Jensen Info wanted

[opossumcrush]

I picked up a pair of old speakers today, I opened them up to find, Jensen C12-SL, in each cab, with two Jensen tweeters in each cab. I can't find any info on the woofers. Can anybody tell me anything about them?

 

[Stephen J]

I picked up a pair of old speakers today, I opened them up to find, Jensen C12-SL, in each cab, with two Jensen tweeters in each cab. I can't find any info on the woofers. Can anybody tell me anything about them?

Gonna need some pics....:yes:

 

[Goodwill_HiFi]

I've never heard of a C12-SL. I'm going to assume it's a ceramic magnet.

I've got a pair of late 50s Jensen Tri-ettes that I tried to sell at AKfest. They didn't sell, but after Andyman pointed out that they're supposed to be oriented horizontal, and not vertical I decided to try them out again. So now, I have them hooked up in the living room. They've got P12NFs, sealed back mids, and horn tweeters. I think I have pictures here on AK someplace. Please post pictures of your new speakers.

 

[cubby01]

Bob, I may have miss-remembered this but these Jensens followed a fairly consistent numbering scheme ... C is for ceramic, then diamter, then the letter after the dash is I believe a wattage handling code - R for 25 watt, N for 50 watt, K for 100 watt, etc. I think S is 15 watt. And I believe the L means it was specifically designed for low frequency. I've only heard of C12S and C12SL being in music instrument amps though. 15 watt ceramic would have been quickly obseleted in the music instrument amp world so that's probably why you don't run across many references. Maybe a real Jensen buff will chime in.

 

[cubby01]

Another take on Jensen letter codes from the web:

Jensen Speaker Codes.
Jensen was a very popular maker of guitar amplifier speakers during the 1950s and 1960s. Fender and Gibson used them, and did many other makers. There are some other codes used on Jensen speakers, as shown below. The first set of codes shows the type of magnet, size and quality of the speaker.
The "P12R" identifies the type of
magnet, the size, and the quality
of the speaker.


The prefix code letter identifies the type of magnet used in the speaker. Prior to the 1950s, Field or ElectroMagnetic magnets were used. Instead of a permanently magnetic magnet, electricity was used to make the magnetic field. These became obsolete with good Alnico magnets and weren't used much past the 1940s. For the best guitar tone, it is generally agreed "permanenent" Alnico V was the magnet of choice. AlNiCo was the mainstay for decades because it produced a strong magnet which worked great in speakers. It was largely discontinued because of higher cost compared to newer materials (there are other rare earth metals now, such as samarium-cobalt and neodymium-iron-boron aka NIB that are now often used). Also Ceramic magnets were cheaper to make than Alnico, hence their usage in the 1960s instead of Alnico.

Prefix Codes:

F = "Field" magnet, which is a powered magnet (often with a small transformer mounted on the speaker).
EM = Electro Magnetic or Electronic Musical (electronic musical instrument speaker, 6"x9" to 15")
P = "Permanent" magnet, Alnico V. At some point in the 1960s Jensen stopped using Alnico V magnets (and used ceramic magnets instead), but kept the "P" prefix!
PM = Permanent Magnet, mostly AlNiCo type (or other earth metal combinations)
C = ceramic
NEO = Permanent Magnet NIB type (newest variety)
The number is the size of the speaker. Jensen made speakers from 4" to 18" sizes.

The suffix code letter identifies the quality of the speaker. Jensen speakers came in varying quality levels. They had a Professional series, a Concert series, and a Standard series. The closer the suffix code letter is to "A", the higher the quality of speaker. For guitar amplifiers, the Concert series is considered the best (the professional series is too efficient and doesn't "break up", the Standard series is too whimpy and can't handle any power). Here are the series code letters:

Professional series: letters J,K,L (made in 18" and 15" sizes only).
Concert series: letters N,P,Q,R (made in 8", 10", 12", 15" sizes). Best for guitar amps.
Standard series: letters S,T,U,V,W,X (codes U,W,X only came 8" and smaller).

That last letter, ie C12S_ I've see S, L, and F. Read where that has to do with cone excursion. S for Short. L for Long. F someone said was for Flexible and are usually accordian style surrounds.

 

[Goodwill_HiFi]

Another take on Jensen letter codes from the web:


That last letter, ie C12S_ I've see S, L, and F. Read where that has to do with cone excursion. S for Short. L for Long. F someone said was for Flexible and are usually accordian style surrounds.

The quoted material says that Jensen still used P for ceramic magents. I have not seen that. I've observed the opposite. My Tri-ettes have Alnico magnets, with P12NF drivers. I've seen Tri-ettes made a year or two later with cermic magnets, with C12NF drivers.

The F is for Flexair, not flexible.

 

[bfishn]

I think if you apply Goodwill HiFi's corrections to cubby01's post, you pretty well covered it. The only thing I'd add from observation of P15LL & P15LS is that while the Long and Short abbreviations apply, it's in reference to the coil stack. Long is overhung and Short is underhung. Since the cone surround and spider are the same on both, the max excursion remains the same, but the linear excursion ranges still differ in the Long & Short.

 

[Goodwill_HiFi]

I think if you apply Goodwill HiFi's corrections to cubby01's post, you pretty well covered it. The only thing I'd add from observation of P15LL & P15LS is that while the Long and Short abbreviations apply, it's in reference to the coil stack. Long is overhung and Short is underhung. Since the cone surround and spider are the same on both, the max excursion remains the same, but the linear excursion ranges still differ in the Long & Short.

Brad? Did you start a new account?

I didn't know about the differences in voice coil. I think I've heard the wattage info before.