[magnaton]

This is super-cool, and the multi-part recordings really show off what's possible with this creation. As someone who works on pipe organs (including their voicing and tonal finishing) for a living, I do want to comment on his statement that "at least in theory, organ pipes produce very simple waveforms". Actually, in both theory and practice they produce a huge range of overtones in addition to the fundamental, with open pipes being capable of producing both even and odd partials while stopped pipes produce only odd partials. While it's possible to construct and voice pipes in a way that comes close to producing only fundamental, it's almost never the goal, the exception being some pedal stops that are intended to produce shake (a sine wave of very low pitch) in the room and minimal color (overtones). Instead, we usually aim to give each stop its own complex and refined tonality consisting of huge numbers of harmonics, the profiles of which are dictated by both the construction and materials of the pipe and the process of voicing (the very delicate manipulation of numerous parts of the pipe to change its color and speech characteristics). Having said that, he's absolutely right that a good acoustic helps make a good instrument -- there's a saying that "the room is half of the organ"!

[Footkerchief]

I think the OP means "simple waveforms" in terms of the ubiquity of square wave oscillators, not simple in the sense of being a pure sine wave.

[EamonnMR]

Maybe simple envelopes would be more accurate. Any waveform played with a rectangular envelope will sound "organy." Add modulation and a more nuanced envelope to avoid this.

[magnaton]

Yes, electronic organs often have rectangular envelopes. Pipe speech has an envelope that is far more complex than one might expect; indeed, one of the goals of voicing is to impart an envelope that allows the pipe to be "articulate", to a degree dependent on the caracteristics of the stop of which it is a member and depending on the overall tonal milieu of the specific instrument. Taken to its extreme, this results in a clunky "chiff" sound at the start of each note, something often heard in instruments designed in the "American Classic" and "Neo-Baroque" styles; but with more refinement, it can produce the gentle puff at the beginning of a flute note, or the "bubble" articulation of a French Horn. And at the other end of the envelope is a characteristic decay, initiated by the closing of the valve beneath the pipe and sustained by the resonance of the pipe body (which, in large pipes, can go on for several seconds).

[Footkerchief]

I didn't know the term "chiff," but looking up videos of the sound, it's very similar to an effect I accidentally created in a recent digital synthesis project by using a low sample rate for the envelope (2kHz). I think the stair-stepped shape of the attack created some inharmonics in the audio.

Is chiff the result of inharmonics created by brief turbulence in the airflow?

[magnaton]

Yes indeed. In extreme cases, it can give the impression of a xylophone! To control chiff, we use a pointy double-sided knife called a "nicking tool" to create a series of evenly-spaced nicks across the entire width of the flue (which is the slot at the base of the mouth, formed by the lower lip and the languid inside the pipe; air leaving the foot of the pipe is focused by the flue on its way towards the upper lip). Often the nicks are cut into both the lower lip and the languid at similar depths and perpendicular to the flue, although there are exceptions; the width, depth, and spacing of the nicks all have tonal implications. Care must be taken to avoid over-nicking, as the articulation -- some of which is necessary even when chiffing is not desired, and which may need to be more prominent when close to the pipe than when listening from the room -- can be completely lost.

[Footkerchief]

Fascinating. This is the most scientific explanation of nicking that I could find:

http://www.colinpykett.org.uk/physics-of-voicing-organ-flue-...

[jsilence]

Wondering whether there is any Organ Dubstep.

[the_other]

I've always heard this as somewhat organ-y: https://youtu.be/uuxOGtAE1Io

But it's

a) almost certainly synth based

b) much closer to a WEM-like desktop organ than a church organ

Your point was more about the sub frequency shaking, right? Nothing like that comes to mind.

[jsilence]

Yes, was thinking about the sub bass that is possible with church organs.