Introduction
The design of Conn trumpets underwent significant changes between the 1920's and the 1960's. However, the different models of trumpet in each period displayed many similarities. In this article I will try to indicate some of those design similarities, and the changes that occured over the years.

The 1910s-1920s
Information on trumpets during the 1910s is a bit sketchy (to me, at least). Instruments built during the first years of the 1920's appear to show some common points. They didn't have a main tuning slide brace, and the number two slide protruded from the valve casing at a right angle. Most instruments from this period didn't have a finger hook on the leadpipe. During this time most trumpets also had a rod attached to the main tuning slide, presumably to keep it from being pulled out too far? Many of these instruments also had a replacement tuning slide with a rotary knob to tune the instrument to A.
Starting sometime in the mid 1920's, the number two slide started curving back towards the player. This is the configuration most people will be familiar with. As far as I know all Conn trumpets from this time on had the number two slide that way. The 26B from 1923 on this site clearly shows the "modern" configuration of the number two slide as well as the other points mentioned in this paragraph.

The 1930s: The era of innovation
With the start of the 1930's most of the models typical to the 1920's disappeared; the 2B through 5B were discontinued in 1932, the 24B through 28B were discontinued in 1930. Only the 22B survived the "purge". By now the 22B had gained a finger hook on the leadpipe, and a main tuning slide brace, bringing it more in line with the new trend which was started by the 2B in 1926. Starting in 1928 Conn came out with several entirely new models, called the "New Era" models. The most distinguishing feature of these was the fact that they were quite a bit longer than the "standard" trumpet. In addition the number three slide attached to the number three valve on the right of the main tuning slide, from the player's point of view. Also, the finger ring on the number three slide was attached to the bottom of the slide, and not the top as is customarily the case these days. All the "New Era" trumpets had a main tuning slide brace and a finger hook on the leadpipe. A good example of the "New Era" trumpet is the 58B on this site. The year 1932 saw the introduction of a "New Era" style instrument with a difference: the 40B Connqueror. It was identical to the other "New Era" trumpets, with one important difference: the bell didn't have a rimwire. It was a so-called "Vocabell" model. Supposedly, this gave the player 15dB more volume with the same effort. The "New Era" lasted to 1938-1941, when the 40B Connqueror was discontinued as the last "New Era" trumpet.
Starting in 1932 Conn built one model trumpet which didn't conform to the "New Era" look: the 8B Symphony Special, also known as the "Gustat" model. Contrary to the "New Era" models, it had the configuration of a "standard" trumpet, with a few exceptions: the number three slide finger ring was located on the bottom of the slide as in the "New Era", and there was a trigger on the number one slide. As far as I know, this was the first time Conn put a trigger on the first slide. It wouldn't be the last time.
The year 1938 saw the introduction of two new models. The first was the 48B Connqueror. It too had a vocabell, but was configured like a traditional trumpet. Apparently the 48B was the first "heavy weight" trumpet through the use of thicker brass. Increasing the weight of a trumpet has the effect of making the sound "darker", and improving "slotting" (see article on "The color of sound"). The second new model was the 12B New York Symphony, with a coprion bell. There is a slight problem with the year of introduction: the serial number list shows 12B's with a serial number dating to 1937, but Dr Margaret Downey-Banks says Conn developed the coprion bell in 1938. The 12B New York Symphony is the coprion bell version of the 22B New Symphony.

The 1940s: Troubled times
The decade of the 1940's saw the demise of the 8B and the introduction of the 2B Symphony. It might be called the succesor to the 8B (as is obvious from the name?). It too had a standard trumpet configuration (the "New Era" was over by now) with a trigger on the first slide and the third slide finger ring below the slide. With the outbreak of world war two at the end of 1941, production of instruments by Conn came to an almost complete halt. Almost, since a few instruments were produced for the military, practically entirely by hand. After the war retooling was slow, followed by a crippling strike in 1947-1948. The production of the 2B, 12B and 22B resumed during this time. Only one new model trumpet was introduced in the 1940's after the war: the 28B Connstellation. This was the first use in a trumpet of the name "Connstellation", and the 28B was a glimpse of things to come: the finger ring on the third slide moved back to its normal postion, and for the first time it was adjustable. Previously this ring was always fixed. There was a significant amount of nickel trim, which before was only seen on some special order models such as the 12B New York Symphony Special. The 28B again featured the trigger on the first slide.

The 1950s: Radical change
The year 1951 was the end of the line for the 2B Symphony and the 48B Connqueror. Other than that, things continued with the same models as in the late 1940's. That is, until the years 1954-1955, during which only one model trumpet survived: the 22B, now renamed the 22B Victor. The change in appearance was a gradual one. Early 1950's models looked just like the 22B Victor in the drawing on this site. In 1955, the production runs of the 12B and 28B came to an end. In 1954 Conn introduced a new line of student models: the 14B and 18B Directors. The years 1954 through 1956 saw some short lived experiments with two models called the "Connquest", the 20B and 21B. The final version of the Connquest saw the light of day in 1957, the 77B.
Back to the year 1955. To replace the 12B New York Symphony and 28B Connstellation three new models were introduced that made no compromises to the quality of the sound: the 6B Victor, the 10B Victor and the 38B Connstellation. All three were quite a bit different from what went before in several respects, but similar to each other. They had a "wide wrap", meaning the distance between the leadpipe and the pipe coming out of the first valve going into the bell was larger than is normally the case. They were all about an inch longer from mouthpiece receiver to valve casing. All three were quite a bit heavier than (most?) other trumpets up until that point except the 48B Connqueror. All three had a #1 bore (0.433"). At that point all Conn trumpets were that bore; the 28B and 48B were the last ones to have a #1 1/2 (0.459") bore. The #1 bore was connected to a large 5 1/8" bell. The bell was a holdover from the 28B as were some other features: the 38B was completely nickel plated, the two Victor models were nickel trimmed. The 38B continued the Connstellation tradition of having a trigger on the first slide and an adjustable third slide finger ring. In 1958/1959 these three trumpets were fine tuned a bit, gaining a different model valve cap and a different mouthpiece receiver and in the case of the 6B and 10B Victors a coprion leadpipe, top spring valves and an adjustable third slide finger ring. Except for the coprion leadpipe this made them even more like the 38B than they already were.

The 1960s: Expanding on a theme
The 14B and 18B Directors were in 1960 replaced by two new models: the 15B and 17B Director. In fact these were very similar to late models 14B and 18B, a case of evolution. The distinct diagonal braces of the 14B/18B were replaced by (for Conn) more common straight braces, and an adjustable third slide finger ring was added (the original 14B/18B didn't have any ring there). In 1959 a "lightweight" Connstellation was introduced, the 36B. The lightweight Victor followed in 1963 with the introduction of the 8B. Both had a much smaller bell than the "heavy" models, 4 5/8" as opposed to 5 1/8". The 10B Victor with coprion bell was discontinued after 1962 (as were similar models such as the 9A cornet). In 1963 Conn introduced a variant of the 6B Victor, the 8B lightweight Victor. It certainly was lightweight: at 2 lbs. 6 oz. it was a full 7 ounces lighter than the 6B. According to the specs, it had some aluminum parts and a smaller 4 5/8" bell. Apparently the 8B was quite popular with jazz artists at the time. In either 1965 or 1966 another new model was introduced: the 60B. Described by Conn as "designed for the professional" and "extremely lightweight", it featured the smaller 4 5/8" bell. One model that was still in production in the 1960's didn't conform to the times at all. Although a "professional model", it had a fixed third slide finger ring and it didn't have a wide wrap: the 22B Victor. Essentially the same trumpet as was in production in the 1930's. What a run!

The 1970s: Decline
Conn was bought by MacMillan (a publisher) in 1969. In 1971 production of student (the "Director") models was moved to Japan, licensed to Yamaha if I am not mistaken. At the same time production of non-student (Victor, Connstellation) models moved from Elkhart, Indiana to Abiline, Texas. From that point on quality decreased considerably. The exact end date of certain models is unknown to me. The 15B and 17B Director were still in production in 1969, however I have never seen one with a serial number from 1970 or later. Several models did make into the 1970's: the 6B and 8B Victor, and the 36B and 38B Connstellation and the 77B Connquest were produced in some cases through 1979. I don't have exact end dates for these models. There is some evidence that the venerable 22B Victor was produced in the 1970's as well. The fate of some models is unknown to me: the 4B, 25B, 34B and 35B probably ended in 1969.

The 1980s: Revival?
In 1980 MacMillan sold Conn to Daniel J Henkin. I gather that Henkin's plan was to restore Conn to its former glory. There is increasing evidence that during this period serial numbers starting at 500,000 were re-used for certain models, including the 38B. There are 38B's in existence (of which I happen to own one) with 500,000 series serial numbers which were produced sometime after 1970 (they lack the "Elkhart" inscription on the bell, among other details). Since serial numbers during the 1970's were pretty consistent, logic dictates that these 38B's were produced after MacMillan sold Conn in 1980. In 1985 Henkin sold Conn to a Swedish company at which time "UMI" was founded. Production moved to the King facilities in Ohio. As far as I am aware, none of the pre-1970 models that may have survived to this point made it beyond 1985. I suspect the 38B Connstellation was the last of the "real Conn" trumpets to disappear. I am told that UMI at some point attempted to recreate some of Conn's historically great models, including the 38B. This in spite of the fact that the technical documentation and the original molds had been lost or destroyed at some point. The same source tells me that UMI was unable to get these models quite right, and none lasted very long.