With the 4027 VCO and Tonus VCF, G-Storm Electro shows analog reproductions of the ARP 2600 oscillator & filter for the Eurorack format.
2020 is definitely the year of the ARP 2600. We have seen many replicas from Korg, Behringer, and smaller manufacturers in the last few months. Now G-Storm Electro also makes an ARP 2600 but in Eurorack format. He currently does not offer a whole system but two parts of the synth: the VCO-2 named 4027 VCO and Tonus VCF, an analog recreation of the 2600 filter. Important to mention, the filter is already on the market since 2017.
Both modules are hand-made in the USA and are limited in number. It is not known whether he will bring all parts of the ARP 2600 to the market as Eurorack modules, it would be nice
The 4027 VCO is a faithful analog recreation of the colorful VCO-2 tone source of the ARP 2600 Synthesizer realized with discrete components in 10HP. It has the waveforms: sine (-4v to 4v), triangle (-4v to 4v), sawtooth (0 to 6v) and pulse (0-6v) w/PWM. It keeps the circuit as close to the original a possible: a matched transistor pair, an Interfet premium dual FET can (because that beautiful Sine is worth it), temperature compensation resistor for tuning stability, low ESR styrene oscillation capacitor, 5-NPN monolithic substrate transistor array, precision Tune and Tracking trimmers, and the 70s spec op amps which are still being offered today.
The 4027 VCO has requisite LDO voltage conditioning to isolate the oscillator tuning from your systems power rails. While each module is fully tested and calibrated, it may need minor TUNE trimmer correction after warm-up to account for variances in different systems. It includes three 30mm throw illuminated Bourns slide pots (frequency, fine-tuning, and pulse with) and three 20mm throw Alpha CV slide pots. Individual waveform outputs, a v/oct input and two CV inputs (wide FM, reduced FM (vibrato)) are onboard.
The Tonus VCF (black/white panel) is a faithful analog recreation of the ARP 2600 filter and is named in honor of the Tonus APP logos that adorned int the first 2600s. It offers a 24dB /octave lowpass filter with resonance that is borrowed from the Moog transistor ladder filter but it isn’t a copy. ARP used different components, used a different buffer circuit, and modified the resonance feedback design.
Like the 4027 VCO, the developer also keeps the design of the Tonus VCF as close to the original as possible including transistor selection, a NOS dual FET package, and a temperature compensation resistor to prevent excessive drift. On the interface, you can find two audio inputs with attenuators, two CV ins, and illuminated Bourns Slider pots (frequency, fine-tuning, and resonance).
G-Storm 4027 VCO is available now for $265 USD, the Tonus VCF for $180 USD.
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