I was just pondering the differences I hear and feel going between full and low power on my 2/90/2. I used to like low but been on high for the last few years. At no time near using the reserve of power this thing has. Although I have tried it through my PS-1 on a couple of occasions so I know where the audible clipping point is in relation to my system signal levels and volume knob settings.
But there is a clear tonal and feel difference even at moderate volumes. Hard to put in words but to me there’s something happening in the midrange and it seems wider over all in some way when in high.
So is the majority of the effect just from the lowered voltages in them selves giving lower power or is it a more a tube thing where the entire system of power tube voltages-transformer-speaker reactance-negative feedback interact and changes? I’m guessing the latter.
If so, could one play with nominal impedance mismatching when in low? Dangerous? Any benefits, or even getting closer to a technically perfect match if not matching the selector switch to the cab?
I always have both channels running and connected to a load of some kind even when I just use it mono with one channel volume knob completely off. Want to get the voltages as right as can be in there.
I just wanted to acknowledge your question. I have been waiting for someone with experience of the 2/90/2 to comment because I don’t have one, so it is hard for me to answer the tone questions. But maybe we get more eyeballs if I bump this.
My take on impedance mismatch is that it does not have any special mojo. You are changing the AC load line of the power section, and it might have some subtle tonal effects. It is just different. Some people get a bit obsessed with these kinds of details, and it turns into an relgious war.
Yeah, I sometimes have a tendency to get caught in the details too much myself
Still, I’m qurious about lowering the voltages in the power amp and the effects I hear and feel. The load line shifts from the lower voltages as well or? And here’s where I run out of knowledge and experience.
Also, I think that sometimes, being able to push different parts of a system in certain subtle ways can give a whole that’s just perfect. Then again perfect will vary over time.
I have a Mesa MkIV too and that has a tweed switch so different in that it lowers all voltages, preamp too, but I find both positions clearly useful. With the SigX you get a really different power amp behaviour with the lowered filtering and tube rectifier. Right now I love it in 40w for both clean and rythm channels.
I was thinking about the 2/90/2 because there’s not much changing when switching from high to low, and it’s really just the power amp with it’s own power supply but there still is a little something happening. A little something that I was thinking maybe could be pushed a little bit further this way or that.
