High Efficiency Speaker Asylum

Posted by Timbo in Oz (A) on August 30, 2007 at 21:39:10

I used a big&wide block-board thick door 35mm thick, and two more layers of 18/19mm MDF that I scrounged! About 17 litres added to the original 5 to 6 litres.

I can make each about 5.7cm's higher still, giving me about 12.5 more litres! IE 60 litres! (The circular holes are about 53 cm's across R being 26.5cm, 2206 cm2, times 5.7. I'd definitely be tuning this to ~20hz or 2/3 the average Fs of 30hz.) Approximately an EBS alignment!

The ports in the spheres are glued in, and would be very hard to remove, so I'm going to stuff the ones in the sphere that will face down into the plinth (becoming part of the bass-only enclosure). I'll put plastic mesh on each end, too.

I can buy 6.6cm i.d. extend-able ports to ~27cm's - the extension's i.d. is probably 7cms. This would fit with room to spare, in the existing 47l encl, plinth plus sphere.

So, ... roughly how long would I need - to start out my testing - for 25hz Fb in 47litres and 20 hz in 60 litres, with one of these. With the sphere sitting on on top - all I have to do - is lift IT up, and off the plinth part, and adjust the port length, and measure, and listen, again!
IT weighs 70 pounds or so!

And, is 6.6 cms enough to avoid air speed problems inside the port in a box this size!?

The next size up in extend-able ports is 8.5 (and 9cm) i.d, to 32cms long - or even more 9cm plumbing pipe!

I estimate there is about 40 cm's port length (interior height less a bit) available now, plus 4 or so more if I do go bigger/higher with the plinth.

TIA





















Warmest

Timbo in Oz
The Skyptical Mensurer and Audio Scrounger

And gladly would he learn and gladly teach - Chaucer. ;-)!

'Still not saluting.'

http://www.theanalogdept.com/tim_bailey.htm

• Don't worry! I now have the TS pars - Timbo in Oz 14:28:50 09/02/07 (2)
  In Reply to: RE: Ping GM! the Vb of the combined sphere and plinth is now about 47-48 litres posted by Timbo in Oz on August 30, 2007 at 21:39:10

  and thanks for the help!
  
  It seems a 60 litre box tuned to just below Fs is a classic EBS alignment.
  
  Even with only 6b of room gain, I should be fine.
  
  
  Warmest

  Timbo in Oz
  The Skyptical Mensurer and Audio Scrounger

  And gladly would he learn and gladly teach - Chaucer. ;-)!

  'Still not saluting.'

  http://www.theanalogdept.com/tim_bailey.htm
  
  

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  • RE: Don't worry! I now have the TS pars - GM 08:41:51 09/04/07 (1)
    In Reply to: RE: Don't worry! I now have the TS pars posted by Timbo in Oz on September 02, 2007 at 14:28:50

    Greets!
    
    You're welcome!
    
    Mind sharing the specs in case I ever need them?
    
    GM
    Loud is Beautiful if it's Clean!
    
    

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    • Soon! busy at present! - Timbo in Oz 03:03:31 09/07/07 (0)
      In Reply to: RE: Don't worry! I now have the TS pars posted by GM on September 04, 2007 at 08:41:51

      more in that post!
      
      
      Warmest

      Timbo in Oz
      The Skyptical Mensurer and Audio Scrounger

      And gladly would he learn and gladly teach - Chaucer. ;-)!

      'Still not saluting.'

      http://www.theanalogdept.com/tim_bailey.htm
      
      

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