Last week, Lynn and I applied a few tricks to the Karnas which were learned during the NiWatt's development, and Lynn let the Karnas extend their visit for a few more days (Lynn likes to call them litter mates).
In February, the NiWatts visited the Karna's predecessors - the Amity Amplifiers as implemented by Gary Dahl.
There's a clear and obvious lineage in these three three amplifiers. In many ways, the NiWatts (while single-ended) bear a stronger resemblance to the push-pull Karnas than the Karnas do to their push-pull predecessors (the Amitys). In other ways, the Amity's and Karna's similarities are front and center.
For those of you not familiar the Karna's architecture, one of their many key design elements involves the use of an output tube (a 45, no less) driving the 300B output stage. Those of you familiar with Sakuma's design principles will no doubt recognize this philosophy.
Lynn has long been a proponent of the 300B for its low distortion and he maintains (correctly in my opinion) that any bloating or other overly warm, sluggish sound attributed to the 300B is a result of a faulty driver tube design.
You don't have to sacrifice speed for tonal beauty.
The importance of the driver is true of all directly heated triodes, and it becomes more important as the output tube's power increases (300B, 211, 845, etc.). 45's and 2A3's are much easier to drive, which is part of the reason people consider them to be less bloated sounding than a 300B. The inattentive designer has a better chance of successfully developing a circuit capable of driving a 45 or a 2A3.
Attention to the driver, along with multiple power supplies were key influences in the design and implementation of the NiWatts.
All three amplifiers (NiWatt, Karna, Amity) are lightning-quick, and when Lynn asked me about a possible name for a commercial version of the Karnas, names like "Photon" and "Lightspeed" came to mind (I know ... how cliche).
Lynn and my wife like the name "Vivid" and I can see this as well, because there is a broad, technicolor thing going on with the Karna (as well as the NiWatt and Amity). I get that too.
This combination of clarity, speed and bold tone colors is what I consider to be a key difference between these three amplifiers and most everything I'm exposed to at audio shows.
Having heard any of these three amplifiers, I can't go back. I struggle to find words to describe this, which is one reason I'll be taking the NiWatts on tour this Summer.
Stay tuned ...