Sorry Don, there are a lot of amps which will take out a resistor in the bias circuit when a power tube blows. ARC has a lot of company, including I suspect some of those you mentioned. But I agree it is a PITA especially when you aren't handy with a soldering iron. Usually it is simple to replace the resistor.
BTW, since you have stated that it is a "poor" design choice, what design would be preferred, and how would its utilization affect the performance of the amp? I suspect that designers may have concluded that using the resistor as a fuse was a preferred solution as opposed to inserting a fuse in the bias loop. But I'm not a designer.....
BTW, since you have stated that it is a "poor" design choice, what design would be preferred, and how would its utilization affect the performance of the amp? I suspect that designers may have concluded that using the resistor as a fuse was a preferred solution as opposed to inserting a fuse in the bias loop. But I'm not a designer.....