Anyone have any first hand experience, or information on these vintage 15"? coaxial drivers?
A buddy of mine picked up a pair at a rummage sale I was wondering if they were worth messing with.
I'm not finding a whole lot of information on the Google machine.
A buddy of mine picked up a pair at a rummage sale I was wondering if they were worth messing with.
I'm not finding a whole lot of information on the Google machine.
Looks like these were used in some models around 1947.
A lot of Jensen data here. You may have to read through however.
New Page 1
If you're the new generation, note that it may have a field-coil instead of a magnet (looking at its time, check again) and simply wiring the voice coil to an amplifier may not bring about any sound. Some more information here on page 38:
All the best.
A lot of Jensen data here. You may have to read through however.
New Page 1
If you're the new generation, note that it may have a field-coil instead of a magnet (looking at its time, check again) and simply wiring the voice coil to an amplifier may not bring about any sound. Some more information here on page 38:
All the best.
Last edited:
Thanks a ton for the info and links.
I had read on another message board that maybe some of these, or drivers of a similar design, were used in jukeboxes?
I do believe they are a field coil design, as indicated by the attached transformer.
I'm a bit late but,
It's not a field coil, but an early permanent magnet. At the time, amplifier output was usually 250 or 500 ohms to field coil, which is itself acting as a transformer winding in the circuit. Early permenant magnet speakers were often paired with a line-to-speaker transformer, common to find them with multi-tap primaries at useful increments, 50-100-250-500 or something like that. Alot of field coil speakers had weird obscure impedance values, but you could match 80 with 100 or 45 with 50ohms etc. These transformers were often basket mounted but can also be found cabinet mounted.
This particular speaker is one that I own, a 1947 with the original cone. The tweeter was missing when I got it, but if it hadn't been, I would have been tempted to separate it. Nested in the center of the cone always seemed like a bad idea to me. Obstruction hasn't ever made a speaker sound better in my experience...
I find it a really great speaker, especially with vocals... I listen to alot of jazz on it. I have the coolest bass reflex box Jensen ever made, in my opinion, and I want to have a relevant if not the correct 12" speaker in it. The tweeter I have paired with it right now is a Jensen paper cone open-backed PM5L, of which I have never seen another example.
It's not a field coil, but an early permanent magnet. At the time, amplifier output was usually 250 or 500 ohms to field coil, which is itself acting as a transformer winding in the circuit. Early permenant magnet speakers were often paired with a line-to-speaker transformer, common to find them with multi-tap primaries at useful increments, 50-100-250-500 or something like that. Alot of field coil speakers had weird obscure impedance values, but you could match 80 with 100 or 45 with 50ohms etc. These transformers were often basket mounted but can also be found cabinet mounted.
This particular speaker is one that I own, a 1947 with the original cone. The tweeter was missing when I got it, but if it hadn't been, I would have been tempted to separate it. Nested in the center of the cone always seemed like a bad idea to me. Obstruction hasn't ever made a speaker sound better in my experience...
I find it a really great speaker, especially with vocals... I listen to alot of jazz on it. I have the coolest bass reflex box Jensen ever made, in my opinion, and I want to have a relevant if not the correct 12" speaker in it. The tweeter I have paired with it right now is a Jensen paper cone open-backed PM5L, of which I have never seen another example.
I also forgot to mention, jap-60 is not the Jensen part number but indicates something else about the assembly, not the transformer but I'm not sure what. You'll find this speaker in allied radio under the code jhp-52, beginning in 1943
Also just correcting myself, those matching transformers are more usually like 250-500-1000-2000 and such, my head is in an amp with 250 out that I'm working on. I'm like 5 radios and 7 amps into this hobby lol. So field coil speakers were usually much higher impedance than I stated...
Also just correcting myself, those matching transformers are more usually like 250-500-1000-2000 and such, my head is in an amp with 250 out that I'm working on. I'm like 5 radios and 7 amps into this hobby lol. So field coil speakers were usually much higher impedance than I stated...
Last edited by a moderator:
Gracious me, jap-60 is in fact the model number, and jhp-52 is a different speaker. From allied catalog 1949:
An externally hosted image should be here but it was not working when we last tested it.
https://imgur.com/a/mqA08PIAn externally hosted image should be here but it was not working when we last tested it.