Jensen Loudspeakers
American speaker maker known for guitar amp speakers.
Jensen Loudspeakers began in Chicago, Illinois, in 1927, founded by Peter Laurits Jensen, who co-invented the first loudspeaker. The company hit its stride in the mid-1940s when its speakers were chosen for the first Fender guitar amplifier, and through the 1950s and 1960s, they became a common sight in amps from Fender, Ampeg, and Gibson. They also made Hi-Fi speakers for home use and supplied OEM drivers to other brands. Production stopped in the early 1970s, but demand for replacements kept interest alive. Since 1996, SICA Altoparlanti in Italy has been making "reissue" versions designed to match the originals, and in 2008 they started producing new designs under the Jensen name. CE Distribution handles U.S. sales for both lines. The current Fender Twin Reverb amp, for instance, uses two 12" Jensen C-12K speakers.
For a time, Jensen and Rola were both owned by the Muter Co. and shared design traits—their 8" and 15" baskets seemed to come from the same tooling. When the Chicago plant closed, Rola locations took over Jensen production. Jensen’s model numbers run four to six characters. The first letter indicates the magnet type: F for field coil, P for alnico, C for ceramic. The P line started in the 1940s, the C line around 1960. The next one or two digits give the speaker diameter (8 for 8", 10 for 10", etc.). The final letter denotes magnet and voice coil size, which affects power rating. The same magnet codes appear on different speaker sizes, with power rising as diameter increases. Ceramic magnets are about 45% heavier than the alnico equivalents with the same code. Examples: K means unknown or 50 oz ceramic; N is 29.5 oz alnico or 29 oz ceramic (the alnico version uses an inefficient ring magnet); Q is 10 oz alnico or 15 oz ceramic; R is 6.8 oz alnico or 10 oz ceramic. So a Jensen C8R is an 8" speaker with a 10 oz ceramic magnet.
Every Jensen speaker also carries a date and manufacturer’s code. Jensen’s source code is 220. This is followed by the last digit of the year and the two-digit week of manufacture, forming a six-digit code usually stamped on the edge or magnet housing. For example, 220534 means a Jensen made in 1945, 1955, or 1965 during the 34th week. In the 1970s, most manufacturers added the last two digits of the year, turning the code into seven digits.
- Founded
- 1927
- Founder
- Peter Laurits Jensen
- Location
- Chicago, Illinois
- Notable users
- Fender, Ampeg, Gibson
- Current distributor (us)
- CE Distribution
- Current manufacturer (reissues)
- SICA Altoparlanti (Italy)
Lore & Background
The former Jensen Radio Manufacturing Company was founded in 1927 by Peter Laurits Jensen, the co-inventor of the first loudspeaker, in Chicago, Illinois. The company gained popularity in its early years, rising to its peak in the mid 1940s when Jensen speakers were selected to be used in the first production of a guitar amplifier by Fender Musical Instruments Corporation. Subsequently, Jensen speakers in the 1940s, 1950s, and 1960s became commonly featured in major amplifier production, including amplifiers produced by Fender, Ampeg, and Gibson. The company also produced Hi-Fi loudspeakers for home use and was a manufacturer of OEM drivers for other brands.
Jensen and Rola were, for a time both under common ownership (subsidiaries of the Muter Co.), and shared various design similarities. Their 8" and 15" baskets appeared to utilize the same tooling. Rola locations took over Jensen product manufacturing when the Chicago plant closed. Jensen speakers used a model number that contained 4 to 6 characters. The first character denotes the magnet type used: F for Field Coil, P for Alnico, C for Ceramic magnet. These are listed in the order in which they were made, with the P line starting in the 1940s and the C line starting around 1960. The next one or two characters denotes speaker size, and the last character denotes the magnet/voice coil size, which directly influences the power rating.
Reader's Guide
Jensen Loudspeakers ceased production of their products in the early 1970s. The speakers remained heavily sought after as replacements for amplifiers originally manufactured with Jensen speakers. Following that demand, SICA Altoparlanti began reproducing reissues of the Jensen speakers in 1996. These speakers are designed to be as close as possible to their original design. In 2008, SICA Altoparlanti began producing new speaker designs under the Jensen name. These speakers and the Jensen reissues are distributed in the United States by CE Distribution. The current Fender Twin Reverb amp uses two 12" Jensen C-12K speakers. Jensen's legacy is tied to its role in the early Fender guitar amplifiers and its widespread use across major amplifier brands. The model numbering system, with codes indicating magnet type, size, and power rating, remains a key identifier for collectors and musicians seeking authentic replacement speakers. The reissue program has kept the Jensen name active in the guitar amplifier market long after the original company closed.
Did You Know?
- Jensen and Rola were both subsidiaries of the Muter Co. and shared design similarities.
- Jensen's EIA source code is 220, and a code like 220534 indicates manufacture in the 34th week of 1945, 1955, or 1965.
- Ceramic magnets in Jensen speakers are roughly 45% heavier than their Alnico equivalents that share the same code.
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