Tap the interface images below to get an explanation for the particular control, click the "Main Screen" link to return

Introduction

Droneo is a synthesizer which drones with various timbres and precise intonations that blur the distinction between tones, timbres and chords.

Droneo is also an excellent way to play with the way chords fuse into timbres — which is why there's such a heavy emphasis on interval specification. You can get a feel for how certain timbres fit "naturally" in certain frequency ranges, how tunings and timbres and chords intertwine.

Droneo can also be used as a pitch source for instrument tuning purposes, or as an aid for learning the difference between Just and Equal Tempered intervals.

This simulation uses 8 tone sources, (here called "reeds") which can be tuned to a number of intervals, randomly detuned, chorused, and modulated. The relative pitch and volume of each reed can be set individually, making for a wide variety of drones. The reeds can be set to various timbres suitable for drones, including vocal-like timbres and evolving, dynamically generated timbres.
The settings for all the reeds, timbres, modulations, volume levels and tunings (called a "Droneo voice") can be recalled with a button press. A set of six of these Droneo voices, called a "voice bank," can be named, saved, renamed, and deleted.
Droneo is a relative of one of my other iPhone Apps, SrutiBox.

To summarize, a Droneo voice is made of these parts:

• Each voice is made of up to 8 "reeds".
• Each reed is set to a certain interval based on a single frequency, the "base frequency". There are many ways to specify that interval and frequency. This interval can be set by typing it in in various formats, or interactively using a special "tone spiral" interface.
• The intervals can be perturbed with a slight amount of randomization.
• Each reed can "churn" (alternate) between two amplitudes and timbres. The speed of this churn is controlled by the "Churn speed slider".
• Each voice can also have a chorus effect put on it. The speed of this effect is controlled by the "Chorus speed slider".
• Some of the timbres change themselves while they are playing (Evolving timbres). Usually, this means a few harmonically related sines are mixed into the timbre. Some of the evolving timbres (Evolving mirrors) use the "other" churn timbre as sonic material instead of a sine wave.
• A master volume control is used to scale the entire sound.

Experiment! Here are some examples of Droneo in action:

VIDEO

Droneo (1.1) introduction video: a fast overview of Droneo 1.1 features

Droneo (1.1+) tour of Droneo timbres (some will be available in 1.2)

AUDIO

Listen to how to build one kind of complex drone with Droneo! In this example, an evolving drone's base frequency is dropped a few times.

This large spiral is an interface for displaying and showing intervals for all of your reeds.

• Each reed is represented by a small circle: . The circle is placed on a black spiral which represents interval values ranging from 1/2 (-1200 cents) to 32/1 (6000 cents). Each loop of the spiral represents another octave, and so the intervals are placed logarithmically on that spiral.
• If the reed has no interval, it's put near the center of the spiral, out of range.
• The center of these circles is slightly transparent, so if more than one reed shares the same interval, the yellow color of the circle with be more intense.
• You can set the interval you'd like for that reed by dragging it to as spot on the spiral.
• You can show various legend guides for intervals, which can help you see where to place the interval in relation to existing intervals.
• If you have snap turned on, your changes are constrained to intervals and octaves of intervals of the current legend guide.
• If you have snap mode turned on, the button next to it , the retune button will move all intervals to the closest one in the current guide.
• If you have free mode turned on, your changes are not constrained.
• If you have free mode turned on, the button next to it , the perturb button will add or subtract a small random amount from all the intervals.
• The silence button turns all the intervals off.
• The revert button resets all the intervals to what they were when you called up the tone spiral.

These are legend guides that help you to see and place intervals using the tone spiral.

• None: removes all legends.
• ET12: shows the familiar 12 tone equal temperament scale lines. Yes, they are equally spaced!
• Just: shows a nice selection of just intervals.
• Partch: shows the famed 43-tone just scale of Harry Partch's fixed tone instruments.
• Original: shows the scale as specified when you called up the tone spiral. The labels are set to the same labels as they are on the main screen.

The legend guides interact with the snap toggle button.

• If you have snap turned on, your changes are constrained to intervals and octaves of intervals of the current legend guide.
• If you have snap mode turned on, the button next to it , the retune button will move all intervals to the closest one in the current guide.
• If you have free mode turned on, your changes are not constrained.
• If you have free mode turned on, the button next to it , the perturb button will add or subtract a small random amount from all the intervals.

Note that if you are using the original legend guide, and your original ratios were all "off", and you have "snap" on, it won't let you set anything!.

• If you have snap mode turned on, the button next to it , the button will move all intervals to the closest one in the current guide.
• If you have free mode turned on, the button next to it , the button will add or subtract a small random amount from all the intervals.

The silence button turns all the intervals off.

The revert button resets all the intervals to what they were when you called up the tone spiral.

All the reeds use this base frequency to tune their intervals relative to that frequency.
The base frequency can be set to values between 0.01 Hz and 2756.25 Hz .
You can change the base frequency to a new Hz value by tapping it and typing it in .
You can also type in a standard note name and it will take that as a base frequency. To specify sharps, you can use '#' or 's', and to specify flats, you can use 'b' or 'f', for example: bb (B flat), c# (C sharp), Df (D flat), Fs (F sharp).
These "named note frequencies" are set in a low octave (based on A3 = 220.0 Hz) by default, so the higher harmonics can be used.
For other octaves (0 through 4), you can type the octave as part of the name, for example, Bb2, C4, Ds1, fs0. Having no octave specified is the same as using octave 3 (E alone is E3).
Low frequencies may be hard to hear through the built-in speaker (if you have one); use higher frequencies, larger intervals in the interval sets, or richer timbres!

The Volume slider is an easy way to set the volume.
You can also use the buttons on the side of the device, but they don't work if you are docking it and using the mini phone jack on the dock.

These are a series of buttons that choose pre-set Droneo voices. This comprises the settings for base frequency, volume, randomness, churn and chorus settings, timbres, and reed volumes and intervals.
Here is a description of the banks of Droneo voices that come pre-installed:
Droneo:

• Just: The Just intervals are are chosen to give a wide spread of harmonious tones.
• Major: These is a Major Scale in 12 tone equal temperament.
• Harm: The Harmonic intervals are to help build chords that fuse into timbres.
• Minor: These is a Major Scale in 12 tone equal temperament.
• Cust1: a place for a custom Droneo voices
• Cust2: a place for another custom Droneo voices

Voices: A bank of Vocal-based drones

• major: A Major chord (D major) in standard 12-tone intonation, using "A"
• major J: A Major chord (D major) in just intonation, using "A"
• A - U: Churning A and U timbres
• O - E: Churning O and E voices in random unison.
• I mirror: Churning Evolving mirror and I timbres, using just intervals.
• U low: U timbre , random unison, low pitch.

Evolving: A bank of Evolving drones.

• Unison: Randomly perturbed unison and fifths, which ripple with evolving amplitude changes.
• Harm E3: Harmonics 1-8, with extra harmonics added by the Evolving 3 timbre, amplitudes biased toward the 4th harmonic.
• E6 H/8: Undertone harmonics in a medium range get compensated with overtone harmonics from the Evolving 6 timbre.
• Mir Duo: Sine 9 (a shimmery sine) churned through the Evolving Mirror 3 with only two reeds, making a kind of duet.
• Em3 I: Justly tuned "I" vocal timbre in a low register is churned through Evolving Mirror 3.
• Em2 U: A major scale, with "U" vocal timbre and Evolving timbre 2.

Insects: A bank of chirping drones.

• Bug1: One insect, chirping once a second.
• Bug Duo: Two insects, chirping 3 against 2.
• Hi & Lo: Two differently pitched insects churning with each other, chirping 2 against 1.
• Synched: Eight insects, all chirping at integral multiples.
• Random: Eight insects chirping a little out of phase with each other.
• Party: A bug party, involving three evolving mirrored insects.

Blank: A completely empty bank

• 1:
• 2:
• 3:
• 4:
• 5:
• 6:

You can chose a Droneo voice by clicking on its name.
By triple clicking on a Droneo voice name, you can rename it, describe it, and specify how the intervals are displayed in the interface.

The four choices are;

• Actual: the interval as it is actually described, that is, as a ratio, cents value or equal temperament setting, possibly showing a more meaningful label of that internal specification. Example:
  1/1 Root will show as "Root"
• Std: the reed frequency as interpreted as a standard 12ET western name, with a possible cents offset. Example:
  With base frequency of "C", 3/2 will be displayed as "G +1.96 ¢"
• Cents: the reed interval in cents, example
  7:13 ( The seventh degree of 13-equal temperament) will be displayed as "646.15 ¢"
• Hertz: the reed frequency in Hertz. Example:
  With base frequency of "C", 1/1 Root will be displayed as "261.63 Hz"

The Rand button, adds a random amount of detuning to each reed. This can be used on any Drone voice. This detuning is in the range of an "eighth tone" (25 cents) sharp or flat from the original interval. This is reflected in the interval's label as, for example "+12¢". Repeatedly tapping the Drone Voice's button will make new detunings from that voice. Tap the Rand button again to turn off this feature.
When saving a Droneo setting that has the random feature on, the fact of "randomness" is saved, but not the actual random interval offsets.

Modulations
The modulation slider controls slowly changing modulations which can add a lot of life to the drone. By tapping the name of the modulation (Chorus or Churn), it chooses the type of modulation you wish to set.

Chorus is a modulator that slowly detunes the left and right channels from each other (they are also slightly mixed) to provide some "motion" in the sound. The speed of the chorus runs from 1 to nearly 60 seconds.
Setting the slider to its maximum value will turn the chorus off. To use the slowest speed, nudge it a bit to the left from the maximum value. Reeds set with a rich timbre or in a complex chord will reveal more "motion".

Churn: When you move the modulation slider in "Churn" mode to the left, the churn feature is turned on and a second set of eight volume sliders appears.
Churn is a modulator that slowly interpolates one set of volume sliders to the other set. The churn amount slider shares the same space as the chorus slider. The speed of the churn runs from 1 to nearly 60 seconds.
Setting the slider to its maximum value will turn the churn off. To use the slowest speed, nudge it a bit to the left from the maximum value. When it's turned off, only the left set of sliders is used as the volume sliders.
A triple touch on the volume sliders works the same on the two columns of sliders: they all will follow the slider you move. A double touch will let you set both volume sliders for a particular interval at the same time.

The Timbre button lets you select the reed timbres. Tapping the timbre's name brings up the timber picker:

As you scroll through the timbres, the timbre will immediately adjust to the currently selected timbre. You can use it by tapping "Use" or go back to the previous one with "Cancel".
There are a number of timbres to choose from, each with differing qualities.

Sines: these wave forms are made by raising a sine to successive odd powers, each time adding more harmonics. Sine - a simple sine wave, no harmonics at all. Sine3 - you can hear a fifth Sine5 - you can hear a third Sine7 - you can hear a seventh. Sine9 - you can hear a ninth. Sine11 - you can hear an eleventh.

Organs: have a few higher harmonics, like an old electronic organ with a few draw bars pulled out. Organ 1, harmonics 1, 2 Organ 2, harmonics 1, 2, 3, 4, 5 Organ 3, harmonics 1, 2, 3, 4, 5, 6, 7, 8

Harmoniums: these have a number of harmonics directly multiplied by internally specified weights. Harmonium 1, taken from the spectrum of a harmonium reed. Harmonium 2, also taken from the spectrum of a harmonium reed. Good with low pitches!

Buzzes: This is a generated timbre with as many harmonics as possible. Buzzy Organ, very buzzy. Odd with some light even harmonics.

Vocals: these are constructed by summing harmonics, which are scaled to the harmonic shape (formants) of the intended vowel, based on the pitches of the reeds. As a side effect, each of the waveforms used by the reeds differs, so each reed may sound quite different in a related way. It calculates these waves when you choose them, which is why there may be a little pause before playing them. A Voices ("karma") U Voices ("tuning" O Voices ("drone") E Voices ("best") I Voices ("bees") Voices benefit from low base frequencies - near that of real human voices - and a little randomness.

Evolving voices. These voices all create timbres for each reed with random harmonics. Each has differing criteria for how they are created and how they blend into the existing voices. Because of this, they also smoothly (for the most part) blend into what's already playing! The new harmonics are scaled so the resulting timbre is not so high in high frequencies. Each reed has its own separately evolving voice - so they blend in and out with each other. They are a little computationally intense, so they may be less "clicky" sounding if unused reeds have their volumes set to 0 or have frequencies set to "off". In general, that's a good idea! Evolving 1: merely fades a sine wave timbre in and out randomly (but slowly). Evolving 2: randomly adds none, 1,2 or 3rd harmonics. Evolving 3: randomly adds up to the 8th harmonic. Evolving 4: randomly adds up to the 12th harmonic, more slowly. Evolving 5: randomly adds up to the 16th harmonic, more slowly. Evolving 6: randomly adds up to the 16th harmonic, more quickly. Using the evolving timbres with chorus, churning and carefully or carelessly designed interval sets makes for a richly evolving palette of droning! These voices are computationally expensive, so may cause the phone to warm up!

Evolving Mirror voices: like the evolving voices, they change with time, but take their timbre waveforms from the "other" churn voice! You can make both voices mirror each other, but after a while, the sound fades out, so it's not much fun. Evolving Mirror 1: fades the opposing timbre in and out randomly (but slowly). Evolving Mirror 2: uses the opposing timbre to build random harmonics, up to the 12th harmonic. Evolving Mirror 3: uses the opposing timbre to build random harmonics, up to the 10th harmonic, but the harmonics are not scaled so there is more definition in the individual tones. Evolving Mirror 4: uses the opposing timbre to build random harmonics, up to the 8th harmonic, slowly choosing a new harmonic, but using it quickly. These voices are also computationally expensive, so may cause the phone to warm up!

Each reed's volume can be individually set, to create a precise mix of intervals and harmonics. Here is where you can have a lot of fun exploring chord voicings and harmonic textures. You don't have to slide these (or any Droneo) sliders, just tap them where you want them to be set. The lowest and highest values have special icons to help you out. If you want to set all the volumes to the same value quickly, triple tap a slider which is set to that value. Since this also works for the "zero" level, it's a fast way to zero out the sound.
Just interval sets, like Harm and Just found in the "Droneo" voice bank, are well suited to making chords which fuse into timbres.
There are a great many philosophies about which intervals should be used to derive scales, and how to use them to build harmonies, dissonances, melodies, and timbres, and I've only chosen to include some in the Droneo voice banks to get a taste of the possibilities of microtonal scales and intervals in this context of drone accompaniment.
To this end, all the Droneo voices' interval sets are customizable — Droneo lets you replace and rename all intervals in the Droneo Voices.
By tapping in the interval name area, you can specify the interval you wish by either:

• typing in a ratio (e.g 3/2, 21/20, 81/256),
• typing in a number indicating the number of "cents" (e.g. 110, 133.33, 701.9), or
• typing in a degree of an equally divided octave (e.g. 5:19 is the 5th note of 19 tone equal temperament). These are numbered from 0!

You can get pretty creative here - since these numbers can even be "real" numbers, you can even make a "ratio" like 1.01/1 or "quarter-tones" in an equal temperament like 7.5:31.
I don't let any of these intervals resolve to a ratio larger than 32/1, that is, 32 times the base frequency. You can set it to really low ratios though, and choose a higher base frequency to get about the same effect.
A Ratio will calculate a frequency that is the base frequency times that ratio, for example, with a base frequency of 110 Hz, 3/2 will become 165 Hz, 15/8 would be 206.25, etc. Cents are somewhat more complicated, but every hundred cents represents a 12 tone equally tempered halftone: 100 would be a standard minor second, 400 a major third, 750 a quarter tone higher than a perfect fifth.
There are a lot of references you can find that translate historical, ethnic and experimental scale intervals into cents.
The formula, for those with a calculator, is
frequency =
base_frequency * 2 (cents/1200).
For the arbitrary equally tempered octave notation (a:b), the formula is a similar: frequency =
base_frequency * 2 (degree/division)
For more information on scale construction and historical intonations, you can get pretty deep into it if you pick up a copy of Scala by Manuel Op de Coul.
You can give an interval a descriptive label by typing that label after the numeric specification of the interval, separated by a space. e.g.
3/2 Just perfect fifth.
81/80 syntonic comma.
Don't make the labels too long (more than 16 characters) or they will be truncated.
You can keep the reed from sounding at all by typing "off" or "zero" or "?" as the interval setting. This different from setting it to "0", which means an interval of 0 cents (that is, the base frequency itself).
You can then set the interval value by tapping save (which you hear immediately if the volume for that reed is up), and also you can both save and pick a new interval value to set by tapping the interval name of the next reed you want to work with.
You can see these intervals expressed in different ways by triple clicking the Drone voice's name and using the segmented selector to change how the interval values are displayed. The internal setting is still what you typed in originally, though. see: this section of the instructions.

Notes and Tips

• As with other iPhone audio applications, if you are connecting the device to an amplifier, you may want to disable the phone function so you don't hear the occasional noise resulting from GSM synchronization. Putting it in "Airplane Mode" will help a lot with that and battery usage! If the phone is enabled, incoming calls will will cause Droneo to save its settings in a voice bank, fade out and let you have have a conversation. After the call, Droneo will relaunch using that saved voice bank.
• Headphones or earbuds are recommended for a good stereo effect.
• Make sure the volume is not too high - your ears - and the iPhone's earbuds and speakers - are delicate!
• I sometimes find the phone tends to heat up during Droneo's operation. Shut off Droneo if this becomes uncomfortable. I also suspect it's not too good for battery life.

More information can be found on the Droneo Web pages at: http://www.jhhl.net/iPhone/Droneo/. That website will carry the current, revised version of these instructions, as well as samples, tips and links.

Thank You!
  Henry Lowengard

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© 2009 Henry Lowengard
Drone picture from http://tvtropes.org/
The formant data for the vocal timbres is taken from CSound.
Thanks! for Appirater - Created by Arash Payan on 9/5/09. http://arashpayan.com