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the Surround Mastering Dynamic Processor
There are countless mono and stereo mastering compressors. However, if you try to find a dynamic processor for 5.1 surround formats, you have to rely on using several rough and ready coupled mono or stereo devices and come to terms with the limited and control facilities.
To offer an alternate device that is not only a 6 channel processor but a device that deals with the special needs of 5.1 surround we are proud to present the dynamic processor DYNAROUND that has dedicated 5.1 circuitry and offers exceptional audio performance that goes beyond most digital formats with and audio bandwidth that exceeds the performance of 24 bit, 96 kHz digital recorders and consoles.
The DYNAROUND is unique in the sense that it is 100% analog and is also a 100% dedicated 5.1 dynamic, multi-processor mastering device. It offers an exceptional amount of options and features. This unit adheres to the to the adt-audio principle of absolutely no compromise in sonic and build quality. This means symmetric circuitry, balanced and floating inputs and outputs, +30dBu headroom from input to output, extensive metering of all activities, special circuits that allow separate treatment of front, surround and LFE channels.
Compressor - Limiter - Expander
Three separate elements are needed for the dynamic processing of a final mix. The mastering compressor should condense the signal and balance out dynamic imbalances. It needs to have wide control ranges to offer all possible ways of processing. This is not only a required for the threshold and ratio but above all for the influence of the attack and release process. The tonal performance characteristics of any compressor are mainly determined by the adjustment of the attack time. Furthermore, an Autogain function is helpful, as the user is excused from the need to readjust the level permanently. As the level shifts with any changing of a setting, actually the real effect of the compression is blurred very fast. It is very comfortable to have a circuitry that readjusts the output level constant as far as possible.
Eventually, any compression effect is based on the effect, that the level of the program material modifies a basic gain; it just turns out in the way that without an input signal there is the maximum gain. Even with settings with only little punch through, this results in a considerable deterioration of the signal to noise ratio. To compensate these effects it is necessary to have an exactly adjustable expander at disposal, which is able to regulate down the basic gain with small input levels and to fade out further distances. Also with the expander it is important to have full control about all the parameters to suit the operation in the way that there are no unpleasant side effects.
As the compression is supposed to condense the program and, more likely a long attack time is needed to produce positive tonal effects, the compressor is not suited to limit the maximum output level. Admittedly, a lot of mastering compressors have a sufficient range to operate as a fast limiter, but of course, than the use of the normal compressor is not possible at the same time. Therefore, an additional, separate limiter is necessary for a complete dynamic processor. The limiter has to have a very fast attack time, to be able to suppress peaks effectively. The most important point of a limiter is not it's tonal behaviour but its ability to rule out peaks in the range of several dBs without negative, audible effects. Since the compressor changes of course the peak level the limiter has to be equipped with its own regulation circuitry, which evaluates the output signal of the compressor.
Multichannel Regulation Amplifiers
Any regulation amplifier with more than one channels needs to be able to couple the regulation. The easiest way to understand the problem is to have a look at the operation of a stereo compressor. If instead of a control coupled stereo processor, two mono compressors are used, its own momentary level separately controls each channel. Therefore the gain of the stereo signal is never exactly matching. As the location of the program essentially depends on the relation of the left and right levels, the position of the sound sources changes permanently. In any case it is necessary, to regulate left and right synchronously to avoid any changes of the left/right level relation. If only one signal is used for the control, only the signal of this channel will be included. A peak in the right will not cause a regulation, if only the left channel is used for the control. It is therefore necessary to combine both of the channels to form a precise control signal. This has to be done in a way, that the channel with the highest level determines the regulation. Do implement this principle separate control voltage converters are needed. If the channels are mixed and processed by only one converter, the regulation depends on the phase shift between both of the channels. A widened stereo signal will produce a lower control voltage as a coherent mono signal with identical levels and phase positions.
The same principle is needed for the expander, even if this seems to be not true at first blush. If there is no signal in one of the channels, of course, the other channel with signal has to lead the regulation and prevent the expander from fading down.