Click below to download the VST plugin (64-bit only):
When designing digital audio effects which have precedent in the analog world, it is often desirable to borrow system architecture and user interface ideas from their analog predecessors. Many audio plugins go even further and mimic the more precise operational characteristic of analog devices, including ostensibly unintended effects such saturation and signal degradation. Taking the extra steps to model the more subtle characteristics of analog audio effects often results in more convincing and pleasing perceptual qualities in the final product.
In Spring 2016 I designed a VST audio plugin which models many of the operational characteristics of tape-based echo effects, taking the Roland RE-201 Space Echo as the main inspiration. Measurements were taken of a recently serviced, functional Roland unit to inform the characteristics of the digital model. The user interface takes cues from the faceplate of the original, allowing user control of the number of echoes, echo volume, and “intensity,” which corresponds to feedback in the delay path. The feedback path has additional filtering which mimics the frequency response of the magnetic tape and tape heads used in the Space Echo, and the plugin also features a user adjustable saturation control which introduces the soft-clipping observed due to tape’s magnetization curve. The mechanical aspects of the tape’s motion are also modeled: the user can adjust the amount of “wobble” in the virtual tape machine, which introduces subtle pitch bends to the echoing sound, and the echo time knob has a ballistic response allowing for tape “slow-down” and “speed-up” sounds.
The VST plugin was designed in MATLAB and generated using the MATLAB Audio System Toolbox. The work was completed as a term project for the ECE 472 – Audio Signal Processing course at University of Rochester, and was a collaborative project with Christian Terjesen of Adventure Audio.