I've worked with many professional VSTi's but the mda JX10 has the best sound! The filter sounds genuinely analog and is thick and sweet. Probably the best I've heard! Currently there is no distinct user interface, but the JX10's parameters are easily accessible without need of a manual. The sound is reminiscent of a Roland Jupiter 8 more than a JX10, which is impressive. The presets are awe-inspiring! This is the most stable VSTi and so light on the CPU! Can you believe, it's free!?!
Inspired from the Roland JX-10, this plugin has no GUI (it uses the GUI of your DAW), but... what an amazing sound!!!
For more information about this astounding plugin, here is below in italics an extract of the description from the original page (before he's gone to Sourceforge where he has upgraded all his old plugins, then ported them to 64-bits... and added some new plugins that are not yet in the KVR Database):
"The plug-in is designed for high quality (lower aliasing than most soft synths) and low processor usage - this means that some features that would increase CPU load have been left out!
Additional patch design by Stefan Andersson and Zeitfraktur, Sascha Kujawa.
Please note that the mda JX10 is not related to the JX series of synths available from JXPlugins.
When Vibrato is set to PWM, the two oscillators are phase-locked and will produce a square wave if set to the same pitch. Pitch modulation of one oscillator then causes Pulse Width Modulation. (pitch modulation of both oscillators for vibrato is still available from the modulation wheel). Unlike other synths, in PWM mode the oscillators can still be detuned to give a wider range of PWM effects."