float box arpeggiator

Figure 6 summary

• cycle over 4 notes
• distribute list over 4 float boxes
• each value stored until selected
• transpose
• notes out

Sequencing the melody

Wiring up [select] objects is fine for making fixed patterns like rhythms to store away, but not much use when you want to change a sequence rapidly without breaking connections. This time the sequence is still fixed in a particular order, just 4 steps that cycle round, but the values at each position are variable. This is sometimes called an arpeggiator, an 8 or 16 step sequencer found on many old analogue modular synths.

Unpacking lists

Instead of sending each of the four notes separately into this sequencer abstraction we have just one inlet [inlet note sequence], that carries a list like [12 34 56 78(. The [select] is fed by [mod 4] and sends a bang to each of 4 outputs in turn. These cause successive [f] boxes to output the float stored in them. To get the note numbers from the list we use [unpack] to split up the list and distribute the numbers, to the left inlet of each float box. The sequence message is always unpacked in the same left to right ordering, but remember the values appear at the outlets of [unpack] in right to left evaluation order just as with any Puredata object.

Transposition

With a wire carrying note numbers as individual floats its easy to transpose, here we add an octave with [+ 12] . The third inlet, [inlet transpose] provides a way to control the transposition from the outside.

Figure 6: melody-seq

E-melody-seq.pd