From: phil_a@tpg.com.au   
      
   "John L Stewart"   
      
   **  DO  NOT  SNIP  THE  CONTEXT   !!!!!!!   
      
   > Over in thread IBM 1953 Phil said-   
      
   ** No fucking way did I post ANYTHING  in that tread !!!   
      
   Now:  RESTORING  the ESSENTIAL CONTEXT !!!   
      
   "  Did an Impedance Plot for the speaker. I need to get me a white & pink   
    noise source. Would make that kind of measurement easier. "   
      
      
   >> ** How so ??   
   >   
   >> Impedance plots are best done with a slow sine wave sweep while feeding   
   >> the speaker from a high impedance ( 600ohms plus) source.   
   >   
   >   
   > PV Speaker Test Hookup   
   >   
   > For the speaker impedance test run I used an HP 200CD (600 ohm) as the   
   > audio source. Connected that thru a Hammond 1700 Series OPT so that   
   > there was a conversion from 2500 ohms to 16 ohms. Then another 150R   
   > straight into the 16 ohm box, much as Phil suggested.   
   >   
   > All done with the speaker box outside (open field) in order to avoid   
   > reflections. Can't afford & don't need an anechoic chamber, long as it   
   > don't rain.   
   >   
   > The results were stored with the Pico Technology ADC216 Virtual   
   > Instrument set to Peak mode. Very time consuming.   
      
      
   ** Huh ??   
      
   Impedance curves for a woofer (with no box) or guitar speaker take about 2   
   minutes using only an audio generator and a scope.   
      
   There is a single impedance peak at resonance and a broad dip around 150 to   
   400Hz  -  then it climbs doubling for every two octaves.  Plot about a dozen   
   spots and you have it.   
      
      
   > I think with a good   
   > audio noise source one could set up the equipment & let it run to   
   > completion.   
      
      
   ** I still see no sign of an explanation of what the fuck you are on about.   
      
      Wot a tedious wanker.   
      
      
   ...   Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)