XPost: sci.electronics.basics   
      
   On Sat, 19 Nov 2011 18:23:36 GMT, spam@spam.com (Don Pearce) wrote:   
      
   >On Sat, 19 Nov 2011 12:17:35 -0600, "krw@att.bizzzzzzzzzzzz"   
   > wrote:   
   >   
   >>On Sat, 19 Nov 2011 10:16:43 GMT, spam@spam.com (Don Pearce) wrote:   
   >>   
   >>>On Sat, 19 Nov 2011 20:22:43 +1100, "Trevor"  wrote:   
   >>>   
   >>>>   
   >>>>"Don Pearce"  wrote in message   
   >>>>news:4ec76c21.174471@news.eternal-september.org...   
   >>>>> On Fri, 18 Nov 2011 13:51:37 -0800 (PST), RichD   
   >>>>>  wrote:   
   >>>>>   
   >>>>>>What's the difference between reverb, echo,  and feedback?   
   >>>>>   
   >>>>> Echo is a single reflection of a sound - the kind you hear when you   
   >>>>> shout "Hello" near a cliff.   
   >>>>   
   >>>>Multiple reflections are also common in such instances.   
   >>>>   
   >>>   
   >>>No they are not. One cliff, one echo. No choice.   
   >>   
   >>Two walls of said cliff; multiple echoes.  If you're on the edge of the cliff   
   >>with no opposing wall there will be zero echo.   
   >>   
   >Since when does one cliff have two walls? The cliff IS the wall.   
      
   Zero intelligence.   
      
   >>>>> Feedback is a situation you only get when you have an amplifier and a   
   >>>>> speaker. The sound arriving from the speaker is a little louder than   
   >>>>> the one that originally hit the microphone, so that comes out of the   
   >>>>> speaker a little louder still. This loop will build until the system   
   >>>>> howls.   
   >>>>   
   >>>>That would be *acoustic feedback* only, There are MANY other types of   
   >>>>course.   
   >>>>   
   >>>In the context of the question it would simply be confusing to discuss   
   >>>- or even mention - other kinds.   
   >>>>   
   >>>>>You cure it by turning down the amplifier so the sound from the   
   >>>>> speaker is always a little softer than the original when it hits the   
   >>>>> microphone.   
   >>>>   
   >>>>Or any other method that reduces the loop gain at the feedback frequency,   
   >>>>notch filtering being a common example.   
   >>>>   
   >>>   
   >>>Again, given the question, no need to complicate the answer.   
   >>   
   >>But you found it necessary to bring up loop gain.  Interesting.  You wouldn't   
   >>be an audiophool, by chance?   
   >   
   >Loop gain greater than unity is what causes feedback howl. There is no   
   >way of avoiding it if you want to explain what causes the feedback.   
      
   Wrong.  *Regenerative* feedback needs a gain > unity.   
      
   >And make no mistake, the feedback the OP was asking about was the loud   
   >howl you get when you turn the PA up too far.   
      
   You can't even keep *your* terms straight.  You *must* be an audiophool (lack   
   of an answer speaks volumes).   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)