ABX Double Blind Comparator Data

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May 7, 1977
The Original SMWTMS ABX Test Results

Power Amplifier Comparison Result Correct p less than Listeners
10 Watt Tubes vs. Dyna 400 Different 63 / 80 = 79% 0.0005 10
Paoli 60M vs. Dyna 400 Different 78 / 126 = 62% 0.005 9
Swartz 40* vs. Dyna 400 Same 41 / 84 = 49% - 6

These were the first three audio double blind tests ever done.
* The Swartz 40 is a 20 Watt per channel power amplifier with quasi-complementary ouputs built exactly to the five transistor per channel design in the RCA Transistor Manual. By the espoused standards of subjectivists, nothing should sound worse than this amplifier.

Different The different symbol means it is unlikely the percent correct score occurred by chance and thus the null hypothesis was disproven, which substantiates a real difference in sound quality.
Same The same symbol means that it is likely the correct score occurred by chance, the null hypothesis is not rejected, which means no difference was found. It does remain possible a difference may be substantianted with further testing.

ABX Test Data

Capacitors CD Players
DA Converters Digital Delay
Distortion Filters, First Order
Filters, Fourth Order Interconnects
Level Difference Mini-Disc
Polarity Phono Cartridges
Phono PreAmps Power Amplifiers
Speakers Speaker Wires
Tape Decks Tape Generations
Video Cables

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