RPLS

varispeed multitap echo. 3 taps (1 recording, 2 playing) cycle through 3 buffers. alter the rate of each playback tap independently from the record tap to create sliced rhythmic & harmonic counterpoint from the input signal in real-time, free from tape head collisions & audible clicks.

a spiritual successor to alliterate.

NOTE: to view images, please read at github.com not norns.community

hardware

required

• norns (210927 or later)
• audio input

also supported

• crow
• grid

install

install from the maiden catalog

or

in the maiden REPL, type:

;install https://github.com/andr-ew/rpls/releases/download/latest/complete-source-code.zip

patch notes

watch the video

read the complete patch notes

norns UI

intro

• K2: increment page
• K3: freeze, buffers will loop the current contents. hold to clear.

the rotating triangle in the center of the screen illustrates the tape process powering rpls. each side of the triangle represents a buffer. one side (dimly lit) is always having audio written to it by the record head. after writing to one side, the rec head cycles to the next one. at the same time, the two playheads are playing back the recorded material from the other two sides of the triangle, cycing behind the rec head.

since the play heads never cross over the record head in the same buffer, they can play back recently recorded material at any speed & pitch without causing clicks.

page C

• E1: clock multiple / division (clock mult). sets the rate at which tape heads cycle between buffers, measured in beats at the global clock tempo.
• E2: volume of playhead 1
• E3: volume of playhead 2

the clock mult param offers different windows into rpls depending on its use:

sync / free

by default, clock mult is in free mode, meaning that a twist of the encoder will shift rpls in & out of time with the global clock. turn clock mult all the way down & continue turning past zero to enter sync mode. clock mult will now be quantized to whole number multiples/divisions of the global clock. additionally, clock sync is more accurate in this mode.

page R

• E1: rate of the record head
• E2: rate of play head 1
• E3: rate of pay head 2

rates simultaneously set the tempo multiple, pitch transposition, & direction of playback for the tape heads’ repsective buffer slices. the actual playback rate of a playhead will always depend on the ratio between that play head & the record head.

assuming rate r = 1, the following rhythmic & harmonic relationships are available:

with rate r > 1, many more relationships are available, including common just-intonnation harmonies & polyrhythms:

((pls let me know if I got any of this wrong, music is hard))

note that the range of rate 1 on the negative side has been reduced to prevent collisions with the adjacent record head.

page >

• E1: feedback, record head back into record head
• E2: feedback, playhead 1 to record head
• E3: feedback, playhead 2 to record head

the rec > rec feedback path resembles the decay control of a typical delay. increase to add echo tails or overdubs. there’s also a ping-pong effect at play, mirroring the stereo field on each pass.

feedback paths involving the play heads lead to continuously transposed overdubs at the respective rate ratio. a rhythmic/harmonic shepard tone !

IMPORTANT: be careful with high values on multiple feedback paths - if all three feedback values add up to be greater than 1.0, volume will quickly grow out of control.

page F

• E1: resonnance of both filters
• E2: cutoff of the highpass filter, affects input only
• E3: cutoff of the lowpass filter, affects output only (both playheads)

IMPORTANT: be careful with high resonnace values - the highpass filter feeds back into the record head, so the input filter can easily self-oscillate & create loud sounds

grid UI

only the first row is used:

crow

any editable control on the norns screen can be mapped to either input of crow. hold K1 and use the encoder associated with the param to assign.

crow outputs 1-3 output triggers at the rate specified by the record head, and playheads 1 & 2, respectively

additional params

a few more params can be accessed exclusively in the params menu:

rate

• slew: slew of all rate controls. note: higher values can cause artifacts in the buffer when modulating rate rec, these can sometimes feed back & get a little loud.
• ~: momentary pitch wobble

clock

• fade: crossfade time for tapehead jumps. this has a particular effect on texture for very fast clock speeds.
• reset: instantly jump to the next buffer. this can be useful for aligning the phase of rpls’ clock with a synchronous input signal.

input

• routing: stereo/mono input setting
• pan: pan the input signal. effectively sets the width of the ping-pong effect.

output

• vol rec: raise to hear playback straight from the record head. this will generally be the same pitch as the input material. rec output is not lowpass filtered.
• routing: the ‘split’ mode turns rpls into a dual mono effect. play heads 1 & 2 will be sent individually out of norns outs L & R for independent external processing

filter

• state: disables the the lowpass filter. useful if you want to use rpls with external filters rather than the internal one.