Behind the scenes of the 'Straight Maths' Virtual Instrument on Pianobook.co.uk

I have been exploring the possibilities of mis-using a sample player recently. Dave Hilowitz's excellent 'Decent Sampler' is, imho, not only much better than merely 'decent', but it has also allowed me to go slightly outside the usual territory of samples and to become an intrepid explorer. Huge thanks also to the team behind Pianobook.co.uk - a great contribution to the world of sampling, created by Christian Henson.

So here is a quick recap of the design thinking behind two of my recent releases on Pianobook.co.uk.

Parallel Inversions

'Parallel Inversions' was my first really developed idea that isn't just a sample replay. It deliberately breaks the rules to produce an 'alien' instrument. In a 5 star review, Michael Milburn said; 

'I don’t understand what these are, but do enjoy the sounds.'

The user interface is the first thing that hits people with this virtual instrument. The top row of controls has 23 vertical faders that look a bit like the 'Mic' sliders that you see in many sample players - except that instead of 2 or 3, or maybe 5, or (extreme) 7 or higher, there are almost two dozen of them! They are split into four sections, and there are some subtleties in the way that these are put together.

The most important section is the one that has the 0 to 4 'Mic' sliders in it. The 'Zero' slider is set at about 75% in the default preset, so that you know it is important. This slider plays the 'fundamental' frequency that is played by Decent Sampler, or rather, it plays that frequency sometimes - the XML code that Decent Sampler uses to specify how samples are played allow all sorts of manipulations, and I'm exploiting this here. So the 'Zero' / '0' slider plays three different octaves, using a random 'Round Robin' assignment. So if you play a C3, then you will actually get a C3, or a C4, or a C5. The ratios are set asymmetrically, with the 'octave down' option half the probability of the others. So for every chord that you play, you may get that chord, or you may get a biased inversion of it instead (a 'bass-light' inversion). This isn't how many instruments work! (But it is an 'alien' instrument...)

The 1 to 4 Mic sliders are actually pitched in semitones up from the 0 (zero), which is why they are arranged in the staggered 'piano keyboard' arrangement. This is immediately obvious if you increase the '1' slider, because you get a C / C# discord! So the 0 to 4 section controls parallel pitches, which (again) isn't how many conventional instruments work - organ drawbars are a bit like this, but...).

The next section to the right is from 5 to 11, and again these are parallel semitones up from the 0 (zero) pitch. The '5' (fifth) slider is set at about 75% in the default preset so that you know it is important (just as with the 0 (zero) slider. So the default preset plays two sine waves, a firth apart, and in both cases, the pitches are inverted (or not) at random, with a preference for one octave up instead of down. All of the inverted pitches are slightly detuned relative to the fundamental pitch, which gives a more interesting tone. All of these 'Parallel & Inverted' sliders are centred in the stereo image.

The combination of fixed parallel intervals (the default 5th is just intended as a hint to get you started) and random inversions kind of breaks 'the rules', and gives this instrument an interesting and unusual character. Have fun breaking all those conventions that you are supposed to follow, and embrace performances that are never the same twice!  

On the far left, there is a single '-12' slider, which was supposed to play a pitch one octave down from the fundamental. Unfortunately, I'm not the world's greatest programmer, and so it actually plays the same pitch as the '0' (zero) slider, except that the random inversions mean that most of the time it plays a different octave. Although Parallel inversions has had 3 versions, I have left this defect in there, because serendipitously, it sounds good. 

The A to K sliders are different again. This time they are panned either hard left or hard right, and they are distorted sine waves, instead of the purity of 0 to 11 and -12. So the A to K sliders add timbre and broaden the stereo image. Again, this isn't how normal instruments tend to work, but...

Finally, the lower row has more 'synthesizer'-type controls than is normal, with a full ADSR 'envelope' control, and I recommend the 'Attack' control for giving gravitas, and the 'Decay' control (with 'Sustain' set to near zero) for adding a 'Radiophonic' or synthetic character that sounds like it is from the 1970s. 

Straight Maths

'Straight Maths' has a busy user interface, but it extends some of the ideas in Parallel Inversions. The left hand side has 48 'Mic' sliders (yep, a lot!), whilst the right hand side has the extended 'synthesizer' controls, but in a more compact vertical format.

The three rows on the left are devoted to three different types of sound source. 

S - Top Row - additive synthesis

The top row (S) is sine waves (with twists) to provide simple Fourier additive synthesis. The '0' (zero) slider is again set as a hint that it is the fundamental in the default preset, but it does tend to get lost with all the other sliders! 

The three blocks of four Mic sliders on the top row have, from left to right:

- a Sine wave (0, 1 or 2 octaves up, shown as 0, 1 or 2), panned to the centre,

- a hollow-sounding, slightly square waveform (-), panned to the centre,

- a slightly bright, slightly sawtooth'y waveform (N (get it?)), panned to the centre, and 

- a detuned stereo 'sweetener' sine waveform (s) that adds a bit of interest and broadens the stereo image. If you want, you can ignore the 's' sliders and add your own preferred chorus effect via VST or outboard...

Yes, there's a bug with the 'S' in the two octaves up section, but that's part of the charm of the user interface, and does not affect the tone! 

The '-2' and '-1' mic sliders are sub-octave sine waves that can add low end to sounds. Use with care! 

As with all additive synthesizers, you mix and match the sliders to give you the combination of harmonics that you want, and then use the ADSR controls to give the sound a bit of shape in time. 

M - Middle Row - Karplus-Strong physical modelling

The second row has 16 different samples of metallic-sounding decaying sounds, derived from the Karplus-Strong hammered/plucked string physical model. '13' is my personal favourite, but it is way too strident for most purposes, and so just the merest hint of it is usually plenty! I resisted the temptation to arrange the sliders in any sort of order (previously I tried a 'tone-to-noise' arrangement), mainly because when I have tried to do this, I have rediscovered just how difficult it is to arrange multi-dimensional differences into a linear order. So I'm afraid that you will just need to play with the sliders until you get used to the sounds. Oh, and 10 and 11 ARE different, but not as different as I wanted! 

The 16 sliders are all tuned slightly differently, and are all stereo. This means that you can use combinations to add harmonics and detuning

My preference is to use the middle row to add a little bit of metallic 'bite' to sounds that are mainly top-row additive at their core. You can completely ignore this and do your own thing, of course!

W- Lower Row - Risset physical modelling

This row mis-uses Risset's work on synthesizing drum sounds, and adapts it to producing 'woody' sounding fast-decaying thumps and clunks to add percussive starts to the higher row sounds. There are four sets of sounds, arranged with the left-most sound in each set being the thickest (three sounds at once) and the others just single sounds. The detuning is toned back for most of these samples. These sounds are in mono, centered in the stereo image. I did play with stereo samples, but at low frequencies there isn't much to gain. To show how self-contradictory I can be, my '9126 Sawtooths' instrument on Pianobook.co.uk has way too much stereo bass!

It is quite fascinating how just a brief 'blip' of woodiness at the start of a sound that is all sine waves can totally change the character and timbre that you perceive. (Oh, and too much reverb is always a good idea!) This low row is influenced by the clicks found in old tone-wheel organs (the idea of adding percussive starts is not 'new' in any way!) and by the rather novel use of samples of the starts of instruments that Roland used in their D-50 synthesizer to augment a simpler digital synthesis technique for the sustained sounds. Roland called this mix of samples and synthesis 'Linear Arithmetic', so 'Straight Maths' is my way of paying homage to a classic 'personal favourite' synthesizer from the 80s. Okay, so now you know where the name comes from!

As before, the lowest row is used to add a little extra bit of character to the sound. The default preset  deliberately adds too much 'W' so that your first experience of 'Straight Maths' is 'Wow!'. Maybe that what the 'W' really stands for? But remember that subtlety is often the best approach, and too much 'W' may take you into cheesy territory...

Trivia

The rows were going to be labelled as: J, AK and C, for Joseph, Alexander, Kevin and Claude, but I thought this might be too obscure. What is interesting is that you now know a famous 'Kevin' - although Karplus still sounds uber-cool to me!

Letiti gave 'Straight Maths' a 5 star review, which is much appreciated, including this comment:

'One of the most innovative and unusual Pianobook entries'

For which I am enormously grateful!

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Music By 300 Strangers = 380 plus me

Every so often, I contribute to a project, safe and secure in the knowledge that no-one will ever hear of it, or hear it. Well, it may be that this time it might be different...

Over the last few weeks, a lot of musicians, who normally contribute virtual instruments, demos, and information to the pianobook.co.uk web-site and forum, have been working on a collaborative 'systems music' project set off by Spitfire Audio's amazing Christian Henson (his Twitter picture should be on the left...) for Pianoday 2020 - the 88th day of 2020 (88 keys!). And, yes, I was a contributor...

Here's the original 'call to arms' from the end of February 2020...







Here's the splash screen from just before the YouTube video of the World Premiere, which was at 17:00 on Saturday the 28th March 2020 (the 88th day, of course):

Christian explains a lot about how the music was made here.

My contribution...

For my contributions I used my MaxForLive chord device, ProbablyChord, to automate the chord sequence provided by Christian, and used the constrained random controls to produce random inversions of the chords. The sounds that I used were produced by the 'Synthesizerwriter's 29 Bagpipes' virtual instrument that is available free on pianobook.co.uk.

Here's the bit in the main 'Music by 300 Strangers' where you can see my screenshot:

...and in the credits...

 ...there I am. My name in lights! Wow!

Links:

Pianoday 2020.   The official web-page for Pianoday 2020

Yamaha's Piano Day page.  Yamaha's page on Pianoday 2020

pianobook.co.uk. The Pianobook page

The collaboration project   Christian's 'call to arms'

systems music. What is 'systems music'?

ProbablyChord.   My MaxForLive device that I used to make my contribution

Synthesizerwriter's 29 Bagpipes.  The source of the sounds that I used in my contribution

YouTube video of the World Premiere.    The World Premiere YouTube video...


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Behind the scenes of 'Synthesizerwriter's 29 Bagpipes...'

At the very end of December 2019, my very late (too late!) non-submission for Christian Henson's '29 Bagpipes' competition finally made it onto the Pianobook Library (if you haven't visited this amazing resource for samplists, synthesists and composers yet, then you should!). This blog post aims to augment the accompanying video (included below) with additional notes, to aid anyone who wants more information on how I produced the core samples, and more discussion about the principles behind the RUSS synthesis technique that I used in Ableton Live and Native Instruments Kontakt to make some example sounds using the samples.

1 of 29...

Principles

First of all, the samples that I extracted from the source '29 bagpipes' recording are not very conventional. They are long (about 22 seconds in this case), looped (so that you can choose any start position - controlled by an LFO, velocity or any other controller), in stereo, and they are split into two parts: a harmonic part and an inharmonic part (the harmonic part contains the 'tuned' part of the sound (the bit that you might try to whistle), whilst the inharmonic bit contains all of the noisy, clunky, thumpy, bang. spectral 'rubbish' that gives the sound its character and realism). The intention is that the samples should contain no information about any timbral changes over the duration of the sample - so, although the samples contain varying mixtures of frequencies, these do not change over time in the same way that would occur for the sound that has been sampled. These are raw sound sources, although they are far removed from the rather sterile oscillators that you find in most subtractive synthesisers. I remember that one reviewer of my book on 'Sound Synthesis and Sampling' took great delight in counting exactly how many pages it took me to finally describe what an oscillator actually did - well, part of the reason is that I don't think that enough time is spent on making the raw sound sources as good as they can be... Suffice it to say that these 'samples used as oscillators' are not sterile, boring or static.

The next thing to think about is the split of the raw source material (those 29 bagpipes et al...) into two 'as-orthogonal-as-I-can-make-them' parts. One of the things that always niggled away at me when using samples was the way that the harmonic 'tuned' bit was always 'bound' with the rest of the untuned, inharmonic 'stuff', so if you changed the pitch of the sample, then the pitch of the harmonic part and the inharmonic part both changed. Now in a real instrument, if you change the pitch of a note that it is producing, then the size of the instrument, its resonances, its rattles, its clunks and bangs, do not necessarily change in pitch in the same way. So I always wanted to be able to work with the harmonic part and the inharmonic part of a sample separately - and this is what I have been researching and working on for many, many years. There's a YouTube video where someone enquires in the comments about whatever happened to me (since I'm not as visible reviewing synthesizers as I was 25 years ago), and so now you know the answer - I've been working on fundamentally changing the way that sound synthesis works. Nothing major...

When you have separate samples for the harmonic and inharmonic part, then all sorts of interesting things open up. A lot of the characteristic timbre-defining 'attack' stage of percussive instruments turns out to be mostly inharmonics, and just making changes to that part can radically change your perception of the sound. Long releases on inharmonics parts sound can sound very much like reverb, but reverb that isn't bogged down in lots of pitched 'mush'. Swapping the inharmonics from one instrument to another doesn't give a simple mixture of the two instruments as you might imagine it would - instead it is more like hearing an unusual and distant relative from the same musical instrument family of the source of the inharmonic part. And that's the disarming bit - it seems that whilst our ears love the pitched part for intelligent, clever things like tunes and melodies, the deeply interesting, satisfying, 'characterful', visceral stuff is actually in those noisy, clangorous, nasty inharmonics.

Extraction

There's a lot of fine detail in taking 51-ish seconds of 29 bagpipes tuning up and turning it into looped stereo samples, and a lot of it is boring, repetitive work - there aren't many tools in this space yet!

The first thing I do is listen to the raw source material:

Audacity is my audio editor of choice, although I have been looking at Serato Studio as a 'next level up' way of assembling beats... From the looks (and sound) of this 51.1 seconds-worth, there's a pretty constant level, and a lot of interesting content: bagpipes, singing and various other background ephemera. The spectrum next:

So the loudest component is at -25 dB and is at 240 Hz - A#3, so that's going to be my first target frequency (although I might try some others...). I tend to scan across the frequency axis, looking for any peaks at multiples of the dominant peak, and there seem to be some candidates. Most notably though, is all of that broad-band noise at just under -48 dB, which looks like it is going to provide lots of inharmonics. If this was a sample of an electric piano tine, then it would look very different, with lots more easily identifiable harmonic components, and a lower 'noise' floor. But Christian deliberately provided challenging source material, so none of this is unexpected!

My current preference is to split the harmonic and inharmonic content into stereo pairs by using two different frequencies for the separation filters. A fixed difference of one hertz seems to give good results, although I've also tried halving the frequency difference per octave up the frequency axis. Because the numbers are easier with fixed differences, then that's what I used here - I will make a spreadsheet to automate the calculations when I have time (and post-Thanksgiving and 'post-'End-of-Year' offers are a big distraction at the moment...)

The extracted harmonic content looks interesting:

This is quite typical for extracted harmonic content. Notice that the dynamic range is higher than the source material, and that a lot of the high frequencies are removed by the low pass filter.

The spectrum reveals more detail:

The harmonics are now much more visible, and the 'noise' floor has dropped by about 20dB, which gives a usable margin, although a bit more time cleaning up the sample would be needed to get to the standards of Spitfire Audio, of course. But this is only a quick example to see what can be extracted from deliberately difficult material, so usable is fine. In many cases, I actually prefer the sound of 'less processed' samples - doing too many passes of separation filtering can start to sound artificial.

Repeating for the lower frequency and combining gives the stereo pair:

The variation in the two channels is not unusual when doing separation! If you listen to just the raw looped samples (which are effectively the first 20 seconds or so of this) then you get lots of interesting stereo imaging and lots of harmonic movement (dynamic timbral changes) - not at all like listening to a conventional sawtooth waveform! The long length of the separated samples is to enable lots of variation of sample start position (via round-robin, velocity, controller...) and is one of the bits of sampling technology that rarely seems to make it into synthesis (except here, as a counter example!). I'm that most dangerous type of samplists and synthesists: an impurist who will use any technique to get good sounds!

The extracted inharmonics are also interesting, but for very different reasons. You can hear some of the singing much more clearly for example. Some samples that I have processed reveal 'noises off' that weren't caught during recording...

Unlike the harmonic content, the inharmonic has less dynamic range, and since all of those high frequencies are not filtered out, it looks a lot like the original source material. But the sound is very different - there is some leakage of harmonic material (no processing is perfect!), but the majority is all of the 'other' stuff that was going on during the recording: singing, tuning up, extraneous sounds, etc.

The stereo pair is revealing:

The combination of lots of broad-band noise plus no filtering of high frequencies gives two apparently similar channels, although if you listen there are some differences. I have experimented with using broader difference frequencies, and different Q factors on the filtering, but I haven't reached any firm conclusions on the best approach yet...

Synthesis...

Using two pairs of looped stereo samples is going to soak up computing resources - sorry! As a partial mitigation, there are only a few samples across the keyboard:

This screenshot is from Ableton Live's Instrument Rack, where I'm using multiple instances of Sampler to play back the samples. The samples are in pairs (harmonics and inharmonics) and there are only four ranges. Remember though, that the looped samples are solely a source of frequencies, and any timbral or volume variation is solely provided by 'synthesis' processing, so a lot of the clues that you get from timing of decays or attacks (or detuning) in normal sample playback are not present. RUSS synthesis is very much a mixture of sampling AND synthesis!

A quick word on inharmonics... I have always wondered why subtractive (and other) synthesizers typically give you several choices of oscillator waveform, but only one (white) or maybe a second (pink) choice for 'noise'? There are lots of other sources of inharmonic 'noise' that could be used (hey, even a ring modulator would be better than nothing!), but what tends to be provided is broad-band noise. Yes, you can do quite a lot with that noise by processing it, but, no, there's lots more to inharmonic noises than just broad-spectrum hiss. Now you may be asking: like what? The answer to which is: separated inharmonic sounds. There's a reason why I've been dissatisfied with conventional synthesis noise provision, and if you are reading this, then you are seeing part of the answer. Maybe at some stage I will release a set of inharmonic samples that are completely useless for conventional tuned sounds, but which are very useful in combination with tuned sounds...

Content tips and hints...

The example Kontakt instruments have 'Vel' as part of the name when they have velocity sensitivity built-in. I'm one of those unusual people who likes extreme levels of velocity-driven variation in sounds, and so the sounds that I make tend to incorporate velocity sensitivity. But this may be unusual, as Paul Ward intimated to me at the 2019 Synthfest UK in Sheffield (thoroughly recommended, btw!), and so if you are a 'Controller-mapper' person, then you may want to avoid the Multis with 'Vel' in the name.

Yes, I can spell 'Kontakt', although the autocorrection 'feature' in various layers between me and the Squarespace web-site for Pianobook seems to think it is spelled 'Contact'!

The Ableton Live Instrument Rack instruments didn't make it into the Pianobook Library zip file, but I will try to get an update that includes them. There's just not enough time!

And finally, some thoughts on what you can do with the inharmonic samples. First, some simple things to try.
1. Use inharmonic samples with fast attacks and decays to form the 'Attack' phase of a sound (as popularised by Roland's D-50 synth...).
2. Use the same envelopes for the harmonics and inharmonics, and then alter the keyboard scaling/tracking of the inharmonics so that it doesn't track at all (0% - and this is one reason why Kontakt lets you do this!) through to 100% or more. At zero percent you get an instrument whose size feels strange, whilst as you move towards 100% you get variations of realism. Filtering the inharmonics (or mapping them to velocity) can give some very metallic sounds.
3. Use slow envelopes for the harmonics, and slower envelopes for the inharmonics, and play with the scaling/tracking of the inharmonics (or even reverse them). Band-pass filtering can be good for placing the apparent resonances of the virtual instrument that you are synthesizing.
4. You CAN detune the inharmonics - they don't care! 5ths, 9ths or even totally out-of-tune (or inverted) are all acceptable. Your ears will hear the harmonics as the 'tuned' part, and will assume that everything else is just an integral part of the sound that the instrument makes whilst being played in that acoustic environment. Your entire life has probably been spent listening to sounds where the harmonics and inharmonics are tightly linked together, so you are exceptionally well trained in assuming that this is the case, even when you hear sounds where it isn't a valid model for how the sound has been constructed.
5. You can take the inharmonics from one sample, and play them with the harmonics from another sample. So you could take the high samples and use them in the low register and vice-versa. More broadly, I have some inharmonics taken from a 'classic' monosynth, and they contain some of the distortion, noise, intermodulation, mains hum, hiss and other artefacts that give that monosynth it's particular sound. Add them to another harmonic sample and you get a strange combination of the two 'characters'... Hmm, that's me talking myself into releasing inharmonic samples again...


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