In fairness, Greg, being able to tell the difference in speaker placement in a mallet or mikado where there’s 2 - 3’ difference between the smokebox and tender isn’t all that difficult when viewed broadside. That distance is similar to my K-27, for which a shift to a smokebox-mounted speaker was a significant improvement in terms of how I perceived the sounds. (No more “talking tender.”)
However, my two true “stereo” QSI-equipped locomotives are my Climax (about 6" separation between speakers) and center cab (around 12" separation) , so it’s not really the same situation as shifting the speaker from the tender to the smokebox in my K-27. Both speakers work in concert, with the balance adjusting the perceived origin of the sound within the narrow space between the two speakers. Maximum separation is only possible when two sounds are pegged fully to opposite channels. A aural/spatial difference of 6" is much harder to perceive at 30’.
Again, if you’re interpreting my post as saying the stereo output of the QSI isn’t cool or isn’t worth the bother, you’d be quite incorrect. When I get to re-doing my B’mann “Connie” installation, I’ll run the second speaker to the smokebox, then balance the various sounds left to right so they “originate” from the appropriate place along the length of the loco, as I’ve done in my Climax and center cab. It’s a cool feature.
Later,
K
P.S. - For the geeks among us, 30’ in 1:29 is 870’. A prototypical sound would take a little over 3/4 of a second to reach our ears standing that far away. A train traveling 60 mph would travel 66’ in 3/4 of a second. So, if we were to be standing 30’ away from a train in our back yard, watching it broadside as it travels 60 scale mph around the line, if the speaker were in the tender of the loco as opposed to the smokebox, we’d hear the sound with a prototypical delay. Okay, that’s totally geeky, but for some reason I just had to do the math.