User manual ARBORETUM HYPERPRISM-DAS

[. . . ] Hyperprism-DAS Manual Table of Contents Copyright ©1999 by Arboretum Systems, Inc. This documentation may not, in whole or in part, be copied, reproduced or translated without prior written consent of Arboretum Systems. Hyperprism-DAS Plug-Ins for MacOS AudioSuite Compatible Applications Digital Signal Processing Software by Arboretum Systems Inc. This documentation current to Hyperprism-DAS Version 1. 5, last revised 11/1/98 Copyright ©1997, 1998 by Arboretum Systems, Inc. This Documentation may not, in whole or in part, be copied, reproduced or translated without prior written consent of Arboretum Systems. What's New in Hyperprism-DAS v1. 5: q q q q q q New Harmonic Exciter, Bass Maximizer and Tube/Tape Saturation effects Frequency Shifter, Limiter and HyperVerb now included in Hyperprism-DAS Improved Low Pass, High Pass Filters; no more distortion Improved Compressor and Noise Gate New simplified Installation procedure Now compatible with Emagic Logic Audio, Avid Media Composer 7. 0 and Avid Xpress 2. 0 Contents License Agreement Introduction to Hyperprism-DAS q q q q q Welcome to Hyperprism-DAS Hyperprism-DAS Effects System Requirements About the Demo Version Installing Hyperprism-DAS r r r r r Before You Install Easy Install Custom Install DAE Memory Management Problems? q q q q Using Hyperprism-DAS Hyperprism-DAS Parameter Sliders About Stereo Effects AudioSuite Preview Buffer Effects Processes q q q q q Hyperprism Filter Processes Hyperprism Modulation Processes Hyperprism Delay and Reverb Processes Hyperprism Stereo Processes Hyperprism Miscellaneous Processes Appendix A: Troubleshooting Appendix B: About Digital Audio Files About This Manual The documentation may be viewed or printed from any browser, such as Netscape Navigator or Microsoft Internet Explorer. [. . . ] For example, an impulse response where the energy is concentrated at a few samples (i. e. . most samples are zero) will have a low echo density, whereas an impulse response with energy spread out in time (i. e. few samples are zero) will have a high echo density. To compare the echo density of various reverberators, plots have been made of the first 200 milliseconds of the of the impulse response. To examine the impulse responses in greater detail they can be downloaded and viewed with an audio editing program. Coloration defines how the reverberator changes the frequency response of a sound. Frequency domain plots were made using Cool Edit Pro, using a 4096 point FFT and a Blackman-Harris window. Successive FFTs were made starting at roughly 500ms to 1000ms and then averaged to get the overall frequency response of the late reflections. Late reflections are those which occur after roughly the first 100ms. In the case of a "well liked" concert hall or room the frequency response of the late reflections will be relatively smooth and uncolored. In other words, there won't be any sharp peaks or valleys in the frequency response. In the case of a poor sounding digital reverberator, there will likely be lots of coloration. For example the common problem of a "ringy" sound corresponds to a few distinct peaks in the frequency response, where as a resonant or metallic sound quality generally corresponds to a very "rough" frequency response. For the purposes of this report we will assume that a good digital reverberator can generate reverberation that is perceptually indistinguishable from actual reverberation of "well liked" acoustical space (e. g. For a good point of reference, we will first examine naturally occurring reverberation. Of course other "unnatural" types of reverberation may be useful in some cases. Here is the first 200ms of impulse responses from a chapel and a large hall. (NOTE: Cyan = Left Channel and Magenta = Right Channel) Looking at these plots we can observe a number of distinguishing features. Some of these features include: q Smooth decay of late reflections (i. e. little flutter) q q q Relatively uncolored frequency response of the late reflections (i. e. no ringing) Sharp attack (usually) Extremely high echo density While these features are generalizations, most naturally occurring reverberation has these properties, especially for rooms and halls with "good acoustics. " Now lets examine some common digital reverberators, including a TC Electronic M2000 and a Lexicon 480L. Sound Forge Reverb: Pros: q Somewhat colorless late decay Cons: q q q Severe lack of echo density Fluttery late decay Echo density does not increase with time Digitech GigaVerb: Pros: q High echo density Cons: q q Very long attack time (it takes over 100ms to reach maximum amplitude) Highly colored late reflections (i. e. resonant and ringy) Power Technology DSP-FX Reverb: Pros: q Moderate echo density (though not always enough) Cons: q q Highly colored late reflections (i. e. [. . . ] Lower sample rates lose high frequency response, and 8-bit storage causes a reduction of your sound's dynamic range, resulting in noisier, "grainy-sounding" audio, especially during softer passages. If you are creating 8-bit audio (for example, for multimedia or Internet distribution), you will get best results if you do all your signal processing at 16-bits and 44. 1 or 48 kHz, and then create an 8-bit file at the end of the process. The distortion of low-level signals can be minimized by normalizing your 16-bit file before 8-bit conversion, or better still, by using dynamic range compression or manual gain-riding to make soft parts of your sounds louder before reducing their resolution. The use of dither can improve the sound quality of 8-bit audio, although at the expense of a slightly noisier signal. [. . . ]