Tyler Barnes — Advanced LSDJ Tutorial: The Ghost Channel (video, 2013)

The original tutorial, and still the only step-by-step for drawing the waves. Its companion thread is s-chipmusic-lsdj-ghost-channel. The transcript is machine-generated, so what follows is what is spoken; values shown only on screen are not in the raw file, and hex numbers heard in speech were checked against the lsdj manual before being written down here.

Key claims#

• The name and the claim, at 0:00: "today I'm going to be demonstrating something I like to call the ghost Channel or Phantom Channel — this is a method I've devised in the wave channel of obtaining two sounds being played simultaneously". The video's description puts it as "4 note polyphony (Not including noise channel)".
• Six demos before any explanation, and they are the argument for the technique: base alone; base and ghost both at constant volume and pitch; ghost volume modulated; ghost pitch modulated over a steady base; base volume modulated under a steady ghost; and both moving. The two voices are independently controllable in volume and pitch — which is what makes the second one read as an instrument rather than as timbre.
• The construction, explained from first principles (7:02–9:19): a square wave is built by pushing sample points a uniform distance away from silence, a sine by pushing them by amounts that grow smoothly. Do the square's uniform push starting from the sine instead of from silence, "and the resulting waveform will look like it has a square wave embedded on top of a sine wave". That is the whole trick: additive superposition inside one wave.
• Drawing (9:19–11:33): his square is "about three units high"; he counts "1 2 3, 1 2 3" while raising each run of pixels the same amount, then repeats the run for every rider octave — "you would continue doing this for every octave", giving a one-octave-up wave, a two-octaves-up wave and so on over the same sine.
• Making the ghost dynamic (11:33–12:09): to get rider volumes, start from the superimposed wave and "decrease those Peaks by one pixel every time until you get back to that original sine wave". A 3-unit rider therefore yields only three usable ghost volumes — the rider's dynamic range is its height in pixels.
• Making the base dynamic (12:09–13:49): the sine has to be redrawn at every volume, "starting from silence all the way to the maximum volume", then that whole sequence is duplicated and every rider octave drawn on top of every frame. "It's an awful lot of frames to be manually editing but it's the only way to make this possible … it's long and tedious but I think it's worth it in the end."
• Playing it (14:24 onwards): the note in the phrase sets the sine's pitch; the wave frame sets the rider. "If I want to change the Octave of that square wave I'm going to be changing the frame … you'll hear that that sine wave stays the same octave but only the square wave moves up and down." The reverse — moving the sine under a fixed ghost — is done "in Reverse": raise the note's octave and step the frame down by the compensating amount.
• He addresses waves by their two-digit wave-screen number (17, 41, 4D, 5A and, in his volume row, a loudest and a quietest frame a few steps apart, "eight is silence on the Square wave"). At 21:10 he oversteps to 3F, finds it "is not on the same waveform as that", and corrects back to 41 — the practical hazard of a bank built this way: every synth holds 16 waves, so a step too far lands in a different family (see lsdj for the 00–FF numbering).
• Working method for a run of frames: enter the two extreme frames, copy and paste the pair, then walk each entry up or down by a fixed amount ("decreasing by one each time", then a run "decrease by two") — a hand-built ramp rather than a table effect.

Practical takeaways#

• Budget the frames before drawing: (sine volume steps) × (rider octaves) × (rider volume steps) waves. This is what makes the technique expensive, not the drawing of any single wave.
• Keep the rider's octaves in one synth's 16 waves where possible; stepping across a synth boundary silently changes instrument character.
• Independent movement is the point. A ghost that never moves sounds like timbre; a ghost that changes octave or fades while the base holds sounds like a second player.

Notable quotes#

"The ghost Channel or Phantom Channel … a method I've devised in the wave channel of obtaining two sounds being played simultaneously."

"It's long and tedious but I think it's worth it in the end."

Relevance to the wiki#

The construction half of ghost-channel: the thread gives the arithmetic, the video gives the drawing method, the frame economy and the fact that the two voices can be moved independently.

To verify#

• The exact wave numbers (17, 41, 4D, 5A, 3F) come from an auto-generated transcript of speech and are his own bank layout, not a fixed recipe — treat them as illustration, not as values to copy (unverified).
• Whether the frame stepping in the demo song is entered as F commands in the phrase or as per-note instrument changes is not stated aloud; the manual documents F as the relative frame stepper for MANUAL wave instruments (unverified for this song).
• The demo song file, "Ghost Channel.lsdsng", is no longer downloadable (app.box.com link dead as of 2026-08-31), so the bank cannot be inspected.

Pages touched#

ghost-channel · wavetable-programming · lsdj · tyler-barnes · harmonic-series