Voxkit

Voxkit 1.2 is being rebuilt; it'll be back in a new form, early 2014!

Voxkit is a MIDI drum controller with a twist. In addition to touch pads on the screen, you can trigger notes with sound. Clap your hands, tap a pencil on a desk, or use your voice -- Voxkit detects the tone of the sound, to trigger a sample from the app, or a MIDI note.

You can customize the sounds that Voxkit makes -- add WAV format samples through iTunes File Sharing, to make the drum kit of your dreams.

What's Different about Voxkit

Unlike most drum pad apps, Voxkit uses external sounds to trigger notes. For drumming, the timing of sharp percussive sounds has to be very precise; any variation is easy to hear, and ruins the musicality. There are two main issues to pay attention to: latency and jitter. For iOS devices, there's a delay of around 10ms between a touch on the screen, and software detecting that touch -- this is latency, and means that at best, an app can produce sound no sooner than 10ms after the touch. In practice, the real latency of converting a touch into a sound is in the range of 20 to 30ms -- just at the edge of what would be acceptable for a keyboard synthesizer, but not great for drums. Even more problematic is the jitter -- variations in the delay by 5 to 10ms, making the drumming sound uneven.

The audio pipeline for iOS devices has been designed to minimize both latency and jitter -- Voxkit can respond to a sound in roughly 12ms, with almost no jitter -- this makes drum triggering much more accurate, and makes playing easier and more expressive. Voxkit can identify up to four different sounds (but only one sample can be triggered at a time). The best way to use Voxkit is to have background rhythm instruments such as shakers be part of a sequenced track -- with Voxkit being used to play samples such as the snare or cymbals, in the "front" of the mix.

There are hundreds of apps that will let you program drums on a grid -- and you wind up with something that sounds stale and mechanical. Break free with Voxkit!

How to Use Voxkit

First things first: when you open the app, you will see either a four-by-four grid (on the iPad), or four large buttons, all on the center of the screen. Touch these, and you should hear different percussion sounds. Clap your hands, and you should see and hear drum sounds triggered. A slider on the right of the screen adjusts volumes. For the iPhone and iPod Touch, touching on the left side of the screen will select different sets of four pads each. For all devices, the left side of the screen will change what samples a sound triggers.

At the bottom of the screen, there is a gear icon; touch this, and the configuration screen will appear.

Configuration

The iPad has all configuration controls on a single screen. For the iPhone and iPod touch, the controls are arranged into three tabs. For both, touching "Voxkit" in red at the top right will take you back to the pad interface.

The Main On-Off Switches

There are four main toggle switches that control Voxkit. If something doesn't work as expected, check these first.

  • Sound triggers notes indicates if Voxkit should listen to sound. One of the key features of Voxkit is the ability to trigger drum sounds by tapping on a desk, clapping your hands, or beat boxing. If sound triggering is turned off, Voxkit will only respond to touches on the screen. Note that you may need to use headphones, to prevent a sound generated by Voxkit from triggering another sound. There is also a slider below this toggle button, to adjust how sensitive Voxkit is to sound. If you have a quiet environment, you can make the app more sensitive by moving the slider to the left. If you are in a noisy environment, you may need to turn off sound triggering entirely.
  • CoreMIDI and DS MIDI toggle switches turn on and off MIDI note sending. If you are only using internal samples, it's safe to leave these off. If you're connecting to external instruments, sequencers, or other apps on the device, turn them on. CoreMIDI is the best option for connecting to Mac hardware, apps on the same device, or to wired MIDI connections using either the Apple Camera Connection Kit, or things like the iRig MIDI interface. DS MIDI is a good way to connect to Windows and Linux PCs over WiFi -- there is a good open source server which we recommend. DS MIDI also works with Mac hardware.
  • Play Audio Samples will toggle the playing of samples from Voxkit. If you are using another app, or external hardware to generate sound, you can turn this off. If you want to hear the sounds from Voxkit, turn it on.

Configuring Pads

Each of the sixteen pads of Voxkit can be configured to play an audio sample, or send a MIDI note. To change the sample or note assignment, touch the relevant pad on the four-by-four grid, and then use the up and down triangles to change the settings. If you are changing the samples, you should hear each sample as you tap through the options. MIDI notes will be triggered as you work through the options. Voxkit contains sixteen different samples; you can add your own through iTunes file sharing (described in more detail below).

To train a pad to recognize a particular sound, touch the "train" button; it will switch to "recording" in red. Make the sound you wish to use to trigger the pad a few times, and then tap the training button again. The sound should be sharp, percussive, and distinctive. Voxkit uses the tones of different sounds to determine which note to trigger -- so the tones must be distinct. A tap of a pencil on a wooden desk will have a different tone than tapping on a glass. You might beat box, and a hissing sound to emulate a cymbal is different a "t" sound to emulate a snare drum. You may have to experiment a bit to find the best way to generate sounds that Voxkit can reliably tell apart. Each pad can also have audio triggering turned off; toggle the microphone icon for the pad.

Best practices: if you are only interested in triggering one or two sounds (many drum parts are primarily bass drum and snare), disable the audio triggers for the pads you are not using. If only one pad is enabled, you'll always get the right sound. When two are enabled, recognition is still good as long as the sounds are distinct. As you enable more pads, the chance of an error increases. Voxkit has limited the number of active pads to four, as this was the most that could be made reliable (with careful playing and well chosen sounds).

Using the pad groups: Voxkit has four different groups of pads (red, yellow, green, and blue); you can switch between them by touching on the left side of the main screen. Only one group of pads responds to audio at a time -- so if you have a drum part where the first section uses two types of drums, and then switches to two other types of drums -- you could configure the red pads to respond to two different sounds, and then the yellow pads to respond to the other sounds. As you play, switch between the groups as needed -- this gives the best accuracy in detecting the right tone.

MIDI Configuration

In addition to turning on and off CoreMIDI and DSMIDI, you can change the MIDI channel that Voxkit uses to send notes. Most drum synthesizers and MIDI files use channel 10 for drums. If Voxkit notes are triggering other synth tones unexpectedly, check to see if the synths are set to "omni mode," where notes on any channel are played.

Next to the midi channel control is a control for tempo. When recording MIDI events, Voxkit will use the tempo when creating a MIDI file. If the tempo is set to match that of a sequencer app, the timings of all notes should be correct.

Backing Tracks and Recordings

Recording within the app is currently disabled, while we sort out a few bugs. We'll add in recording within the app, and audio copy and paste, in the next release.

Playing Voxkit

To play Voxkit, either touch the pads on the screen, or make sounds to trigger notes. Switch between groups of pads with the control on the left side of the screen, and adjust the volume with the slider on the right.

The volume of notes triggered by sound triggers will adjust with the volume of the sound. If you make a loud sound, you should hear a loud sample. If you make a soft sound, you'll hear a soft sample. The variation in volume is one of the things that makes "real" drumming sound different from a drum machine, and gives it the human touch.

Recording

Many musicians use their iOS devices for portable recording, or as a sketch pad for song ideas. Most drum apps and sequencers feature a grid for each measure, with drum parts being programmed in. While this might be appropriate for some types of music, most drummers usually have a swing to their playing, moving slightly ahead of the beat in driving sections, and then laying back into the pocket in other parts.

To record drum tracks that sound live, rather than sequenced, connect Voxkit to an Audiobus-compatible app, and record there (we would recommend MIDI Control, of course!). We'll expand support for in-app recording in the next release.

Questions? Comments?

Please feel free to contact us; we'll do our best to resolve any problems you might run into.