amSynth is now officially at version 1.4.0. If you don't already have it available in your distro's repositories, you can compile it yourself very easily, at the amsynth development page here:
This newest version includes soundbanks 1-11. I've completed soundbanks 12, 13 and 14, which can now be downloaded here:
There are two pages of amSynth audio demos.
One page showcases banks 1-13. I've decided to use some basic plugin effects (chorus, delay, reverb) in the newer banks (from about Bank 8 onwards). To hear these demos, click here: AmSynth demos, single instance
The second audio-demo page showcases amSynth in multiple instances. To hear these demos, click here: AmSynth demos, multiple instance
I hope to dedicate more time to multiple instances in the near future.
AmSynth, created by Nick Dowell, uses the traditional subtractive synthesis approach to sound design, and can be run either as a standalone instrument or as a DSSI plug-in within a digital audio workstation such as Ardour or Qtractor.
AmSynth is a realtime, polyphonic/monophonic virtual synthesizer with touch-sensitivity. It includes two oscillators, each capable of generating several types of classic waveforms: the square wave can be modulated to reach a pulse wave, the triangle wave can be modulated to the point of a standard saw wave, and sine, noise and sample-and-hold waveforms are also provided. Oscillator 2 can be synced to oscillator 1, and it can also be detuned (finetuning to 4 semitones, semi-tones of 12 increments, positive and negative, and whole-octave detuning: down one or up two) to create broader and dissonant-type timbres. Syncing the oscillator and adjusting the semitone detuning gives some interesting FM-like timbres. An oscillator mix knob allows control of the balance between the two, and turning it all the way to the left or right will isolate the one or the other. Ring modulation is also provided in this area.
A standard ADSR amplitude envelope controls the development of the audio level when a note is played, and the same ADSR structure is provided for the filter. The filter section includes 6 filters: low-pass, high-pass, bandpass filters, each at 12dB and 24dB.
An envelope strength knob controls the depth of the filter effect, and provides both positive and negative envelope possibilites. Resonance and cutoff are included in this section of the GUI as well.
AmSynth has one Low Frequency Oscillator. This LFO can be completely off, or affecting the pitch, filter and amplitude, or any combination of the three. Square, triangle, sine, sample-and-hold, saw-up, saw-down and noise waveform types are provided.
Together with the main volume and drive (distortion) controls, amSynth includes a plate-type reverb, a size knob to adjust wideness, stereo and damping knobs. Additional features of the newer version include mono/legato/poly control, and a very broad portamento capability.
My use of amSynth on debian-based versions of linux such as Ubuntu Studio (with KXStudio), antiX and BodhiLinux, has shown that multiple instances of amSynth (I haven't gone beyond 4 instances yet..) can be run simultaneously with less than 50% CPU usage on newer machines. Using multiple instances allows to assign the modulation wheel of any external MIDI keyboard to different controls, and pitch bend (now adjustable in the newer release) and portamento parameters can all be set individually, permitting to create some very rich, unique sounds. See the multi-instance link above for more information.
Another neat feature is the random function (sometimes called a "lazy button"). Using the ctrl+r keys, all controls are set to a randomly-assigned level. A kind of "evolution" mode, this function often produces uninteresting or unplayable sounds. But it sometimes produces some very interesting results. My newer banks (from Bank 10 onwards) mostly use this approach to soundmaking (with as little "cleaning" as possible). My goal, as always, is to make unique, playable patches. (To me, that's what synthesizers are all about: very unique, yet playable sounds.)
AmSynth has unlimited polyphony capability, although 16-note polyphony is usually sufficient, and probably recommended when using multiple instances. Pitchbend function can be selected in halfsteps, up to 2 octaves. I run amSynth through the Jack audio control, although Alsa also works well.