Comparison

Beat Kitchen Harmonic Synth vs Rubberband

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Beat Kitchen Harmonic Synth

Shape the overtone series directly to create unique sounds. This additive synthesizer allows real-time manipulation of harmonics, LFOs, and envelopes. Explore sound design and synthesis on your device.

Highlights
  • Additive synthesis engine
  • Overtone series shaping
  • Live waveform and spectrum response
  • Modulation matrix with LFOs and envelopes
  • AUv3 support
  • On-device processing
Features
Read full description

BKS Harmonic is an additive synthesizer that builds sound from individual overtones, then gives you tools to shape, scan and filter them by harmony. Load it as an Audio Unit v3 inside AUM, GarageBand, Cubasis, Loopy Pro or any AUv3 host, or run it standalone. A TUNER THAT KNOWS ABOUT STRETCH Tune mode turns the scope into a tuner: it names the note it hears and shows how far sharp or flat it is in cents, with a ring that closes as you land on the pitch. It tunes against the stretch curve rather than equal temperament, so it follows a real instrument. Stretch shapes the overtones inside a note; Key Stretch makes the keyboard follow it, so octaves widen the way a piano's do. FOURTEEN TUNING SYSTEMS, AND A TEMPERAMENT EDITOR Equal and Just, five historical temperaments, and six from outside the European tradition including Maqam Rast, Turkish Rast, Slendro, Pelog and the Harmonic Series. The Temperament slider is a morph, not a switch: fully left is Just, fully right is whichever you chose. Twelve bars show any system as cents away from equal; drag one to make the tuning yours, then copy it out as plain text. Tunings save with the preset. FIVE HUNDRED SCALES Searchable by alternate name: malkauns, nikriz, bhupali and freygish find the right set. THE PARTIALS ARE THE INSTRUMENT The partials display shows every overtone in your sound, and four tools work on it directly. FOLD sweeps upper partials below the fundamental, redistributing energy across harmonic layers — not a filter. The OVERTONE SCAN steps a spotlight through individual partials with triangle, saw or random patterns, and can visit only partials in the active scale. The HARMONIC GATE reinforces partials whose pitch class matches your chord and suppresses the rest: capture a chord, follow MIDI, split the keyboard, or pick the notes on the gate's own keys. SCULPT draws the level and pan of every partial, slides the curve up the grid as a formant, and locks partials in place while the rest moves. THE HARMONIC VOCODER Pass live input or a sample through the synth as an effect. Your sound travels through a bank of tuned peaking bells rather than being replaced by filtered noise: open the Air and the source stays dry, tighten it and the bands resonate into it. Key Track is the mode switch: on it plays as an instrument, off it is a fixed filter you can sweep. Aimed at a sample, the bands track that sample's spectrum as it evolves. One level-matched Blend control crossfades it against the oscillators. PULSE-WIDTH MODULATION Set the core to a saw and Source 2 to a saw: the two ramps subtract, which is what a pulse wave is, and the phase between them sets the duty cycle. Modulate it and you have PWM. A preset in the Utility folder is ready to play. MODULATION A cog on almost every control, so the synth's own engine can drive nearly anything in the interface, including the display. Sources include velocity, envelopes, LFOs, how many notes you hold, how many oscillators sound, the synth's own output level, and Atmo, a shape driven by 84 years of barometric weather data from the Beat Kitchen Weather Sonification Project. Rates run from audio rate down to cycles that span years. THE SCOPE A stereoscope, oscilloscope, spectrum and a live per-partial display. Glow takes the trace from a hard line to a diffuse bloom, Colour sets the hue, Trace Speed and Dot set how it draws — and every one is a modulation target. Route velocity to Colour and the trace shifts as you play. LIVE INPUT A headphone button passes the side-chain straight to the output, so you can hear and see your input with nothing held: green when signal arrives, amber when a bus is connected but silent, red when nothing is. Resynth Speed locks a sample's playback speed to pitch, tape-style, or keeps them independent. Every control has a tooltip, presets work offline, and a harmony wheel follows what you play. One purchase, every update. Made by Beat Kitchen, a music production and teaching community.

About

Rubberband

Features
Read full description

RUBBERBAND is not a keyboard. It's an elastic surface where every line is a magnet: you glide, and GRAVITY pulls notes toward the scale. All the way up, you can't play out of tune. At zero, it's free glissando. In between, your ear decides. A microtonal synth built to be both an instant toy and a serious instrument — played like a theremin or a ribbon controller, tuned like the world. THE WORLD'S TUNINGS RUBBERBAND truly speaks microtonality — not an effect, the heart of the instrument. Arabic maqam, Turkish makam, Persian dastgah, just intonation, just blues and barbershop, klezmer modes, Southeast-Asian equiheptatonic, xenharmonic temperaments (19- and 31-TET, the harmonic series), Western scales — with region-adjustable neutral tuning. The engine thinks in cents: any tuning on Earth is within reach. 36 VOICES Plucked strings, basses, bowed instruments (violin, cello, kamancheh, sarangi), bells and bars, synth voices, the RUBBER↔STRING morph, the instruments of the East (oud, qanun, santur, ney, zurna, duduk), and granular clouds. Every voice is physically modelled and rendered in real time — no samples. EXPRESSIVE UNDER THE FINGER (MPE) Pressure is dynamics; gliding along a string changes the colour, from sul tasto to ponticello; vertical is pitch. Tilt the phone and it becomes an axis of expression. MPE MIDI out drives your other synths with the same gestures. LISTEN TO THE ROOM RUBBERBAND hears the music around you, detects the key, and tunes to it. Play along with anyone, in tune. ALSO A DRONE holding the tonic under your playing, a sympathetic halo that rings the neighbouring strings, a LOOPER to stack loops, and recording your takes straight to your device. IN YOUR LANGUAGE Full interface in English, French, Spanish, Italian, Portuguese (Brazil), German, Turkish, Japanese, Simplified Chinese, Korean and Arabic — with real musician vocabulary in each, not machine translation. Haptics, Metal rendering, fully native. No account, no ads, no data collected — the microphone is analysed locally and never recorded or sent. FREE, THEN PRO Start free: the full elastic surface, starter voices, and a taste of the world's tunings. The RUBBERBAND PRO unlock (one-time purchase) opens all 36 voices, the full catalogue of world tunings, recording and sharing, MPE MIDI output, MOTION and LISTEN. One-time purchase. No subscription.

Screenshots

Beat Kitchen Harmonic Synth4 screens
Rubberband4 screens

Verdict

The call

The clearest difference is update cadence: Beat Kitchen Harmonic Synth at every 3 days against Rubberband's monthly. On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Beat Kitchen Harmonic Synth sells 1 one-off in-app purchase and Rubberband sells 2 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Beat Kitchen Harmonic Synth ships an update every 3 days, Rubberband monthly. The most recent releases landed on October 24, 2026 and October 25, 2026 respectively.

Scorecard1 real difference · 9 level
Beat Kitchen Harmonic Synth versus Rubberband: the parameters behind the verdict, then further details
ParameterBeat Kitchen Harmonic SynthRubberband
PriceFreeFree
Rating4.8 (12 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings12 — better—
Update frequencyEvery 3 days — betterMonthly
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, iPadiPhone, iPad
Requires iOS16.0 — better17.0
Further details — not scored
Size60 MB3 MB
Age rating4+4+
DeveloperBeat Kitchen LLCThinkspark

In-app purchases

1 purchases

Beat Kitchen Harmonic Synth

One-time1
  • Full Unlock$14.99
2 purchases

Rubberband

One-time2
  • RUBBERBAND PRO$12.99
  • RUBBERBAND STUDIO$12.99

Questions

Is Beat Kitchen Harmonic Synth free?
Beat Kitchen Harmonic Synth is free to download, with in-app purchases available.
Is Rubberband free?
Rubberband is free to download, with in-app purchases available.
Do Beat Kitchen Harmonic Synth or Rubberband have ads?
Neither Beat Kitchen Harmonic Synth nor Rubberband shows ads.
Which is updated more often, Beat Kitchen Harmonic Synth or Rubberband?
Beat Kitchen Harmonic Synth ships an update every 3 days, and Rubberband monthly. Most recently, Beat Kitchen Harmonic Synth was updated on October 24, 2026 and Rubberband on October 25, 2026.

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