MOS or Maryland Organ Service was a provider of service and maintenance for Pipe, Parlor, and Electronic Organs in the Baltimore / Washington area from 1972 to 2005.

Business card circa 1972Maryland Organ Service began in 1972 as a “retirement plan” for James Henthorn. At that time, he, a lifelong church organist and physics graduate of Johns Hopkins University, having spent most of his career life as an engineer at Hopkins Applied Physics Laboratory and at the Bendix Corp., decided that “fixing 3 or 4 organs a month” would be a good way to occupy himself in his retirement.

He was wrong.

Not only did he fix many more organs than that “3 or 4 a month” but he also was delightfully surprised to find there was a great market for organ repair.

From 1969 or so, until 1972 Mr. Henthorn repaired organs on a “side job” basis. During this time he began to establish himself as a technician for many manufacturers. By the mid 70’s he had accomplished being “Factory Authorized” by almost every major manufacturer and had achieved “Master Technician” status with the Hammond Organ Company.

During the 80’s he achieved status as a member of the “Baldwin Master Organ Guild” and joined as a charter member of MITA (Musical Instruments Technicians Association) International.

On December 31st 1995, James E. Henthorn, Jr. retired from “active” service with MOS, although he still occasionally provides me with a helping hand as I did for him so many years ago.

It was during the summer of 1975 that I, at age 5, began my career. Crawling into the chambers of a pipe organ, I tuned my first pipe.

It took almost 30 minutes! Now I can tune an entire rank (61 pipes) and more in that time.

From there, spending summers tagging along on service calls became a tradition. It wasn’t long before I started “toying” with electronics and reading technical manuals. I continued to do more mechanical work, holding keys, taking off and reinstalling organ backs, etc. By my high school years I had enrolled in a 3 year “Computers, Electronics and Robotics” course offered through the school system, and concurrently was instructed in “Vacuum Tube Technology” by my grandfather, Mr. Henthorn.

In 1988 I became a full fledged employee of Maryland Organ Service. Though I left in 1994 to work at a local pipe organ restoration shop. I returned in winter of 1995-96 to take the reigns of Maryland Organ Service.

1997-2005 were marked with and expansion into the DC and Northern Virgina areas in order to combat continually declining revenues.  MOS provided support for Yamaha digital pianos and diskclaviers in addition to it’s regular customers.

Late in 2004 I was approached by Steve Hayes of Speakeasy Vintage Music about designing a new motor controller that would overcome the short comings of other products that were available at that time.  I designed what would become the Caribbean Motor Controller.

In 2005, MOS was handed over to Speakeasy Vintage Music and I accepted a position with them as General Manager and Design Engineer, thus ending 33 years of MOS history.

Time Line


  • James E. Henthorn, Jr. Born in Baltimore, MD.


  • James Henthorn enrolls in Johns Hopkins University as a Premed Student, later changed to Physics.


  • James Henthorn graduates from JHU as a Physics Major, Math Minor.


  • James Henthorn attends graduate school at JHU, while working in the spectroscopy center on NDRC (National Defense Research Council) research.


  • Joins the staff at Hopkins APL (Applied Physics Laboratory).


  • Works at the APL developing advanced models of the “Proximity Fuze”


  • Leaves APL for a new job at Bendix


  • Works as an Engineer at the Bendix Corporation. Work includes design and construction of everything from radios transceivers and radar systems, to NASA tracking stations and Nuclear powered Submarines (He was part of the team that developed the control systems for the nuclear reactor aboard the Nautilus, the US Navy’s first nuclear powered sub).


  • Theodore E. Thompson Born in Baltimore, MD. (the son of Mr. Henthorn’s 2nd daughter)


  • Ed Henthorn starts “Sight and Sound Service”, soon changed to Maryland Organ Service.


  • Ed Henthorn begins training a new generation of technician, who calls him “pop-pop”.
  • Ed Henthorn is awarded “Master Technician” status by the Hammond Organ Company.


  • Ted Thompson, having developed a pastime of reading service manuals, begins his apprenticeship in earnest.


  • Ted Thompson enrolls in a 3 year electronics course at school


  • Ted Thompson becomes a full time employee of Maryland Organ Service, marking the end of his apprenticeship. He begins “flying solo” taking on a percentage of the service work himself.


  • Ted Thompson temporarily takes over as head of MOS while Mr. Henthorn is treated, successfully, for cancer.


  • April 14th – Ted and Deborah are married.


  • Ted Thompson leaves MOS to take a job at; and train with David M. Storey.


  • February 16th – Ted Thompson achieves “Factory Authorized Technician” status with the Roland Corporation USA.
  • While at David M. Storey Ted Thompson works on the “Old Otterbien” and “St. Leo’s” restorations in Baltimore, MD.
  • December 31st – James Henthorn retires from active duty at MOS


  • Ted Thompson takes over as head of MOS
  • MOSweb web site project begins


  • MOS relocates to Halethorpe, MD.


  • Ted Thompson accepts a part time position at Speakeasy Vintage Music as acting General Manager.


  • Ted Thompson becomes General Manager, Engineer, and Lead Piano Technician at Speakeasy Vintage Music.
  • Maryland Organ Service is taken over, and subsequently closed, by Speakeasy Vintage Music.