@j-jericho said in The difference in timbre caused by using additional valves:
I hear timbre and intonation changes with different valve combinations, but the timbre changes aren't enough to sound like a different horn. I just write the phenomenon off to "nature of the beast".
This matches my experience.
The clearest example might be between F# in first space of the system. Easy enough to alternate between a 2 and a "123+trigger" and get the same note at the same pitch. In this experirement I hear a clear timbre difference. That said, I would not really consider using 123 for making music.
So, add my vote to "yes I can hear it but does it matter".
As for why it happens, Rowuk's summary really says it all -- I'd only add that bit about the number of sharp turns that you mentioned yourself, @Trumpetb:
The change in timbre is based on the cylindrical to tapered proportions as well as the specific partial being played.
Many modern piston trumpets have been homogenised for a generally even tone.
When it comes to cornets, I believe there are differences that affect the timbre more than the number of sharp/smooth turns. Notably the length of the leadpipe taper, before going into the cylindrical valve block, as well as the ratio between the narrowest diameter of the mouthpiece and the bell radius.
