Robin that have been helping Musical Android out some times lately made me aware that Jasuto was now just about a Euro/Dollar (about two weeks ago and being full up mentally I thought that I mentioned it but alas no!). So this is definitevely one of the more interesting apps on Android for anyone that likes possibilities and depth.
My guess is that the price is lowered as the developer is indisposed for a indefinite time and so can not support the application. It seems that some people have problems with the microphone input for example but would say that even if there is some things that do not work properly it is totally worth it as even a fifth of what the app can do is worth much more.

Google Play:
https://play.google.com/store/apps/details?id=com.jasuto.droid&hl=en

It is a nice video to see as there is a sense of the potential of Jasuto.

One of the more interesting apps for Android has been Jasuto but for me I have been waiting that it would get updated before wanting to use it as it seemed pretty buggy and it had been out for a long time seemingly not being supported anymore making compatibility with newer Android versions shady. In either case now it had a big update and finally there is a fun shiny "new" toy for me and maybe for you?
My impression is that the Android versions it allows for on the Play Store are set to low.
So to be aware that it could be problematic on a device that is not strong even if it is said that it should be working.

So here are all the specifications:
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Jasuto allows you to visually construct your own synths/effects, and use them to make sequences all on your device! With the addition of a fully-featured sampler you can now record/resample/edit, and even create entirely new samples by drawing right in the app.

Jasuto uses the relative position of nodes and their connections to control the sound. So the scene not only represents the synthesis structure, but also a custom multi-touch control surface. Motion can be recorded per node giving you rich, flexible automation.

Connections can be created automatically by simply dragging nodes around, or manually. Each wire can be double-tapped to allow even more control of each connection.

Jasuto comes installed with 75+ modules as well as 200+ pre-loaded scenes and samples. Each of the modules have been hand-optimized for your device's CPU, allowing you to create extremely complex scenes.

[NOTABLE FEATURES]

- Anti-aliased oscillators with hard-sync, FM, PWM, PM 
- Analog style filters (ap, lp, hp, bp, ladder emulation) 
- Signal control (compressor, limiter, gate, follower) 
- Zoomable sampler editor with several loop modes (normal, 1 shot, ping, granular) 
- ADSR envelope editor 
- Multipage/octave sequencer 
- Tape style analog delay 
- Reverb, phaser, several waveshapers 
- Resample/record the current playback 
- Audio copy via the pasteboard 
- Incoming OSC for notes and CC's

[FEATURES AND UPDATES INTRODUCED IN v1.6]

- Updated UI graphics 
- Zillions of bugs squashed 
- A shiny new manual 
- Added background audio support 
- Low latency audio (256 samples) 
- Sample sharing through SoundCloud 
- Dropbox syncing of samples/scenes 
- New ADSR2, AP, Brick, EXP, Mix, Power, ZeroX, Tanh, Gain Node Modules
- High Fidelity (HI-FI) audio
- Additional Node Modules: Chorus, Detuned, Dirty, Morph and Space 
- MIDI-In & Out support with tempo sync 
- Nodes can now be grouped together 
- Solo nodes and groups 
- New Convolution Module 
- New nodes: Abs, Clamp, Delay2, Pan, Group/GRecv/Gsend, MidiNote, MidiCC & Synced 
- Sampler node is now in stereo & has higher quality interpolation 
- Bands can now edit individual bins while frozen 
- Fixed insert bug 
- Additional bugs and behind the scene fixes 
- Delay nodes are tempo syncable 
- LFO is triggerable, syncable & now has 4 shapes 
- New Scenes and Samples added

[NOTE]
We've only been testing version 1.6 on modern Android devices (Arm7 based with or without NEON). If you have an issue with a device, please post in our forum.
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Here is a demonstration of the app on a iOS device and you get a idea of how deep the app can be. There is also some older tutorials that the developer made but not for the new update. There is also the video on the Play Store that seems like it is not uploaded to YouTube. Luckily there is a new manual available on the website and much more information plus a forum.

Play Store link:
Jasuto Modular Synthesizer

Homepage:
http://www.jasuto.com/main/