When first version of Expanse came out it was already one of the most advanced synthesizers available in Reason. Expanse synth is developed by Blamsoft - company that brought lots of Rack Extensions including two best-selling RE synths - Viking and Zero. Based on their great experience and understanding of Reason environment and workflows - Expanse 1 was more advanced then any other wavetable synth - combining wavetable, additive and subtractive synthesis in one powerful unit.
With Propellerhead's introduction of Reason 9.2 and new Rack Extension SDK - Blamsoft updated Expanse to the version 2 and made it free update for existing users (though I’m sure most of them would be happy to pay a fee to get the ability to import their own waveforms).
Sample import was one of the most expected features for REs SDK. And apparently Propellerhead team was quietly working with Blamsoft to make Expanse 2 ready on the Reason 9.2 launch day.
Expanse comes with nice selection of waveforms made by renowned sound designer eXode. Even without importing your own waveforms you already have large collection to play with. Each osciallator has 4 modifiers - each can be setup as FM, Phase Distortion, Ring Modulation, Wrap, Decimate, Invert etc. BTW, Serum has only one modifier per OSC - and here we got 4 which makes sound shaping capabilities literally unlimited. With the newest version (requires Reason 9.2) you can load up wavetables. Blamsoft says that all Serum wavetables are compatible with eXpanse. But also you can take wavetables from everywhere: free wavetables banks that you can find on the forums (if you search you can easilty find collection of Virus TI wavetables and other synths), wavetables packs from other synths - it is not just Serum but also Waves Codex, iOS-synth Animoog etc. And of course you can just import any wav-file as a wavetable (just make sure it is pretty short), play with position modulation and modifiers - and you instantly get unique sound.
If you compare Expanse to Serum - Serum has better control on the waveforms (with its waveform editor) but it has 2 wavetable oscillators (+one noise OSC that can play files and sub-osc) and only one modifier control (warp, sync etc) while eXpanse has 4 wavetable oscillators and 4 modifiers per each osc.
Filters and Amps: eXpanse has 2 filters that can run in serial or parallel mode and 2 independent AMPs!!! - that something that can make really interesting patches - from cool stereo effects to nice evolving sounds.
eXpanse is probably the most advanced synth in terms of the modulation: 5 envelopes with adjustable slopes, 3 LFOs, Random and Noise as Modulation sources, really nice Step Sequencer with two CCs that can modulate any parameter.
Modulation matrix with 6 modulation slots with 3 destinations per modulation, drag’n’drop modulation destination assignments, lots of CV ins etc.
Effects: Effects section has pretty much everything you would expect from top-synth this days: Compressor, EQ, Distortion, Phaser, Delay, Reverb. We don’t stop here much because Reason is cool modular environment with great amount of various FX devices - you can easily add other REs for effects and combine it into single Combinator patch.
Overall: If you’re already using Reason to make music - eXpanse is a must have Rack Extension. Just the ability to import your own samples as wavetables is worth buying it. It is well thought-out interface that looks very natural in the Reason rack (particularly with the dark-color scheme).