Aaron Wishnick is the Research Manager at iZotope, where he's worked for nearly eight years on every aspect of DSP algorithm development. Aaron's team has worked closely with the Ozone 7 team in developing almost all of the new modules. While not typically focused on analog modeling, when tasked with its conception and execution, they often found themselves going back to formula in their quest to achieve both faithful reproduction and expanded control.
Wishnick recalls one of iZotope's founders posing the question "If there were aliens that had never learned anything about analog hardware design, how would they be designing plug-ins?"
"That's sometimes an approach we like to take," he says.
Wishnick and his DSP development team managed a considerable scope of new algorithms in helping to build Ozone 7, and dedicated much of their energy to perfecting new features like its vintage emulation. In designing these features, they worked hard to preserve "the best of both worlds," beginning with a resolution to faithfully reproduce cherished, specific analog qualities. Then, when this was achieved to their satisfaction, they incorporated digitally enhancing processes into the modules that can't be accomplished with hardware.
Engineers rely on a Maximizer to boost volume to peak levels while containing or eliminating any clipping, distortion, or pumping. Ozone's Maximizer is well-known for its IRC (Intelligent Release Control) algorithm, which analyzes the properties of a signal and decides, in real time, how to make the best trade-offs to make it sound good. The most recent iteration prior to Ozone 7 was IRC III, which uses psychoacoustic models of the human auditory system to determine how audible different types of distortion will be, and then picks what actually sounds the best to the human ear.
For Ozone 7, the smart algorithm has been improved with IRC IV. In addition to intelligently limiting peaks and boosting program level, IRC IV also gently adjusts the frequency content in real time and works smoothly across many bands of limiting, acting more selectively on frequencies that contain excess energy.
"If you have some drums, and you also have some vocals at the same time, using a conventional limiter to prevent the drums from clipping would also cause pumping in the vocals," says Wishnick. "IRC IV is going to be able to reduce the drums without touching the vocals so much."
Ozone 7's Vintage Limiter is used to affect dynamic range in a way that glues things together and brings warmth and character to a signal through analog-based modeling. Loosely inspired by the tube-driven Fairchild 660 and 670, it's been optimized to minimize tube-gain saturation/distortion and fit well into a mastering chain, but also to function as an analog-inspired feedback-compressor, doing level detection on its output. As a result, the Vintage Limiter has no "look-ahead," and offers a range of smoother, more genuine analog sound contouring.
Vintage EQ in Ozone 7 Advanced is modeled on Pultec EQP-1A (for low and high frequencies) and MEQ-5 (for mid-range frequencies) equalizers. Providing a slightly more restrictive workflow in comparison to parametric EQs, the plugin allows for more sweeping, creatively inspired shaping and texturing with a focused set of options but remains exactingly calibrated for smooth behavior and accurate frequency response, especially in high bands. Low bands can be both boosted and cut at the same time, and iZotope sound designers have optimized this unique feature for the goals of mastering.
"It's helpful for broad gestures," says Wishnick. "'I'd like to make this a little brighter,' or 'I'd like to add some bass.' We found that there is a low boost and cut frequency that would be really useful to have for mastering that didn't exist on the original unit, so we actually added that in."
The sound of tape can blend elements together nicely, adding saturation and altering frequency response. Ozone 7 Advanced includes vintage tape emulation that gives users another creative tool to be able to get the sound that they want, modeled on the best analog devices and enhanced to allow for more control when adding tape-inspired sonic qualities to your digital mix.
Beginning with a Studer tape machine, iZotope engineers analyzed and emulated the original analog process and then expanded on its unique sound signature by adding controls to further sculpt and tweak its innate sonic qualities. Each frequency range is sampled individually to reproduce and control distortion levels according to the original model's natural analog behavior.
"Our model of frequency-dependent distortion—how much different frequencies distort—is really accurate," says Wishnick. "It matches the original machine really well. And another kind of unique thing that we modelled is the phase distortion that this machine introduces... through interactions with the electromagnetic field, you get some amount of phase rotation, so we've actually modelled that as part of our algorithm."
The Vintage Compressor module in Ozone 7 Advanced is a feedback compressor that incorporates qualities from numerous classic compressors without being modeled on a single unit. It offers controlled dynamic range and another way to amalgamate myriad musical elements to forge a different sound. Like the Vintage Limiter, it does level detection on compressor output rather than input signal, which, as Wishnick describes, is a very analog quality, and one which his team had to work hard to emulate in the digital realm.
"That's something that analog hardware does really well and computers don't do so well... we've used some pretty cool techniques to really accurately model this thing."
Ozone's Vintage Compressor is designed for single-band workflow, with no look-ahead, which gives it a particular sound. It allows for slightly higher distortion levels, characterizing your signal in emulation of the roundness and richness of a vintage analog device. In addition, it offers a wide array of sidechain filter options that let you filter the signal the compressor is seeing, for example, allowing you to high-pass out low frequencies to reduce pumping. Visualization of the sidechain filter's frequency response and a smorgasbord of control options keep compression as malleable and intuitive as possible.
With four new modules and a new IRC mode, iZotope's Ozone 7 Advanced has added breadth to its already deep functionality in digital signal processing and continues to build on its reputation as a world-class one-stop mastering suite. Incorporating exciting new elements including IRC IV and dedicated modules for vintage analog emulation, the Ozone 7 Advanced upgrade is designed to build on its already popular, familiar framework. Its new tools add to the platform's versatility and expand its capabilities to encompass a new level of sound contouring and signal manipulation through precise yet intuitive user interfaces.
"As the manager of our research team, and someone who is involved with this development effort, I'm immensely proud of everything that came out of this," says Wishnick, who emphasizes the value of having brought together sound designers, audio engineers, and signal processing specialists in achieving a final product that reflects the observations and objectives of each constituency.
"There are times when you want to reach for those digital tools that Ozone has offered for some time, and I think there are other times that you want to reach for those things with different kinds of character, those vintage emulations," he says. "I hope people really enjoy the opportunity to use both of those things and choose the right tool for the job."