An electronics magazine, Electronics Today International, published in Australia in the 1970s. In 1973, ETI commissioned Australian electronics engineer Trevor Marshall to design a monophonic, semi-modular synth whose design would be published in the magazine, subsequent to which the magazine would offer the synth to readers in kit form. Marshall designed two models, referred to as the 3600 and the 4600, with the latter being physically larger and more featured. The first installment of the design and construction articles ran in the magazine in October 1973 edition, and continued for the next two years.
The models were unusual in that, similar to the EMS VCS3, they used a pin matrix for patching. However, both models and the 4600 in particular were more capable synths than the VCS3. The basic specifications for the 4600 were:
- Four voltage controlled oscillators, with sine, triangle, sawtooth, ramp, and pulse wave outputs. Any of the four could be switched to a low range to act as a low frequency oscillator.
- Two multimode voltage controlled filters
- Two voltage controlled amplifiers, either of which could be used as a ring modulator
- Three envelope generators. Two were of ADSR type with an additional delay control, and one was a six-segment envelope. One of the ADSRs was dedicated to one of the VCAs; the other ADSR and the six-segment envelope were labeled as "transient generators" and were available on the pin matrix.
- A spring reverb and a five-band equalizer.
- A 48-note keyboard (F to E), and a two-axis joystick, having both axes patchable at the pin matrix.
In the UK, the electronics retailer Maplin picked up distribution of the ETI synths and sold them under its own name, labeling the two models as the 3800 and 5600s respectively. These had somewhat revised panels, but were otherwise identical to the ETI products. As was the case with the ETI synths, these were available as kits only. Sales continued until about 1978.
Today, both of these models are hard to find. As is the case with most complex kit-built products, many of the kits purchased were either never completed, or were assembled poorly and did not work properly. To come across one in good working condition is rare, and such are quite valuable on the collectors' market.