PPG & VS Brightness and Vicious Bass

abluesky · 2023-09-16T12:41:27.754Z

“Transposing a waveform way down in pitch causes strange upper harmonics – images of the original harmonic pattern – to appear if not “properly” filtered. These images are what gives the PPG (and VS) its brightness as well as vicious bass. I was raving for months (much to the bafflement of Josh and Tony) in particular about the sound a PPG makes where only the lowest and highest harmonics seem to be present. One day, as I walked into the lab while Josh was testing the VS hardware, I happily exclaimed “That’s it! That’s it!! That’s the sound I mean! What’s the waveform?” It turned out it was only a sine wave, but it was tuned so low that the image of its one fundamental harmonic was audible as a very high, airy harmonic. “

I’m wondering if anyone here has any ideas of how to achieve this using approaches other than PPG style wavetable and VS vector synthesis. I know I could grab the Arturia plugin, and I have the PPG VST, but it constantly crashes Bitwig. I was thinking of using the Digitone hopefully because that is my only Elektron box at the moment.

Anyone down to chat about it?

bwo · 2023-09-16T14:45:56.418Z

I believe the effect is achieved with a low bitrate and a very high sample rate and no aliasing, I believe PPG had high variable sample rate, while VS just had a very high fixed rate. Something in the range of 250kHz. The effect cause harmonics images of the oscillators to appear in the upper registers. Can’t say I totally understand it but I think it is essentially aliasing without the “bad” harmonics. Not sure what the first steps in imitating that in fm synthesis, but a theory would be creating a voice using half of you tools and then attempt to make the harmonic images with the other half.

Waldorf M has some of that PPG spirit in hardware, I believe its classic mode is 240kHz at 8bit.

abluesky · 2023-09-16T15:40:40.964Z

That’s very interesting. I’m actually a fan of aliasing sometimes and I this makes lots of sense.