[Overview]
This item is an extremely rare pair of JENSEN IMPERIAL PR-100 16Ω 3-way speaker systems, released by JENSEN in the 1950s.
Founded in 1927, Jensen was once a supplier of speaker units and related components to Western Electric, hereafter referred to as WE. Drawing on its knowledge of iconic WE products such as the 755A and the 555 driver, Jensen went on to become a leading force in the theater sound industry after WE’s decline.
Alongside the Triplex, this IMPERIAL PR-100 is one of Jensen’s representative models. At the time, 3-way systems that reproduced the low, mid, and high frequency ranges with dedicated speakers for each band were the standard approach. This model is no exception. It became one of Jensen’s signature 3-way speakers and was widely used in many theaters and homes.
Cabinet
The PR-100 series uses the MODEL BL-250 BASS-ULTRAFLEX cabinet, a design that brought together Jensen’s technical expertise.
By adopting a back-loaded design with openings on both sides, the cabinet achieves rich low-frequency amplification. It pairs exceptionally well with Jensen’s excellent woofer units such as the G610B and Type H.
Its appearance is also artistic, with a refined beauty that had rarely been seen in theater sound systems up to that point. Two finishes were available: blonde and mahogany. This pair features the mahogany cabinet.
Jensen’s relentless pursuit of improved design during that era was truly incomparable to other manufacturers. This becomes clear when looking at the previously mentioned Triplex or the appearance of this model.
Sound Quality and Unit Configuration
The PR-100 consists of three speakers — woofer, mid horn, and tweeter — plus three networks.
Woofer
The woofer section uses the MODEL P15-LL, a 15-inch Alnico unit that inherited technology from models such as the G610B.
The know-how Jensen gained while supplying units to WE is clearly reflected here, delivering rich, highly efficient, and excellent bass performance. Its appearance is reminiscent of ALTEC’s mainstream 803 woofer, which was a competing model at the time.
The network section uses the MODEL A-61. Since the crossover point is set relatively high at 600Hz, the bass has a well-defined, firm, and tenacious character.
Mid Horn and Tweeter
Signals above 600Hz are sent to the MODEL A-402 network, where they are further divided into three paths.
The mid horn unit uses the Alnico MODEL RP-201. This unit also delivers a rich, powerful sound with high resolution reminiscent of the Western Electric lineage, offering excellent clarity and texture.
The crossover range is 600–4000Hz, and it felt as though this important central range, which carries much of the musical information, was reproduced without omission.
Frequencies above 4000Hz are sent to the MODEL 1131 network and then output through the final stage, the MODEL RP-302 Alnico tweeter.
Although it may sound like a common impression, the highs are open, extended, and highly transparent. There are no harsh or piercing peaks, and the sound is honest and natural, somewhat close to WE, yet different from the Altec sound.
At the time, two tweeter options were available, the RP-202 and RP-302, allowing users to choose according to their intended use. This unit is equipped with the RP-302.
Despite its vintage age, the enclosure, speaker cone paper, and edges can all be considered to be in good condition. Please judge the exterior condition from the photos.
Enclosure Specifications
Despite being a vintage item, both the exterior and interior are in very good condition.
Aside from some minor scuffs and scratches, the exterior is clean, as can be seen in the photos.
Size, per speaker: Width 820mm × Height 1380mm × Depth 625mm
Weight, per speaker: Approximately 65–75kg
Operation Confirmation Video
Sound output has been tested and confirmed. Operation is guaranteed.