Old Alnico Jensen, do i have a P12P or a P12R?

Discussion in 'Amp Central Station' started by Guns1rose, Mar 1, 2010.

  1. Guns1rose

    Guns1rose Tele-Meister

    Posts:
    296
    Joined:
    Feb 14, 2009
    Location:
    Richmond, Va
    Ive got this old speaker, but never knew whether its a P12P or a P12R. the letter after P12 is smudged, so i cant really tell. Anybody know?
    Thanks.
    Gettin ready to try it in a '64 deluxe reverb, but would like to know how many watts it can handle!

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
    Last edited: Mar 1, 2010
  2. Guns1rose

    Guns1rose Tele-Meister

    Posts:
    296
    Joined:
    Feb 14, 2009
    Location:
    Richmond, Va
    pics up.
     
  3. zag1

    zag1 Tele-Meister

    Posts:
    378
    Joined:
    Dec 5, 2009
    Location:
    Washington, DC
    It very well could be an "R", which would make it a 25 watt. I've never heard of a P12P. But thats just me...........
     
  4. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    39
    Posts:
    5,913
    Joined:
    Dec 3, 2005
    Location:
    SW CR IA US NA PE
    Fender didn't exactly make full use of the Jensen line. The P12P would have fallen somewhere between the 12-watt P12R and 18-watt P12N.

    I probably wouldn't use it in a DR, at least without being reconed for heavier duty.

    - Scott
     
  5. Guns1rose

    Guns1rose Tele-Meister

    Posts:
    296
    Joined:
    Feb 14, 2009
    Location:
    Richmond, Va
    So your saying its a P12P?

    1 vote P12R
    1 vote P12P
     
  6. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    39
    Posts:
    5,913
    Joined:
    Dec 3, 2005
    Location:
    SW CR IA US NA PE
    I'm not 100%, but the magnet assembly looks bigger than the one on this picture of a 1961 P12Q:
    [​IMG]

    Bigger than on the reissue P12Qs and P12Rs, too.

    Here is an old Jensen price chart showing the P12N and P12R specs. We can probably extrapolate that a P12P would have been 16 watts and a P12Q 14 watts.
    [​IMG]

    - Scott
     
  7. Billm

    Billm RIP

    Posts:
    2,227
    Joined:
    Mar 26, 2008
    Location:
    New Jersey
    I don't ever recall hearing of a P12P. Was there ever such a thing, extrapolation notwithstanding?

    I say it's a P12R. And I hope it sounds better than the current reissue P12R. The chart says 12 watts, so your DRRI should have no trouble destroying it, especially if you play with distortion.
     
  8. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    39
    Posts:
    5,913
    Joined:
    Dec 3, 2005
    Location:
    SW CR IA US NA PE
    There are a couple P12P's on eBay.
     
  9. BiggerJohn

    BiggerJohn Friend of Leo's

    Posts:
    3,311
    Joined:
    Jun 1, 2009
    Location:
    California
    I have a P12P here somewhere.

    Show a side shot that shows the plug magnet.
     
  10. 6942

    6942 Poster Extraordinaire

    Age:
    66
    Posts:
    6,333
    Joined:
    Apr 15, 2006
    Location:
    Santa Fe, NM
    Yes, there are Jensen P12P speakers.
    I own a 1960 Jensen P12R, and the magnet assembly on your speaker, looks larger?


    Steve
     
  11. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,833
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    That is a nice '55 P12P or so it looks from here by the nagnet assembly size. They are not very common. I also agree with BillM that it would probably live a short life in a BF DeluxeREverb. That amp needs 30 watts of speaker minimum, imo.
     
  12. BiggerJohn

    BiggerJohn Friend of Leo's

    Posts:
    3,311
    Joined:
    Jun 1, 2009
    Location:
    California
    We wll not be able to positively identify the thing until we get a clear side shot showing the innards of that field case. The P will have a larger diameter plug magnet compared to the R.

    Like I said, I do have a P12P here somewhere so I can do a better eyeball comparison once you post a side view.

    Basically if the plug magnet in your speaker is about 1" diameter, it's an R. If the magnet is more like 1.25" diameter, it's a P or a Q.
     
  13. stingray_65

    stingray_65 Tele-Meister

    Posts:
    210
    Joined:
    Aug 30, 2008
    Location:
    blissfield michigan
    I've recently pulled a 1958 Jensen P12P from a 1958 Wurlitzer.

    The magnet (as best I could measure) is 2"

    The Voice coil (again best as I can measure) is 1 3/4"

    The manual that came with the organ states the amplifier is rated at 35W output.

    And again from that schematic, push pull 7027 with 385V on the plates should be about that 35W

    http://www.nj7p.org/Tube4.php?tube=7027A

    from the size of the magnet, voice coil, amp power rating and the way everything was built back then, I would guess at a likley higher power rating, say 45- 50W.

    the real issue would be the cone is 50+yr old paper, no doping on the surround.

    I'd be afraid to pump more than 25W with mild distortion into it.

    Ray
     
  14. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

    Age:
    67
    Posts:
    9,474
    Joined:
    Mar 2, 2003
    Location:
    Lawndale CA
    More like 15 watts clean, 5-10 w/ mild overdrive. That's the info I was given by the late-great Ted Weber. He said any Jensens (alnico or ceramic) over 30 years old should be treated like they have 1/3 the original power handling. He was actually even more conservative than my number with distortion, which rips apart the old,stiff glue on the cone.
     
  15. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,833
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Teh vitage P12P was something like an 18-20 watt speaker when new.
    The handling cpacity is not determined solely by the magnet and voice coil size.
    As evidenced by the 10" alnicos that Eminence was building back in the early and mid 90's. The two models had the saem voice coils andmagnets, but the formers were made of different materials. The paper former model...simular to the vintage JEnsens in construction....were rated at 20 watts. The Kapton former was rated at 35 watts. Eminence no longer builds the paper former model...probably for good reason. IF you push that 20 watter hard...even with just a 15 watt amp, it will not be able to dissipate theheat and it will fail. The Kapton former dissipates heat better...hence the higher rating and better performance under the demands of mostm odern plyaers..who like to hear some distoriton.
    FWIW, the bright blue Emi Alnicos that came in the first 5F6A Bassman REissue amps were the paper former models and are well regarded...much superior imho to the JEnsen that FEnder went to later. Some hold that EMinence to be as good as the WEber ALnico that simulates the original JEnsens.
     
  16. slider313

    slider313 Tele-Afflicted

    Posts:
    1,189
    Joined:
    Jan 6, 2011
    Location:
    NC
    That looks like a '55 P12P by the weld on the magnet. It has a 1.5 inch voice coil and was rated, conservativly, at 16 watts.


    [​IMG]
     
  17. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,833
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    I stand corrected on the capacity....hey, the chart is right above in this thread and I missed it! LOL
     
  18. BiggerJohn

    BiggerJohn Friend of Leo's

    Posts:
    3,311
    Joined:
    Jun 1, 2009
    Location:
    California
    Need a side view so we can see the slug magnet.
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.