From: mblack@pubnix.net   
      
   On Thu, 1 Nov 2018, Ralph Mowery wrote:   
      
   > In article ,   
   > default@defaulter.net says...   
   >>   
   >> Digital amps can produce large amounts of power cheaply.  They are   
   >> more akin to switching power supplies that are modulated by a music   
   >> source.   
   >>   
   >>   
   >   
   > I bought a couple of the 5 watt or so switching amps form China to play   
   > with.  Put them on a scope and it was interisting.  Instead of seeing a   
   > sine wave, it looked like a bunch of pulses.  It sounded ok to my   
   > untrained ear for voice quality.   
   >   
   >   
   I remember a 555 based class D amplifier in Elementary Electronicsi n the   
   mid-seventies.  And it relied on the speaker, and the ear, to do the   
   filtering.  So of course on a scope it would look digital, but might sound   
   'fine".   
      
   I've not paid enough attention to more serious work to know how much   
   relies on the speaker to do the filtering and how much is doen by   
   deliberate filters.   
      
      Michael   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)