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What happened to perpetual technologies?
(andy) wrote in message ...
did somebody experienced the DeQX devices?
Yes. I heard some DeQX-corrected NHT Pro A-20s at CES a couple of
years ago, when they were still known as ClarityEQ. Very interesting
comparison as the uncorrected system had a larger and more enveloping
soundstage, while with correction on, the sound got tighter and more
focused, but at the expense of the soundstage. I'd say it's not a
clear choice which one is better.
Overall the BOM cost of digital correction systems is VERY low, so we
are going to pay for the IP (which is OK). Still I feel very promising
for the medium- to low-end system the technologt fallout in the near
future. Still it does not seem to happen so near ..
I disgree about the cost of room correction systems. Research seems
to indicate that at least 1 second of room correction (or 1 Hz
correction resolution) is desirable. At 44.1 kHz, and done with FIR
filters, this amounts to about 44.1k*44.1k = 1.9 billion multiply and
additions (MACs) per second, and over 8 billion MACs per second for 96
kHz processing, a sample rate at which many receivers and surround
prepros are operating at today. That is well beyond affordable, and
even achievable. Top-of-the-line Pentiums and Athlons can barely
achieve Dhyrstone MIPS at half these numbers, and those numbers are
unrealistic and inflated anyway, given that Dhrystone isn't a
realistic, or even meaningful benchmark.
If you want less latency than 1 second (and that is desirable for
systems that have to deal with video), then the computational
requirements go up even more. People have had success at running bass
correction at lower sampling rates (like 1 kHz), and lowering
computational costs greatly, but this requires some non-trivial amount
of technical know-how as well as good taste in audio to judge the
different tradeoffs. Unfortunately in the audio world, good audio
taste and technical know-how seem to be contradictory traits.
And that's just for the implementation of the correction playback
side. The measurement side that determines what needs to be corrected
has its own set of challenges, which include a simple enough user
interface so that typical receiver owners can use it effectively, and
having enough smarts to correct the right things, and leave other
things alone, and do it all fast enough (less than 1 minute is
desirable) for a casual user. Many correction systems have
measurements that don't correspond at all to human hearing, but rather
are convenient mathematical computations. Taste, experience, and
technical know-how again are required here.
--Andre
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