Woofers No Longer Produce Bass Like Before
I recently acquired some used Boston Acoustics A70s. When I got them, they struggled to play anything below 100Hz. The foam around the drivers was all but completely missing, so I replaced it. After the adhesive had dried, I tested the speakers, and they were producing frequencies as low as 50Hz just as loud as those in the midrange. Over the next two days, I didn't use them much.
Last night I listened at a moderate volume for no more than an hour, and they still sounded great. This morning I noticed a significant lack of bass, so I tested them. Starting at 130Hz, there is a consistent drop in volume until the notes are too low to be reproduced audibly by the speakers (50Hz is about 30dB less than 130Hz).
I checked the foam that I had replaced, and everything looks intact and secure. I can't hear anything wrong with the tones between 50Hz and 130Hz; they're just very quiet. Nothing has changed in the setup between last night and this morning.