Optimus ConcertMate 990 Keyboard (Rebranded Casio CTK-601)

Experience the vintage charm of the Optimus ConcertMate 990, a rebranding of the popular Casio CTK-601, packed with classic sounds and advanced features. This 61-key keyboard combines expressive, touch-responsive playing with a wide selection of tones, rhythms, and built-in effects.

This is an interesting take on a home / prosumer  keyboard.   Like many of the nicer 1990s keyboards this one has pressure sensitivity (velocity sensitivity), pretty decent sounds and Midi input and outputs, and some decent onboard effects (reverb etc.) It also has 61 keys, step up from some of the smaller 49 key keyboards out there at the time.

But what really sets this one apart is how you can manipulate the built in sample sounds by applying envelopes to both the volume of the sound and the pitch of the sound across the various sections of the waveform (Attack, decay, sustain, release).   So a piano or a violin sound can take on a totally different characteristic, sounding like totally different instruments when these changes are applied.

This model, the Optimus 1200 (sold by Radio Shack) appears to be a Re-branded Casio, similar to the CTK-631, judging by pictures that come up on image searches and comparing to this keyboard.  The models in the Casio CTK 600 line and their Optimus counterparts all have similar envelope controls to this.

Key Features:

• 200 Tones & 100 Rhythms: From pianos and strings to synths and guitars, this keyboard covers a wide range of musical genres, providing endless creative possibilities.
• Custom Tone Synthesizer: Tweak your sounds using the custom synth functions, allowing you to shape both the amp envelope (decay, sustain) and the pitch envelope (vibrato, others), a feature highly sought after by lo-fi electronic music producers.
• Digital Reverb System: Enhance your sounds with built-in reverb (Hall, Stage, Room), giving your music depth and ambience.
• 2-Way Multi-Track Memory: Record and layer multiple tracks for creative compositions using the memory track/drum pad system.
• Envelope Controls: The Amp Envelope allows for precise control over the sound's attack and decay, while the Pitch Envelope modulates the pitch over time, offering dynamic vibrato and other modulation effects—essential for crafting unique, evolving sounds in electronic and ambient music.
• 61 Full-Size, Touch-Sensitive Keys: The keyboard's velocity-sensitive keys respond to your playing dynamics, providing a more expressive performance.
• MIDI Connectivity: Perfect for studio setups or interfacing with external devices.

The ConcertMate 990 offers a wide variety of tools to expand your creative horizon. It's particularly beloved in the lo-fi and experimental electronic music scenes, thanks to its tweakable synth features and warm vintage sounds.

This is a rare chance to own a piece of retro music gear that combines ease of use with deep sound design potential.