The Black Hole

Vibration Tests

The following tests were performed with a PicoScope 4224 oscilloscope at 16-bit resolution. A piezoelectric vibration sensor was mounted to the circuit board inside a Sony DVP-SR500H CD/DVD player. Test CDs were all played at 10 seconds into track number 3.

These tests reveal The Black Hole CD Mat has a definite vibrational effect with most CDs. Each CD that we tested has a unique vibrational "signature." From twenty CDs that were tested for this experiment, the following three are representative of the variety of results. We do not expect that all CDs of a particular title will provide identical results, because we believe these results are caused by irregularities in the balance of the individual CD and will vary from one to another.

1. The first example shows results from a CD that produces a low-frequency vibration. This CD is Herb Alpert & The Tijuana Brass from our collection:

Without The Black Hole:

CD Vibration Chart

With The Black Hole:

CD w/The Black Hole Vibration Chart

The amplitude of the vibration patterns is designated at the bottom of the chart by "AC RMS." This is the current generated by the sensor. You can see that without The Black Hole, vibrations generate 3.91 mV of AC current from the sensor mounted on the circuit board. With The Black Hole, vibrations are reduced to 2.472 mV, a reduction of about 1/3.

2. The Second sample is a CD that generates a higher average frequency vibration. With this CD, the amplitude of vibrations is virtually the same with and without The Black Hole (in fact, vibration amplitude is slightly increased with The Black Hole). However, the maximum vibration frequency is reduced by 400 Hz and the average frequency by about 100 Hz. The CD is Jennifer Warnes' Famous Blue Raincoat.

Without the Black Hole:

Cd Player Vibration

With The Black Hole:

CD Player Vibration w/The Black Hole

The Black Hole provides a very nice, though somewhat subtle sonic improvement to this disc, smoothing out some harshness and reducing some irritating sibilance. Because of this disc's susceptibility to being tweaked by a CD mat, this disc has been a reference for prototyping and testing ever since the original grungebuster CD Mat in 2003.

3. Lastly, a CD that seems to sound about the same whether The Black Hole is used with it or not, Vicor Music 40th Anniversary Collection.

Without The Black Hole:

DCD/CD Circuit Board Vibration

With The Black Hole:

DVD/CD Player w/The Black Hole Circuit Board Vibration Chart

Keep in mind, the frequency values in the data bars at the bottom of the above charts refer to peak vibrations only. A spectral analysis of these vibrations show they fill the gamut all the way from virtually zero Hz to beyond 20 Mhz.

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So what does all this mean? How does any of this affect the audio output?

Part Two