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Have I cited that article?

I don't even have a copy of it.

Also, I know that some amplifiers do indeed sound different from some other amplifiers. DBTs have shown some high fidelity amplifiers sound different when driving complex loads such as found in many speakers. That has not prevented a number of people from saying that others believe every amplifier sounds the same--it's a big straw man thrown around in controversy. Some throw that idiocy at me from time to time.

In the June 1991 issue, Stereo Review published an article by E. Brad Meyer called "The Amp/Speaker Interface: Are you loudspeakers turning your amplifier into a tone control?" A tube and a solid state amplifier were tested with two different speakers. One speaker offered a difficult load to the amplifier, one did not (the loads are not specified). With pink noise, the tests showed to a very high degree of probability that the differences between the two amplifiers were audible using either speaker.

With the music selections, the tests showed audible differences between the two amplifiers to a high degree of probability using the speaker with a difficult load. Using the speaker presenting the easier load, the tests results did not disprove the null hypothesis using those music selections, though it's always possible that with other music or other listeners the differences would have been shown to be audible. In any case, they were shown to be audible with pink noise.

Stereophile and Soundstage show the frequency responses of the amplifiers they measure into a standardized dummy speaker load. Some of the mainstream magazines did so, too. Quite a while ago, I emailed Doug Schneider of Soundstage and suggested that they include a graph of the load offered by the dummy speaker load used by BHK labs in amplifier tests. He agreed and the graph showing impedance vs. frequency and electrical phase vs. frequency is now shown at the following URL as part of the explanation of how they measure amplifiers:

http://www.soundstagemagazine.com/measurements/test_amplifiers.htm


-----
"A fool and his money are soon parted." --- Thomas Tusser


Edits: 07/22/10 07/22/10
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