theremin while hitting a footpedal is extremely difficult. So, to use a looping pedal one must plan the music so that the foot pedal presses don't interfere with the Theremin playing.
Since my music is all "written out" (rather
