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Section Two: Analog vs. Digital Signal Processing
Section Two: Analog vs. Digital Signal Processing
The ongoing debate continues: what sounds better, digital or analog signal processing? Audio engineers
ALL have an opinion on this, but the lack of documented research on the topic makes all conclusions
tentative. Nonetheless, the audio industry is slowly moving to digital as circuit designs continuously
improve and technology advances into the realm of 24-bit resolution — which provides finer audio detail,
particularly at low levels of dynamic range. The tentative conclusion we would suggest is that the sound
of digital circuits is widely variable, encompassing the capacity to sound remarkably like analog
circuits…and much more. Beyond these considerations, however, there are undeniable advantages to
digital signal processing…and one disadvantage that we believe we have solved with the Sabine
GRAPHI-Q.
THE ADVANTAGES:
1.
GREATER PRECISION AND REPEATABLE ACCURACY. Analog circuitry produces less exact
and repeatable adjustment. Identical analog circuits may produce different results when processing
an identical audio signal, due to the tolerance of components comprising the analog circuit. Digital
circuits rely on repeatable mathematical calculations and thus are more consistent. For equalizers,
this means that the slope, shape, and symmetry of digital EQs are consistent across frequencies,
and from one application to the next.
2.
LESS PHASE DISTORTION. All equalizers cause some degree of phase shifting. In analog filters,
this phase shift exceeds the width of the filter—often by a considerable margin. In other words, the
phase shift encompasses frequencies beyond the boost or cut range of the filter. With digital filters,
this phase shift can be restricted to within the filter width.
3.
LESS FILTER DRIFT. Analog circuits rely on components that vary as they age and/or are
subjected to different ambient temperatures. This variation can in turn cause analog filters to drift
from their original settings. In contrast, digital filters are based on mathematical formulas and will
remain constant over time and changing temperatures.
4.
LESS NOISE. As analog parts wear, get dirty, or corrode, readjusting them can introduce noise into
the signal path. All audio engineers are familiar with the sound of a “scratchy fader.” Digital controls
affect the signal, but are not actually in the audio path and thus cannot introduce noise.
5.
RECALL AND STORAGE OF SETTINGS. Because digital filters can be represented mathemati-
cally, settings are easily stored, recalled, and copied to other channels or units. Analog filters are
dependent on the physical position of potentiometers and sliders, and storing and recalling settings
requires servo motors and automated repositioning of controls. This is both more expensive to build
and produces less accurate results.
6.
COST. As technology improves, features increase and prices plummet. Nowhere is this trend more
apparent than in the digital world. DSP circuitry is generally smaller, less costly, and more powerful
than comparable analog circuitry, which means you get a lot more bang for your buck (or
DeutschMark, pound, or peso) with a digital box. Compare the price of the GRAPHI-Q to a high
quality analog graphic equalizer, and you’ll see what we mean—especially when you add a
compressor, delay, FBX and parametric EQ, and software interface to the comparison.
THE DISADVANTAGES.
1.
FAMILIARITY AND EASE OF USE. The sole disadvantage of digital processors that few if any
sound engineers will argue has to do with the familiarity and user-friendliness of the digital control
interface. Many powerful DSP products are menu-driven and difficult to use. One very special
feature of the GraphiQ 3102 and 3101 models is the familiar analog-style interface of the front panel.
The control surface looks, feels, and operates like a graphic equalizer from the 1970’s—with the
power and features of 21
st
century technology. If you’re a 21
st
century technophile who loves
computers and knobs, then you won’t be disappointed either—just plug in a serial cable, load up the
software, and you’ll find a whole new world of hacker-pleasing software control waiting for your
command.
The GRAPHI-Q truly offers the best of both worlds — or maybe even the best of three worlds and five
dimensions.
