BAM!!! Here comes the next one: Realtime PWM Synthesis with native Renoise XRNI.
Okay, first a short introduction to PWM, so you can understand what we’re doing.
PWM stands for Pulse Width Modulation. In PWM a signal is modulated by comparing two signals with each other continuously. The demodulated result is the arithmetic average.
Let’s say somewhere on our timeline (the sample position within a looped waveform) we have Signal A with a value of +100 and Signal B with a value of -100, then the result is 0. 0 means right on the signal axis, so this would be silence.
We have a signal A with a value of +100 and a signal B with a value of -50. The resulting value is +50, which creates a signal beyond the sample axis.
Now, that’s the basics to understand what’s going on.
What you need now is (as an example) a ramped, looped sample, usually a plain saw and layer it within your Renoise instrument with a phase inverted clone. The result is… silence. WTF? Well, to create our modulation now, we have to fintune one of both samples, so there appear differences in the comparison. Do some finetuning and theeere is your SIDish PWM sound. The higher the difference in finetuning of both signals, the faster the modulation. Modulation depth can be set via volume difference, equal volume = max. depth.
Variations in sound can be done by moving the loop position/sample phase (do NOT change the loop length! - unless you know what you do). You can also try to transpose one of both, modulate more than only two samples with each other and so on. When you know what you’re doing, you’re able to create some really phatt synths this way and of course the typical SID sound.
I’ve created some examples, so you get an idea of what I’m talking about. After 7 I’ve lost motivation, but you will see, it is pretty easy to create your own.
Download (7 Instruments, 12kb only )