From: spam@spam.com   
      
   On Sun, 3 Feb 2019 16:17:27 -0800 (PST), Phil Allison   
    wrote:   
      
   >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   
      
   This is all vital stuff. You must consider that a guitar amplifier is   
   not a reproduction device. It is an integral part of the instrument,   
   and confers a large amount of the sound of the instrument. Flat   
   response and low distortion are the last things a guitar amplifier   
   designer is looking for.   
      
   d   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)