Apparently the Chinook uses two 6922s per channel. If that’s not correct, stop reading this, because I don’t want to mislead you. If it is correct then you would mess around with the tubes closest to the centerline of the chassis. That’s if it’s constructed like my Steelheadwhich seems a reasonable bet. OR ask Manley which of the two tubes in each channel is part of the gain circuit. They’re cool.
As to SLN tubes, who could argue against the idea? Problem is that the SLN characteristic is transitory. And there’s no telling how long it will be before any given tube will go noisy. Also, in the particular case of the Chinook the single gain tube is part of a hybrid cascode where the bottom element is a FET. In such a topology the noise characteristic of the tube section is less crucial to output noise,partly because the tube per se does less work on gain. Not that it still isn’t a good idea to use a low noise tube.
As to SLN tubes, who could argue against the idea? Problem is that the SLN characteristic is transitory. And there’s no telling how long it will be before any given tube will go noisy. Also, in the particular case of the Chinook the single gain tube is part of a hybrid cascode where the bottom element is a FET. In such a topology the noise characteristic of the tube section is less crucial to output noise,partly because the tube per se does less work on gain. Not that it still isn’t a good idea to use a low noise tube.
