XPost: comp.sys.mac.system   
   From: burns4@nowhere.com   
      
   On 2/9/14, 7:15 PM, Salmon Egg wrote:   
   > In article ,   
   >   Alan Browne  wrote:   
   >   
   >> On 2014.02.07, 23:38 , J Burns wrote:   
   >>> On 2/7/14, 4:45 PM, Alan Browne wrote:   
   >>>> On 2014.02.05, 22:14 , J Burns wrote:   
   >>>>   
   >>>>>>   
   >>>>> I remember in 1982 plugging my headphones into a receiver at a stereo   
   >>>>> shop to compare it to my 1972 receiver at home.  I was amazed at the   
   >>>>> fidelity of the sound of running water.  This receiver used ICs for the   
   >>>>> outputs, and I guess the crossover distortion was much lower than my old   
   >>>>> receiver with discrete transistors (and simpler circuitry).   
   >>>>   
   >>>> Could be many other things including the amplification stage prior to   
   >>>> the power amps.  FWIW my old discrete H-K (1985 ish) sounds great and my   
   >>>> home theatre amp (2006 ish) in straight stereo mode (bypasses signal   
   >>>> processing) sounds just as good.  (The old H-K does start noisily - the   
   >>>> balance control seems to be noisy - but a few twists of the knob work it   
   >>>> out; also a small but noticeable channel imbalance.  Got to bring home   
   >>>> an o-scope and sort that out).   
   >>>>   
   >>>> Filtering for the crossover is typically resistors that absorbs the   
   >>>> current during crossover distortion - smoothing the output a little (the   
   >>>> voltage is low so there isn't mcuh current - still there's what looks to   
   >>>> be a pair of 25W or thereabouts resistors for each output in my home   
   >>>> theatre amp in the vicinity of the push pull transistors.   
   >>>>   
   >>>> I bought a Yamaha home theatre amp last year (really nice machine) but   
   >>>> the sound was noticeably different from the H-K.  For that and other   
   >>>> reasons I returned the Yamaha.   
   >>>>   
   >>> I don't understand the electronic and loudspeaker advances, but it   
   >>> impressed me that some speakers in 1982 could reproduce a violin better   
   >>> than speakers I'd heard in the past.   
   >>>   
   >>> Sometime after 2000, I bought a $10 MP3 player and $5 headphones.  They   
   >>> reproduced the acoustics of Bob Dylan's guitar from his coffee-house   
   >>> days better than I'd thought possible, better than a CD played on a   
   >>> full-sized stereo.  I don't understand it!   
   >>   
   >> My hearing isn't what it used to be either...   
   >   
   > Continue on alt.engineering.electrical.   
   >   
   > I think that you cannot judge fidelity of running water because there is   
   > no standard for it. Water in bathtub is going to sound different that in   
   > yours.   
      
   The sound of water running into a bathtub is like white noise.  A   
   sound-effects man could probably simulate it in different ways.  The   
   sound I heard was trickling or dripping.  It was familiar in real life,   
   but I hadn't known it could come over a radio so clearly.   
   >   
   > Resistive filters for crossover makes no sense. It is reactive   
   > components or their electronic equivalents that actually separates the   
   > bands of audio from one another. Resistive filter by itself can give   
   > equivalent signals out but no frequency response modification.   
      
   We're talking about crossing over from positive to negative in a   
   push-pull amplifier.  A feedback resistor sounds like the way to   
   mitigate it.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)