To help determine the manufacturing date of Hammond organs and Leslie speakers.Use this form if you would like to submit your Hammond Organ for inclusion in these tables.
All available information must be taken as a whole, and, combined with some general tips and observations provided below, a narrow range of probable production years can be arrived at which in many cases will be accurate enough for most people's desires.
One thing to remember in this chronological quest is these instruments were built to be played, not (in most cases) to become museum pieces.
In the example shown, 190-7215 was made in the 15th week of 1972.
Earlier Leslie motors have a stamped four digit code.
Recently, the production data was found and there is no longer any need for guessing.
This information is being compiled, organized and edited into a soon to be released book that details all sorts of production and manufacturing information, including tables showing serial numbers and their date of production.
285642 would be a Rola speaker made in the 42 week of 19x6 (you have to figure out which decade using other information).
For additional speaker manufacturer codes, see Ted Weber's listing at Weber Speakers.
Even the above is fraught with some risk, as replacement parts used for repair or modification will occasionally skew the overall picture.
Additionally, some organs have been pieced together in order to get one working unit out of many; this will produce inconsistent and unlikely date code ranges.
Most of the tone generator wax and Mylar capacitors do, as well as pre- and power amplifier multi-section can electrolytic capacitors.