From Sound-on-Sound:

The world’s first commercially available string synthesizer, the Eminent 310, came from an unlikely source, a Dutch home organ manufacturer. It was further advanced through an even more unlikely partnership, with the legendary American synth makers ARP…

In 1972, the same year that Freeman demonstrated Prototype #3 of what would eventually become his String Symphonizer, at the Frankfurt Musikmesse, the world’s first actual string synthesizer appeared. Utilising quite a different approach to generate its ensemble effect, it was the grandfather of almost all string synths. Yet, despite its importance, it went almost completely unnoticed. This is because it wasn’t a ‘pro’ keyboard at all. Manufactured by the Dutch company Eminent, it was a home organ: the Eminent 310 Unique.

The article continues here: SoundonSound