Given the sophistication and novelty of Crystal, you can make a case that it was/is the most GENEROUS free VST ever. And there's some tough competition for that title.

Learning to use it is an education is synthesis.

The .sf2 was the topper. All of sudden, untold GB of sample data became fodder for Crystal's bottomless mangling architecture.

Crytsal is a synth I would program for fun and exercise, not in support of a song or composition but just for its own sake--every bit as much as Cameleon 5000.

It's strength, obvioulsy is movement and modulation. I loved it from the start, but it wasn't til I heard the Tim Conrardy banls that I was able to understand its rhythmic potential. The enevenlopes are still the best of their kind, imo, not that I've checked out all the "competition." The frequency splitter is a trip. The Mod Matrix is pretty much bottomless, for all intents and purposes. Stability is excellent, CPU usage can go from modest to extreme. .Sf2 support was a brilliant stroke.

It's weakness, frankly, is in (the lack of) thickness and solidity of its core sound and an LP filter that to my ears is no great shakes. I am not able to coax fat, high character lead sounds out of Crystal, but so what? Keeping in the free domain, we have Synth1, Triangle 2, and the Iblits for that.

Crystal is, uh, an absolute gem. Glen/Green Oaks' generosity with this one is truly humbling.Read more

USER INTERFACE
Every button and slider in Crystal is placed just where it's needed, and the synth is as a result remarkable easy to use, considering its complexity. It's also a very nice-looking synth, and has the best patch browser I've seen in any freeware synth (and better than the ones in many commercial ones).

SOUND
You know those stock analog sounds, the ones that every free VA synth seems to do, and do well? Crystal doesn't do those. You can't squeeze a typical supersaw or crunchy bass out of this thing without a lot of effort. So what does it do? Just about everything else. From glitched-up, snarly, hissing pads to so-pristine-it-can't-be-real chimes to massive (and really massive!) soundscapes to...well, use your imagination, or run through the presets. This synth will create sounds you can't get any other way.
I suppose I can break it down more. The oscillators, in particular, are a real strength of the synth, rich and powerful. The filters are likewise very thick and heavy, though as I mentioned, not at all "analog"-sounding. The effects section consists of four delays that you can use however you want--and with the modulation options being what they are, this means you can make phasers, choruses, flangers, comb filters, ping-pong delays, and unique effects that, at least for now, don't even have names.

FEATURES
I hate to write a review that sounds like a list, but I can't resist the chance to rattle them off. Three independent oscs, each with its own multimode filter, FM or ring modulation, hard sync (called "mogrify," who knows why), and soundfont loading that allows them to work as ROMplers or, better yet, granular oscs. 6 higly tweakable LFOs and multi-breakpoint envelopes that can be routed to whatever weird place your heart desires (which means, as many targets as I've seen in ANY synth), besides the envelopes for each oscillator's amplitude and filter. Four delays that have built-in filters and can be tweaked however you want - or tweaked using the envelopes and LFOs. Four-way frequency splitter.
That gives you a taste of the possibilities, but to really understand what this means, you have to download the synth and really dig into it. There's more to this synth that I could exhaust in a lifetime.
That said, I have to mention Crystal's one major flaw - its CPU useage. Many patches on Crystal have very modest CPU consumption, but others, especially when using a lot of polyphony, are outrageously CPU-heavy. Of course, all this means is that you have to render tracks a lot when using the synth, but it's still an unfortunate issue with the synth.

DOCUMENTATION
Extensive manual, nice tutorials - what more can you ask for? It was actually the first synth I ever used, and even for a beginner it wasn't impossible to get into.

PRESETS
The patches built in are brilliant. There's a factory bank, and the website has several others, and they all sound exceptional, giving a great taste of what this thing is capable of. Amazing stuff.Read more

This synth is capable of a huge range of sounds, from searing leads to thumping basses, but its strength is in dynamic, evolving sounds. The huge set of controls you have over the sound means you never feel limited by the ways you can warp the sound in interesting ways.

I like that you can use it simply, just pushing the Breed button to make clever new inspiring patches. This feature always leads to something you can use.

But, if you want to plunge in further, you have a lot of things to play with. FM synthesis, granular synthesis, wave sequencing, hard sync and bunch of filters to tweak the sound endlessly, all modulated by any number of things, including tempo syncable loopable multi stage envelopes.

There are a lot of nice touches here that set is aside from typical free synths, including midi learn, a complete online manual, and rock solid stability.

In short, you can\'t do better as a basic synth to use as a foundation for your synth tracks. You can\'t help but find useful and inspiring sounds here.Read more

As others have said, this is a long-established free synth, and yet, it's still one of the most surprising
and pleasing. Usually, I find myself forgiving all kinds of horrible quirks in free stuff, but there's no need to with Crystal. There's basically nothing not to like.

More to the point, there's a helluva lot to be pleased about, and grateful for. I'm kinda new to soft synths -- although I messed with hardware in the past -- so wasn't really prepared for an item like this, which is rich in features. Just the one feature of 'breeding' two separate presets kept me amused for an hour.

Crystal produces excellent pads, that's true. But that's only one aspect. There are many banks of excellent presets by other sound designers, and there's nothing to stop you creating your own. It's just as capable of lead voices as it is of making pads. It's 100 per cent stable, has a pretty decent online manual, and has consistently evolved over the years. It certainly has more tweakability than I know how to usefully employ at present, and always delivers something useful whenever I fire it up.Read more