A/V Test 05 ~ Signal~to~Noise Ratio

Signal~to~Noise Ratio
HQ: http://www.youtube.com/watch?v=OZ5YyCj3Byg&fmt=18

[1] Zero Digital Level "Infinite Zero" emphasis off 0:20
[2] Zero Digital Level "Infinite Zero" emphasis on 0:20

After a 1,000Hz calibration signal at 0dB, the two tests are cut at an absolute silence level (so-called "infinite zero" or "digital zero"). The first test [1] is without emphasis, the second one [2] is emphasized. Thus, you can measure or hear the noise and you will know then if the system circuits are disturbing quality or not.

At a normal listeningt distance, you must hear no background noise. If there is some, the first defective component will probably be the soundblaster, then the amplifier. But if the noise stops or decrease when you stop the YT player, then the player and|or the converter YT program is|are wrong.

After calibration on 1KHz signal, you will measure the residual tension on each tests. Before testing, be sure to check all the laboratory system and connections because the background noise you have to measure is very low. If possible, use filters to eliminate frequencies outside the audible spectrum (30Hz-16KHz). Note that a "A" weighting system (cutting high and low frequencies of audible spectrum) will give non interesting resuls on such a little noise: they will always be excellent. At the contrary, if you have a "D" wieghting sistem (giving importance to same frequencies we are very sensitive to, in high medium), you will get more interesting figures (but out of any official hifi measurement standard).

Video: 320x240 MPEG-2 2Mbps CBR
Audio: MPEG Layer II 48KHz 384Kbps

Next: Transient Signal Response http://www.youtube.com/watch?v=vqW4Tx_3xws&fmt=18

WARNING: THE NEXT TEST CONTAINS HIGH LEVELS OF HIGH FREQUENCIES AND MUST NOT BE PLAYED AT HIGH VOLUMES IF LOUDSPEAKERS DAMAGE IS TO BE AVOIDED. That "A/V Test" is private (for caution). It can be used only by a contact list (A/V Test) of YT users. To use it, send me a message ( http://www.youtube.com/outbox?to_user=pjoef ), so I can send you a friend invite. If you accept, I can add you to "A/V TEST" contact list.

To run all tests go to playlist "A/V Test": [ http://www.youtube.com/view_play_list?p=482F80F926310013 ]

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