WARBL doesn't make any sound on its own, so you'll need to plug it in to a MIDI host device. This is very easy, because most portable devices (and desktops) support MIDI, and there are lots of free or inexpensive MIDI apps. I highly recommend iOS (Apple) devices because they handle MIDI very well and are easiest to set up. Some suggestions for iOS apps include Appcordions Celtic Sounds, Universal Piper, and Roland Sound Canvas. Connecting WARBL to an iOS device also requires the Apple Camera Connection kit or equivalent adapter that converts USB to Lightning plug.

Yes, WARBL works with any device that can recognize MIDI controllers. Some devices may have more latency or take additional time to set up than others. Android phones and tablets usually require a USB On-The-Go (OTG) adapter to connect to WARBL. If you'd like to have tin whistle sound on Android, Windows, or Mac, you can try using an app that plays SoundFont files, like FluidSynth, for Android, or Sforzando for Windows or Mac. You can then use those to play the tin whistle SoundFont file that I made, which you can download here. I also found a bagpipes SoundFont online that works well and contains two different GHB as well as smallpipes sounds. You can download it here. With this SoundFont, set the key in the in the WARBL Configuration Tool to A3. Drones can be controlled with MIDI note 45. There is more information about it here.

The Configuration Tool (and the WARBL iOS app) is only designed for adjusting the settings on WARBL, and not for producing sound. Although it includes a simple electronic sound, that is intended just for quickly testing settings. An app or hardware MIDI host is required for producing high-quality sound. Please see the top question above for a list of low-cost MIDI apps that work well with WARBL.

The hole spacing is the same as that on a great highland pipes standard practice chanter. I arrived at that as a good compromise that will feel familiar to both whistle players and pipers. Here's a photo of the WARBL hole spacing.

WARBL produces no sound on its own, and the 3.5 mm jack is only for the optional "bell" sensor for emulating uilleann bagpipes. If you use the bell sensor, be sure to also use the special right-angle micro USB cord with the slim plug (supplied with the sensor). Many micro USB cords have a wider plug that could put too much pressure on the sensor and cause damage to the device.

I'll consider adding more fingering patterns if they are ones that are close to real intruments and will have broad appeal. Because of limited space, I do need to be somewhat selective. Feel free to contact me with suggestions.

Yes! WARBL is open-source, so you are free to modify the software and use it as you wish, as long it you keep it open source. It is available on the Documentation page and uses the Arduino language. Information about uploading the software from the Arduino IDE is available on the WARBL GitHub page. If you aren't comfortable with coding but have ideas for software improvements, feel free to contact me with suggestions for future updates.

Here's a screenshot of an example setup for controlling drones and regulators. Byte 3 in the button configuration section is the velocity (volume) of the regulators, so you can adjust that to your preference. The drones will turn on and off if you click button 1 while covering only the right index-finger hole. There is a full list of possible drones and regulators here (click on "more" to see the full description of the app with command list).

Many connection problems with MIDI apps can be solved by forcing the app to close (on iOS, double-click the home button and swipe the app upward), unplugging/replugging WARBL, or a combination of those two things. Note: If you have been sending CC messages from WARBL to control the volume of the app with the pressure sensor, after every breath, the volume of the app may be turned down to zero. It is easy to forget about this after changing settings, so if your app isn't making sound, check to make sure the volume control in the app itself isn't turned all the way down.

Chrome sometimes freezes if a MIDI device that it's connected to is unplugged before closing the browser. There is now an option in Chrome that solves this problem if you are using Windows 10, which involves telling Chrome to use the Windows built-in MIDI API. In your Chrome address bar, enter this address: chrome://flags/#use-winrt-midi-api Then, change "Use WIndows Runtime MIDI API" to "Enabled". You can also use Firefox or Safari with the Web MIDI plugin, which seems to be quite stable.

WARBL uses MIDI CC messages on channel 8 to communicate with the Configuration Tool. If it has been connected to the Configuration Tool, it will continue sending messages until it is unplugged. Most MIDI apps and modules will ignore CC messages in this range (CC 102-119), but if they are causing any problems you can just unplug WARBL and plug it in again to make it stop sending.

Bluetooth audio unfortunately has too much latency (delay) to work with MIDI devices, so it would be very difficult to play using Bluetooth audio. Wired speakers or headphones are recommended instead. Please see the question below if your device doesn't have a headphone jack.

Unfortunately Apple has made it more difficult to use USB MIDI devices by removing the headphone jack on newer products, but you can use an adapter to add a headphone jack. I have tested this adapter with a few iOS devices, and it seems to work well. A USB hub with an internal soundcard is also a good option. I have been told that this one in particular works well with WARBL, and it also allows you to power both WARBL and your iPhone/iPad using a micro USB cable. A disadvantage of the second one is that you also still need the Apple Camera Connection Kit to plug the above adapter into your iPhone or iPad.