Planar Speaker Asylum

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RE: The full quote is rather less negative

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In Reply to: RE: The full quote is rather less negative posted by JLindborg on September 17, 2012 at 15:47:27

You can always go to a parallel arrangement to get the resistance back down with lower mass foil. But there are so many things they could have changed. I don't even know if the midrange is the same width, or has the same number of magnets and loops, or even if it covers a single frequency band. I'm guessing they're using a .5-way somewhere, acoustical or electrical, to accommodate single pole crossovers. If it's in the woofer, they could potentially have made the midrange narrower to minimize beaming at the crossover to the tweeter. Or the could have .5-wayed the midrange, or maybe it was already narrow enough. Lots of possibilities.

Follow Ups:

RE: The full quote is rather less negative - JLindborg 09:26:46 09/18/12 (9)
Josh wrote: "You can always go to a parallel arrangement to get the resistance back down with lower mass foil. But there are so many things they could have changed. I don't even know if the midrange is the same width, or has the same number of magnets and loops, or even if it covers a single frequency band. I'm guessing they're using a .5-way somewhere, acoustical or electrical, to accommodate single pole crossovers. If it's in the woofer, they could potentially have made the midrange narrower to minimize beaming at the crossover to the tweeter. Or the could have .5-wayed the midrange, or maybe it was already narrow enough. Lots of possibilities."

Going parallel with lower mass foil would not make any sense as the weight would immediately double again. hehe
Making the midrange half the size with thinner alu-foil to compensate for the lower resistance would however do it.
But as You point out, we are merely speculating.

Cheers!

The one who succeeded was the one who didn't know it was impossible.
- RE: The full quote is rather less negative - josh358 09:56:39 09/18/12 (8)
  I was thinking two side-by-side segments, e.g., if you divided a 4 ohm midrange into two halves they'd each be 2 ohms. Then parallel those two halves, and you end up with 1 ohm. So to get back to 4 ohms, you reduce foil thickness to 1/4 of what it was and end up with 1/4 the mass.
  - RE: The full quote is rather less negative - JLindborg 10:24:26 09/18/12 (7)
    I am sorry Josh but You will ALWAYS have the same mass from the aluminum at any given resistance.
    In Your example You still have the 1/4 of the mass but You will have 1/4 of the membrane size too!
    This is because You divided the segments/size 4 times.
    
    The one who succeeded was the one who didn't know it was impossible.
    - RE: The full quote is rather less negative - josh358 10:39:24 09/18/12 (6)
      ?
      
      Same membrane size, same segments. I've just replaced this:
      
      +UUUU-
      
      with this
      
      +UU- +UU-
      
      and then paralleled the two halves. So if each "U" is 1 ohm, the first is 4 ohms. The two halves are 2 ohms each. Parallel the two halves and you get 1/2 + 1/2 = 1/Rt, so the total load becomes 1 ohm. Same diaphragm area, same foil, just connected differently.
      
      Now you can get back up to a total of 4 ohms by reducing the thickness of the foil traces, and therefore its conductivity and mass, to 1/4 of the original value.
      - RE: The full quote is rather less negative - Roger Gustavsson 09:41:13 09/19/12 (1)
        
        In Reply to: RE: The full quote is rather less negative posted by josh358 on September 18, 2012 at 10:39:24
        
        Josh,
        
        That is what the mids of most Magepan 3-ways are like. You cannot reduce the thickness of the wire without loosing effeciency. It is already on the low side. The total moving mass, Mylar+wire+glue, is not the only parameter that counts. I think the restrictions of the Magneplanar type of driver has something to do with the tensioned diaphragm to some degree.
        
        The mid driver of the MG 20/20.1 seems to be shorter than the mid of the MG 3.6/3.7. If the impedance/resistance remain the same, the wire (round or flat section) are thinner/lighter for the MG20/20.1.
        
        As the "pure" mid drivers of the Tympani IVa, MG20/20.1/20.7, seems to have the diaphragm divided into smaller sections. The masses of the various sections are smaller than the rather large midrange section of the 3-series . Still, the mid driver of the 3-series is not very far from the tweeters of the 2-series.
        
        RE: The full quote is rather less negative - josh358 11:22:31 09/19/12 (0)
        
        In Reply to: RE: The full quote is rather less negative posted by Roger Gustavsson on September 19, 2012 at 09:41:13
        
        Yes, I assume the Bl product goes down when you reduce the mass by paralleling segments. However, this can be compensated by increasing B, which is presumably doubled in the opposing magnet 20 series, assuming they keep the same Xmax. So they could reduce the mass of the midrange conductors while maintaining the same impedance and efficiency.
        
        Compliance also affects efficiency, as does driver area. And I assume the limit on the diaphragm mass of the 20's is the physical strength of the Mylar under tension.
      - RE: The full quote is rather less negative - JLindborg 10:44:52 09/18/12 (3)
        
        In Reply to: RE: The full quote is rather less negative posted by josh358 on September 18, 2012 at 10:39:24
        
        Yes yes. You are right there.
        I had a slight mental design dip. hehe
        
        The one who succeeded was the one who didn't know it was impossible.
        
        RE: The full quote is rather less negative - josh358 11:00:03 09/18/12 (2)
        
        In Reply to: RE: The full quote is rather less negative posted by JLindborg on September 18, 2012 at 10:44:52
        
        LOL, happens to me more and more. -- What were we talking about?
        
        RE: The full quote is rather less negative - JLindborg 11:59:51 09/18/12 (1)
        
        In Reply to: RE: The full quote is rather less negative posted by josh358 on September 18, 2012 at 11:00:03
        
        "LOL, happens to me more and more. -- What were we talking about? "
        
        You know... I actually have no clue! LOL
        The one who succeeded was the one who didn't know it was impossible.
        
        From the Balcony ... Statler and Waldorf - Satie 17:11:05 09/18/12 (0)
        
        In Reply to: RE: The full quote is rather less negative posted by JLindborg on September 18, 2012 at 11:59:51
        
        Yeah guys
        
        Forget stuff going from rec room to kitchen

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