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In a music world that's becoming increasingly digital, analogue is a word that's being used more and more

The phrases 'virtual analogue' and 'analogue sounding' are used so much these days they've become almost meaningless. Are claims of an anologue heritage from Alesis, a company with a long and illustrious history of digital technology, more than just a marketing ploy?

Specification

The first thing you'll notice with the Andromeda is its sheer bulk. The next thing is its weight – we could only just lift it.

Alesis claim that the Andromeda (also known as the A6) is a '16-Voice Real Analogue Synthesizer'. What you get for your money is a two-oscillator per voice synth with two filters, three envelopes, ring modulator, three LFOs and sample and tracking generators.

It's worth pointing out that while the signal path is completely analogue, the control of all these elements is handled by a Motorola Coldfire microprocessor.

The envelopes and all other modulations are done in software, but unlike some earlier designs, these are generated at 16-bit and are fast enough to compete with, or even surpass, their analogue counterparts.

Circuits

The Andromeda design team allegedly had a synth 'shoot-out' before deciding on which oscillator and filter designs to use in the Andromeda.

They decided that the Moog Modular and Oberheim Four Voice were the 'best-sounding' out of a renowned field.

This led the guys at Alesis to settle on the Moog 921 VCO (voltage controlled oscillator) and the Moog 904 low-pass filter (24dB/ octave) paired with the Oberheim SEM multimode filter (12dB/octave) – both undeniable classics.

Alesis then built their own take on these circuits from discrete components (you know – resistors, capacitors and transistors) before having the designs re-engineered as integrated circuits.

Modulation

Like its Moog forebear, each VCO in the oscillator (Osc) section has sine, triangle, saw and square (pulse) waves available simultaneously.

Each waveform can be switched on and off individually, while the square wave has adjustable pulse width and level controls.

The two VCOs can be hard or soft sync'd and Osc 1 can be frequency modulated by Osc 2. The oscillators are freely tunable in semi-tones, cents and millicents (1/10th of a cent) and Envelope 1 is hardwired to VCO pitch.

The VCOs are mixed together in the Pre Filter Mix module alongside a ring modulated output, noise (white, pink, red or even an external audio signal) and sine wave sub-oscillators one octave below the fundamental.

All levels are completely variable and, once again, can be modulated in numerous ways.

Care needs to be taken with the levels though, as it's easy to overload the internal mixer if everything is turned up.

This is perhaps the price you pay for a true analogue signal path, as analogue synths can create sounds with a vast dynamic range, making it easy to use all the available headroom.