Yamaha Saxophone HistoryModel: YAS-21

Years: 1971(1970)-1979
Key: Eb
Auxiliary Keys: N/A
Engraving: No
Finish: Clear Lacquer
Keys: Nickel-Plated
Finger Buttons: Plastic
Current Model: YAS-23

The Yamaha YAS-21 serials match the Vito YAS-21 serials up until 1980 when the Yamaha YAS-23 is introduced but the Vitos still use YAS-21 parts until 1989 when the Vitos start using YAS-23 parts nearly 10 years after Yamaha introduced the YAS-23.
The Vito YAS-23 serial numbers beginning with a 5 like 501000 starting in 1989 do not match the Yamaha YAS-23 serials but the Vito YAS-21 serials from 1970-1980 do match the Yamaha YAS-21 serials.

After 1980 the Vito serials don't seem to match.
From the Yamaha serial numbers and purchase dates I've seen the Vito serials do match the Yamahas for the YAS-21 up to 1980.
The YAS-21 seems to become the YAS-23 around 1980 and the YAS-23/25 seems to become the YAS-275 around 2000/2001.

Vito and Yamaha YAS-21 serials

1970 1 500
1971 501 2155
1972 2156 3529
1973 3530 4421
1974 4422 12000
1975 12001 25603
1976 25604 30827
1977 30828 33947
1978 33948 38844
1979 38845 42434
1980 42435 47975

Vito YAS-21 and YAS-23 serials

Model 7131RK
1970 1 500
1971 501 2155
1972 2156 3529
1973 3530 4421
1974 4422 12000
1975 12001 25603
1976 25604 30827
1977 30828 33947
1978 33948 38844
1979 38845 42434
1980 42435 47975
1981 47976 52455
1982 52456 58306
1983 58307 62177
1984 62178 68524
1985 68525 72535
1986 72536 78579
1987 78580 85091
1988 85092 89758
1989 89759 501000 (Sudden Jump into 5XXXXX serials because the Vito YAS-21 changes to YAS-23. The Vito 5XXXXX serial number Altos are YAS-23 models. The YAS-21 has a removable bell, the YAS-23 has a soldered bell-bow connection.)
1990 501098 510332
1991 510333 511518
1992 511519 515800
1993 515801 519845
1994 519846 526925
1995 526926 533097
1996 533098 537807
1997 537808 552998
1998 552999 560613
1999 560614 575843
2000 575842 587455
2001 587456 624567
2002 624568 654084

The YAS-23 starts in 1979/1980 and the YAS-21 has a removable bell and the YAS-23 has a soldered bell-bow connection.

The Yamaha serial numbers are sequential for each model and only for that particular model.
Each new Yamaha model starts with a new sequential serial number sequence.
That means that the YAS-23 sequential serial numbers are not a continuation of the sequential YAS-21 serial numbers.

1. The YAS-23's have big 3-tuning-forks in circle emblem on top, with YAMAHA below and JAPAN below that. Serial numbers begin with a 0?

2. The YAS-23's have a smaller emblem in front of the YAMAHA on the same line, followed by JAPAN on the line below. Serial numbers starting with a 0 or 1?

3. The YAS-23's have big 3-tuning-forks in circle emblem on top, with YAMAHA below and Established in 1857 on the bottom. Serial numbers starting with a 1?

4. The YAS-23's appear to only say YAMAHA followed by JAPAN on the line below. I've seen serial numbers starting with a 1 or 2?.

5. The YAS-23's have no tuning-fork emblems, and have YAMAHA on top, Established in 1857 in the middle and JAPAN on bottom. Serial numbers starting with a 2 or 3?

So you can see the sequential nature of the serials from older to newer 0XXXXX to 1XXXXX to 2XXXXX to 3XXXXX.

Yamaha have a different sequential serial numbering format for every different model and the model serial numbers don't always start from 0.