Calf Wavetable is a realtime polyphonic wavetable synthesizer plugin developed by Krzysztof Foltman of the Calf Plugin Team, and is included with the Calf plugin package available in most linux repositories.
The Calf Wavetable Synth consists of two oscillators, each with volume level, offset, semitime transposition and detuning. There are a variety of waveforms to choose from, including bell, brass, guitar, pluck, sync, and about 15 others. Below this section is an Envelope Matrix section. This section includes the following controls: Source (selects the control source, such as the velocity of the midi keyboard), Mapping (whether the control is linear, exponential, etc.), Modulator (which parameter will do the modulating), Amount (intensity, from 0 to 100), Destination (what parameter will be affected, such as the pitch of oscillator 1 or 2).
The section on the right side of the GUI is divided into two areas: LFOs and Envelopes. There are two LFOs available for modulating. The Envelope section has three envelopes with standard ADSR layout but with an additional fade slider. Envelope 1 can be dedicated to amplitude, if needed.
A few presets of my own: Wavetable Presets 01. All Calf Presets (both instrument presets and effects presets) are saved in the hidden ".calfpresets" file in your home folder. To use the presets in the file here, just copy and paste the lines into your .calfpreset file and save.
Calf Plugin Website