Airwindows

PurestDrive

TL;DW: The magic saturation plugin of subtlety and French House tone.

The funny thing about PurestDrive is that I didn’t expect much from it at all.

This plugin (now coming to VST and open source) was simply an experiment. I’d been making complicated plugins with things like anti-aliasing, just a lot of calculation going on, and wasn’t sure I was getting what I wanted. It didn’t seem to be furthering the ‘Airwindows sound’. And I’d hit on an interesting tactic, noise shaping for the floating point buss. It seemed to me that you might be able to get a good sound by the opposite to complication: simplifying things, running the math at the highest possible resolution (in this case, long double precision, which is 80 bits on Intel and possibly 106 bits on PPC, which Airwindows still supports)

The saturation algorithm was going to be sin(), which is the smoothest saturation curve you can have. Then I thought it’d be good to get a little more sophisticated than that because I had quite a few plugins based on sin(), so I did this:

inputSample = sin(inputSample);
apply = (fabs(previousSample + inputSample) / 2.0) * intensity;
inputSample = (drySample * (1.0 – apply)) + (inputSample * apply);

That’s it. That’s what makes PurestDrive (apart from some code supporting it, which is up and documented on GitHub as part of making it open source).

What it does is this: it keeps the previous dry sample around, and ‘apply’ will be the combination of that and the saturated one. This makes apply be large if we’re on a low frequency wave, and if we’re doing a really bright transient apply might be zero. Intensity is how we include the slider control (0 to 1) and can also make apply be lower. Then, we’re adding the sin() effect, but ONLY relating to apply: we saturate the body of the sound, but as things get brighter or lower volume, we’re dynamically doing a dry/wet control at audio frequencies, so PurestDrive only throws saturation on dense solid material: airy highs, subtleties, get through more easily. As a side-effect, if our input gets super hot we can end up subtracting a little dry from the saturated inputSample.

What PurestDrive did… was take off and become hugely popular. I didn’t expect that, it was simply an experiment in tone purity and I didn’t think anyone would notice. I knew the little tweak with ‘apply’ sounded good, but I figured the whole thing was so subtle that it wasn’t going to set the world on fire. Yet, PurestDrive developed incredibly dedicated fans, using it all over their mixes, swearing by its tone.

And now, it’s a free and open source plugin, AU and Mac and PC VST. Remember it’s designed to not be a big obvious coat of paint over everything: because it’s using the dry sample so intensely, it cleans up and stays out of the way. But because it’s modulating between saturation and dry at audio frequencies based on both the current and previous sample, there’s a lot of textural effect on the sound. I never got so much mileage out of so few lines of code. Hope you like it. :)

I wouldn’t have been able to get here (releasing PurestDrive as VST and open source) if not for my Patreon: this is how I fund such generosity. It lets me not have to play by the same rules as commercial software makers. It even lets me provide stuff like this TO commercial software makers so long as they can work with the very permissive MIT license (requiring credit to me for the bits I did, and inclusion of the MIT license terms themselves). It’s generally possible to reverse-engineer whether someone’s using PurestDrive, or Console, etc. so I suggest just running with it and publicizing the use of open Airwindows algorithms. Plenty of folks are already coding using the MIT license, the water is lovely and warm, hop on in :)

Date February 4, 2018
Author Chris
Comments 4 Comments

GrooveWear

TL;DW: Scrubbing highs off mechanically like a stylus would.

GrooveWear

Here’s something interesting! I revisited some pieces of ToVinyl4, one of ’em being GrooveWear. In fiddling with it, I discovered that I could put in a dedicated wet/dry for just that one part, and if I did, I got perfect high-frequency rolloff at 50%. In other words, as an effect it was working as intended (bit of overshoot available, like the needle was loose in the groove), but I could also redesign it as a tone-softener.

It’s all based on variations of averaging. I’ve got Average to soften just only sample values (it has some interesting quirks but I swear by that algorithm for naturally rolling off highs in a way that doesn’t sound digital). GrooveWear goes one step beyond that, and averages slews (not sample values). That means it’s averaging the rate of change. Then, later (and will be coming to VST) I did Aura, which is averaging the rate of change OF the rate of change… but that’s another story ;)

More importantly, I came up with a nice feature doing the revision. The GrooveWear contained in ToVinyl uses two stages of processing, since it can be a subtle effect. I worked out a convenient way to make the dry/wet control handle multiple stages so, as you increase it, you’re progressively adding stage after stage with the final stage going from dry to wet: it means you can start off with a very mathematically clean amount of effect, just one stage dry/wet, and then keep adding more. And in the spirit of that, I doubled the stages so now GrooveWear has four.

So, you can adjust the intensity control that specifies how much slew averaging the stages are doing (acts like a sort of frequency range control for the effect) or you can adjust the dry/wet to go from pristine to incredibly deep groove wear. It’s partly roll-off of the highs but it’s not JUST normal EQ, texturally it’s quite different because the effect doesn’t try to stop big transients like a square-wave’s sides, it tries to stop smaller-scale detail stuff while retaining the big harmonic content of waves. It’s averaging slew, not deleting it, so certain waveforms get through untouched… you’ll see.

Patreon is doing nicely which makes me happy: as you can see, when I start to get resources I do things like try to make Eurorack modules for people, and I’ve been super busy thinking up ways to do that which are (a) cool and (b) people can do for very little cost. That seems the best thing, and I’ve discovered some great tips and tricks and things. More on that later.

I’m also keeping an eye on the VCV Rack open-source virtual modular project: music made entirely in it seems not quite as good as hardware modular synth music. It’s almost like the modules and digital mixing in there could benefit from adding modules for making digital mixing sound more analog-like, stuff which can handle/elicit more in the way of warmth and vibe and depth and space and stuff.

I might just be able to help with that one ;)

Date January 28, 2018
Author Chris
Comments 5 Comments

Noise

TL;DW: The Airwindows deep noise oscillator, as a sound reinforcer.

Noise

Here’s a post from airwindows-land, just to show you I’m still working ;)

Noise started out as a plugin called Voice Of The Starship. It’s an algorithm that generates brownian-motion noise which won’t ‘wander’ into excessive DC offset, but without a highpass filter needed! The original Voice Of The Starship can be made to do any sort of deep rumble, including purely subsonic rumble that still works as an audio stream. When that one comes out, it’s definitely going to the open source repo.

Oh, did I mention? Airwindows Open Source is live. That’s been taking a lot of my effort as I’ve tried to provide the templates I use to make plugins, AND several basic starter plugins ‘as shipped’ (when my stuff goes OSS it’s strictly as I made it without alterations, but the templates should be customized so you can use them as yourself and not me)

And it’s still not really complete, and I won’t be able to help people get plugins compiling on their systems as that’s my nemesis in the first place, but it’s a start!

And I’ve also been putting in a LOT of work on a project (inspired greatly by Bastl) for helping people DIY Eurorack synth modules. I have some straight-up awesome ideas for Euro-stuff, including things people can do themselves, and I’m scheming up ways to get the necessary parts into your hands provided you can solder things together (always good). I want to get people making stuff for less than $100. You should be able to have a Eurorack hacker kit for very little money, and all the information you’d need to do as I do and make large amounts of stuff.

Thanks to a year (and more!) of Patreon, I’ve got just enough resources to run with this and learn what’s good, and even get into stuff out of my childhood. I had a Radio Shack Concertmate Moog when I was a kid. Now, I got my first Mother32, and am hot on the trail of the impending DFAM (which I think is going to be the ultimate modular kick for reasons I’ll explain later, having to do with both the sound of the thing and details on how the Moog sequencer tempo stuff works), and yeah: I’m exhausted. I have plugins ready to come out (including PurestDrive!) but I’ve had an awful lot going on (second funeral for Mom, and my gray cat is approaching the end of her life), and in some ways I’m taking refuge in this new stream of work. I think you’ll be interested. One thing about it, if it works we’ll suddenly be moving past the same old Airwindows demo music, in a good way.

Oh, right, Noise. Noise is like Voice Of The Spaceship, except it also triggers on input sounds. It can pretty closely track rhythms coming in, and you can combine it with underlying stuff with Dry/Wet, and the Distance control applies to both Dry AND Wet, to blend and darken them together.

Hope you like it, and next week I’ll give you a whole new take on Groove Wear (out of ToVinyl). :)

Date January 21, 2018
Author Chris
Comments 5 Comments

ToVinyl4

TL;DW: Elliptical EQ, acceleration limiter, groove sim.

ToVinyl4

ToVinyl has several uses. You can use it to reshape the bass in your track, making it more mono or tightening up the center. It’s a special multipole IIR filter that acts almost like a ‘mega-bass’ plugin: it doesn’t just take away, it rearranges (so don’t expect it to act like a normal digital cut, you might see increased peak energy down low.)

Then, there’s the acceleration limiter. This algorithm is unlike any other Airwindows treble-reducer: it zeroes in on just the sorts of transients that’d burn up a cutting head, and zaps them ruthlessly. (if you own a cutting head you’re responsible for checking this, but some of you folks are still using Spitfish, and I’m pretty sure this will way outperform Spitfish.) The effect is treble softening without any obvious treble reduction, and it’ll make stuff sound like classic vinyl grooves very effectively.

But that’s nothing compared to the next control, Groove Wear. This one analyzes the virtual groove, and then sets up an imaginary stylus going down that groove, and gives it a tiny bit of inertia. It’s more slew mojo (and not tied to any particular frequency, it doesn’t even know what a frequency is) and the effect (should you choose to use it) is a very characteristic darkening and slight trashening of the most extreme highs. You can shut it off entirely, or turn it up, and you can combine it with the acceleration limiter to get pretty much any ‘vinyl LP high end’ you want. Some settings even bring a touch of moving-coil sparkle: it’s not all darken, in fact Groove Wear is very much its own thing distortion-wise.

Combine it all together and you’ve got ToVinyl4, the up-to-date version of a classic Airwindows for-pay plugin, that did quite well at $50. This time it’s free, because…

This work is made possible by Patreon, which is why you can simply download the latest ToVinyl and use it. If it’s super useful to you (and if you can), you should zip over to Patreon and act as if you’re buying it as a permanent license. Why? Because it is, and because if people who can still buy plugins choose to bump my Patreon by roughly $50 a year whenever they’ve added a bunch of new secret weapons to their arsenal, I’ll be able to continue what I do. Also, if you get crazy enough with it, talk to me and I’ll totally promote your music :) there’s a three/four/five plugin club on the Airwindows site, waiting to have people go listen to the fruits of all this freeness.

Date January 7, 2018
Author Chris
Comments 10 Comments

Chris

PurestDrive

GrooveWear

Noise

ToVinyl4

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