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Logan Electronics

Logan String Melody portable keyboard was in production from 1973 to 1982 being released in two versions. The instrument was manufactured under the brand name Logan, as well as a product of Hohner company. The keyboard was made in Italy.

The polyphonic instrument was characterized by such specs as a variable gain amplifier, as well as a BBD (Bucket Brigade Delay) chorus, which gave the sound that synth string section nuance.

The 4-octave keyboard supported split function (the lower zone was meant for Bass, the upper one was called Treble), each of which could combine 3 string sounds (Cello, Viola and Violin) using faders, including not only individual but also global ones for each zone - sustain and release, the lower range of sounds could be sculpted by using the Bass and Perc faders. Percussion bass sounds reminded more of a percussion sub bass with a pretty quick attack parameter. The different sounds were pitched in an octave from each other.
The first version of Logan String Melody had an Orchestra button with pre-patched settings that disabled fader functions for string voices. In 1977, the second version of the String Melody II instrument was released, which added 4 new presets: O (light chorus effect), ACC (accordion), SOLO (vibrato effect with the addition of chorus) and ORGAN (another nice phaser-like chorus).

As for the purely technical aspect, the sound generating started with a high-frequency square wave generator, then the signal was routed to the frequency divider, Mostek MK50240N integrated circuit (often used in the electronic organs back then, for the lower octaves SAJ210 were introduced). A square wave passed through a variable gain amplifier, then it was processed by a mixer, chorus and filter. Monophonic bass of the lower keyboard zone didn’t pass through the amplifier, but was affected by a low-pass filter. The chorus comprised two modules: a dual LFO and a triple oscillator, using a delay line as the main timing element (delay line oscillator). The oscillator was based on 3 TCA350 circuits - 185 MOS chain sampled an audio signal, FM modulated subsequently by a dual LFO.

String Melody may not have as many editable parameters as similar synthesizers produced by Roland or ARP, however, the instrument sounds excellent and by no means is a simpler alternative - String Melody has its own unique character of an Italian string synthesizer.
Initially, the keyboard was produced under the hardly known brand Logan Electronics. The second version of the keyboard brought the brand greater commercial success, and today you might find the “mark II” version of the synthesizer on the second-hand market. The original one is a real rarity. But why is Logan Electronics so hard to find as a brand of full value? It's because outside of Italy String Melody was distributed by Hohner International. Those instruments were badged Hohner String Melody.