The only brand new guitar I've ever owned is the one I built last year. When I first got it together I was a bit disappointed that it sounded brighter and thinner than I had hoped. It has a heavily chambered mahogany body with a 1/4" maple top and a maple neck. The wood was all very old (decades old). However, I swear it now sounds thicker, richer, and darker. And not just because my ears adapted to it: I have a 1977 Gibson to directly compare it to. That was my yardstick for fat, and now it seems bright in comparison. So, do new guitars and/or pickups mellow or darken in sound over the first several months of their lives? Or am I totally losing my marbles?
I cannot speak to electric guitars; however, acoustic guitar most definitely sound better with age and it is not just over the first year. This could be due to the reduction in stresses as the guitar ages. I have friends that place their guitars in front of their stereo speaker so the guitar will vibrate in harmony with the music that they play, as if the guitar is being played, to help the aging process.
It is still getting used to being a guitar instead of just dead wood. Seasonal changes will also affect how a guitar plays and sounds. I used to lean my guitars against speakers too, for the same reason. Now they have a tool specifically designed to simulate "play in" by vibrating the strings. ToneRite for Guitar | stewmac.com.
Just my two cents ... When I bought my acoustic back in 2006 (it was a new instrument right out of the box. They removed the paper around the strings just there) the salesperson told me to play a lot over the next few months and to play all registers to "open up" the sound. I can imagine that applies to electrics in some ways too.
Thank you for confirming that I am not crazy! It is essentially a hollowbody so I think the aging/mellowing could certainly apply, just not to the degree of an acoustic. I am really glad to learn this because I was disappointed with the thin, stiff sound it first exhibited.
