Some interesting information from a poster on Sax on the web (
http://forum.saxontheweb.net/showthread.php?29773-Pruefer-Woodwind-Company-When-in-Operation ) who relates this timeline for the Penzel Mueller / Pruefer partnership:
History:
Pruefer started clarinet company in 1906.
In 1914 he merged with Penzel and Mueller to form Penzel Mueller and Pruefer
In 1920 Pezel had died, Mueller gained control of the company and Pruefer retired
In 1920 Gus Pruefer had traveled to Markneukirchen, Germany and helped Moennig to modernize factory
1921 Restarted Pruefer clarinet company in US (young Hans Moennig joins Pruefer in RI)
1976 Factory in RI burned
I don't know what the source of the information is ultimately, but the dates fit quite well with those we already know.
Additionally, a good number of the earliest serialized Penzel Mueller clarinets have original bakelite bells. Often we tend to think a bell of a different material means a substituted bell, but it might more often be an original bell;- particularly with Penzel Mueller clarinets.
Bakelite had become broadly adopted for many uses by 1920. We can place a rough marker of circa 1920+ for the earliest Penzel Mueller clarinets with original bakelite bells. Given what we have found so far, circa 1920, following the death of G. Penzel, serialization began and bakelite bells became the most common ones. Whether these changes occurred nearly simultaneously or in close sequence remains to be determined. One thing that is certain, Pruefer clarinet serial 2410 is very nearly identical in manufacture to a Penzel Mueller Pruefer that has no serial as well as Penzel Mueller #7727, which has a bakelite bell. Thus knowing a little about the history of G. Pruefer sheds light on the "circa 1920" Penzel Mueller history.
