Ditch the 'virtual analogue' style synths in your setup and use a synth with more interesting synthesis methods. For more interesting tinkering, use synths that allow for more interesting methods of sound generation and distortion.
FM and wavetable synths can do some really cool stuff. Start by exploring how those synthesis methods function to understand the modulation possibilities inherent in each method.
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Some virtual analogue synths have elements of
Frequency Modulation (FM),
Ring Modulation (RM),
Amplitude Modulation (AM) and
Phase Distortion (PD).
To explain what each synthesis type does is beyond my ability in a short post, needless to say, google is our friend... (I've hotlinked a google search to each term mentioned above).
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Some ideas:
Wavetables can be scanned through at different speeds, which can lead to some interesting sounds. Better wavetable synths allow the phase width of the signal peaks to be modulated. This is the same as
pulse width modulation of square waves, only functions on any waveform!
Some synths offer built in waveshapers. Starting with a simple sine wave, using a waveshaper can provide some interesting timbres.
Further to this, understanding how different pitches can intermodulate to cause
beating is fun. (Detune one oscillator by a few cents from the pitch of a second oscillator).
This is how 'unison' works which Deadly Habit mentioned above. Unison adds a delayed copy of the original voice, creating thicker 'spreads' of sound.
An often overlooked type of sound is pure noise. One can shape noise using filters (wind anyone), use it to sharpen the attack on percussive sounds and pop it through effects like reverbs and chorusses.
Another thing to mess with, as mentioned above, is portamento (glide). Medium to long portamento times can provide interesting (if woosy) results when using your synth in 'monophonic' mode and notes are sequenced to overlap eachother.
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Finally, an obvious but often overlooked modulation destination is the modulation rate of a second LFO. Try tieing one LFO to the pitch of your oscillator, then a second LFO to the rate control of the first LFO. Start by using a sine wave on the first LFO and a square wave on the second. This should give you an idea of what's possible when the first LFO is modulating something like the phase width or index scanning speed of a wavetable synth...
You will probably be interested in the free ebook entitled 'How to Make a Noise' available here --->
http://www.noisesculpture.com/htman.html It covers many synthesis techniques in tutorial format.
