Curvature
The easiest to use, yet most advanced compressor in the world
FEATURES
- Unique compression curves unavailable in other plugins
- World's first compressor to use the Black-Scholes model
- World's first compressor to use a Quantum tunnelling model
- Extremely easy to use retro page
- Preset page offers more control and random generation
- Expert page has full control over the algorithms
- Extremely fast and easy side chain EQ with external side chain input.
- Side chain EQ able to be applied to the main out
- Oversampling
- 5 more mystery algorithms to come
- Lifetime free upgrades
FULL VERSION WITH DEMO
Curvature will automatically run in demo mode until activated. The demo emits intermittent white noise and loading of the knob positions is disabled. The classic algorithm doesn't have white noise. Hashes at the bottom of the page.
INSTALLATION
AP Mastering plugins do not ship with installer wizards and random undisclosed bloatware. If you have ever installed a plugin by simply moving it into your plugin directory, then you already know what to do. For anyone who is stuck, watch this youtube video.
USER MANUAL & FEATURE OVERVIEW
THE FOUR CONTROLLER PAGES
Imagine a classic games console. You have the console itself but without a game, it doesn't do anything. This is like the compression engine of Curvature. You need to load a game or, in our case, a compression model. Inserting a game cartridge, the console boots up and you see something on the TV screen. But you can't move the character or do anything yet. You first need to plug in a controller. But which one? The most popular peripheral for the NES, after the standard controller pad, was actually the NES Zapper, the laser gun. But with the zapper, you can't do all that much. Surely the joystick controller is better because it's more powerful with more controls? And don't forget the adapter which allowed you to add four controllers instead of just two!
Curvature is the same as the NES in this regard.
| NES Zapper | → | Retro page |
| Stock controller pad | → | Preset page |
| Joystick | → | Expert page |
| Input expansion | → | Side chain page |
THE RETRO PAGE
I have previously been critical of skeuomorphic interface designs. For me personally, aesthetics is irrelevant. DSP is the most important part of a plugin. But the NES Zapper was the biggest selling peripheral for the NES for a reason. Despite the fact it is limited, some people just want to shoot stuff with a lazer gun. Why? Because it's fun.
Curvature doesn't require a PhD to use. On the retro page, you can press a button and turn the knobs until you get the sound you like. A couple of the modes even just have one single big knob. So for all the people who thought Curvature version 1 was too deep to use, this page is for you.
The look is inspired by some of my favourite vintage studio hardware such as the EMS VCS3, which inspired the overall shape and wooden look. The buttons are a nod to my favourite console, the SSL 4k. The big chicken head knobs are reminiscent of my favourite hardware compressor, the Abbey Road EMI TG1... the fact that they are massive is because, well, Shadow Hills does it, so why not.
The wooden side panels are crafted from celestial rainforest tonewood, resonating with the hidden harmonics of the earth’s most exotic trees - each constitute a hymn to sonic perfection, infused with the soul of a thousand sunsets dripping in the opulence of nature's rarest song.
THE PRESET PAGE
Just like the stock controller pad for the NES, this is likely going to be the default page for most people. You don't need to understand everything about the models, you can just click the presets, tweak the attack and release times to taste, and you have greater control over the gain structure. FB is feedback model and FF is feedforward mode. If you want to prevent self oscillation, put it in FF mode.
Hitting the dice button will randomize all of the core parameters to the model, most of which are not visible on the preset page. So although you have significantly more control than on the retro page, you don't actually have to know or care about the fine details of the internal parameters.
The preset + random workflow is super fast, intuitive and lets you instantly get creative with zero friction. But when you need to do some fine tuning, you have exactly the right controls in front of you.
The shape of the curves shows the approximate gain reduction behaviour of each algorithm, similar to what you would see in the Delta Expose plugin.
There are no ratio, threshold, or knee knobs on the main screen — those aren't necessary to get a decent compressor sound. Just like with an 1176, to hit the threshold harder, simply crank up the input gain. And similar to New York-style compression, aim for an exaggerated version of what you're after, then dial it back using the MIX knob to blend in the clean signal.
THE EXPERT PAGE
If you want full access to all of the controls, short only of the hidden controls and those specific to the side chain control, this is the right page.
Looking at this page might be overwhelming for some users but it is not necessary to understand or use this page to get results with Curvature. Most plugins hide almost all of their parameters from their users, and just give them some basic stuff with a pretty interface and limited knob ranges. If you want to further tweak the sound, tough luck, you need to buy a whole new plugin. This is one of the dirty secrets of the plugin industry. Make one compressor and then sell it multiple times, just changing the graphics and permitted parameter ranges. In my own research, the primary thing which differentiates 1176 type plugins from SSL mix bus style plugins, is that the 1176 ones limit the time constants to the annoyingly fast range, whereas the SSL ones limit the time constants to somewhere in between annoyingly fast and not slow enough to be a mastering compressor. But if you just had access to sensible parameters and ranges, you could easily do all three with one plugin. But there's less money in that. This is one of the fundemental things I wanted to do differently with Curvature. Offer wide and complete parameter ranges, so you can do anything you want. But there's a difficult balancing act with doing that, between giving powerful controls and overwhelming the user.
In other plugins, you just won't be given these controls. It's not like there "aren't there", they have just not be given to you, as a deliberate design choice to restrict you. Well if you want to be restricted, just don't use the expert page. There you go. Now that's just like using other plugins that have enforced restriction. The difference is that with Curvature, you make the choice yourself.
For this reason, it is a mistake to say that Curvature is complicated because it has too many controls or you need to have a PhD to use it. There will likely be more reviews about how it slows down your workflow with advanced stuff but these people have all missed the point of the expert page. If you want to play Duck Hunt, don't use the joystick. Use the laser gun. Obviously.
THE SIDE CHAIN PAGE
On the side chain page, you can very quickly shape the sound of the main signal and/or the detector path using a bunch of different EQ / filter settings that you can simply click on. You can also do side chain compression, activate a look ahead, control the stereo link and even use the EQ settings directly on the sound you are hearing without the need to use it in the detector path. That's why you have separate buttons to apply the EQ to the detector path or main output, so it is possible to do either or both. This screen is extremely handy, obviously if you want to do ducking style compression etc, but also as an extremely fast way to EQ a sound without having to bring up a dedicated EQ plugin, making Curvature step into the feature set of a channel strip. That said, for standard compression tasks, you don't need this page at all.
Many people don't understand what "side chain" or lookahead means on a compressor. Most people think that it is some advanced feature, separate from normal operation, which allows you to connect an "external input". Or that lookahead lets the compressor look ahead, into the future. I'm not sure why people forget that time machines aren't a real thing when it comes to audio. So I'd like to clear up these confusions for anyone who cares.
SIDE CHAIN - EXT
Firstly, since compressors don't normally produce sound of their own, everything is an "external source". It's not as though the normal main signal is somehow internal. It all comes from outside of the compressor. And it's not as though the side chain input is doing anything magically different either. A compressor is essentially just a volume knob who's level is automatically adjusted based on the loudness of some signal. So the compressor has two paths, the amplification path and the detector path. When a compressor mode is set to "internal", this means the detector path is fed with the same signal as the amplification path. When it is set to "external" then the detector path is fed by some other signal instead. There is no magical or complex difference between these two things. You just send a different signal into the detector path if you want to do what is typically referred to as "side chain compression". But "side chain input" or "External mode" are kind of misnomers because whether you use one signal or two different signals, both are external sources to the compressor and in both cases you send something into the detector path.
With Curvature, "side chain" just means any signal that is feeding the detector path, whether that is the same signal that you are hearing or another one. And when you activate the "EXT" button, it takes the signal you are sending into channels 3+4, or however your DAW handles side chain inputs, instead of the one you are hearing.
LOOKAHEAD
Compressors can't time travel. Lookahead is an illusion. Nothing is ahead really. The compressor's detector path is fed a signal in the completely normal fashion, nothing different happens there at all. It is the amplification path which is delayed. This shifts the gain reduction caused by the detector path earlier relative to the side chain signal but the main signal you actually hear now is delayed. The reason why you don't hear a delay in your session when using lookahead is not because the delay is very small (although it usually is) but rather because your DAW delays everything else to compensate. Guitarists who play through plugins intuitively notice stuff like this because it adds total system latency. Lookahead compression is better able to "catch transients" so can really make stuff sound mushy. Curvature is powerful enough to even smooth over a drum recording, removing the transients. For the most part, you want to absolutely avoid that kind of processing for most things. However, some instruments benefit massively from this kind of processing. Bass guitar and vocals are two which come immediately to mind, for certain genres.
THRESHOLD
Curvature does not have a threshold control as this is functionally identical to adjusting the side chain gain (the detector path), only you get more compression by increasing the side chain gain, whereas with a threshold knob you get more compression by turning it down, which is slightly unintuitive for some. You can picture this as smashing the signal up into the compressor's threshold VS crushing the threshold down into the signal. It's six of one and half a dozen of the other.
STEREO LINK
This is an important control for stereo compressors. It is not affected by the presets on the main page and it should mostly be left on max, or some amount above 50%, so compression is applied equally to both channels, avoiding imbalances in the stereo image. Unless you want imbalance, then turn the knob down.
GAIN STRUCTURE IS EVERYTHING
Increasing the input gain causes the output gain to be automatically reduced, and vice versa. Unlike most plugins which fool you into thinking the compression sounds better, just because it gets louder when you add more, Curvature behaves in a much more honest way. Once you start hitting gain reduction, Curvature does exactly that: it reduces the gain. Contrary to lay belief, (regular downwards) compression doesn't make stuff louder, it actually turns stuff down. Then you adjust the gain back up to compensate. But how the gain is compensated is extremely important.
Many, if not most compressor plugins on the market, apply automatic gain makeup based on the threshold. But this is a psychoacoustic sleight of hand. Why? Well unless the amount of gain reduction is exactly equivalent to the amount of make-up gain applied, which is rarely the case, the loudness will likely increase the more compression is applied, instead of staying approximately constant. This is problematic because, when presented with two sounds, and one is slightly louder, the louder one will generally be preferred. So using this kind of gain compensation makes your ears more gullible, fooling you into thinking the compression sounds good.
The way Curvature works is importantly different. Increasing the input gain, decreases the output gain in a 1:1 relationship, yielding zero difference in loudness until you start hitting gain reduction. At which point, the gain reduction starts to compound with the negative gain compensation and the result is that the overall loudness becomes quieter the more compression you apply. This makes your ears more skeptical. Meaning, the compression has to be genuinely good for you to prefer it.
Adjusting the output gain does not change the input level, maintaining the amount of compression. If you want to adjust the input gain independently, just hold the SHIFT key.
SCREAMING FEEDBACK - WARNING!
There is a warning light which comes on when you increase the output gain past unity. This is because doing so in FF mode will result in self oscillation AKA screaming feedback. This might seem unintuitive but under certain circumstances, if you have FF mode on, and the feedback is cranked up, turning DOWN the input gain will actually result in screaming feedback. This is because when you turn the input gain knob down, without holding shift, it will turn UP the output gain to counter balance the level. But where the feedback on the main out is post output gain knob, you are essentially increasing the feedback by doing this.
If that all sounds too complicated, don't worry. Just make sure the warning light doesn't come on if you don't want unexpected feedback. You can still generate feedback if you crank the feedback knob or click the randomize button, if that results in a setting with high feedback. This plugin can get wild. It is supposed to.
In case you are interested, the feedback for the side chain path happens PRE output gain, so adjusting the output knob doesn't mess with your compression level. On the expert page, the TILT knob will determine whether the feedback is low frequency or high frequency. Cranking the output gain will also drive harder into the saturation ceiling, as that comes last in the chain. However, the clean signal which you can dial back in with the MIX knob stays untouched, unaffected and ignores the output gain knob. Resultantly, if you are creating a complex blend of distortion and feedback and the output level really matters, you need to make sure your audio is hitting Curvature at a decent level. Gain structure is one of the most important aspects of audio engineering, and to get the most out of Curvature, you have to know what's going on with your levels in your session.
THE ALGORITHMS
Unlike many compressor plugins, having multiple "algorithms" doesn't just mean there's actually just one main piece of code inside with some tweaking of the internal constants. As you can see with Curvature, you have access to the internal constants anyway, and with the help of Delta Expose, it's obvious to see that each algorithm is actually doing something unique. At the time of Version 2, there are 10 different algorithms and here's what they do:
| Algorithm | Characteristic |
|---|---|
| Classic | This is one of the most basic and widely used compression algorithms in the industry. Some large percentage of compressor plugins do something identical or very similar to this, regardless of the flowery adjectives they use in their marketing materials. If you check this out in Delta Expose, you will see a convex attack and concave release. This is the hallmark of bog standard compression code and so many plugins just do this. But in addition, there is RMS shaping isolated to the attack phase, so the release stays constant. This classic algorithm alone is more flexible and potentially better sounding than many of the overpriced SSL style bus compressor plugins on the market which have fancy analogue style graphics but a limited selection of time constants and no RMS. |
| Log2 | This is a significantly more refined and powerful version of the idea behind Versatile Compressor. With the Kappa and Gamma knobs, you can dial in an impressive amount of attack curve shapes. From a ruler flat linear attack, to linear with a small convex apex, to a larger apex, to extremely rounded. The release can also be shaped from a standard concave behaviour, to a slight S curve, completely independently of the attack phase. This algorithm alone, when intelligently used, can create many, if not most, compression flavours. |
| Linear | Linear style compressors are less common as they can sound aggressive, choppy, digital, unrefined or otherwise not as musical or analogue sounding as the classic convex-concave style ubiquitous in compressor plugins. TDR Molot has a couple of modes which tend towards almost linear behaviour, and this is one of the better sounding compressor plugins out there. So although linear can sound bad, the key is in the implementation, particularly whether the apexes are rounded or hard. With gamma on minimum, you get a ruler straight line with a totally sharp apex, which is a pretty harsh sound. But with the gamma knob turned up, you round off the apex, creating a sound which is still very aggressive, but much more natural. |
| Lin Log | Same as the linear algorithm but with a concave release |
| Log Lin | Same as the linear algorithm but with a classic convex attack |
| Analog | This algorithm creates very smooth S shaped attack and release curves. But the attack time significantly influences the release time. |
| Chaos | It is difficult to explain what is happening here. The algorithm is especially creative, weird and unintuitive. The majority of the weirdness is found with input signals around the threshold with minimal gain reduction. In fact, the more gain reduction, the less strong the effect. Putting the stereo link on minimum can introduce extreme stereo image instability around the threshold level depending on the settings. This one is definitely better suited to individual sounds for creative processing. Also, turning down the mix knob will cause the signal to phase cancel, further increasing the effect, until the delta is reached. |
| Brick Wall Limiter | This is a pretty standard implementation of a brick wall limiter. It is good, reasonably transparent and has almost no parameters. This means it is light weight and easy to use. The downside is that it is not as advanced as more full featured dedicated limiters and may not achieve crushingly loud EDM masters. In the retro page, it is just one single knob, which is input gain. In the expert page you also get control over the release time. But there are some important things to keep in mind... This limiter was designed for a 1ms lookahead time. So, although it defaults to that, if you change this, you will be tuning the limiter yourself. Which might be exactly what you want to do. But if you don't have a strong opinion, leave it on 1ms. Also very important to note: it is only a brick wall limiter if oversampling is enabled. If you turn oversampling off, you will not catch intersample peaks and so you will get a bunch of clipping. Although perhaps otherwise contrary to the philosophy of Curvature, where users have access to all the controls if they want them, there is no control for margin and output gain is deactivated. This is because margin is inherently stupid. Everyone should want their brickwall limiter to hit -0.1db. There is no use case for having a brick wall limiter with a positive margin, and a larger margin defeats the object of brick walling something in the first place (sorry MFiT). There is only one single correct answer as to which margin a brick wall limiter should have, and this is what it has. There are no further controls merely because the algorithm is simple. For future updates I can imagine making a less transparent and louder sounding limiter option. |
| Quantum tunnelling model | The concept is described in more detail below. However, some pointers would be to have much longer attack and release times than normal, if you don't want a distorted sound. This is not because quantum tunnelling math somehow results in inherently different time properties, it's merely because I scaled them by a factor of 10. The reason for this is that really weird and interesting things happen with short release times. Scaling the release times gave finer granularity in these very short times and you can make very cool sounds, even with a simple sine wave, playing around with fast times close to the tunnelling probability threshold. If the barrier thickness is set to be too thin, the electrons will start spontaneously tunnelling and give gain reduction in unexpected ways. Again, this is cool with very fast time constants. Just don't expect this algorithm to behave like a bog standard compressor. It is a radically different concept and the sweet spot is not huge between it doing basically nothing and nose diving the gain reduction. So in my initial tests, it may be best suited to LESS dynamic material, like synths. But it's a totally new thing, so be creative and find your favourite use! |
| Money / Black-Scholes | The knobs STRIKE and EXPIRATION directly determine the strike price and expiration date fed into the black scholes model. EXPOSURE scales the output from the generalized autoregressive conditional heteroskedasticity model since this is, given the fictional context, roughly functionally akin to increasing the portfolio allocation to a given asset. In english this means that turning up the EXPOSURE knob causes more compression. VOLATILITY scales the relative influence of the alpha and beta coefficients of the GARCH model. In english this means turning up the knob produces a more erratic sound with more sensitivity to recent signal dynamic. This interacts with the time values of the compressor. |
The world's first Black Scholes Compressor
One of the most unique features of Curvature is the Black Scholes algorithm. It's highly likely that this is the first audio compressor ever made using the Black-Scholes-Merton option pricing model. After scouring the internet, there's literally zero evidence anyone has tried this before.
Does it work? Yes. Shockingly well. It's probably not going to become a go-to mastering compressor but for creative work on individual elements in the mix, it sounds incredibly unique. When set up correctly, it can do quirky things that no other compressor currently available can do.
WTF is Black-Scholes?
Nerd answer: The Black-Scholes-Merton options pricing model is a parabolic partial differential equation derived under the assumption that the underlying asset follows a geometric Brownian motion, implying log-normal price dynamics with the discounted asset price evolving as a martingale under the risk-neutral measure.
Translation: It's the math that options traders on Wall Street use to make or lose millions of dollars every day in the stock market. It's also a particularly beautiful bit of math which won the Nobel Prize. Well, Fisher Black passed away two years before the award but Robert Merton and Myron Scholes both received the Nobel prize.
Stolen from financial mathematics
Stock options are basically fancy gambling contracts. You're betting on where a stock price will be at some future date. The option's value doesn't just depend on the current stock price though. It's a complex dance between multiple variables:
- Stock price (is Apple at $90 or $120?)
- Strike price (what price did you bet on?)
- Time to expiration (Options contracts lose value over time)
- Volatility (how wildly is the stock price bouncing around?)
- Exposure (how much money are you risking?)
The closer you get to expiration, the more dramatic the value swings become. High volatility means more uncertainty, so option sellers demand higher prices to cover their risk. The Black-Scholes model crunches all this chaos into a single valuation.
Now here's the cool part - audio compression has extremely similar moving parts. It's almost identical:
The Result?
A compressor which takes into account the dynamic range of the input signal and responds in a dynamic and unique way, much more dramatically than typical "program dependent" compressors. Applying essentially identical signal processing techniques found in quantitative finance to audio opens up a completely new sound of compression that has literally never been heard before. Yes it is a bit experimental, unpredictable and slightly CPU hungry, but that's part of the fun of the algorithm.
Academic paper
For anyone with a background in finance or mathematics, I wrote a paper on the topic which goes into more technical detail on the inner workings. Although the actual implementation used in Curvature will remain proprietary, and more complex than just the Black Scholes model, since there is also GARCH-esque volatility forecasting in there too, the mini paper details the mappings.
The world's first Quantum tunnelling Compressor
For years pseudoscientific charlatans have spouted all kinds of nonsense about "quantum physics". The word "quantum" has been so misused that it induces immediate eyebrow raising in anyone with a half functioning bullshit detector. This is why I was initially skeptical about labeling this algorithm with the Q word, but it turns out, this is actually really interesting. So there is an actual academically valid effect called Quantum tunnelling which is well studied and documented. From my perspective as a non-physicist, it's fairly standard stuff in the world of quantum mechanics. Neil deGrasse Tyson gives a lay explanation of the concept, and there are other great youtube videos from people explaining it. I saw one in which the guy demonstrated the effect by pushing his finger on a glass of water. I was intrigued since, just like the Black-Scholes model, the inputs and outputs seemed to make a compelling metaphor to the input and output of an audio device. The energy of an electron versus a barrier could translate to the gain of a sample versus a threshold. And the probability of the electron tunnelling through this barrier could make an interesting stochastically coloured gain reduction circuit.
The idea being, if an electron has a sufficiently large amount of energy to go around the barrier, or the barrier is thin enough to permit quantum tunnelling of that electron probabilistically, then the electron tunnels to the other side of the barrier which accumulates to increase the gain reduction. The rate of dissipation of these electrons, can then be determined by the release time. This somehow felt distantly related to Karplus–Strong synthesis and intuitively seemed promising. I used the exact academically correct mathematics to calculate the probability of a quantum tunnelling event for every sample. The probability is tested against a random value in order to determine whether a tunnelling event actually occurs for the given sample, and if so, it increments the slew level by a factor of the attack coefficient. The slewed signal is then used in the regular way. Just like the Black-Scholes model, you are probably not going to use this as your go-to master bus compressor, but it gives incredibly interesting results and there isn’t anything else like it.
THE SETTINGS PAGE
After conducting a poll, it was clear that most people couldn't care less about the previous themes and only a few people considered it useful to have different themes to identify plugin instances. Almost nobody cared about custom themes. So I ditched the skins and custom theme support in favour of improving the overall interface design. However, to retain the quick visual identification feature, despite the previous lack of enthusiasm, there are now selectable colour indicators on the sides. Based on a YouTube review where one of the main cons was seen to be a slow meter speed, I added the ability to change the decay speed of the meters. Aside from oversampling, which is self evident, the only remaining button to explain is enable retro. Although this is also self evident, it requires a bit of clarification. All the graphics on the retro page take up a fair amount of RAM. If you absolutely don't want to use the retro page, perhaps you don't like skeuomorphism, then deactivating the retro page will make Curvature lighter weight, as it will not read all of those images into memory on start up. That said, I have optimised RAM usage so that only one set of images is ever loaded. You can have as many instances as you like and it will not use more RAM for images. However, in order for these changes to actually take effect, in either direction, you need to fully restart your DAW. Just removing the plugin and reloading it is likely insufficient because of super technical memory allocation stuff.
ADVANCED STUFF
FEEDBACK BEHAVIOUR
When the external side chain input is selected (EXT), the side chain path takes the external signal directly without any feedback. In normal internal operation, the detector path is determined by the FF and FB buttons. When FB is selected, not only is the feedback permitted/engaged on the main output, but Curvature also uses the main output signal for the side chain input, regardless of the position of the feedback knob on the expert page. This is feed-back compression which is more wild and interesting sounding than modern feed-forward compression.
When FF is selected, not only is feedback no longer permitted on the main out, but it also changes the detector circuit behaviour. Curvature will then feed the side chain path from a paralleled version of the input signal when the feedback knob on the expert page is on minimum. This is feed-forward behaviour which is modern, standard, clean and less exciting than feedback.
HIDDEN CONTROLS
There are a couple of hidden controls not accessable from the interface. This is because, for almost all users, these settings should just be left as they are. But for full details for anyone who wants to know the exact behaviour of the plugin, perhaps when running it through plugin doctor or something, these parameters are hidden and accessible from the parameter list view or automation lane view, depending on your DAW:
Filter DC
After getting some early initial feedback from White Sea Studios (he was the first engineer to see the plugin), he noticed that when using feedback, he was getting DC errors from his sensitive RME converters. Looking into this, it was not a case of the plugin generating DC itself but rather, the feedback knob significantly amplified any DC that might have been present in the source material. So I simply added a butterworth high pass at 20Hz which kills all DC. In case anyone cares, this uses a state variable topology whereas all the other filters in Curvature are vanilla biquads. So although this DC offset filter can be completely ignored and forgotten, anyone who happens to want to turn it off for some special reason, can do so.
FILTER ULTRASONICS
The feedback knob can cause some really cool squealing which is cool. However, what is not cool is a gigantic resonance near nyquist which causes the passband to choke and tweeters to explode. This is why, even when oversampling is turned off, if you are analysing the plugin using plugin doctor or Bertom EQ analyser, you will see an IIR low pass round 20kHz. This has nothing to do with antialiasing. The antialiasing uses a FIR lowpass. This additional lowpass is specifically to prevent ultrasonic feedback. If you disable feedback, and for some special reason also do not want an IIR low pass in the circuit, you can disable it with the hidden parameter. However, I recommend leaving this on because the plugin does exhibit instability in ultrasonic frequencies when using feedback without this filter.
INTERNAL TRIM
this is used for (very approximately) gain matching the presets after hearing more excellent feedback from White Sea Studios. Note that this is overwritten every time you select a preset so there is zero utility in touching this control and it can also be ignored.
CLIP EXCESSIVE LEVELS
this is on by default and prevents crazy levels. It is a straight digital clip when output signals get above around +12dbFS. If you have good gain structure, this should never be an issue. The only time you might want to turn this safety off is if you need weird gain structure for a reason I can't anticipate.
PRESET HACKING
The presets are supposed to be curated, quick starting points to save having to spend time learning how to use the expert screen. They are not intended to replace the plugin preset system built into your DAW. If you want to save and load presets, use the normal method for managing presets built into your DAW. Just like a piece of hardware that says "DO NOT OPEN, NO USER SERVICEABLE PARTS INSIDE", this makes me want to open it up and see what exactly is in side. In this spirit, the presets are NOT USER EDITABLE. The XML file where they are all stored is, for example on Mac, here:
~/Library/Application Support/AP Mastering/Curvature.presets
If you want to reset back to factory defaults, simply delete the file and it will be regenerated with the factory settings next time you load Curvature. Note that if Curvature encounters a presets file with an incorrect format, it will override it with the factory defaults on launch without any warning or confirmation. So if you are putting effort into editing these presets, make sure to copy the file to another directory as backup.
VERIFY HASHES
To verify the integrity of the downloaded files, make sure the hashes are identical. On Linux use use the command:
shasum -a 256 /path/to/file
Windows is not POSIX-compliant and lacks basic interfaces and utilities which proper operating systems guarantee. Try loading powershell and run this:
Get-FileHash "C:\path\to\file" -Algorithm SHA256
HASHES
curvature-v2.0.1-linux.zip: 91e035a1d94491576c5b8a957ffb2793d1b15efa1cb0bd3d0cf29658087312db
curvature-v2.0.1-mac.dmg: 96ff51e042fe7e48fa3d8e66f9680d733664d47347130ae8ef242dd845d323f8
curvature-v2.0.1-windows.zip: 373478bb11a34838615dd784f9902ca8411d67ba314cfe8ab2fdc4a96b33ca67