DSP ON BOARD
Once DAT recorders evolved to their technical limits,
the Alesis Masterlink stepped in to carry on. It’s more than a 24-bit /
96-kHz recorder and CD burner. The on-board Analog Devices Sharcä
DSP chip has incredible power, although the knob-less interface limits
its potential. While the focus of this article is on increasing
the hard disk space, George Petersen at MIX Magazine asked me to investigate
the DSP features for a Power Tools article, which I have done in a cursory
way here and plan to elaborate upon in the future.
Once Alesis gets back into full swing after recovering
from Bankruptcy and subsequent purchase by Numark's Jack O'Donnell, they
will hopefully start thinking about MASTERLINK II, see my WISH
LIST at the end of the article. Feel free to make suggestions
that I will post.
Of the handful of users I interviewed, only one takes
advantage of the onboard DSP — Compressor (DSP-1), Multi-band EQ (DSP-2)
and Peak Limiter (DSP-3) — the others treat Masterlink as a storage device.
Recording, basic editing, CD burning and archiving are a breeze.
I have found the DSP to be quite useful if you have the patience to scroll
through the various menus and paramters...
Of all the DSP functions, Normalization (DSP-4) was the
least understood. In a traditional workstation, a track is scanned for
its peaks, the distance between them and "digital zero" is determined and
if desired, the level of the entire track can be raised by that amount
and, typically, a new file is rendered.
MasterLink can also scan the track for peaks, entering
the amount into a "window" so users can tweak or toggle on-and-off in real
time. Because Normalization is a DSP process there is no need to render
a new file. However, since DSP-4 is at the end of the chain it becomes
a moving target, subject to the amount of the "other" processing being
done. For example, calculating the headroom above the peaks — with all
processes off — might yield 4dB of headroom. Add some Compression, EQ and
Limiting and the amount of Normalization will change. Since Normalization
is virtual and therefore "real time," it can be switched in and out. You’ll
know right away if re-calculation is necessary.
Masterlink’s Compressor Threshold starts at 0-dBFS (as
in Full Scale), the only place to go is down. The Gain Reduction is quite
literal — the reverse of what I expected, because some compressors add
gain to meet the Threshold — but the Alesis approach allows for some headroom
for the processing that follows. There is a very helpful metering option
within the DSP-1 menu structure in Version 2.11. Greg Prestopino is the
one interviewee who makes use of the compressor. His starting point includes
the following: a Ratio of 4:1, soft knee, fast attack and slow release.
The lack of an interface makes EQ the most challenging.
You have to paint with broad strokes because microsurgery is just too tedious.
With three bands plus "Q" for each band (all the way to shelf) there are
plenty of options. Patient people will either be rewarded or carried off
to the loony bin. Here’s one complaint aimed at all DSP designers. When
will Q be represented in something tangible, like OCTAVES? As users, we
should at least have the option to chose.
Like the Compressor, Limiter Threshold starts at 0-dBFS.
From there it behaves in a completely opposite manner, Gain is increased
as Threshold decreases. Attack is fixed fast while Release has an extremely
wide range — from 25-microseconds to 9.9 seconds. Last in the chain is
the Normalizing tool. Consider it a "level scanner" reporting the Headroom
Margin. The resulting report can be engaged or not or anything in between.
Part of the Mastering Process is to make all the pieces fit — this does
not always mean maximizing the level. Rather than continue the habit of
"slamming zeroes," 24-bit technology allows our ears a little relief. You
can commit and dither later…