Have you ever noticed that during certain years Conn's serial numbers appear to "jump"? For example, 1954-1955: The year 1953 started with the (brass) serial number 420,057. The year 1954 started with 427,301, suggesting approximately 7,000 brass instruments were produced during 1953. The year 1955 starts with serial number 500,001. This is a bit unusual for two reasons: First, it suggests that during 1954 almost 73,000 brass instruments were produced compared to about 7,000 the previous year. Second, for serial numbers to end up at exactly 500,001 is too much of a coincidence. Conclusion: there is a jump from 1954 to 1955.
The same thing happens again in 1962-1963. In 1961 serial numbers started at 898,556. 1962 started with 949,465. Guess where 1963 starts.... C00,501. Sounds familiar? You will never see a Conn instrument with a serial number starting with Axx,xxx or Bxx,xxx.
What might have happened during those years? If you take a look at the model number list, you will notice a lot of instruments with a production run ending or beginning in 1955. For example, the 12A, 12B, 12H all ended in 1955. So did the 28B Connstellation. The Pan American line of instruments? The last year was 1954. Models introduced in 1955: 6A, 6B, 10A, 10B, 28A, 38B. The "Director" models replaced the Pan American line, starting in 1954. I suspect this is the reason for the jump in serial numbers: a major change over in models.
How about the 1963 jump? A close examination of the model number list shows that certain models with a Coprion bell didn't survive after 1962/1963, such as the 9A, 10B, 10H Victor. The 38A Connstellation short model cornet with Coprion bell was last produced in 1963. Thereafter the 37A Connstellation with brass bell (short model) was renamed to 38A. My guess is that the number of models with a Coprion bell was reduced significantly to cut cost. After all, the Coprion process is an expensive procedure.
Those are the obvious jumps with serial numbers starting at a whole number. There are some not so obvious ones too. I have yet to see an instrument with a serial number starting with Dxx,xxx (1964-1965), Fxx,xxx or Gxx,xxx (1965-1966), Ixx,xxx or Jxx,xxx (1966-1967). There are no obvious changes in models during those years, so there must be another reason for these jumps. It is known that Conn instruments produced during the 1970's are of considerably lower quality than those produced in the 1960's. However, for quite a while I have suspected that Conn started reducing cost in the 1960's by carefully reducing the amount of metal used in instruments. It is possible that these jumps in serial numbers reflect those cost cutting measures.
Then there are the minor changes. This is where facts might prove me wrong in the future, but I suspect that the 6A, 6B, 10A and 10B models switched from being bottom spring to top spring at serial number 700,000. The style of valve caps changed with serial number 600,000 and again at 700,000. At serial number 800,000 Conn introduced lacquered valve caps on instruments with a nickel plated valve casing.
Just a thought.