The Black Hole
Vibration Tests
Part Three
Here is a 1kHz sine wave at -90dB on the Pioneer Elite, graphed at a magnification of fifty times compared to the square waves on the previous page:
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The audio signal (red line) looks more like noise than a sine wave and seems to be independent of circuit board vibration (blue line). However, if we leave the audio signal portion of the graph alone and magnify just the blue line, this is what we get:
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Even with a higher-quality player, very low-level information seems to be influenced by micro-vibrations even when those micro-vibrations are extremely low in amplitude.
For reference and perspective, here is the same disc playing no signal (at -0dB):
When we further magnified this red line, there seemed to be little or no correlation between it and vibrations and appeared much like pink noise. The red line, with no signal, is the total noise from electromagnetic interference and electronic component parts. The chart represents an amazingly high signal-to-noise ratio, which we can equate to a "signal-to-distortion" ratio. Unfortunately, as soon as an audio signal is introduced, that "signal-to-distortion" ratio collapses significantly.
Here again is the 1kHz sine wave, this time at -86dB:
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At -80dB:
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With CD or DVD audio playback, we'll never get a low-level signal as purely as a high-powered signal. That's an unfortunate drawback of digital sampling and electronics limitations.
At -72dB (rescaled, with both lines at equal magnification):
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At -60dB (rescaled):
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At -60dB, the sine wave above is very well defined and will only get better as the signal strength increases.
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At -0dB:
At last, a perfectly appearing sine wave. (Interestingly, these results are virtually the opposite of what we find with an analog recording. A similar sequence of sine waves taken from a reel-to-reel analog recording shows very well-formed waves at lower amplitude. As the amplitude increases, more distortion occurs. At -0dB, distortion is considerable and goes all to pieces in the + region.)
Herbie's Audio Lab performed multiple tests with the Pioneer Elite and found that spectral analysis and waveforms yielded very similar results with and without The Black Hole. We found some differences here and there, but nothing really significant. Still, in-house auditions, double-blind testing, and customer reports consistently indicate The Black Hole provides audible improvements with Pioneer Elite and other high-end CD and DVD players.
If improvements can be heard with the human ear, then why can't instruments "hear" the improvements? An oscilloscope can indeed hear everything the human ear can, and then some. The problem is, it hears too much. Electronic devices pick up all kinds of electromagnetic interference and electronic noise. At very low levels, where a lot of the musical data contains ambient information, instrumental decay and the falling edge of dynamics, a sonic spectrogram shows mostly just a bunch of junk. At low levels, a readout of the audio signal that an oscilloscope "hears" is obscured by electronic noise and distortion.