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2005-09-20T12:30:57Z
CorrectionsHiFi.doc - Microsoft Word
2008-11-01T16:40:37-07:00
2008-11-01T16:40:37-07:00
application/pdf
Jon Dattorro
Comments on: "The Implementation of Recursive Digital Filters for High-Fidelity Audio"
Digital Filter Design - Digital Signal Processing - Digital Filter Topology and Implementation
This paper does not purport to be a design
review of the Lexicon OPUS digital parametric equalization
filters. Although the equalization subsystem
for OPUS was my responsibility unril 1987
I never
indicated that the paper represented that which was
offered to the customers. The system
OPUS
is only
mentioned in the biography because my design experience
is relevant to the paper's topic. I also designed
the original OPUS mainframe backplane and I shared
the console filter-strip facade and electronics design.
I imagine that much has changed during the interim
between my completion of the task in 1987 and the
introduction of the equalization subsystem this past
November at the 85th Convention of the Audio Engineering
Society. Indeed
Mr. Eagle was not a Lexicon
employee or consultant prior to my departure. Mr. Eagle
has declined to share any technical information since
I joined ENSONIQ
so I have no knowledge of the
extent to which my work was used.
I would like to note several errors which appeared in this paper.
It is important to note that this second-degree
source of truncation error is nonexistent in the truncation
error feedback topologies discussed in Secs. 2.3 and
2.4. That is because the error feedback coefficients
were trivial multipliers there.
As for my interpretation of the truncation error cancellation
circuit
which I believe is correct
it is important to understand that truncation error cancellation is a special case of error spectrum shaping (ESS)
which
is truly a truncation error feedback technique and not
a means of increasing purely numeric precision. The
benefits of ESS are established in the frequency domain
as a means of reducing truncation noise buildup. Truncation
error cancellation may well be viewed as a double precision
implementation. In Sec. 2.5.0
a subtle distinction
between truncation error cancellation and
standard double precision was expressed in terms of
the double-precision realization: 1) the signal feed-forward paths...
Adobe Acrobat 8.12 Paper Capture Plug-in
This paper does not purport to be a design
review of the Lexicon OPUS digital parametric equalization
filters. Although the equalization subsystem
for OPUS was my responsibility unril 1987, I never
indicated that the paper represented that which was
offered to the customers. The system, OPUS, is only
mentioned in the biography because my design experience
is relevant to the paper's topic. I also designed
the original OPUS mainframe backplane and I shared
the console filter-strip facade and electronics design.
I imagine that much has changed during the interim,
between my completion of the task in 1987 and the
introduction of the equalization subsystem this past
November at the 85th Convention of the Audio Engineering
Society. Indeed, Mr. Eagle was not a Lexicon
employee or consultant prior to my departure. Mr. Eagle
has declined to share any technical information since
I joined ENSONIQ, so I have no knowledge of the
extent to which my work was used.
I would like to note several errors which appeared in this paper.
It is important to note that this second-degree
source of truncation error is nonexistent in the truncation
error feedback topologies discussed in Secs. 2.3 and
2.4. That is because the error feedback coefficients
were trivial multipliers there.
As for my interpretation of the truncation error cancellation
circuit, which I believe is correct, it is important to understand that truncation error cancellation is a special case of error spectrum shaping (ESS), which
is truly a truncation error feedback technique and not
a means of increasing purely numeric precision. The
benefits of ESS are established in the frequency domain
as a means of reducing truncation noise buildup. Truncation
error cancellation may well be viewed as a double precision
implementation. In Sec. 2.5.0, a subtle distinction
between truncation error cancellation and
standard double precision was expressed in terms of
the double-precision realization: 1) the signal feed-forward paths...
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