Although the story begins with speaker size, that's not the interesting thing about this. I recently filled in for my old band and shared a backline on a small stage. After 25 years of only playing with 15s I got to plug my amp into an Ampeg 6x8. We didn't have much time for sound check but all sounded good and I didn't notice a huge difference in tone. After 3 songs I was feeling uncomfortable in my left hand. I kept adjusting where the bass was sitting on my shoulder but that wasn't it so I started paying attention to what was happening. I realized during the next song that I was hanging on to the notes a fraction longer than I normally would. In the language of ADSR synthesizer envelopes, the release time seemed faster in the Ampeg cab than it does in my 15 inch cabs. What's cool about this is that my body had adjusted to the difference before my brain had registered it. It gives me confidence that I can still sound like me with just about any setup.
Speakers don't respond "faster" or "slower," but brighter cabs tend to give you that impression that they're faster because you can hear the high end better. And speaker size is unrelated to tone, but is wholly a matter of the design of the speakers and the box you put them in. You can design speakers of any size to sound how you want, but the reason bigger speakers tend to be voiced lower than smaller is more a matter of efficiency. For example...to get as much power handling from a 10" cab as a 15" cab, you would usually need two 10"s to hang with one 15". And a guy like Phil Jones designs bass cabs using 6" speakers and loves how they sound, and through targeted speaker design and porting methods, he can get solid low end out of them. But he'd need a lot more of them to get the output you can get from a single 15", so that's why you don't see a whole lot of bass cabs using 6"s. It can get as complicated as you want, but cab and speaker design is all about making the right compromises to achieve a tone and volume you want, and the only thing you can tell from speaker size alone is the size of the speaker. So you're best to let the whole speaker size thing go and just trust your ears. And when you hear a cab you like, buy it.
I don't think the OP is talking about fast/slow/bright etc. If I understand, he is describing a cab that to him sounded like notes decayed (the "D" in ASDR) faster than the decay he was accustomed to with other cabs. His response to this faster decay was to hold each note longer, leading to a sense of discomfort in his fretting hand, all of which occurred involuntarily. At least that's what I took from it when I read it.
I hate to tag you in twice in less that 24 hours, but.... @agedhorse is this a thing? Can 8" speakers cause a note to decay so much faster than 15" speakers that your technique will adjust accordingly?
Not due to size that I am aware of or have heard of, but... There is the perception of lack of low frequency extension that can be described this way, especially indoors where the boundaries at low frequencies typically have longer RT-60 times. The other perception is damping, a speaker with higher moving mass tuned to an underdamped response condition can feel this way too. This is assuming that there isn't a gate being used in the system which can certainly be responsible for such an effect.
This seems to be descending into a discussion about speaker \ cab properties, which I thought we'd done to death here. What I was really interested in is how my playing had changed to compensate for the different sound and I only noticed because my hand felt different. I wonder if the sensation of an instrument or any bit of gear "feeling right" or "speaking to" someone has to do with how physically, subconsciously adapt to make it sound the way we like.
Just to note "headroom". Lots of players talk about "headroom" while there is physically no more headroom nothing at all. In the past lots of folks talked frequently about phase issues while physically there was most of the time no reason to talk about it. Sometimes people want to talk about things beyond their head. Nothing wrong with this "issue" cause everybody is welcome to any forum.
Yup pretty much. Musicians can not only hear it, but feel it. And I completely adapted my playing style to a 810E. Has a whole bag of tricks that other cabinets can't unleash. Especially from ported to sealed. Actually using the sustain release to describe it makes sense But otherwise I adapted even came up with new technique using sealed 810