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The NC20 weighs 2 pounds and is bigger dell'NC14 loooong, and handles much better than the current, although it has a lot more permeable core. For a long
not use the NC20 el'NC21 (the last time I used the NC21 was linked to the contrary, driven by a RL12T15 in graphite, the working point 600V - 30 mA, pushing a PSE 211 in A2 disarming ease and distortions irrelevant, I can not remember the exact value, but close to zero), but I tried them several times in different ways and I am quite certain that the distortion introduced is perfectly consistent with the data-sheet.
The data-sheet says: NC20, driven by a valve with Ri 5Kohm swings and 20 mA BIAS 150 Vrms (few?), Distortion = 0.1%.
I remember a test with the EC8020 to 20 mA, Swing exaggeration of volts peak to peak values \u200b\u200bof distortion very contained, if I remember well below zero (and with a straight 5K at 20 mA, are certainly due to the valve) .
During this time I'm too busy, but next time I ricapitano under the NC20, definitely pay attention to distortion parameter, but right now I'd bet that there will be nothing to report.
If I had any doubt about this transformation, as they do not do cert'uni incarogniscono you want to convince the neighbor at all costs. I sent through eBay auction valves and various objects at all latitudes: Australia, Canada, Singapore, Korea, USA, Thailand, Hong Kong, Japan, Panama, I would have no heartache at auction to put the NC20.
were used by the great Shishido in a project that appeared in Glass Audio Vol 1 No. 6 of 1994, the same design was then "revisited" at No. 3 Vol 9, 1997, reporting to the scheme:
propose this project as well suited to the topics under discussion.
Shishido, after trying different valves and tested various configurations, including even a 4-stage cathode follower to drive the 300B, at the end to decide the interstage transformer as the best solution. If the transformer
NC20 had introduced high distortions, would not have had this preference.
In the first version of the processor 94 NC20 is used with DC current rather low, 13.4 mA, if it were a problem it slide more, but the doubts are quelled in 1997, when Shishido revisits the unit and doubles to 26 mA current in the transformer.
He varies this parameter in the complex act to reduce the harmonic distortion cancellation, then the distortion parameter is the more kept an eye on.
If the DC current in the transformer NC20 was critical so dramatically, doubling, even going beyond the recommended value of 20 mA, the distortion would increase dramatically, leading to desist Shishido.
But, as shown in the next image, it is not.
These objects survive in the market for a lifetime, regardless of the cost nor allows considerable popularity, no one may ever have had to repeat, may, having only one dissenting voice, that is precisely the one which recover to get the picture? Can there be room to consider, even just for a fleeting instant, that having an entire community for decades uniquely oriented, then perhaps there might be a subjective situation?
If I had plenty of NC20-distorting every time you get up to 1 mA DC current, then I would do some checking before giving it away .... For example
measure Henry and in the event that a significantly greater extent than the nominal value, they become unhealthy possible hypotheses about the GAP
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