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Rosetta 200

Two-channel converter and more By Frank Moldstad

When I first heard about Apogee's Rosetta 200 (MSRP $1,995), I assumed it was merely the two-channel version of the Rosetta 800, which we previously reviewed here. But on closer examination there's a little more to it than that.

While this two channel A/D D/A device employs the same high-performance converters as the eight-channel Rosetta 800, it has a couple of valuable features not found on Rosetta 800. Principally among these is built-in sample rate conversion (SRC), marking the first time Apogee has ever offered this in a product.

Anyone who records digitally at a sample rate higher than 16-bit/44.1k needs an SRC solution if their final output medium is the CD. There are many different ways of performing this conversion. My usual method is to go from 48k to 44.1k through an external SRC converter made by Z-Sys. But having the SRC built right into the Rosetta 200 offered much greater flexibility, since it has a wide range of SRC conversion options -- up to 192kHz in addition to the more usual 96k, 88.2k, 48k and 44.1k rates. It also streamlined things considerably, since it replaced an extra box with two cables and a power cord to contend with in my workspace. The conversion is transparent -- at least I couldn't tell the difference between before and after.

A future software upgrade for the Rosetta 200 will add Auto SRC, automatically applying sample rate conversion to digital inputs when needed (firmware updates can be loaded via onboard MIDI ports). If a selected digital input is detected to be non-synchronous with the units clock, sample rate conversion is automatically applied to the input and the corresponding SRC LED lights. Until this feature is implemented, the Auto SRC button on the front panel cannot be selected. The Auto SRC will provide some handy additional functions not readily apparent at first glance.

For instance, "non-synchronous" digital sources such as DAT machines, CD players and digital synth outputs often need to have an entire digital system locked to them in order to work, which besides being a hassle can degrade clock quality. But Rosetta 200's Auto SRC will make it possible to set either Source path to a non-synchronous input without modifying the sample rate or clock source. As a result, a Rosetta 200 serving as the master of a system at 96kHz can accept input from a 48kHz device without clocking to that input or changing sample rate.

The SRC feature is actually just one of three elements in the Rosetta 200's CODA Audio Finishing Module, the other two being UV22HR and Aptomizer. (You've got to hand it to them, the names are catchy. Who wouldn't want to Aptomize their audio?) All three functions are related -- UV22HR being Apogee's well-known proprietary process for dithering 24-bit files to 16-bit, and Aptomizer being a brand new Apogee technology developed for the Rosetta 200. What the Aptomizer does is set A/D and D/A calibration levels by detecting peak level information at the A/D converter. Then it adjusts both analog inputs and outputs for the optimal setting.

Another new feature introduced in the Rosetta 200 is full channel metering, with a range of LEDs from -50 dBfs to "Ouch" displaying input and output levels on each of the two channels. This has great advantages over the "green" or "red" LEDs on the Rosetta 800, showing you exactly how far under 0dBfs you are at any time -- instead of just over or under indicators.

As with other newer units in Apogee's line, which include the AD16X, DA 16X and Rosetta 800 and the Big Ben master clock, the Rosetta 200 has an expansion card slot for Apogee's X-Series cards for direct connection to Pro Tools HD and Mix (X-HD and X-Digi-Mix cards). It can also accomodate a direct FireWire connection with the X-FireWire card that supports S800/S400 standards.

Of course, at its heart the Rosetta 200 is a superb two-channel A/D D/A converter, exhibiting the same performance characteristics as the Rosetta 800. It's a great unit for those who only need two channels in and out, or who can only afford two channels but want professional conversion. The included features, especially the SRC, give it versatility that will prove useful even if a user's setup becomes more elaborate later on -- the high quality conversion alone will see to that. I would highly recommend this to anyone seeking affordable conversion without compromises.


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Related Keywords:Apogee, Rosetta 200, sample rate conversion, SRC, A/D D/A, converters


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