addition to GS
ZXNet echo conference «real.speccy»
* Crossposted in REAL.SPECCY
* Crossposted in ZX.SPECTRUM
Hi, All!
Information from X-TRADE.
We are pleased to inform everyone, as well as the lucky owners of the
GENERAL SOUND music card, that we We continue our research in the field of digital sound.
Based on our objective as well as subjective psychoacoustic
research, we have developed a very useful gadget for GS.
This gadget (which does not yet have a name) represents is an eighth-order stereophonic active Chebyshev low-pass filter with an amplitude-frequency
characteristic characteristic of filters with a quality factor of 0.707.
Psychoacoustic criteria were based on a subjective assessment of the comfort
of sound, as well as fatigue during prolonged use. listening to modules and sound
of games.
Objective criteria were based on statistics regarding the frequency
with which most samples were digitized. (min - 8 kHz, max - 24 kHz.)
As a result of the research, it was noted that due to interpolation in GS The spectrum of digital interference does not “stick together” with the spectrum of the useful signal and therefore can be effectively filtered. (For example, on the Amiga, the signal and noise spectra
are nearby, so filtering without significant losses of the RF component
is impossible.The experiment fully confirmed this.) As a result, the optimal filter cutoff frequency was determined to be approximately 10 kHz.
And now about what exactly your ears will feel. And so, the fairly clean sound of the GS is now completely free from digital grinding and hissing, which is caused, rather, not by a lack of the interpolation algorithm, but by the insufficient quality of the digitized samples. Since the spectrum of overtones lies in the high-frequency region of the sound signal and even beyond the limits of audibility, this causes unpleasant sensations when listening. The result is mild discomfort, smoothly flowing into a headache, etc. Now the sound of the modules will be free from such shortcomings. At the same time,
a considerable number of musical moments emerge in the music, which previously seemed insignificant,
timbral resolution increases significantly, samples with a complex timbre (chords, effects, etc.) are reproduced more naturally
The above-mentioned bells and whistles will be structurally designed in in the form of a small board installed on the audio output connector. The sound will now be taken from
this small board. Naturally, this gadget will not affect software compatibility. The estimated cost of the gadget is low - approximately
$4. We hope to release a gadgetby the New Year, or, in extreme cases, by
the end of January.
The gadget will probably be called that - a filter for “GS”.
P.S. After the GS tuning, we can quite confidently say that for the money that spektrumists can shell out, everything possible has been squeezed out of the 8bit/8..24 kHz audio format in the form in which it exists.
All the best.
Dmitry.
..LD..X-TRADE..