From: pallison49@gmail.com   
      
   Big Bad Bob wrote:   
      
   > >   
   > >>   
   > >> And of course a guitar amp is probably going to be designed to pass a   
   > >> more limited frequency range.  You can see that when you look at   
   > >> replacement output transformers, typically rated for 100Hz to maybe 4kHz   
   > >> as opposed to a 20Hz-20kHz range for hifi/stereo amplifiers.   
   > >>   
   > >   
   > > ** The output transformers used in tube guitar amps are normally a lot   
   better than you suggest.   
   > >   
   > > Eg:  A Marshall 50W output transformer has its upper -3dB point at 45kHz.   
   > >   
   > > The small signal, low frequency response is -3dB at 1Hz (yes, one Hertz)   
   but core saturation at rated power becomes dominant below about 5OHz.   
   > >   
   > > IME most output transformers used in brand name amps have similar specs.   
   >   
   >   
   > hmmm, that goes against what I've read over on 'amplifiedparts.com' for   
   > 'original replacement' transformers, as opposed to the ones made by   
   > Hammond (which are nearly always better).   
   >   
      
    ** Never rely on " information " posted on web sites written by musicians and   
   storekeepers.   
      
      
      
   > the DC blocking capacitors in guitar amps _are_ de-rated a bit over what   
   > you'd see in a hi fi system, last I went through one.  Tone controls are   
   > also a little strange compared to hi fi equivalents.  But it's part of   
   > "the sound" [and also costs less, which I think is what drove it].   
      
      
      
   ** Guitar amps have many differences from " hi-fi" amps, the most significant   
   of which are:   
      
   1. Low or no negative feedback around the output stage, so THD is relatively   
   high at 2 to 5% below clipping.   
      
   2. Low class AB bias, so full power operation is mainly class B exaggerating   
   point 1.   
      
   3. High output impedance, due mainly to point 1.   
      
   4. Non flat response from the tone circuits ( typically the treble end is   
   boosted ) and deliberate distortion incorporated in same.   
      
   Of course, the speakers fitted to combo amps have limited response, 70 to 4kHz   
   with a presence peak around 2 to 3 KHz being typical.   
      
   But they ARE damn efficient, up to 105dB/watt for some 12 inch models.   
      
      
   ....   Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)