Owner`s manual

You can use UV22HR in conjunction with a wide range of both lossy and lossless compression technologies
used in DVD mastering, such as Dolby AC-3, DTS, and MLP (Meridian Lossless Packing). In addition, UV22HR is
a very useful technique when used in conjunction with Internet audio delivery systems such as ‘MP3’ (MPEG1
Layer III), Real Audio, QuickTime and other systems, where the ability of UV22HR to maintain high-resolution
quality and detail at the 16-bit level means smaller, better-sounding files and streaming audio signals, offering
more effective use of available bandwidth.
Application Notes
High-Density Conversion, Word Lengths and Interconnects
Despite the apparent proliferation of “96 kHz” devices, and the apparent demand for them from end-users, it
is only recently that standards have been agreed for “high density” (ie 24 or more bit, 88.2 kHz, 96 kHz and
above) conversion. Nowhere is this more true than in the world of digital interconnection.
You can either use a single AES interface at double-speed (we call this ‘single-wire’or ‘double-fast’ mode),
or a pair of interfaces at normal speed (we refer to this as ‘double-wire’ or ‘double-wide’). Both have advan-
tages and disadvantages, and as a result their adoption in the industry is about 50/50. However it is worth not-
ing that few, if any, digital cables are able to carry ‘double-fast’ signals any great distance. In most cases, the
usable length of a digital cable is reduced by a factor of four. In addition, some AES/EBU routers may not sup-
port ‘double fast’ operation.
Apogee supplies both the single-wire and double-wire formats in the Rosetta 96. The formats are selectable
via DIP switch #n on the back panel (see page 20).
At present, we do not support the use of UV22HR at high sample rates. The reason is simple: it is almost
completely unnecessary. (If you’re using the one machine we have ever heard of that records at 16-bit, 96 kHz,
then I’m afraid we can’t help you.) In most cases you will want to use shorter word-lengths in conjunction with
lower sample rates – perhaps you’ll record at 24/88.2, but you want to get a CD master at the end of the day.
Or you are recording at 24/96 for a 20-bit, 48 kHz DVD-Video release.
Do your sample rate conversion first. The
longer you maintain the maximum word-length, the better it will sound. Apply UV22HR to the 24-bit signal at
the final sample rate.
We are aware of the fact that the DVD-Audio specification allows for different sample rates in the same
“family” (44.1/88.2/176.4 kHz or 48/96/192 kHz) for different surround channels – say 96 kHz for the front and
48 kHz for the rear – and that in theory you can use different word lengths as well or instead, including 88.2 and
96 kHz at 16 or 20 bits. However, the general view at present is that longer word lengths are worth maintain-
ing, even more than high sample rates.
We are keeping a careful eye on developments in these areas and will review our design criteria in the light
of industry requirements and developments. Check our Web site for the latest word: http://www.apogeedigi-
tal.com/
Rosetta AD User’s Guide
Page 20