We (Zacht Automaat) use an Acoustic 370 for bass amplification. This is a nicely built, powerful amp. We have had this since about 2008. The bassist lives in the U.K. and we only play twice a year, so this sits and waits most of the time. Recently we noticed a loss of definition of tone (and could hear something rattling around inside). The amp sounded muffled but otherwise worked.
Inspection revealed a loose inductor inside the case. This turned out to be the (I think) 6H coil associated with the 50hz band of the EQ. I believe this was letting junk sub-bass into the signal and was causing the foggy sound. A few minutes work and it was back in place. The coil beside the missing one was also loose (cracked soldier) and this was repaired as well. These small details will hopefully restore the 5band EQ (which cannot be bypassed) and cure the bad tone issues.
