Understanding wave-shapes?

edited May 2022 in Drambo

Hey, so I've been having a lot of fun drawing waveforms with the no-antialiasing saw -> graphic shaper trick, and with the new shaper updates, that's more powerful than ever—but it's also got me thinking about waveforms in general, on how to conceptualize/interpret/anticipate the effect of a given change at this or that point in the cycle. Is there a logic to it? Apart from, you know, sharp shifts introducing more high harmonics, rounded ones lending themselves more to darker tones, etc. Like, for example, if the graph of a waveform represented frequency x amplitude, one could focus on the lower region to alter low frequency content, etc. But the x-axis doesn't plot frequency, right? Seeing as a shift in the waveform's phase doesn't fundamentally alter the frequency content of the wave. I guess it's more abstract? Do any of you guys have a way of thinking about waveforms that helps you shape them in a more deliberate way?


  • Well, I'm one of those 'crazy' people who love to draw waveforms by finger-painting 😎

    That's a 64-sample long 8-bit waveform in the SunVox sampler and I'm just 'painting' with my finger.

    Somehow I like the sound/effect of a sample being changed while it's being played back which is what the above thing does.

    SunVox plays back the sample and the sample is changed on-the-fly.

    As for the actual wave-shape, it doesn't always have to affect the way things sound but...

    (That's a simple square-wave where an all-pass filter is used, the shape changes but sound stays the same (it would be like a 'phaser' if I mixed in the original waveform with the all-passed wave, that is how phasers work).

    If the 'waveform' is used for modulation purposes at slower speed the 'shape' will definitely have an effect on the modulated parameter.

    Here's another example of using the Graphical Modulator as an Oscillator, it can't go super fast but it's a good way to experiment how the shape affects the sound and if it's also used for modulation of parameters.

    One of my 'wishes' is a WaveTable editor for Drambo's WaveTable oscillator where we can create 'Frames'(ie. a 2048 sample loop) by finger-painting or using the current drawing-tools and then chain multiple Frames into a Table.


  • edited May 2022

    Results are usually pretty harsh

    so it’s a good idea to filter it down

  • Since you can draw all kinds of oddities

    make sure you don’t create dc offset

  • Use a highpass filter to remove dc offset

  • edited May 2022

    @samu Very cool! Caustic has a similar free-form wave draw feature I used to use a lot. And for some reason, with the way it works, if you use two fingers and drag them around, it will draw between them in really cool ways. I'll post a video of what I mean, it's worth seeing. I hadn't considered using the bar tool and a high grid resolution to sort of pseudo-freehand like that, kind of like Serum. I would kill for a wavetable editor in Drambo, though! I've tried a thousand different ways to generate wavetables with Drambo, mostly just making 2-bar clips with heaps of automation, then working them in Serum. Sadly I missed the boat on those Wolfgang Palm apps, they're said to've been pretty great for making wavetables.

    Here's the Caustic thing I mentioned:

    @lala Wasn't aware that a HPF could fix DC offset, good to know! Would Scale+Offset come in handy for that, too? I guess it's in the name, "Offset", after all. What specifically, by the way, does Scale on the Graphic Shaper do? Seems that values below 1.0 have some kind of rectifying effect, but generally I'm not sure what Scale specifically refers to there.

  • edited May 2022

    Or you can just completely forget what you are seeing

    and go after what you are hearing

    Did you notice this reacts to level?

    wiggle an amp before it ;)

    this kind of gos uuuaaaaoooo

  • I think it's quite safe to assume that when it comes to 'oscillator wave shapes' they can be divided into two categories depending on their intended purpose as either modulation source or audio source.

    For modulation the shape plays a bigger role than it does for audio.

    A perfect example is a saw wave that goes either up or down, they will 'sound the same' but have completely different effect on the parameter they are controlling (ie. rising or falling frequency as a basic example).

    The phase of the waveform has no audible effect unless it's mixed with another waveform.

    When mixing waveforms the audio can sound the same but the peak-level of the audio is way higher (look at the square wave passed thru an all-pass filter, it looks and sounds the same but peaks change) this is partially why some prefer to change the polarity of a waveform/sample to keep levels under control.

    One feature that I still miss in Drambo's basic oscillators is to set the waveforms start-phase when using the sync option, the WaveTable oscillator already has this functionality. This is especially handy when doing calculated modulation waveforms.

    Even though I like to 'draw' the waveforms I usually close my eyes and use the ears and when 'painting it'.

    I'm not always looking for a specific 'shape' when it's 'audio'...

    ...but when used for 'modulation' it's precise point-by-point drawing as then I see it more as a 'step value sequencer'.

    So yeah, this is 'geekery' at it's finest 😎

  • Setting a finer X grid can help.

  • Yepp, I'm well aware and it's a BIG step up from the previous version...

    There's one synth (Odin 2) that uses curves to draw the waveforms with an option to 'render wave-table' that can be loaded/set as an LFO waveform or an oscillator, super handy.

    For true '8-BIt Nostalgia' the X-Grid could have options for both 128 and 256 as well as Y-Grid up to 255 with snap to center.

    Still the real charm of 'drawing the waveform' is that it's treated as a 'sample' with all its interpolation aliasing glory when picked up or down.

    (There's a big difference in sound when adding for example a bit-reduction before the last amp-envelope than putting it after).


  • ^^

    i wished for more oversampling on this

    but I know u like it dirty @samu

  • edited May 2022

    hm, there are to little volume changes without the envelope to make a big effect, I guess (in the end we are changing number of possible loudness steps here)

    with the envelope you can hear it farting down at end of envelope time ...

    before the envelope you cant hear much

    low bits are hard to hear, sometimes u need to turn it below 8 bit to hear something otherwise its just stairs that show up on your scope that u "cant hear" / the low bit resolution

    I always wonder why ppl want 24 bit/44.1 instead of 16 bit/48 but maybe that is just me.

    mess with frequency content is much easier to hear than mess with bit resolution. 👾

  • @lala 24bit gives you more headroom if you can't fix your levels. 48k helps a bit if you can't fix your anti-aliasing filters.

  • edited May 2022

    48 kHz Recording and Playback really makes a difference I can hear,

    (at least I could A few years ago 🤫😜 )

    44.1 isn’t really enough

    i cant Tell 96khz from 48

    but i could tell 48 from 44.1 played a b

  • My problem when it comes to hearing is that my ears are too sensitive, especially to noise...

    I can't record in a total vacuum and the microphone captures a wider frequency range than my ears.

    The only quantifiable 'difference' I can actually hear between 96k and 48k when recording with a microphone is that the 96k sounds a bit more 'airy' and 'breathes' a bit more and then there's the advantage when pitching down sounds as there's a bit more points to do math with.

    I've tried to learn to 'ignore' the noise when it's RMS level is <85dbFS.

    The MDR-7506's are sensitive and reveal a lot, maybe they are sometimes a bit too 'analytical' 😂


  • edited May 2022

    hm, I guess most mics aren't made for this, they will crap out at 17 / 18 kHz or so.

    to not cut the frequencies of a cymbal a measurement mic is needed - they go up to 30 kHz ...

    (since you like to pitch down things too)

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