We are Outer Space Sounds (OSS), a global team dedicated to the creation of sound hardware. Our motivation is to expand the practice of sound synthesis by producing inspiring, sonically powerful and easy to play devices.

What is MOSTRO?
MOSTRO is a polyphonic Frequency Modulation (FM) hardware synthesizer designed and built by Outer Space Sounds (OSS). It features full control of each synthesis parameter allowing continous sound manipulation, offering a new color palette complementary of typical additive/subtractive synthesizers.
Why is MOSTRO an FM synth?
Hardware FM synthesizers have been historically labeled as "very powerful yet difficult to control" because when tweaking some of the main parameters the sonic result was somehow unpredictable. In Outer Space Sounds we thought of this context as a great opportunity to bring FM back to hardware by designing new interaction paradigms which make the MOSTRO a straightforward synthesizer, so when you tweak a parameter you have an idea of where you are heading.
What are the specs of the current MOSTRO prototype?
  • It is a 4 voice polyphonic synthesizer each voice having its own envelope, LFO and sub oscillator.
  • The voices are composed of a sinusoidal carrier/modulator system where the carrier modulator ratio, the modulation index, and the feedback can be controlled from the interface.
  • It has a delay unit and a glide control.
  • It has an internal memory to store up to 100 presets.
  • It has MIDI in and out connections so it can be controlled via external hardware.
  • It has a one octave keyboard that when set to monophonic mode can be adjusted to play different scales (from chromatic to exotic scales) and in polyphonic mode can play chords in different keys.
  • The MOSTRO is packed in a wooden chassis with a painted steel cover.
What is the current status of the MOSTRO?
So far we have developed our first MOSTRO prototypes and for months we have been testing its performance, checking that everything works fine and our production processes have the high quality standards we need. We have a direct connection with the people that manufactures each detail of the synthesizer and have used the best circuitry design practices as well as the best electro-mechanical components. These first prototypes are fully functional synthesizers but in the process of testing them we have designed some extra features that will be included in the first edition MOSTROs which will be available for sale.
So what are the extra features of the MOSTRO that I can buy?

First we have improved all the inner components of the MOSTRO to be top of the line so it can have a healthy life once we ship it. Additional features are:

  • All buttons are high quality Cherry ML buttons, very popular in the keyboard modding community, due to their nice tactile response and durability. They can be tweaked millions of times without any damage.
  • All knobs have been specially selected to ensure the best tweaking sensation, precision and durability.
  • It will have a looping system.
  • It will have voltage control (CV) inputs so that it can be part of your modular rack with four CV and one Gate inputs.
So how can I get a MOSTRO?
We are planning a first limited edition of numbered MOSTRO synthesizers that you can pre-order on the "Get Involved" section below. If you have any extra questions please get in touch with us.


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