Ursa Major Space Station

October 19, 2011 · Posted in Uncategorized 

The Space Station, or SST-282, was described as a “reverberation effect.” It could apparently get reverb times of up to 3.5 seconds. This may not seem like a particularly long time by modern standards, but it was a huge achievement given the architecture that was used. In the SST-282, the reverb effect was obtained by using a single delay line, with 15 output taps from the delay buffer summed and used for feedback, and an additional 8 taps used to monitor the delay line. Multitap delay lines such as this, where several taps are summed and used for feedback, can quickly reach a high reflection density. However, they are notoriously unstable, with the maximum feedback gain being allowed under conventional circumstances being equal to 1 divided by the number out output taps.

The heart of the new Space Station is a single 140MHz Motorola DSP chip programmed with faithful recreations of the original Space Station’s algorithms, some updated versions, plus the new Room reverb. The unique aspect, though, is that the unit is packaged in a slim panel with wooden side cheeks, which is designed to sit on a desk. It measures just 165 x 127 x 150mm (hwd) and weighs next to nothing, with a four-metre connecting cable which terminates in a pair of XLR connectors and a compact universal mains power supply. The latter accepts the usual IEC mains lead and operates on AC voltages from 90V to 260V, consuming less than one Watt of power.

Audio connections are provided only in digital form, with stereo AES input and output provided on flying XLR connectors. The SST206 is a stereo output device, like the original, but where it differs is that it accepts a stereo source where the original was a mono-input device. However, the stereo input is a convenient by-product of adopting the AES input format, and the stereo input is summed to mono to feed the delay/reverb processor. A dedicated Dry Level control allows a percentage of the stereo source signal to be passed through to the stereo outputs, if required.

The unit is optimised for use at a 48kHz sampling rate with 24-bit resolution. It will also operate happily at 44.1kHz and even 32kHz — although the control calibration will be inaccurate at these lower sample rates since the delay and decay times are related to the sampling rate. Similarly, it can also be used at 88.2kHz and 96kHz (but only with the SST Reverb and Echo programs), with proportionally shorter delay and decay times again.

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