gofar99 Messages: 1947 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi All, An update on the KT120 mono-blocks. These are tubes you can love to hate. As I mentioned in the earlier post they are not as linear as most others in the KT series. Another diyer I confer with from overseas came up with similar results and conclusions. But all is not lost. It seems that without going into complicated designs you can come up with a powerful amp. You can take your choice though, really clean up to 15-20 watts and so-so at the top or a little higher level of distortion that rises more or less linearly but ends up a little less than the alternative build. I like the lower distortion at normal levels as that is where most listening takes place. I can get distortion below 1% out to 15 wrms and 2.6% to 25 wrms, but at 45 wrms it is 6.2%. At 10 watts it is .6% These numbers are not bad for a amp with nearly no NFB, but other members of the KT family can do better within their power ratings. Band width is excellent less than 0.1db (+or-) from 20HZ to 30KHZ. Only down .16 db at 10HZ. The -3dbv point on the high end is 53KHZ. S/N is over 86 db at one watt. Clipping BTW is at 55 watts and actually it is compressing from about 50 on to that point.
More study and evaluations to go, but IMHO, having a sole source for the tubes is their downfall.
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As I mentioned in the earlier post they are not as linear as most others in the KT series. Another diyer I confer with from overseas came up with similar results and conclusions. But all is not lost. It seems that without going into complicated designs you can come up with a powerful amp. You can take your choice though, really clean up to 15-20 watts and so-so at the top or a little higher level of distortion that rises more or less linearly but ends up a little less than the alternative build. I like the lower distortion at normal levels as that is where most listening takes place. I can get distortion below 1% out to 15 wrms and 2.6% to 25 wrms, but at 45 wrms it is 6.2%. At 10 watts it is .6% These numbers are not bad for a amp with nearly no NFB, but other members of the KT family can do better within their power ratings. Band width is excellent less than 0.1db (+or-) from 20HZ to 30KHZ. Only down .16 db at 10HZ. The -3dbv point on the high end is 53KHZ. S/N is over 86 db at one watt. Clipping BTW is at 55 watts and actually it is compressing from about 50 on to that point. 
