Product Review Supplement - Cinema DSP: A Deep Dig into the Yamaha RX-V795A Signal Processing - December, 1999
Almost any surround processor you come across includes a selection of “DSP modes”. “Hall”, “Theater”, and “Jazz Club” are just some of the names given to these various “modes” that fiddle with the sound. In the case of the Yamaha receivers, they don’t just add some reverb and give it a name. They’ve been out to real world locations like cinemas, churches, clubs and concert venues. There, they observe and scientifically measure the behavior of the sound. The result is a sonic simulation of these environments on their processors. They can be mildly pleasant to outright distressful, depending on the material and the mode used. On the whole, I find it an interesting new way to listen to familiar material. In the case of film sound, Yamaha takes decoded soundtracks and superimposes variations of their sound fields in an effort to deliver a more “cinematic” experience. My first Yamaha receiver with Cinema DSP, as they call it, was terrific. Only the rear surrounds got processed and the result was a perfect simulation of a movie theater’s surround speaker array. My next Yamaha receiver was a step up and had independent processing of the rear as well as the main front speakers (“Duo-Field”). This worked great until someone’s voice would pan from left to right. It would be processed and artificial at the left, become normal through the center, and back to artificial on the right. Fortunately the 795A puts the power in your hands to make changes to the sound fields and tailor them to your tastes.
As you sit in a venue (theater), several facsimiles of the sound reach your ears. Let’s assume a lone piano in a concert hall. When the pianist plays a note, the first sound to reach your ears comes directly from the instrument. It is quickly followed by a refection of the sound off the ceiling above the piano, and perhaps a little later by a fainter reflection off the back wall. It is these reflections, early reflections we call them, that give a venue its character. It is the ability for the user to change the early reflection parameters that make the 795A so flexible. (Animated concert hall GIF is copyright Yamaha Corporation.)
Here are the settings Yamaha makes available to us:
Surround Delay: For surround sound, delay compensate for rear speakers being closer to our ears than the front ones. Range: 15-30ms for Dolby Surround, 0 - 15 ms for Dolby Digital and DTS, 15 - 49 ms for the music modes.
Room Size: Changes the apparent size of the venue. A smaller setting will generate early reflections in quick succession, a larger value will have them occurring at greater intervals. Range: 0.1-2.0 (1.0 is default)
Initial Delay: Changes the apparent distance to the source by changing the time between the direct sound and the first set of early reflections. Range: 1 - 99 ms for global or front, 1 - 49 ms for surround.
Liveness: Changes the apparent reflectivity of the venue’s walls by making the early reflections diminish quickly or slowly. Range: 0 - 10.
Reverberation time: Changes the apparent size of the venue by specifying the time it takes for reverberations (after the early reflections) to be down by 60 dB (1 kHz). Range: 1.0 - 5.0 seconds.
Reverberation Level: Sets the level of the reverberations relative to the last early reflection. Range: 0 - 100%.
The following table lists which settings are available for the various programs. Note that for the Cinema DSP programs there is a unique set of settings for Dolby Surround, Dolby Digital, and DTS. (I.E., The settings for “70mm Adventure” can be different for Pro Logic, Dolby Digital, and DTS).
On the whole, use of the Yamaha modes is trial and error depending on the combination of media and mode. Because so much “character” is being added to the signal, I feel the whole system favors home theaters which themselves are primarily dead acoustically. By manipulating the Pro Logic/AC-3/DTS Enhanced mode, I’ve got it to a point where I always use it in place of “regular” surround. 70mm General, Rock Concert, and Jazz Club are usable as well. Church and Disco are absolutely out of control and can’t seem to be tamed to the point where I’d actually use them. Play with the sound fields. You just might chance upon something you like.
- Brian Florian -
© Copyright 1999 Secrets of Home Theater & High Fidelity
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