Jan Plummer of TBI Sounds

Jan Plummer of TBI

The genius behind TBI Audio Systems is Mr. Jan P. Plummer. Jan has been an indefatigable explorer for truth in the reproduction of sound for over thirty years. As a youngster his interest in electronics began when he blew up the family’s television set at the age of 14. He dropped out of college after only one semester because he wanted to turn all his attention to electronics.


He started building loudspeakers in the late 1960’s. He built custom units for many popular musicians and also traveled with them as the sound technician. He had during this time received a patent (in the 1970’s) on a speaker design that he labeled the E.T.M. (Equal treatment of midrange).  However he still was noticing problems due to cone breakup and distortion at frequencies in the higher and lower ranges. It was at an outdoor concert in Denver where he noticed that some speakers he had wrapped in plastic due to the inclement weather had a clearer than usual sound.


He pursued this theme through much trial and error before developing the Acoustic Power Lens (APL) patented in 1990. The lens made of a type of plastic allowed for the use of smaller drivers. It acted as a passive radiator and reduced the membrane vibration of the drivers. But the lens design proved difficult to manufacture and assemble in economically appropriate quantities. Prior to the lens invention, Jan developed in the 1980’s the “sound-mate”, which allowed for remote control sound adjustment. He received a patent for this valuable addition to manual speaker frequency control.


The APL technology was adaptable for tweeters, mid-range drivers, and woofers (which reproduce frequencies as low as 40 cycles. A customer approached Jan in the late 1990’s who wanted him to produce a subwoofer (which reproduces frequencies below 40 cycles).  Jan had never applied the APL technology to subwoofers but he did and the result was good but nothing outstanding. Jan attempted to eliminate the sound waves escaping from the subwoofer by enveloping the baffle board and the front of the subwoofer in a foam material. No great improvement.

One day while playing the subwoofer with the glued foam covering, he placed it in a drawer of a cabinet he was designing for electronic components. He said,  “He immediately noticed the sound changing in a positive way”. He followed up this unexpected trail, which led him to develop the “Embedded Transmission Line” (ETL).


The ETL technology (patent pending) allowed for the elimination of the lens, created a subwoofer acclaimed as the “most musical in the world” (the Magellan series), and led to the development of the Majestic Diamond loudspeakers.


The Majestic Diamonds loudspeaker crown Jan’s thirty-year search for a single point speaker that can produce a full range of sound without the inevitable distortion produced by added drivers and their corresponding cross-over networks. This monumental achievement allows a loudspeaker, in real-time, to self-regulate any frequency by increasing pressure when and as necessary without any electronic or human intervention.


TBI calls this technology “HDSS” (High Definition Sound Standard), which claims the most faithful reproduction of sound.