This is something that's been kind-of aggravating me, but only for the past few days. And being the inquisitive engineering-type, I'm compelled to seek an answer/solution. I have a theory or two about what may be going on, but to avoid biasing responses, I'll hold them for the moment.
What will cause two different guitars to rapidly start sounding 'muddy?' 'Muddy' to my ears means unbalanced in the bass response -- heavy and 'boom' bass from otherwise bright-sounding and well-balanced guitars (my Sitka/Makore GA and my Euro/Tasmanian Tiger Myrtle GS-12).
Right now, I'm at my residence in San Antonio, whereas I have mostly been playing at my residence in Lorena; so the rooms I'm using are sized and furnished differently. Acknowledging that the acoustics are going to be different, I will mention that I've played in this room in San Antonio before, and have not previously had any perceptions of 'muddiness.'
I've brought three guitars (the Makore GA; the Tasmanian Tiger Myrtle GS-12; and my GS Mini, in case I wanted something portable) with me from Lorena. Given the choice, I prefer playing the GA and GS-12 over the GS Mini, so those are the two I've been using since arriving in San Antonio, with the GS Mini remaining in its case the entire time. The strings on my Makore GA and GS Mini are probably nearing the ends of their lives, but the ones on my Tasmanian Tiger Myrtle GS-12 are still in pretty good shape, so I've kind-of ruled out strings. I don't have any new sets of strings with me to test out that premise; my replacement string sets are in Lorena, and I'd prefer not to go out and buy more of what I've already got just to dispel that one assumption.
I will also mention that my preferred pick began cracking about a week ago, and finally broke yesterday; so I'm using another brand of pick until I can get a replacement for it. But the guitars were starting to sound 'muddy' to me even before my preferred pick broke, and still sound 'muddy' with the substitute picks I have on hand (I've tried two entire different brands), so I'm inclined to rule out the picks as well.
As recently as a few days ago, both the GA and GS-12 sounded 'normal' to me. Yesterday, both had been sitting in a guitar stand, out of their respective cases for most of the day (as has been my practice since arriving last Wednesday from Lorena; both guitars have been returned to their cases, with presumably good [at least they're not rock-hard] Humidipaks, for overnight storage). But both started sounding 'muddy' when I began practicing on-and-off yesterday afternoon and evening; the Makore GA sounded particularly off to me. Ultimately, I was tired (and becoming aggravated), so I put he guitars away and hit the sack. After about 10 hours or so stored in their cases, the Makore GA sounded a bit better; I don't know if it was confirmation bias or what. I left it in the guitar stand while I ran out of the house for a few hours, and when I got back, it was sounding 'muddy' again. I checked the GS-12, which I'd also put out in it's guitar stand, and it was sounding about the same as yesterday evening -- 'muddy,' but not to the extent to which the Makore GA was. But that could just be because it's a 'jangly' 12-string... I pulled out the GS Mini, and straight out of its case it sounded a bit 'muddy' too. Now, a few months back I had only brought the GS Mini with me to San Antonio, and at that time I didn't have any perception of 'muddiness' from it. On a lark, I pulled up the
local atmospheric conditions for the past three days in San Antonio. It's interesting how much the relative humidity has varied over that period; and how rapidly it's trended toward dryness from a couple days ago...
So what's going on here folks? Is it all in my mind? Changing atmospheric conditions? Pick? Strings? A combination?