Thursday, May 31, 2012

Synthesis Chronicles: Basic Filtering

Yes, another synthesis post. There's not much gaming wise I've been doing, but I have been doing a lot of synthesizing and researching and such, so here we go!

As previously described, a filter acts like an easily controllable EQ. I have scratched the surface of various filter types, but let me elaborate upon the main types: LPF, HPF, BP, BR, Comb, and a special Notch. Here is a chart* showing LPF, HPF, BP and BR filters:

However, comb and notch filters are a bit more complex, but still use the basic "remove frequencies" principle:

So, the first is obviously a type of comb (which, this is pretty extreme, it could also just look like a sine wave), but you may ask why I am saying a notch filter is a square wave. Truth is, there are many kinds of notch, all being multi-band-reject filters. In this case, a notch filter would be removing the bass-mids and trebles. Both of these are hard to achieve using just EQ's due to most EQ's being cubic or some other smooth curvature.

Cutoff is the audible frequency at which the filter starts to affect the sound. With LPF and HPFs, the cutoff control simply moves that effect range. In BP and BR filters, the cutoff control moves that frequency band around. In Comb and Notch filters, the cutoff control actually shifts the "waveform," if you will. 

Resonance is a totally different beast, and can be very important. The effect on LP and HPFs is similar:

The effect on band pass filters is really just a more accurate band:

And, on band reject filters, resonance acts very much like it does with band pass filters:

You may have noticed that I have not done one with Comb and notch filters. This is because the effect is easy to describe: on comb filters, resonance affects how sinusoidal or sharp the filter is. The above comb filter representation is a very high-resonance filter. For notch filters, resonance affects depth; that is, how near 0 the climaxes of the waveform are.

I hope this little lesson has helped you better understand filtering, and if you have any questions please feel free to ask!

*The charts show graphs which are proportionate to a graphic EQ; the left is lows, the right is highs, and the curvature shows essentially what a graphic EQ would.

Sunday, May 13, 2012

Synth Chronicles 3: Creating Sounds

The cool thing with synthesizers is that you can create amazing, complex, undefinable, unthinkable sounds. The bad thing with synthesizers is that you can create amazing, complex, undefinable, unthinkable sounds. In this particular Chronicle, I will tell you ways to create certain sounds using the most popular form of synthesis, subtractive.

Most people tell you how to create the sounds of normal instruments, like pianos, trumpets, guitars, various strings, et cetera, and therefore I have no real reason to tell you how to make those sounds. I'll tell you how you can create 5 interesting sounds: a full-sounding saw lead, a square-saw lead with a 'squelchy' sound, a sine wave without using a sine wave, the lately-popular Wobble bass, and the familiar 8-bit 'blip.' Shall we get started?

First, let's get one thing straight: I have so much synthesis power I'm not entirely sure what I can do with it all, so if there is something you can't do in this little series, don't fret! I will tell you what instrument I am using for each sound (even though they could all very well be done on my favourite, the Minimogue va by Gunnar). They are all free downloads from teh interwebz!!

1. Full Sounding Saw Lead

Synth: ElektroStudio's Sixth Month June

Let's start with the LFO. Set it to a moderate speed, and if you can set it to have a fairly long delay. Make sure it doesn't reset after you press a key. Make sure that it affects the pitch of the oscillators. Now, the oscillators. Yes, multiple. You want a square wave with a fair amount of pulse width modulation, such that it sounds like it's going through a high-pass filter. This is what gives the next oscillator some punch. Now set up a ramp wave. It's similar to a saw wave, and if that's all you have use it.

Set the whole synth's tuning down an octave. This is important as somewhat lower frequencies tend to give a fuller feel. Now, set up a Low Pass Filter to use a normal envelope generator to control its cutoff frequency. If you can, give it some keyboard tracking, also affecting cutoff. This will give you epic lows and singing highs. Now the important parts: Set the cutoff frequency to about 40%, resonance around 20%.

Finally, set up your envelope generator(s) to have 0 attack speed and nearly 0 release speed. Give it max decay and about 80% sustain. Set up your VCA to use this as well to control volume. Finally, play. You may need to screw with the setting just a tad, and if you want add some delay!

2. Square-Saw Lead With a 'Squelchy' Sound (say that five times fast)

Synth: Minimogue va

Using a normal square and saw wave, set your cutoff frequency on a low pass filter to about 35%, and resonance to about 90%. Give it the ability to use an EG, about 90%. Then, set up your filter EG to ADSR=0,55,0,0. Adjust the decay rate as needed, but this should give you a nice "squelch" on the decay of your note. You can also use aftertouch and release rates to control this squelch, which may be easier and more useful if you want a less constant squelch.

3. Sine Wave Without A Sine Wave

Synth: Minimogue va. You can really use anything with multiple waveforms and a low pass filter.

Use anything but a sine wave: in this case, a saw wave. Note: it takes a lot more than this lesson to get a true sine wave, but you will get damned close. Now, very simply set your low pass filter to have a cutoff frequency which sounds like a sine wave. That was hard.

"WTF, bro??" Look, all waves have higher harmonics, even triangle waves. Using a low pass filter filters out these higher harmonics, leaving you with a purer and purer signal, until eventually you are only passing sub-audible sounds. A filter saw looks more like a really round saw, a square will end up really close to a sine, a triangle will become a sine very quickly, even noise can be a really dirty sine wave. Don't believe me? Record each filtered wave and look at the waveforms. Not perfect sines, but damned close.

4. Wobble Bass

Synth: Dubtron by Psychic Modulation (note that there is a demo version available)

This sound is used a lot in heavier electronic music, and prominently in Dubstep. Use (yes, again) a saw and square wave, and set them to an octave down. If you can, set up a sine wave two octaves lower. This is a sub-octave way to destroy club walls. Now, put the first two oscillators through a low pass filter (all of them is ok, too), set the cutoff to 50% for now, no resonance, no EG following.

Set your LFO to a moderate speed and a sine wave. If you can, set the LFO's speed to track the keyboard such that the lower pitches are slower and higher is faster. If you are using Dubtron, just set the oscillator LFO's the same and use the Master Wub control to do tracking. Cool thing with Dubtron is that you have a separate filter and LFO for each oscillator.

Of course, you will have to change the LFO speed and Cutoff Frequency to suit your needs, but this is a good starting point.

5. 8-Bit Blip

Synth: Bleep' by Tonebytes

Use a triangle and square wave, detuning the triangle an octave. Set your ADSR to about 35,60,0,30 respectively. Here's where having multiple filters helps: run the triangle through a band pass filter, then both through a high pass filter. Set both filters to 100% cutoff and 0 resonance.

Then, just set up an arpeggiator to go up at 1/8th note speed or so, and let it cover 2 octaves. Given maybe some messing with the ADSR, you now have a classic 8-bit blip heard sometimes in some of OVERWERK's songs, namely n00b pwner.

So, I hope you have learned something interesting today, and if you want help synthesizing any other sounds, please leave a comment! I will be glad to help you.

Next post will be about how to synthesize a sound by ear!

Tuesday, May 8, 2012

Crazy Idea

As you know, I am crazy and possibly too inquisitive. And, since I am, for God knows what reason, getting into electronics and how they work, I'm thinking... build my own analogue subtractive synth. Let me explain...

I had an idea after seeing what the KORG Mono/Poly can do, and decided to mix that, an Arp 2600, and an Etherwave together, and then add some of my own touches. Here's that plan thus far:

Name: Yoa KereMAX P

Oscillators: 4, each able to do saw, ramp, sine, triangle, square, "digital" (sample and hold on a sine wave probably) and noise, with octave, frequency, fine frequency, and volume controls with kill switches.
PWM: specially noted because I want it to be able to modulate saw, ramp, square, and the sample length of "digital" waveforms, and modulate the LFO's
Unison: with detuning and spreading
LFO's: 3 (you'll see later why), with level, wave, and frequency controls
EG's: 3, one for each oscillator's amplitude, each filter, and each oscillator's pitch, as well as master VCA EG. All EG controls are sliders.
Filters: either 5 separate or 2 switchable, just because I want a comb, HP, LP, BP, and BR filter, all with Cutoff and Resonance controls, maybe more controls. 5 would be more interesting, probably.
Aftertouch: acts as a CV to control whatever, with amount control and 3 patch bays (WHAT??? Keep reading)
Portamento: has time, retrigger, and legato controls
Bend range amount: from -12 to +12
Master EQ: Just to help smooth out any scary edges that subtractive synthesis tends to have sometimes
Effects: Overdrive, Distortion, Ringmod, Bitcrusher?, and then Stereo Delay, Reverb, Chorus, Flanger, and Phaser
Arp: it's a gated arp with speed control, with the gate part helping the...
Sequencer: yes, as in a 16-step sequencer using held pitches, speed, and volume controls
Controllers: Just one more interesting thing is that aside from a keyboard, it will also have theremin antennae and possibly a MIDI-CV converter
X-phony: Crazy idea that's totally not stolen from KORG, the ability to have monophony, polyphony, unison, chord, and note hold options.
Vocoder: pretty obvious, uses...
VCA: has a mixer for all osc's, audio I/O (including RCA), effects, and a master volume.
Audio I/O/T: Allows for you to use an external audio source as an oscillator, has stereo audio out, headphones out located in the front, and audio through so you can simply use the synth as a cable extender, should you need to. Though, as you'll find out why shortly, this need only act as a kind of patch bay.
RCA I/O's: for using either sound sources or effects modules using RCA connectors. Also a patch bay kind of deal, just with RCA I/O.
Fans and heatsinks: I feel like this thing will get hot.

Some other things may be added.

And, the neatest part which makes it all make sense... Full modularity.

So, what does this mean? Well, it's basically the world's most incredible synthesizer plan to date. Sure, other synths have neat modulators and stuff, and if this thing wasn't already packed full of everything you'd ever need I'd add them.

You can technically use it as the most scarily complex themermin in the world. Or it can be a simple monosynth. Or you can use the keyboard to control a pad as you screw with the lead part with the theremin. Or whatever.

Now, I'm not sure how I can implement all of this, but if I work in true modularity (like, say, having the keyboard needing to be patched, and having the individual oscillators patchable, and even separate the antennae and make them patchable), then I can at least pull off some of it. Cool thing is, I have schematics for a lot of this stuff. I just need to know how to throw it all together. It'll take some time, I'm sure, mainly because I can't quite afford all the jacks, panels, switches, knobs, and components I'll need for this project. I still don't even know how things will be set up, so it's still just an idea. I'll try to draw it in AutoCAD and hopefully make it smaller than the size of a room. LOL

Yours in music and insanity,