High Efficiency Speaker Asylum

Posted by FloridaJim (A) on October 11, 2009 at 14:45:23

Hello Inmates,

After much research, I decided to try open baffles.

Somewhere on this site there is a post about going to Home Depot picking up a 4X8 3/4" birch ply and having them cut it into 6 pieces. I had mine cut into 2 each 10" and 4 each 18" pieces. I assembled each pair of 18" panels to a 10" panel using 4' piano hinges.

I am using Lowther PMA6 drivers -- the 15 ohm units with silver windings. At this point they are not yet broken in, but sounding better every day. I could not be more pleased.

I have yet to experiment with placement. I just plopped then down where the old BLH cabinets used to be.

Any advice, thoughts, or suggestions would be appreciated.

One thing I have noticed is that there is some viberation which I plan to eliminate. Other than that these are one hell of a deal.

Best regards,
Jim Bailey

• RE: Just Completed My First Open Baffle - Very Pleased - Retsel 13:45:41 10/13/09 (3)
  In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 11, 2009 at 14:45:23

  It would be worthwile knowing the frequency response to see if you need to adjust the frequency response of the Lowthers. I have DX4s on open baffle, and without a crossover, they were unlistenable (high frequencies were tipped up). Because of the weaker magnets of the PM6s, you very well could do without a crossover.
  
  You definitely need a set of subwoofers, so tieing those in and developing a seamless crossover will be challenging, but very worthwhile.
  
  The Lowthers do not have sufficient x-max for running wide open on open baffles. You should plan on high passing them with a 1st or 2nd order crossover at around 100 to 150 hz. It is good having 15 ohm drivers because of the greater x-max.
  
  Retsel
  

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  • RE: Just Completed My First Open Baffle - Very Pleased - FloridaJim 17:39:04 10/13/09 (1)
    In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by Retsel on October 13, 2009 at 13:45:41

    Thanks for your comments.
    
    Re: "The Lowthers do not have sufficient x-max for running wide open on open baffles", I have read about x-max, but cannot say that I understand it. With respect to my Lowthers, why should I care about it? Will I damage the drivers or is it a performance issue or both?
    
    Best regards,
    Jim
    

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    • RE: Just Completed My First Open Baffle - Very Pleased - Retsel 13:48:42 10/16/09 (0)
      In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 13, 2009 at 17:39:04

      X-max is the distance that the driver can travel before the magnet leaves the gap, and distortion skyrockets. You definitely want to keep your drivers operating within the x-max of the drivers. The x-max for 15 ohm Lowthers is 3 mm which is not very much....
      
      X-mech is the mechanical limit for the driver, beyond which the driver can be damaged. I don't know what the x-mech is for Lowthers, but Jon ver Halen has suggested high-passing the Lowthers at 150 hz to protect the drivers.
      
      If the driver is moving a lot to reproduce bass signals, it is likely distorting the midrange sound of the driver. This is because of doppler distortion (the driver is reproducing midrange signals which is being reproduced with small driver movements, while reproducing bass signals with large driver movements - the midrange signals are being distorted). For this reason, bass signals should be left for woofers and the Lowthers reserved solely for midrange and high frequencies.
      
      Retsel
      

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  • RE: Just Completed My First Open Baffle - Very Pleased - FloridaJim 16:00:41 10/13/09 (0)
    In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by Retsel on October 13, 2009 at 13:45:41

    I have a pair of 85hz high pass filters -- uninstalled. Is this close enough to 100 hz?
    
    Thanks,
    Jim Bailey
    

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• Close to Tampa?...nt - tweakk 15:55:24 10/12/09 (1)
  In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 11, 2009 at 14:45:23

  nt
  

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  • RE: Close to Tampa?...nt - FloridaJim 22:47:55 10/12/09 (0)
    In Reply to: RE: Close to Tampa?...nt posted by tweakk on October 12, 2009 at 15:55:24

    my home is in Hollywood
    

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• RE: Just Completed My First Open Baffle - Very Pleased - nl 09:33:37 10/12/09 (1)
  In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 11, 2009 at 14:45:23

  It might have been me that popularized the hinged open baffle here.
  
  I didn't invent it of course: PHY-HP has had plans for years for a piano hinge baffle for their 12" drivers. And, this 1930s Western Electric Mirrorphonic system has a hinged open baffle.
  
  http://www.audioanthology.com/audio4.htm
  
  With that said, you can do as well or better with some sort of fixed baffle. The hinges are not actually all that useful.
  

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  • Bent hinges... - Godzilla. 10:16:53 10/12/09 (0)
    In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by nl on October 12, 2009 at 09:33:37

    If the hinges are bent do you actually gain the benefits of a larger baffle? Does the driver see around the corner of the piano hinge? I experimented with this a little and subjectively found unless the baffle was opened up completely or nearly completely there were no sonic benefits i could hear when the 'wings' were folded back.
    
    Truly,
    Godzilla
    

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• Welcome to the Club! - Gerry E. 20:34:57 10/11/09 (3)
  In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 11, 2009 at 14:45:23

  Open Baffle speakers may not be for everyone, but they are an optimal choice for many. Of course the major trade-off is bass response. However, with a bit of work, it is very possible to successfully integrate a powered subwoofer into an OB system.
  
  The only other advice I would give at this time is to experiment with the placement of your OBs, especially the distance to the wall behind them.
  
  Gerry
  

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  • RE: Welcome to the Club! - FloridaJim 22:59:25 10/12/09 (2)
    In Reply to: RE: Welcome to the Club! posted by Gerry E. on October 11, 2009 at 20:34:57

    The powered sub is my strategy. In fact, I have a pair of ACI Force XLs, but I do not know how to go about the integration. What I have done so far is just trial and error. Is there a written procedure? I was thinking that a test CD with bass at different frequencies might be useful.
    
    Thanks for the welcome.
    Jim
    

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    • Today is Your Lucky Day - Gerry E. 05:57:20 10/13/09 (1)
      In Reply to: RE: Welcome to the Club! posted by FloridaJim on October 12, 2009 at 22:59:25

      "The powered sub is my strategy. In fact, I have a pair of ACI Force XLs, but I do not know how to go about the integration."

      I also use an ACI Force! Original version, not the XL. I actually started out with a pair, but discovered that one was sufficient for my purposes.

      You will need to purchase two items that will cost about $75 total. The Radio Shack Sound Level Meter (go for the digital version, it's easier to use) and the Rives Audio Test CD #2 (see the link below).

      Just follow the instructions that comes with the test CD and you will be able to fine tune your subs to near perfection. Using these tools, I ended up lowering the subs level, but increasing the crossover frequency to get flat response.

      Gerry

      • Rives Audio Test CD #2   (Open in New Window)

      
      

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      Edits: 10/13/09

      • RE: Today is Your Lucky Day - FloridaJim 06:19:21 10/13/09 (0)
        In Reply to: RE: Today is Your Lucky Day posted by Gerry E. on October 13, 2009 at 05:57:20

        Good news. I will give it a try.
        
        Thx and best regards,
        
        Jim
        

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• RE: Just Completed My First Open Baffle - Very Pleased - chopper87@aol.com 16:20:00 10/11/09 (0)
  In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 11, 2009 at 14:45:23

  Jim,
  
  You are in for a fun ride.
  

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• RE: Just Completed My First Open Baffle - Very Pleased - Wendell Narrod 16:17:13 10/11/09 (1)
  In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 11, 2009 at 14:45:23

  How about some pictures? It would be fun to check out your handiwork.
  
  
  -Wendell
  
  

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  • RE: Just Completed My First Open Baffle - Very Pleased - FloridaJim 16:20:29 10/21/09 (0)
    In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by Wendell Narrod on October 11, 2009 at 16:17:13

    
    
    

    
    Here U go.
    

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• RE: Just Completed My First Open Baffle - Very Pleased - somejoe 15:07:33 10/11/09 (1)
  In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by FloridaJim on October 11, 2009 at 14:45:23

  Jim,
  
  I have not heard open baffles yet. Whereabouts in FL are you?
  
  TIA,
  
  
  

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  • RE: Just Completed My First Open Baffle - Very Pleased - FloridaJim 22:51:02 10/12/09 (0)
    In Reply to: RE: Just Completed My First Open Baffle - Very Pleased posted by somejoe on October 11, 2009 at 15:07:33

    Hollywood
    

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