Zoë Blade's notebook


1 PPS (short for 1 pulse per step) is in certain contexts a clock resolution also known as 4 PPQN (short for 4 pulses per quarter note), and in other contexts simply a rhythmic series of triggers. Either way, it usually takes the form of a series of V-trig triggers sent over a phone jack.

Used as a low resolution clock (the lowest possible, in fact), it's transmitted as a steady series of clock pulses sent out at regular intervals, signifying sixteenths, eighths, or any other note length. It's then up to the receiving sequencer to work out whether each given pulse should cue a note or a rest. Used this way, it can be a 4 PPQN clock for sixteenths, or even a 2 PPQN clock for eighths (as with much of Tangerine Dream's output).

As each pulse signifies a new potential note, you can't rely on any intermediate pulses to tell you when that note should end, as there aren't any. You therefore have two options for inferring the note's gate length: you can either interpret each pulse as a gate, if it's high long enough (this is often the case, as the clock is often simply an LFO generating a square wave); or you can ignore its length in favour of one of your own choosing, as Moog's 961 Interface does.

The other way a 1 PPS signal can be used is rhythmically, with the receiving arpeggiator or sequencer having no concept of rests, and the transmitter being another sequencer that only sends a trigger in the first place at rhythmic rather than regular intervals. Used this way, it's not really a clock at all, but a rhythmic series of triggers.

Drum machines such as the TR-808 and TR-606 have trigger outputs specifically to use in this way. Similarly, with a MIDI to CV converter, you can tap out a rhythm on your keyboard at any pitch, and use its gate as a trigger for a sequencer or arpeggiator. This is ideal, as the rhythm can even be swung, or left unquantised. Moog's 961 Interface can even convert audio into a series of rhythmic triggers.

It's worth noting, so to speak, that each step doesn't even need to represent a note. It could just as easily be used to sequence a series of, say, lowpass filter cutoff points, as with AFX's appropriately titled "Steppingfilter 101", or my own "Vitruvian Shift".


I had the clock out, I think, from the Roland 707 and hooked the wire into the arpeggiator clock in on the Juno-6, and it just happened. I just hit a chord with two hands on the keyboard and the Juno-6 arpeggiated it. I never could recreate that, it was just something that happened in the midst of me experimenting, and I got it on tape.

— Larry Heard, 1992[1]

I've always fancied an analogue sequencer, and the Roland is great because you do all your tuning by first twiddling the knobs, so you make the tuning up as you go along. You can also take the CV out of one of the Model 100s, and instead of controlling pitch, you can have it running from MIDI so that while it's playing it's opening and closing the filters, which is interesting.

— Paul Hartnoll, Orbital, 1994[2]

I would usually start with some kind of rhythmic bassline or sound with a 101 or a Pro-One. I used to go to those because they have very simple but elegant sequencers built into them, where you add your notes and then trigger them from the 909 or 808. What that allows you to do is very quickly find a series of notes that you like, but then work with a drum machine interface and then move the placements of the notes around. And what was also great about that was that as you're programming drums and maybe three or four different bar variations you could change trigger points so that the melody is still there, but the melody is just playing in slight variations.

Richie Hawtin, 2019[3]


  1. "Touching Bass" Simon Trask, Music Technology, May 1992, pp. 48—52
  2. "Music of Spheres" Nigel Humberstone, Sound On Sound, Apr 1994
  3. "Signal Path: Richie Hawtin on His Origins as F.U.S.E. and How He Made Techno in the Early '90s" Maya-Roisin Slater, Fact, May 2019

Clock resolutions: 1 PPS