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Why no bell covers on new Jensen Alnico speakers?

Discussion in 'Amp Central Station' started by gmm52, Sep 22, 2017.

  1. gmm52

    gmm52 Tele-Meister

    196
    Sep 23, 2016
    Southern Ontario
    I've been looking at some new Jensen Alnico speakers, like the P10R, but they don't appear to come with bell covers like the originals from the fifties/sixties? Why is this? Wouldn't consumers want something that looks just like the originals if in fact a speaker is being sold as the same speaker?
     

  2. TimothyC

    TimothyC Tele-Holic

    886
    May 12, 2016
    California
    The alnico p12q that came in my DRRI came with the bell cover. Maybe they just don't display them for marketing purposes?
     

  3. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    It's not the same company or speakers. Recoton (the Italian owners of "Jensen Musical Industries") did not buy the Jensen Manufacturing Company specifications - just trademarks, part numbers etc.

    Some of the basket designs are also different (as are magnet sizes), and as many people (and installers) removed bells they could have decided not to pay for the additional tooling for all models. It's not cheap to have parts like that made in Italy & importing them from China could change the "Made in..." information.

    Bells wouldn't change the sound so I'm guessing they considered them an unnecessary expense - especially when not making identical speakers.
     

  4. 1300 E Valencia

    1300 E Valencia Tele-Afflicted

    Dec 13, 2010
    Fullerton CA
    AFAIK, the P10Q has never had a bell cover. I believe none of the current 10" models are available with a bell.

    Some of the 12" models have the bell added on for some Fender Special Edition amps, I think.

    The P12N is readily available both ways.
     

  5. gmm52

    gmm52 Tele-Meister

    196
    Sep 23, 2016
    Southern Ontario
    Thanks for the helpful info on Jensen. At the risk of starting a "does wood make a difference in an electric guitar kind of debate" ;-) I think a bell could make a difference, albeit minor. As frequencies increase, geometry plays an ever increasing roll in how sound is transmitted or reflected, and it is easy to imagine high frequencies leaving the back of the speaker in a different way depending on the geometry on the way out, e.g., encountering the bell. Now it may be a negligible or completely masked by what's happening at the front of the speaker, but there would have to be some kind of effect of a bell on sound leaving the back of the speaker. I have read accounts of certain high end speaker manufacturers putting a radius on the edges of speaker cabinets as an acoustic design consideration because of how highs would react or leave the cabinet at edges.
     
    Last edited: Sep 23, 2017

  6. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    I'm talking about "sound" - not math.

    I've used and worked on hundreds of amps....maybe in the thousands...with vintage Jensens since they were new both with and without bells, and while there may be a measurable difference there is NO audible one.

    Differences not heard by the human ear are irrelevant.
     

  7. gmm52

    gmm52 Tele-Meister

    196
    Sep 23, 2016
    Southern Ontario
    Any idea why they put them on in the first place?
     

  8. Tootone

    Tootone Tele-Meister

    176
    Sep 4, 2015
    Perth WA
    I believe the bell covers were there to stop direct knocks/ bumps/hits on the alnico driver magnets, which can change or decrease magnetiism.

    ...and now somebody will tell me I am wrong.
     
    JustABluesGuy and BobbyZ like this.

  9. Dacious

    Dacious Friend of Leo's

    Mar 16, 2003
    Godzone
    Originally a lot of speakers had open backs, not just in record/wax cylinder players but theatre speakers and so forth. Weather, corrosion, dust protectionn. End of the day one maker did to dress up an exposed back, the rest followed suit.

    A lot of amps the bell cover will interfere with the chassis. It was probably always optional. 1958 Jensen P15R from a Motorola console obviously never had one. Plus cheaper/lower power handling maybe companies were not inclined to pay for them

    IMG_20170918_163115.jpg
     

  10. BobbyZ

    BobbyZ Doctor of Teleocity

    Jan 12, 2011
    Snellman MN
    Originally like in the 50's I'm guessing Jensen charged a little extra for the covers. Builders seemed to use them on higher end things, like a Fender tweed Twin, a very expensive amp at the time. But I don't recall seeing them in Hammonds where you normally can't see the speaker or in cheaper amps. Although I did an early 50s Newcomb pa with a covered P10P or something. That thing split and the speaker was exposed when in use so that's probably why.
     

  11. xafinity

    xafinity Friend of Leo's Ad Free Member

    Dec 24, 2015
    west of I-10
    The bell covers were to alter magnetically induced waves of ultra high frequency microphonics that often canceled out the more desirable tones in our hearing spectrum. The new designs don't come close to the complete range of the originals so it matters little.
    TONE RANGERS!
     
    Archtop Bill likes this.

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