BeepStreet Drambo

There has been a great deal of interest in it since it was first announced. In recent months, a number of videos have been posted demonstrating its many features. After a long and desperate but also somewhat entertaining wait, Drambo was officially released to the public on April 1st, 2020.

Drambo is a sequencer and easy-to-use modular synth with user sample support. For an FAQ, scroll to the end of this article.

App type: App and AUv3

App store link:

Developer: Beep Street

Developer AB Forum Handle: @giku_beepstreet


NOTE: Some of this page and some videos below were created while the software was in beta. The software was released to the public on April 1, 2020.

Drambo is a virtual modular synthesis and sequencing studio that consists of modular synthesis tracks, each with a corresponding sequencer track. The synthesis tracks can be chosen by hitting the corresponding drum pads. An audio mixer channel representation of all tracks that also allows for scrolling through tracks can be shown by hitting the upper right “burger menu” symbol, while a grid representation of all sequencer tracks can be shown by hitting the upper right dot grid symbol. As Drambo supports both landscape and portrait orientations of your iDevice, more sequencer or modular synthesis tracks can be seen by turning the device into portrait mode. It can be a good idea to place tracks next to each other that may require simultaneous tweaking, especially when using AUv3 plugins that rely on visuals.

Drambo's sequencer is built around a pattern concept. Each pattern has a certain number of steps and repeats and unless the “Loop” symbol on the transport bar is enabled, all patterns will play in a linear sequence. After the last pattern has finished playing, Drambo will continue playing the first pattern again.

The sequencer has a modular concept, much like the synthesis modules but with features specific to sequencing. Sequencer step modules are called “Step Components” and they can be shown by hitting the STEP button on the right. Apart from the most common “Note” component, many other step components are available that perform certain actions or define conditions under which the following step component is executed. This is one way to play, for example, a sequenced note only every 4th pattern repeat or randomly at this position. Polymetric sequences with different sequencer lengths on different tracks can be achieved by adding a “Jump” step component on any sequencer step. It allows for jumping to any other step in the sequence as soon as the playhead in this sequence reaches that step.

In addition to the main sequencer tracks, there are sequencer modules that work like classic modular CV/Gate sequencers. The most important one would likely be the Misc ⇒ Gate+Velocity Sequencer module which can also used for controlling oscillator pitch.

Drambo allows you to connect modules without wires. Tapping on a signal port which is not yet connected will show all ports that can it can be connected to, which are all modules that are located before the module you're about to connect. When designing modular creations, keep this limitation in mind, as it may in some cases (instant Feedback) require a few duplicate modules to achieve the same effect as in classic modular systems. Connections are indicated in two ways: The color of a signal port is the same as the module it receives from, and when you tap on a signal port, both the port and the connected port will flash in orange color. Double-tapping on a signal port will open a popup menu to disconnect that port.

Routing is not limited to a track. You can also route signals between tracks, including track mixer modules in the “Main” channel. When routing MIDI signals, be aware that routing MIDI to a track will make the MIDI signal available to track modules, not to the sequencer.

There are different types of signals inside Drambo. Some of them are unique, others are interchangeable and only have different labels to facilitate a straightforward workflow. As of December 2020, Drambo works with the following signal types:

Audio, Pitch, Gate, Velocity, Time

These all behave like “analog signals” like you find them in hardware modular systems. Check Drambo's built-in manual (page 6) for details. These signals are interchangeable, you might need math modules to adjust their levels to work together as intended though.


A stream of MIDI messages. It's a unique signal that can only be used with modules that have MIDI ports. There's a number of modules available though to convert between MIDI and control signals.


Another unique signal that can only be used inside a Wavetable Oscillator rack, currently only suported by the “Wave effect” and “Wave filter” modules. (Tip: Here is where you can have low, high and band pass filters with arbitrary steepness by combining Wave filter modules and using your sampled waveforms processed to 2048 samples length.)

Modifying signals

Most signals (except “MIDI” and “Spectrum/Wavetable”) can be processed by a multitude of general processing, math, mixer and utility modules. One very handy module is the Graphic Shaper which allows for drawing arbitrary curves that map a unipolar or bipolar signal to an output signal. This could be a simple velocity re-mapper, a time signal groove quantizer feeding Gate/Velocity and CV sequencers or a value scaler to optimize MIDI control of certain parameters, but since it runs at full audio rate, it can also be used for wave shaping and more exotic sound design. By feeding it with a simple sawtooth oscillator which has Anti-aliasing turned off, you can draw any oscillator waveform.

Drambo offers multiple methods to manually and automatically change one or multiple parameters, knobs and buttons. They all have the same type of destination, the parameter(s) under control but they have different sources. These sources are available:

Parameter locks (p-locks):

These are tied to sequencer steps. Each step can store one or more value changes. Changes to parameters remain active until the next non-empty step in the sequence of the same track. Note that these are the only way to store parameter changes inside a sequencer pattern.


A wide choice of modulation sources is available. You can use LFOs, oscillators, envelopes, graphic modulators, or even the Flexi sampler which could be used to record an automation signal and play it back either whenever triggered, or in a loop and in sync with the pattern playback.


Independent from patterns and track modulators, scenes can store parameter changes as “presets” or “snapshots”, so to say. Up to 16 different snapshots can be stored and recalled on scene pads A to P, and choosing a scene is done by hitting either the left or right button next to the horizontal crossfader which will allow for seamless morphing between the snapshots stored on the scenes chosen on the buttons left and right from the crossfader. Like modulators, these are independent from the pattern sequences and will work globally.

Since february 2021, the Sampler can automatically import and map samples to appropriate key and up to 4 velocity ranges.

For this to work, your samples need to follow one of these file name conventions: {SampleName}_{NoteNameOr3digitNoteNumber}_{3digitVelocity}.fileextension

{NoteName}{space or _ }{optional: letter v}{3 digits velocity}

{NoteNumber}{space or _ }{optional: letter v}{3 digits velocity}

Upper or lower case shouldn't matter but make sure file names don't have more than two spaces or underlines, they separate file name from note numbers and velocity values.

Supported formats are M4A/AAC, MP3, WAV, AIF, any bit depth and any sample rate and 1 or 2 channels. Flexible sample rate support also allows you to adapt each sample's sample rate in order to save space, something that had often been done in 80s and 90s hardware samplers to get the most out of very limited RAM in these machines.

Sampler will try to map samples according to note name (also setting the root key from the given note name/number) and velocity between 001 and 127 for up to 4 samples stacked and velocity switched. Vertical and horizontal gaps are filled automatically by stretching the mapped range to the next neighbor in a hopefully sensible way.

Levels will be uniform across different velocity windows in order to not destroy the velocity response in a typical setup where you would follow the Sampler with an ADSR that already adds adjustable polyphonic velocity response.

Since auto mapping completely relies on sample names, you won't need any SFZ or EXS files for import, just the correct sample names. Batch renaming files can be done on MacOS using Finder rename or on Windows using the Multi Rename tool in Ghisler Total Commander. You drop all files into one folder, upload them to Drambo and in Sampler, use the “Create zones from folder” > “Select current folder” function.

Open the Drambo cookbook with tips and tricks about using modules efficiently.

  • Ben Richards has posted a number of Drambo tutorials, demonstrations and tracks on his YouTube channel
  • SoundForMore has posted a large collection of Drambo tutorials on his YouTube channel.

Quick start (6 minutes):

A more detailed tutorial (38 minutes):

A fun video teaser – Digital Katharsis 2 – from @Giku_beepstreet:

QuickStart — from bcrichards

Copy/Paste Trick

WaveSequencing Experiment

Tutorial Series (Playlist):

This section lists Drambo-related vieos some of which were posted while it was still in beta. Many of these were posted in theMonster thread on the Audiobus forum.

Publicly Accessible

Videos Marked Private

A number of videos have been marked private since they were originally posted, presumably because they contain content that is either outdated or that should be limited only to the beta test team.

@giku_beepstreet published this module list

  1. XY pad
  2. Reverb
  3. Reset time
  4. MIDI to CV
  5. Scale
  6. CV glide
  7. Frequency shifter
  8. Transient detector
  9. Half rectify
  10. Maximum
  11. AN kick
  12. MIDI monitor
  13. Recorder
  14. Mixer
  15. Flexi sampler
  16. Poly to mono
  17. X-Fader
  18. Decimator
  19. Env AD mod
  20. Audio input
  21. S&H
  22. Exp
  23. Shift time
  24. Retrigger
  25. L/R to stereo
  26. MIDI output
  27. Integrator
  28. MIDI CC
  29. Pulse divider
  30. Noise
  31. Env AD
  32. LFO
  33. Add
  34. Quantize
  35. Phaser
  36. Bend time
  37. Freq to CV
  38. Pitch (oct,semi,fine)
  39. MIDI delay
  40. MIDI humanizer
  41. Pan
  42. Env Flex
  43. AND
  44. Gyroscope
  45. Reverse time
  46. Multiply
  47. MIDI to Poly
  48. Shaper
  49. Shot sampler
  50. Filter
  51. Compressor
  52. Peaking EQ
  53. Pitch
  54. Amp env ADSR
  55. Cosinus
  56. Delay rack
  57. Gate+velocity sequencer
  58. Offset
  59. Graphic shaper
  60. Layers
  61. OR
  62. Voice selector
  63. Pitch shifter
  64. Scale time
  65. Clip
  66. Full rectify
  67. Gate inverter
  68. Sampler
  69. MIDI CC generator
  70. Amp
  71. Number
  72. Clock generator
  73. Env ADSR
  74. Slew limiter
  75. CV quantizer
  76. Procesor rack
  77. Impulse
  78. Instrument rack
  79. Oscillator
  80. Oscillator: Supersaw
  81. Graphic env
  82. CV to freq
  83. Envelope follower
  84. LFO (stereo)
  85. MIDI key pressure modulator
  86. Oscillator (semi)
  87. Bit redux
  88. Negate
  89. Amp env AD
  90. Sqrt
  91. Stereo to mono
  92. Delay FX
  93. Adder
  94. XOR
  95. Minimum
  96. Subtract
  97. CV sequencer
  98. Amp env AHD
  99. Counter
  100. Audio out
  101. Sinus
  102. AMP env AD mod
  103. Function
  104. Stochastic gate gen
  105. Comb filter
  106. Section
  107. 1/x
  108. Random
  109. Log
  110. Divide
  111. Pitch (overtone)
  112. Knob
  113. Oscilloscope
  114. Stereo width
  115. Delay
  116. Layer mixer
  117. Modal resonator
  118. Trigger button
  119. FM operator
  120. Mono to stereo
  121. Chorus
  122. Stereo to L/R
  123. Text box
  124. Voice number
  • Holding Mute and tapping on track will solo it, mute will remain blinking while such solo is enabled
  • Dragging unit slightly to the side reveals (+) button to add unit in between, when you release the finger while seeing the (+) button, the Add unit popover will show up and the unit will be added in the respective place.

Stems recording allows to save audio files into Drambo/Samples/Recordings directory. It works via “tape” icon in the top bar (left to BPM). There are same tape icons on each track within Main track (above solo button). By default, Master track stem recording is turned on (the icon is red), which means all the output from Master will be captured. You can select any number of tracks you want to capture for recording and each track will be saved into a separate file.

For starting stems recording, the tape in top bar must be on (red) and playback must be running. The moment the recording is started depends on:

  1. If the recording was turned on while playback was stopped, it starts immediately after playback is started
  2. If the recording was turned on while playback was running, it start immediately after recording tape icon is pressed.

Note you can find out if the stems recording is running by “pulsating” color of the tape icon.

To stop the recording, you there are also two options:

  1. Stop playback, which will immediately cut the recording the moment you hit the stop button.
  2. Turn off tape icon in top bar, then the recording will be stopped after the next bar, allowing you to record files that are stopped precisely on the bar end - perfect for using the stems as loops.

After a recording is saved, you see an information text with where the file(s) were saved, it should be Drambo / Samples / Recordings. The files are store in a directory named in format “[project name] - [bpm]” and files are named in format “[timestamp as YY-MM-DD m:s] - T-[track name]”.


  • beepstreet_drambo.txt
  • Last modified: 2024/04/10 19:56
  • by _ki