comebackplayer wrote: ↑Sat Mar 30, 2024 8:44 am
On the local market here there's also a 6420ii Yamaha trombone. It looks at least 10+ years old, but hard to tell. It's another one that I can't find anything on. I'm imagining it's a version of the 640.
4-digit model number was used around late 1970s to at least early 1980s.
My understanding (which might be very wrong) is that they used 3-digit system at first (for example YSL-251, 353, 446, 641, 643, 651, 653, 448, 842, 844 for tenors, and YBL-611, 612, 613 for basses).
This is semi-systematic. The first digit is the level, as always. The second SEEMS to be bell size (1 for 10”, 2 for 9.5”, 4 for 8.5”, 5 for 8” and 7.5”). And the last SEEMS to denote particular model in the lineup which is related to bore size. Most tenors (NOT ALL) follow these rules:
1. Odd number denotes straight and even number denotes rotor
2. 1, 2, 7, 8 are large bore, 3, 4, 5, 6 are either medium/MS bore
So a YSL-842 should be, and is/was, a Custom level horn (8), with a 8.5 inch bell (4), and large bore with rotor (2). A 653 should be, and is/was, a professional level horn (6), with small bell (5), and with medium bore (3).
For basses it seems like they just applied different last digit for different models, but still follow the rule for the first 2 digits. The 611 is a pro level horn (6) with 10” bell (1), while the single-rotor 321 (which evolved to the current 421G) is a standard level horn (3) with 9.5” bell (2).
Then they added 0, maybe just for JDM since I very rarely see the model with 0 outside Japan. So 353 became 3530, 641 became 6410, 842 became 8420, YBL-613 became 6130, and so on. You can still see this type of model number in some parts of the current horns, for example TUNING SLIDE FERRULE UPPER YBL6110R in YBL-620G.
Then they switched back to 3-digit system, but not the same as the old one. And the conversion is inconsistent, as usual. For some tenors they cut 4. So the 6410 became the 610 (large bore, straight), the 6420 became the 620 (large bore, rotor), the 8420 became the 820 (and then evolved further to the current 820GII), and so on. For other tenors and basses they just reverted back to the original system (removes 0) like nothing happened.
And with newer models seemingly arbitrary numbering (like the YBL-622, 822, 830, 835 and YSL-891, 895, 882) and even some overrides the old convention (the 354 comes to mind, itself an evolution of the 353, and also the 613H which has almost nothing to do with the 613 and has 9.5” bell), we arrive at the chaotic system in use today.