Full disclosure: Soundyan gave me a free license key of Interstellar Waterphone to test and make a review of it.
Review done with Logic X (AU) under High Sierra using the 1.2 version of IW. From the web site: "There is no 32-bit version yet. Only 64-bit at the moment. MacOS version is for both x86 and ARM processors.". Windows version also available. System requirements: 64-bit Windows 7 or higher, Windows 10 is recommended.
Simple installation/authorization process (email + key). Soundyan offers online and offline registration if your main computer doesn't have access to Internet.
Downloaded installer file is 974.1 MB. I would have preferred the option to install the needed audio sample files to an external disk, but there's no way doing it yet.
Controls available to sculpt your sounds. The amp envelope (ADSR), the Start Offset and two filters, currently a low cut + low pass ones.
Interstellar Waterphone is quite a niche instrument. It comes with what Soundyan called sound banks. There's six ones named "Interstellar Water", "Dry Space", "Dark Chimes, "Light Path", "Full Proximity", and "Slow Voltage". From the web site: "The waterphone sounds have been recorded using different Interstellar Waterphone instruments made exclusively by waterphone.pl". Samples sound great and offer variety. What's interesting with this plugin is his playable/customizable aspect. While most of the time Waterphone's Libraries are aiming at FX/Sound Design work, depending of the chosen instrument (Sound Bank), you'll be able to play some melodicmusical content too.
Playing IW using a MIDI controller.
While going true different octaves, it'll play different set of samples. Extended on few notes, or many... The dev surely didn't want to over stretch the audio sources. It'll have an effect on the available notes/sounds needed for what you're looking for. E.g., play a melody vs creating atonal Sound FX or simply create some ambiances. The first bank (Interstellar Water) is out of tune. Of course the "water effect" causes this typical Waterphone note bending effect. However, I felt that a little pitch tweaking could have made it usable for melodic content. Using a pitch bend automation as a work around, I could get clause enough to handle a melody... Dry Space has some register where the tuning is definitely manageable. I was rapidly able to make an interesting layered sound with an acoustic piano. In that case, I made used of the IW's Start Offset feature (setting to adjust the starting point of samples). Slow Voltage has great potential for melodic/musical material. Waterphone produces some complex sound not necessarily made to play melodies at first, but IW will let you explore this territory while imposing you some limits. If you're aiming for the sound FX/ambient territory, you'll be pretty well served with this instrument. There's enough tweaking options to make IW quite versatile. Mixed with the Virtual Bow (following), it can become addictive.
Playing IW using the Virtual Bow (Waterphone icon knob).
It'll generate a MIDI sequence of notes based on intervals. It works in conjuncture with the Steps, Offset, Bow Velocity, and Velocity Randomness sliders. Steps: 1 = semi tone, 2 = whole tone, 3 = minor third, etc... Offset: -12 to +12 semi tone to change the sequence starting note. The other two are pretty self explanatory. The best will be to assign them to some MIDI CCs. MIDI assignation process is straight forward. Right click (Mac) to "learn/unlearn" the desired CC. That would have been great to have a way to restraint the register of the Virtual Bow. Some app will let you do that when using MIDI CCs, but it would have been convenient to have this option internally. But what I found really missing is the option to choose scales. Even better. Holding a chord and have the Virtual Bow arpeggiating it.
Other welcomed features Scalable UI. Show/Hide visualiser. Double click to default parameters. Active voices monitoring (max 256).
All in all, Interstellar Waterphone is an interesting and good sounding instrument. The better way to know if it fits your need is to try the demo version. Here's the Demo Mode limitations (from the web site):
"The unregistered and not activated software can run in demo mode with limited functionality. List of limitations Time limitation - after some time the application will turn off the audio. Sound set limitation - Only two sound sets are available in demo version, instead of six. Commercial limitation - You can't use the Interstellar Waterphone software for commercial purposes without purchasing a license."