From: info@turneraudio.com.au   
      
   I correct a mistake I made in my last previous post about adjustable levels of   
   mids and treble in my last post. The schematic Phil sent us to view DOES HAVE   
   variable level adjustements for mid- treble units. Perhaps the mid-treble   
   parts of schematic do    
   have differences to what i found - some 7? years back, but the owner recently   
   emailed me to say how pleased he was about the sound after I totally rebuilt   
   the speakers using two lower midrange drivers supplied from AR and two   
   Peerless upper mids I    
   supplied. I cannot recall if I replaced the tweeters.   
       
   But the bass speaker part of schematic is different to what I found, and   
   because all 4 bass drivers worked OK I retained them, but used them in series.   
      
   I well remember how difficult it was to get all drivers to work properly with   
   a total of 6 slightly over damped second order filters and give a flat   
   response at 3 metres, and have an acceptable impedance curve. The trade off   
   was that the overall    
   sensitivity of the bass speakers was determined by the bass acoustic levels at   
   50-80Hz with all mids&treble set for center switch position.    
      
   I concluded that a 4 way speaker is never needed because it can be done better   
   and more easily with 3 way, from 20Hz to 20kHz, and a sub-woofer isn't needed   
   because you pick a decent bass that goes as low as subs do, and then have   
   their cut off at around    
   250Hz. The mid-treble X-over is then placed at 3kHz, and each driver thus does   
   a decade of frequencies.    
   Patrick Turner.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)