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Do It Yourself (DIY) paradise for tube and SET project builders.

RE: Dennis, you never answered the question.


The SET craze arrived here in the US in the 90's by way of Sound Practices magazine, and this was over a decade later than it arrived in Japan. The reception then by the audio mainstream here was interesting to say the least. John Atkinson declared the first SET tested in Stereophile a "...tone control". By far the best article from that time was a test of a 300B SET in Audio magazine*. The author was quite surprised at the slew rate performance of this 8 Watt amp. With a sine wave as a test signal we are frequently focused on the top and bottom of the wave and where and how drastic clipping occurs. However the greatest rates of change are in the middle sections of the wave. The results that the author got from his tests revealed that the slew rate (in volts per micro-second) of this 8 Watt amp could only be equaled by 90 Watt class A transistor amp! Now this begs the question of course as to how much slewing induced distortion is audible in an amps performance, or at what point does it become an issue. There seems to be a lack of interest in the mainstream audio magazines to look into this dark room, as there is a similar lack of interest to look into frequency modulation distortion and amplitude modulation distortion in speakers, but this is not surprising in that J.Gordon Holt didn't like horns, and John Atkinson has stated that he is "...suspicious of horn loaded designs." Along with the interest in SET's came a renewed interest in horns which are at a distinct advantage over direct radiator speakers in regards of FM and AM distortion performance.

*It would be nice if someone less lazy than me would dig up the mid 90's Audio article, or find a link to it online.

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