Please help ID this Field Coil speaker

[oldsoundz]

Hi Folks

I have had this speaker for better than a year now and can't say for sure
what it is.

I always thought it looked like it may say Jensen but the font was wrong so
I kinda let it go. A couple of days ago I saw an ebay auction with the same
speaker and the seller claims it is a Jensen 13.5 inch tube auditorium speaker.

It came to me with another very old field coil speaker that looks much different.

Can anyone help verify this?

[Sam Cogley]

Can you get a picture of the cone from the front?

I'm about 99% sure that is a VERY early Jensen. In fact, I've seen an almost identical unit that was so old it had a fold-over seam in the cone.

http://www.audiokarma.org/forums/showpost.php?p=3123841&postcount=17

[oldsoundz]

Thanks Sam

Here is a cone pic

[Eaulive]

Wow!

Can this thing be restored? It's kind of beautiful in it's own special way :applaud:

[Sam Cogley]

And there's the seam...

Super old, but I couldn't even start to give you a reasonable guess on the date. Definitely Jensen, though.

[JoMoCo]

I just went to ebay to check out the Jensen Field Coil Drivers....:duel:

http://cgi.ebay.com/FS-ACX-Field-Coil-Drivers-Lowther-Voigt-Jensen_W0QQitemZ170403538451QQcmdZViewItemQQptZVin tage_Electronics_R2?hash=item27acd7a613

Imagine Pippin and Merry enjoying their tree frog ale and smoking the pipe weed sitting on the wall in Lord of the Rings movie when Gandalf and crew ride up and Pippin says

"and I particularly enjoyed the Goat Leather Surrounds" :blink:

guess you had to be there....:moon:

[oldsoundz]

I'm about 99% sure that is a VERY early Jensen. In fact, I've seen an almost identical unit that was so old it had a fold-over seam in the cone.

http://www.audiokarma.org/forums/showpost.php?p=3123841&postcount=17

After seeing the picture of the one you link to here, I'm pretty sure it's Jensen. But it makes me think about this other one I have too....

Wondering if this could be a Jensen as well....

[Sam Cogley]

After seeing the picture of the one you link to here, I'm pretty sure it's Jensen. But it makes me think about this other one I have too....

Wondering if this could be a Jensen as well....

Considering that the wording on the remaining label is exactly the same as the known Jensen, I'd consider the ID to be beyond a doubt.

That second one is also almost certainly a Jensen, IMHO. The look is right on all of the parts.

[spkrman57]

Since there is no tube rectifier, could that be a (high-power) selenium rectifier???

What else could it be!

I helped identify a Jensen 18" like the original poster in this thread for a friend of mine years ago. I don't remember if the surround was all paper(most likely), or if it had the different material for the surround.

Definitely neat items. And they go for good $$$ on that you know what place.

Regards, Ron

[Sam Cogley]

Selenium rectifiers were invented in 1933, so it's possible that those two Jensens (the AK link and the second one pictured here) indeed feature solid-state rectification. I would have thought they were a bit older than that, but maybe not.

http://en.wikipedia.org/wiki/Selenium_rectifiers

I'm not sure when copper-oxide rectifiers were invented, but that's another possibility.

[oldsoundz]

Wow!

Can this thing be restored? It's kind of beautiful in it's own special way :applaud:

I am pretty sure it can be. I have seen a few brought back to life on various web pages.

Thank you to Ron and Sam. I was very curious what that crazy looking thing was.

Sam I was thinking older as well.

Anyone else have experience with old Jensen field coils?

[herki the cat]

And there's the seam...

Super old, but I couldn't even start to give you a reasonable guess on the date. Definitely Jensen, though.
-----------------------------------------------------------------------------------

You asked in one post "Can this be restored?"...Defnitely yes, it can.

The surround was always very thin "kid Skin" extremely thin and very plyable. You can nearly always find ladie's kid skin gloves in the Goodwill stores. "Plyabond, water-based cement" is excellent.

it looks in the picture like the voice coil & center pole piece are exposed so you can place a shim in there usng a piece of 35 mm film availale from WallGreen drug stores for 65 cents.

The rectifier in one picture looks like it is a copper oxide type. These were also used by RCA extensively on their high quality field coil speakers. You will probably not find any filter capacitors in either of the two speaker field supplys. They have a "hum-bucking coil in series with the voice in reverse phase to cancel the raw rectified DC current product, and they can be very quiet.
-----------------------------------------------
Cheers, herki the cat

[oldsoundz]

Thanks herki

Any chance you could help to date this item?

Selenium rectifiers seem to have appeared around 33'. What about the copper oxide? I did a wiki search and it did not clarify...

[herki the cat]

Thanks herki

Any chance you could help to date this item?

Selenium rectifiers seem to have appeared around 33'. What about the copper oxide? I did a wiki search and it did not clarify...
------------------------------------------------------------------------
I worked in a music store in 1936 that had an RCA franchise and over 100 pianos on the floor in addition to a basement 1/2 block long full of old trade-in radios of all descriptions many dating back before 1930, and well before the depression when people had money to buy these rather expensive radios that became an old used commodity which nobody wanted even in the early 1930s. I remember seeing some RCA Radiola consoles with a huge amplifier loaded with push pull parallel 45 tubes driving a magnificient 12 inch field coil speaker with huge long copper oxide rectifiers strapped on the cone basket. These were the first radios to use 45 type tubes. If you can find the date 45 tubes became a reality, copper oxide rectifiers will predate that time period.

[herki the cat]

Originally Posted by Sam Cogley http://www.audioheritage.org/vbulletin/images/buttons/viewpost.gif (http://www.audioheritage.org/vbulletin/showthread.php?p=273617#post273617)


=You asked in one post "Can this be restored?"...Defnitely yes, it can. The surround was always very thin "kid Skin" extremely thin and very plyable.
-----------------------------------------------------
For History buffs...Regarding speakers with leather surrounds...All the RCA speakers in the very beginng had very thin "kid skin" surrounds fabricated from several circular segments. The massive Camden RCA plant occupied some four blocks located next to the largest kid-leather tanning faciiity in the world along the Delaware River in Camden, vertually under the huge Ben Franklen Bridge connectng to center city Philadelphia, Pa.

As late as 1950, for stable, predictable laboratory "sound source" loud speakers, RCA Engineering still used the kid skin surround. I went to that tannery to select some kid skins for myself...I was immeditely told "you RCA fellows have been here before many times. We were once asked by RCA engineering to generate a specification for production procurement. all we could say was...'Well, we know it squeaks... they make hand bags , gloves, and exquiste ladie's jackets, etc...you are most welcome to select your skins."
----------------------------------------------
Cheers, herki the cat