Abstrakt Instruments Avalon
The praised Avalon not only tries to be an exact-as-possible 303 clone, also it expands the possiblities and amount of features of the bassline in almost every respect. From the sub-oscillator and external input, the enhanced cutoff range, the amount of envelopes, variable slide time, over an arpeggiator, enhanced sequencer up to a plethora of connections and the rock-solid build quality.
Despite its extended feature set the analog core of the Avalon is based on the TB-303's circuitry and their special components like carbon film resistors, poly foil capacitors, particular transistors and even the genuine integrated circuits (ICs) from back then. An authentic sound is possible without a doubt.
The low amount of controls is fine in all its minimalism, but there's so much more potential which the Avalon bassline does exploit. There are potentiometers for the level of the sub-oscillator or the external audio signal, filter tracking as well as a number of envelope parameters: accent decay time; VCA decay time; attack and decay time of the utility envelope as well as its bi-polar modulation intensity to VCF and VCA. The VCO has been enhanced by a sub-oscillator and the slide time has four settings.
Although backwards compatible to the "pattern write" mode of the 303 the Avalon's sequencers has got what it takes, way more than the limited and hard-to-program original sequencer. Pattern can be up to 64 steps long (four sections of 16 steps each) and have various time signatures, includign triplets. The sequencer can be edited in real-time and allows access to slide time, various trigger modes of the utility envelope, omitting steps, playback direction, rotation, randome and shuffle. Even an arpeggiatior is included which can be used in real-time or be programmed directly into the pattern.
There's 112 pattern memory locations, organized in seven banks, each with two groups of eight patterns. The Avalon's sound engine can be played by MIDI notes when the sequencer is stopped.
DIN Sync is not a bad timing format but more is possible, though: For synchronisation to/with external gear Avalon offers as well DIN Sync as MIDI, both with input and output sockets. For further communication there's a class-compliant USB-MIDI conenctor and a number of minisockets for CV and gate signals. Latter are there not only for modulating the sound parameters - the sequencer and the envelopes emit signals and also the oscillator waveforms are available at individual sockets for further use, e.g. in your modular system.