Jensen Duette



Jensen Duette "Treasure Chest" [DU300] finished in Mahogany from the mid 50s

Jensen Duette "Treasure Chest" [deluxe version of the one below] interior view, 2-way system with P8RL mid-woofer, RP106 cylindrical metal horn tweeter. The phenolic diaphragmed alnico magnet compression driver is the same motor assembly used in the later RP102 and RP103. Simple 1st order crossover network using a 2uf paper capacitor [beeswax?] and a transformer for attenuation and impedance matching. These came with bare panels and best left alone for ultimate sonics.


Jensen Duette "Reproducer" [DU201]. Essentially the same speaker as above but uses a plastic horn lens and cheaper Fabrikoid finish, from the mid 50s


Heathkit SS1 sold as a kit in the mid 50s until the 60s. Simple 2-way bass reflex utilizing the driver components below. The crossover consist merely of a 2uf paper cap and an L-pad tweeter attenuator. Also no damping inside the plywood box.

Jensen P8RL 8" woofer: frequency response 50 - 3,000 cycles, impedance: 8 ohms, 1/2 lb. alnico magnet, maximum power 20W
Jensen RP103 tweeter: compression horn driver with alnico magnet and phenolic diaphragm frequency response 2,000-15,000, impedance 16 ohms, maximum power 30W
These are the components [or later versions] typically encountered inside the Heathkit SS1 and Eico HFS-1 speaker systems.


Looking for something a little less exotic and more affordable than WE or Altec. Try these Jensens which sold in great numbers in the 50s-60s. These are JE Labs budget vintage speaker faves. Perhaps a little less transparent over the entire frequency range and less "snappy" in the midrange, but they are pretty damn musical and efficient. I am listening to my Duettes right now driven by my SE71A amp.

If you can find them with the cabinets in good condition, these may have great WAF, especially if she is into modern retro or mid century modern designs like Charles Eames, George Nelson, Noguchi and etc. I am still looking forward to finding a pair of Heathkit SS1 or DU300 in blonde oak finish with matching wooden or metal wire stands at a yard sale or thrift store. So ask around, maybe an old relative has them stored in the basement or attic.

The Jensen P8RL 8" woofer may look cheap [in spite of the fact that people pay $300/pr. for similar the looking and even smaller 6" Diatone PM610 FR] but what sets it apart from modern designs is its natural sounding midrange due to the stiff paper cone that has a built in surround which makes it a pretty quick responding driver [good for the midrange] yet if properly loaded in a proper bass reflex cabinet, there is enough energy below 80 hz to keep you happy just like any modern monitors. I can assure you that the smooth midrange response up to 3,000 is a bit pessimistic because it is almost usable as a full range driver that's why only a 2uf cap in series to the RP103 was used to crossover at 5,000 cycles. The RP103 may not have the silky, detailed and ribbon like response of an Altec 3000, but this phenolic diaphragmed horn tweeter is smooth and sweet with plenty of detail until it rolls off gently above 13 khz. 

Compared to the Jensen Duette, the Heathkit version has slightly bolder presentation because of more energy in the bass frequencies. This maybe due to the heavier cabinet material [5/8" plywood as opposed to 1/2" used in the Jensen] and lower tuning of the bass reflex [that cabinet is a bit deeper]. However the Jensen sounds smoother and slightly more refined. I can live with either one. Unfortunately I do not have a copy of the Heathkit cabinet plan. If someone can send me a jpeg scan, I will upload it in this page.

Take note that these cabinets were designed to be placed horizontally on bookshelves and during that time, people did not pay much attention to mirror image placement of drivers. Stand mounting horizontally is best for pure sound if you have the space. If you crave for that sweet and airy extreme highs which will bring these speakers abreast with the 21st century you may also add the Fostex FT-17H as a super tweeter Just use a .5uf oil cap and adjust levels to taste with an 8 ohm L-pad.
If you have or find the drivers without the cabinet, try the two Jensen plans below. Make sure you use 1/2" plywood as per instructions and make it rigid. No damping material required for best sound and please don't use MDF. The only modification I may consider is using a removable grill covered with silk cloth as suggested by Walt Bender in his "Ask Walt" series. These two drivers also sound good in an open baffle.
Cabinet plans from Jensen


Eico also marketed their own version, the HFS-1, using these two Jensen drivers. I have seen them but never heard them in a system. These are also worth hunting down. Just remember that these were budget designs and if your taste and pocket crave for ultimate transparency and finesse, these may not be suitable. But for apartment dwellers or those on a tight budget who dabble with SE amps these speaker systems may be your ticket to musical pleasure.

I am sure there other sleepers out there, particularly drivers imported from Japan and Germany by radio chain stores during the late 50s and 60s. Actually some choice Japanese models from this era are now being re-exported back to Japan. 


Link to Jensen Ultraflex enclosure

Comments

  1. I have a question if you may know it. What is the difference in the p8r-l driver and the p8r-s driver. Any information would be helpful.

    Christopher

    cpcuccia@gmail.com
    646 248 2914

    ReplyDelete
    Replies
    1. AFAIK, they are both woofers with relatively greater compliance than a somewhat similar looking P8R-X, which in old catalogs are marketed as a "full range". However for stereo, I suggest using P8R-Ls or P8R-S in pairs.

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  2. I have had a couple of the heathkit SS-1's(Currently using one with a homemade bass and HF Extender) and have found that they do sound better with the internal walls of the cabinet lined with 1/2" padding. I put a double layer directly behind the P8R to catch the backwave. My extender is a single 12" university sound series 200 312 diffusicone and a t-202 supertweeter. The diffusicone is set up to roll off at 70 hz and the super runs wide open after 12,000 khz. It is very sweet sounding(especially voice material) and for many recordings I prefer it to my AR3a's and Tannoy gold's

    ReplyDelete
    Replies
    1. Good to hear another point of view! Anything that further enhances musical enjoyment is good in my book, happy listening!

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