Music for Tablets – Droneo

Print Friendly, PDF & Email


The return of an oldie but a goodie – one of the earliest iPad apps gets a makeover, and the results are very pleasing.


by Warren Burt, Nov. 2016


Henry Lowengard has been around computer arts – music, graphics and animation, since the mid-70s. In the late 80s, his program RGS, for the Amiga, was one of the first spectrogram painting programs.  For the past six years or so, he has also been extending his work into the iOS platform, and the result has been a stream of interesting and useful sound making apps. Among these have been Tondo (an update on the concepts behind RGS), Ellipsynth (elegant sample scrubbing), Synthicity Itself (like it says, with a simple but effective virtual analog synthesis performance interface), Wind Chimes (with different tunings, timbres and ranges settable), and two programs that were designed to play sustained sounds, Sruti Box and Droneo.

Of these, only Droneo is currently Audiobus compatible.  Droneo has been around since at least 2009, but has had a number of upgrades since then.  The most recent of these brings it to version 1.5.1, with the addition of a number of new features, such as AudioCopy / AudioShare compatibility and full AudioBus / IAA integration, as well as the addition of a random choice routine for the harmonic pattern facility (more on that later) and the addition of harmonics 33-64 to the harmonic pattern facility (ditto later). I’ve used Droneo since 2010, but these new features have led me to a deeper exploration of it, and it’s now becoming one of my favourite go-to applications for sonic exploration.

Droneo, like the name implies, is a program for primarily making drones, or sustained electronic sounds. For those who don’t know, there has been a sub-category of electronic music called “drone music” since the 1960s.  Some of the names associated with it are

(among many others). To do this well, a program should have a lot of ways to specify different kinds of turnings, and should have very precise pitch resolution. After all, the “gold standard” for this kind of a program was set back in the 80s with David Rayna’s digital synthesiser, built for composer La Monte Young, which featured .00005 Hz pitch resolution, but which had a price tag on it that guaranteed that composers such as myself would never be able to get their hands on it. Droneo has very precise pitch resolution of .00000000093132 Hz per step, or between any two steps, a beat rate of about 6 hours and 45 minutes per beat, and lets you specify pitches in a variety of different ways.  And it only costs $4.49 US.  That, I can afford. Some examples of those ways of specifying pitch in a moment, but first, an overview of the app is in order.

Droneo is an eight oscillator synthesiser. These oscillator voices are called “reeds” (after each of the reeds in the Sruti Box, the Indian drone playing harmonium), and each of them has a pitch control, a volume control, and a timbre setting.  In the bottom half of the main screen are eight horizontal areas, each with a space to type in frequency specifications on the left and a volume slider for the individual oscillators on the right.  Timbre is selected with the horizontal band above the oscillators.  See Figure 1 below for a look at the main screen. 


Since Droneo is primarily (but not always) about setting up precise frequency relations, there are a number of ways to set the frequencies of the oscillators.  All the oscillators derive their frequency from the “Base Frequency” set near the top of the screen.  This is set either in Hz (cycles per seconds) or with standard note names like “C1” or “A3”.  Then for the individual oscillators, you can specify frequencies in a number of ways.  Ratios are probably the most common way.  Typing in 1/1 for example, with a Base Frequency of 261.63 Hz (Middle C or MIDI note 60) will cause that oscillator to play 261.63 Hz, or Middle C.  (261.63 x 1/1= 261.63) Setting the ratio to 3/2 will cause the oscillator to play 392.45 Hz, or the G above that (261.63 x 3/2 = 392.45).  If ratios aren’t your cup of tea, you can specify a note in terms of its degree in an equal tempered scale.  For example setting an oscillator to 7:12, with the same fundamental, will produce the G above middle C as tuned in 12 note piano tuning.   This means that you can have ANY scale degree in ANY equal temperament as a pitch in Droneo.  And with both ratios and degree notation, you can use decimal points, so notations such as 1.01/1 (which will produce a note very slightly above the Base Frequency, or 12.4:19.3 (the 12.4th degree of a tuning of 19.3 notes per octave) are both possible.  As well, you can use cents (1/1200th of an octave) to specify your pitch.  Just a single number typed will produce these – such as 386.3 or 701.955 will produce pitches a major 3rd (the first one) or a perfect 5th (the second one) above your Base Frequency.  A negative cents value will produce a pitch below the Base Frequency.  And with eight oscillators to play with, the potential for exploring what different chords sound like is pretty great.


More Ways of Measuring Pitch


There are two other ways of specifying pitch for advanced users.  Both use the “@” symbol to divide ANY interval into equal slices.  The notation 4:33@33/16 would divide the ratio 33/16 (just over an octave) into 33 equal divisions, then give you the 4th degree of that!  The notation 4:33@&433 (note the & sign) will divide 433 cents (1/3 of a semitone greater than a major 3rd) into 33 equal parts, and give you the 4th degree of that.  Obviously, if you’re just starting out, these kinds of divisions probably won’t be something you want to play with, but if you’re ever interested, it’s nice to know they’re there.


These pitch specifications all produce steady pitches.  There are a number of ways Droneo provides, however, to do changing patterns, and we’ll look at them later.

Returning to our tour of the main screen, at the top of the main screen there are four buttons and a title panel: “i” takes you to the well revised manual; “S” takes you to the Save page; a panel for the name of the voice bank; a record button; and a button that looks like a spiral, which takes you to the Tone Spiral page (more later on that).  The record button can be set up (in the main iPad Settings page) so that whatever is recorded is automatically sent to either AudioCopy or AudioShare.  Or it can be saved so that it can be downloaded from iTunes file sharing.

Below those buttons are six buttons which have the names of patches in them.  You can change freely between your six selected patches in real time.  You can also save and load individual patches by triple-tapping on the name of any patch.  You can also Export and Import patches which have been saved in a plain text format.  This means that you can save a set of patches in text format, then reload individual patches into a set of six that you might want to use together in performance.  Below that is the Base Frequency.  As stated above, this can be given in either normal note names, or in precise cycles per second.

Then, continuing down the screen is a volume slider; a Rand control, which will detune all the notes by up to 25 cents sharp or flat of the specified pitch (press it a second time to return to your original pitches); and two controls, which share the same box – a chorus control, and a “churn” control.  The chorus control slightly detunes the patch and combines it with the original to produce a shimmering chorus sound.  It can be set from 1 second to 59 seconds.  The “churn” control sets up a second user-specifiable timbre (with individually settable volumes for each oscillator) and cross fades between the two timbres with their individual volume settings.  Again, the range of cross fade is from 1 to 59 seconds.

Then comes a Timbre selector.  Pressing this gives access to a range of timbres, some of which are what is expected, such as various sines, triangles, squares, organ sounds, voice timbres, etc.  But other timbres are actually pattern players, some of which do preset patterns of moving between various harmonics, while others allow the user to set up patterns of changing harmonics, from 1 to 64.  Some of these patterns can be set up to play sequentially, and with the addition of a “?”, they can be set up to be randomly reordered on the fly. Finally, there is a “Custom Pattern” timbre, which allows you to specify an individual timbre, speed of progression, fade rate, and a set of harmonics to alternate between, for each of the eight oscillators.

These patterns deserve a closer look, because they extend the power of Droneo significantly.  For the normal Droneo timbres, a steady pitch is produced.  But there are several timbres which don’t play just a single pitch, but change their pitch in various ways.  These timbres are called “Evolving,” “Evolving Mirror,” “Counting Mirror,” “Pattern Mirror,” and “Custom Pattern.”  Evolvers bring in and out random patterns of particular harmonics of the given pitch.  For example “Evolving 6” randomly adds sine waves up to the 16th harmonic, fairly quickly.  Other Evolvers add other sets of harmonics at different tempi. “Evolving Mirrors” do the same, but with these, you turn on the “Churn” control, set a timbre in the second voice, turn off the Churn control, and then, instead of sine waves, the timbre you select will be transposed by the chosen harmonic ratios.  “Counting Mirror” will turn on and off all the eight oscillators in various patterns, described in the manual.  Again, since it’s a “mirror,” you can set a timbre for your oscillators with the timbre selector for the second timbre in the “Churn” control.” 

“Pattern Mirror” goes two steps further.  Not only can you set a timbre for your oscillators, but you can specify the pattern of which harmonics you want to choose for your transpositions, in which order.  You can choose harmonics from 1-64 for your patterns.  Plus you can specify 0 for a silence in the pattern.  In the manual, there is a listing of the way to notate the harmonics with letter symbols.  0 = silence.  1-9 – harmonics 1-9 of your given pitch.  Small letters a-z = harmonics 10-35.  Capital letters A-Z = harmonics 36-61.  “+” = 62, “-“ = 63, and “=” = 64.  So this pattern, for example:


would play 3 silences, harmonics 10, 11, 12, 3 more silences, harmonics 60, 61, 62 (better have a low fundamental for those!), followed by 3 more silences.  This pattern would repeat.  If you have different length patterns on different oscillators, you will get phasing relations between the voices.

But there is one more added feature.  Putting a “?” at the start of the pattern would give you the elements of your sequence in a random order.  So the above sequence starting off with a “?”:


will give you a randomized pattern where each new note will choose between nine silences and six pitches at the given harmonics.  The potential for exploration of this is pretty huge.  I’ve been burning up hours exploring only a few of the possibilities of these patterns.

Finally, there is the ultimate, the “Custom Pattern.”  In this, for each oscillator, you specify a pitch, a timbre, the time between changes, the time taken to fade in, and the pattern as given above.  For example, here would be a typical oscillator Custom Pattern string:

1/4 o3,15,5,?6789ab

This would mean a pitch that is two octaves below the Base Frequency, played with Organ 3 timbre, 15 units (each unit is about 1/11th of a second) between pitch changes, an attack time of 5 units, and a random selection of harmonics 6, 7, 8, 9, 10 and 11.

This Custom Pattern String:

11/1 o1,3,2,?bcdefghij0000000000

produces pretty quick random melodies of harmonics 11-19 with about equal amounts of notes and silence.  This Custom Pattern facility takes a little while to get your head around, but once you’ve gotten it, it’s a very powerful tool for exploration.

The next image below shows a more complex pattern made with the Custom Pattern.  In this the long chains of numbers and letters at the end of each oscillator specification show a different pattern of silences (0s) and harmonics 59-64 (letters X Y Z and + – and =).  These all repeat, but since the time between attacks is slightly different (the 12, 13 and 14 figures second in each list) those repeating patterns are going to phase.  Pitches are not shown in this figure. The first three oscillators are tuned to 1/1, the next three to 3/2 (a perfect 5th above), and the bottom to at 9/4 (a perfect 5th above the 3/2).  Note that the base frequency is the sub-sonic 5 Hz.  This allows the high harmonics 59-64 to be heard in a middle musical range.  (5 Hz x 59 = 295 Hz; 5 x 64 x 9/4 = 720 Hz.  So the pitch range of the piece is roughly between D above middle C and F# an octave and a 4th above that.)


There is one more way of specifying pitches in Droneo. This uses a separate page called the Tone Spiral, as shown in the next image. On this page there is a large spiral showing pitch progressing through the octaves as a large spiral.  The individual pitches are shown as numbered circles.  You move these tokens around the spiral to set up patterns of pitches.  Selection buttons on the bottom allow you to work in different scale systems.  These are ET12 (our normal tuning), Just (a limited set of ratio pitches), Partch (Harry Partch’s 43 tone just intonation scale), and Equal.  The equal has a ratio box next to it, so you can specify which equal tempered scale you want to work in.  In this example, the spiral is tuned to Partch’s scale.  There is also a set of buttons for “Free” where the pitches can be anywhere, or “Snap” where they can be limited to the pitches of the scale chosen.  If you press the large tick button on the upper left, the scale will be applied to the settings on the main screen.  This can be used in real time, so the Tone Spiral can be used as a live-performance device.

It’s obviously very clear by now that Droneo is a program for those who want to explore the realm of musical tuning, and that exploration necessarily involves the use of numbers.  Clearly, this is not a program for the arithmetically challenged.  But if you can master a few basic tuning concepts, and you’re interested in exploring this area, Droneo can provide you with a large set of musical resources to work with.  I worked with it many years ago, and since these updates have come along, it has become one of my constant musical companions.  I can’t think of anything nicer to say about a program.


Ways of Measuring Pitch


In Western music, we normally divide the octave into twelve equal steps, called semitones.  In the late 1800s Hermann Helmholtz and Alexander Ellis devised a way of dividing the octave into 1200 equal parts, which are called “cents.”  (100 cents = 1 semitone.)  So each step in 12 tone equal temperament = 100 cents.  For other octave based equal temperaments, just divide 1200 by the number of steps in the scale.  So 19 tone equal temperament = 1200/19 = 63.157 cents.  So each step in 19 tone equal temperament = 63.157 cents.  11 steps in 19-tone equal temperament = 63.157×11 = 694.736 cents.  A normal “perfect 5th” in 12-tone equal temperament = 700 cents.  So the “fifth” in 19 tone equal temperament is just 6 cents flat (or 1/16 of a semitone) from its 12-tone cousin.  Notice we haven’t mentioned frequency in cycles per second (Hertz) here.  That’s because each interval given in cents is heard as the same size no matter whether it’s high or low in frequency.  So, for example, an interval of 702c above G=98 Hz = 147 Hz.  But an interval of 702c above G=392 Hz = 588 Hz.  But because there is the same ratio between both of those intervals, (147/98 = 588/392 = 3/2) they will be heard as the same interval, just in different octaves.


One can also use these intervals to measure any pitch.  Intervals made with small-number ratios are often very close in sound and size to the normal intervals in our normal 12-tone equally tempered tuning.  So, for example, a perfect 5th in normal 12-tone tuning is 700 cents wide.  A “just” perfect 5th is the ratio 3/2, which in cents is 701.955 cents wide.  Just a tinier bit wider than the “normal” fifth.  Except that unlike the “normal” 5th, this one won’t “beat” or “throb” when the two notes comprising it are played together.  With a major 3rd, things are a bit trickier. The “normal” 12-tone major 3rd is 400 cents wide.  But a just major third, which uses the ratio 5/4, weighs in at 386.314 cents.  That’s about 1/6 of a semitone flatter.  Yet when played with the right timbre, the 5/4 major 3rd interval does not beat, but the 400 cent 12-tone equally tempered major third does beat.  Whether one likes this beating or not is down to individual taste, but Droneo allows one to hear both, easily, and then decide for oneself which one (or both, or some other tuning) is for you.  If you’re looking for a guide to these kinds of ways of measuring pitch, a great tool for exploring them is the freeware software Scala. ( )


SoundBytes mailing list

Browse SB articles

Welcome to SoundBytes Magazine, a free online magazine devoted to the subject of computer sound and music production.


If you share these interests, you’ve come to the right place for gear reviews, developer interviews, tips and techniques and other music related articles. But first and foremost, SoundBytes is about “gear” in the form of music and audio processing software. .


We hope you'll enjoy reading what you find here and visit this site on a regular basis.

Hit Counter provided by technology news