I know this should be stuck in the portaflex thread being that it concerns a 70s B15n, but here we is. I had assumed that, back when I had but one bass, a J, because I was jamming in similar sized rooms, it was the room's fault that I'd have to be very light when touching E's, and moderately gentle on the other ten notes to have A's not totally disappear. I then went through a few other basses (EB, Vette, P) and tunings, same problem, same fix. It's all of the A's on the fingerboard regardless of string gauge and tuning. Been playing in a far smaller than usual room lately and a stupid large hall, and in both places the problem persists. Is it the Thiele cab? Does the amp itself need to be looked at by someone more qualified than a Lockheed engineer moonlighting as an enthusiastic Ampeg hobbyist (the guy I had swap the caps and tubes a few years back)?