Speaker Asylum

• RE: But stronger motors - villastrangiato 20:34:24 03/30/12 (3)
  In Reply to: RE: But stronger motors posted by badman on March 30, 2012 at 10:31:23

  Not true. Higher flux density fields allow the use of fewer voice coil turns which then results in reduced inductance and therefore reduced Le(x). Read Klippel's papers. Shorting rings are certainly one method but they are not the only method for reducing non linear distortion in drivers that results from flux modulation. A good number of pro drivers without shorting rings (some of the best in the business) sport some of the lowest distortion of any transducer available and also provide outstanding sensitivity which is something that is often lacking in designs that use shorting rings - particularly full copper sleeves covering the pole piece. Managing flux modulation (whether attributed to Le(x) or Le(i)) is not simply a matter of using shorting rings or the failure to use them. The transducer designer has a few tools in the tool box to deal with the problem whether working with an overhung or underhung design.
  

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  • You're mixing single-factor and multi-factor - badman 11:08:05 04/02/12 (2)
    In Reply to: RE: But stronger motors posted by villastrangiato on March 30, 2012 at 20:34:24

    My point is only that all things being equal, Le related distortions are not controlled by adding motor strength. Shorting rings aren't everything but they do have significant upside when used properly. A reasonably thick sleeve does a lot to control many issues in motors.
    
    
    
    Bass is supposed to sound big. 6.5" is not a woofer size.
    
    
    
    

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    • RE: You're mixing single-factor and multi-factor - villastrangiato 17:03:59 04/02/12 (1)
      In Reply to: RE: You're mixing single-factor and multi-factor posted by badman on April 02, 2012 at 11:08:05

      Steve (assuming that's you),

      I created this thread to uncover certain myths pertaining to shorting rings. They have limitations, they have a downside, and they are not necessary to reduce or effectively eliminate flux modulation based distortion in a loudspeaker. There is no "all things being equal" when it comes to different transducer design methods. You are totally incorrect when you said:

      " Le related distortions are not controlled by adding motor strength"

      Motor strength or more specifically - the intensity of the magnetic field and the tolerance maintained between pole plate and voice coil are CRITICAL in determining the ratio of field strength acting on the voice coil to the strength of field fluctuations produced by the current in the coil and the coil's movement. And THAT is all that matters in the end - the ratio of the forces produced by these two influences is what determines the percentage of distortion generated.

      To illustrate this example clearly and unquestionably, you can look at a readily accessible distortion comparison of speakers that use different design methods. One achieves incredibly low distortion without shorting rings and maintains a much higher sensitivity - 18 Sound 6nd430. The other uses copper caps/rings to achieve low distortion but has much lower sensitivity - Scan Speak 18W8531. The BL rating of the 18 Sound is almost twice that of the Scan Speak. You can see a detailed comparison here:

      http://zaphaudio.com/6.5test/compare.html

      As for your suggestion about using a "thick sleeve" - that is one of the poorer choices when using a magnetic isolator because it increases the separation from the voice coil to the pole plate - cutting sensitivity more than a copper cap or shorting ring above or below the gap. An example of this is the 8945P Usher which despite having a higher BL measurement than the Scan Speak, actually has lower sensitivity. And when it comes to sensitivity, as you know, every decibel counts. The 18 Sound requires almost 1/4 the power of the other two drivers to produce the same output at the test frequency.

      I know from what I speak. And my assertions about shorting rings are not simply my own - they are well documented and noted by many prominent industry professionals including Mr. Klippel whose papers I encouraged you to research earlier. If you had done so, you would have discovered the same information I've been trying to put forth in this thread. It is a total myth to proclaim that a speaker without shorting rings will by design have high or excessive flux modulation induced distortion. Shorting rings are only one method to reduce that type of distortion and their use comes with a price.
      

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      Edits: 04/02/12   04/02/12

      • Sigh.... - badman 09:33:26 04/03/12 (0)
        In Reply to: RE: You're mixing single-factor and multi-factor posted by villastrangiato on April 02, 2012 at 17:03:59

        I'm not Steve, and you're comparing apples and oranges. Thick is a relative term, it doesn't need to be 1/4".
        
        "I know from what I speak." You understand things pretty well, I agree, but your writing comes off as a condemnation of the use of shorting rings. They're a useful tool and used properly can improve motors and lower distortion. I never made the broad claims you ascribe to me.
        
        
        
        Bass is supposed to sound big. 6.5" is not a woofer size.
        
        
        
        

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