PSYN-tology 1 [Echoes]
OK, as promised, this is the first installment in a series of PSYN mini-tutorials which will try to demonstrate various programming techniques by deconstructing PSYN patches. I'll keep the subject line in the form of PSYN-tology [
tutorial number][
patch] to ease searching later, as I hope this will become a long-running series. Enough BS; let's dig in. Fire up P5 and load the Echoes patch from the
downloadable 128 presets package available from Cakewalk.
At first glance, it's a fairly simple patch: two oscillators, two filters in series, and an amplitude envelope. The key to this one is the mode button between the oscillators. Notice it's set to Sync. This means that Osc 2 (or 4) is slaved to Osc 1 (or 3). This usually results in a 'thicker' sounding, harmonically rich patch if the core pitches of the oscillators are the same or close in pitch. But here you'll notice that the slave osc is set to +3 octaves while the master is at -5 octaves.
So what does that mean? For a technical discussion,
go here. But the net effect is that as this low frequency waveform crosses zero (repeats it's waveform), it restarts Osc 2, resulting in a choppy, echo-like sound.
First, click off Osc 1. Now you hear the main oscillator sound provided by Osc 2 (as run through the filters and the EG. More on this later ...). Now enable Osc 1 again and increment the octave switch. The 'echoes' increase their 'delay speed' until you eventualy reach +3 octaves: a classic hard sync sound. Perhaps it would be a good idea to disable Unison (3 oscillators per note) and double-click Detune to hear this better, as the two blur the concept a bit. Also, changing the actual notes played changes the relationship here, increasing speed with pitch. You can't play too low with this patch due to the filter setup. (More later ...). One final experiment: disable the Keys switch for Osc 1. With the master now disengaged from your KB (and outputting a static pitch), the 'delay time' become static, too.
The filters are setup up in a serial fashion. Think of filters as a flood gate. With the Cutoff Frequency completely clockwise, the gates are wide open. You're hearing all the harmonics output by you choice of waveform; in this case, not many with a Sine wave. As you back off the CF a bit, you're actually hearing less of the waveform. This is the heart of subtractive synthesis. Now here you have two floodgates in a row: the first is a Highpass filter set to 4186.8 Hz. It opens top to bottom: high frequencies pass, lower ones are choked. The sound meets the second gate: a lowpass filter with the CF set to 4522.5 Hz, which is slightly higher than the first. This allows sound to pass from bottom to top, and serves here to shave off some high aliasing-type clicky sound and almost create a narrow Bandpass area for frequencies to peek through the two gates. This results in the 'ethereal' sound demonstrated here. Try disabling one or the other to hear the differences.
The only EG used hear affect the amplitude (volume envelope). The Delay, Sustain, and Slope are effectively out of the mix in this one. The Attack is slowed to provide a gradual fade-in. The Decay and long release time work with the slow release shape to reinforce the echo simulation. The Amount is set for the maximum effect on your waveform.
You can skip all this and make similar sounds by using an LFO or a repeating envelope shape. For the first, disable Osc 1 and enable LFO 2 (bonus question: find out why I chose LFO 2 rather than LFO 1 to detail settings). Bring the Depth to 100% and the Speed to .7 Hz. (Bonus question #2: Is this setting also technically correct?). Set the Modulation Dest1 to Lev-All or Level-02 and bring up the Depth control there. Almost the same sound, but subtly different. [
Edit: Actually, the correct speed is closer to what's labeled as .6 Hz. in LFO 2, and select a Square waveform for the most distinct comparison.]
Now disable LFO2 and go to the Amplitude Envelope [EG A]. Keep the Amount at 100% and drop the rest of the sliders. Change the Set from Normal to Repeat [Norm to Rep]. Now play a note and gradually increase the Decay slider to about 252.6 ms. Again, quite like the sync setup.
So why go through all the trouble with Sync? For one, in the LFO and EG examples, the 'delay time' is static, but the main reason is to add yet another color to your sonic palette. This patch (or tutorial) really doesn't scratch the surface of the variety of tone colors you can achieve with oscillator sync, but hopefully this little discussion gets you curious about the possibilities.
[OK, so there's number one. It was straight through, without editing, so it might be a bit rambling. Too technical? Not technical enough? Errors traded for simplicity? Not what you expected? Too dry? No comic relief? Too long? Not enough detail? Favorite patch analysis request? Want to build a lead line from scratch, DA? Keep those cards and letters coming. <g>]
Edit: First of a (searchable) series, and I misspell the name of the synth in the subject line. I'm firing my proofreader! Oh, that's me ...
< Message edited by b rock -- 11/5/2004 10:31:53 PM >