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Guide
How to read a wavetable heatmap
Some tools draw a wavetable as a block of colour. It looks like a weather map. Once you know what each direction means, it tells you how the table will sound before you play it.
One common layout
A wavetable is a stack of frames. Each frame is one cycle of a wave, stored as a list of numbers. A heatmap turns that stack into a picture. Each frame becomes one row. Each number in the frame becomes one coloured cell. The colour says how far above or below zero the wave is at that spot.
Tools differ. Some put the frames on the vertical axis and some on the horizontal axis. Some use one colour ramp from dark to light, and some use two colours, one for above zero and one for below. Read the labels on the axes first.
The diagram
Here is a small made up table with 8 frames. Yellow is above zero and blue is below zero. A strong colour is far from zero and a faint colour is near zero.
Reading across a row
A row is one frame, so reading across it is reading the shape of the wave from the start of the cycle to the end.
- One yellow band and one blue band make a sine. That is the plainest tone.
- Three yellow bands and three blue bands mean the wave goes up and down three times in the frame. It sounds three times higher in pitch than the sine, when both are played at the same note.
- Many thin bands, or a speckle with no pattern, mean a bright or noisy tone.
- A row of faint colour is a quiet frame. A row with no colour at all is silence.
- The left edge and the right edge of a row meet when the table loops, because the end of one cycle leads straight into the start of the next. If the two edges have different colours, the wave jumps there, and you will hear a click.
Reading down the rows
Reading down is reading how the tone changes as you move the position control.
- Colours that shift a little from row to row are a smooth morph. This is what you want for a slow sweep.
- Straight vertical bands of colour mean every frame is the same shape. Moving the position does nothing to the tone.
- A row that looks nothing like its neighbours is a jump. Scanning past it will sound like a step.
What the Hayterwave tables look like
Each table in the Cymatic Wavetable Pack has 64 frames of 2048 samples. Each is a closed path moving across a drum or plate pattern, so every row loops without a seam. The tables are calculated from formulas, so a heatmap of one shows the maths, not a recording.
What to try
- Open any wavetable in a synthesizer or editor that shows it as colour. Find which axis is the frames.
- Pick the frame that looks plainest and play it alone. Then pick the most crowded one.
- Find the row where the picture changes most from its neighbours. Scan across it slowly and listen for a step.
- Check the left and right edge of a few rows for a colour mismatch.
Limits
A heatmap shows the shape of each frame and not the loudness you will hear. A frame can look faint and still sound loud once the synthesizer normalises it, and the colour scale differs from tool to tool.
Keep going
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