21345063   
   From: IainNG@kolumbus.fi   
      
   "NX211"  wrote in message   
   news:38e42d9a-3b25-40b8-9626-a062c8f93539@w2g2000yqb.googlegroups.com...   
   On Jan 9, 4:46 pm, Stretto  wrote:   
   > I am trying to diagnose a problem with an amplifier. I was using a   
   > freq. sweep input and noticed than when I turned the gain up the I was   
   > hearing the sound. There is no speakers hooked up and the sound seems   
   > to be an exact replica. I did not try other sounds as it seems pretty   
   > obvious that something is making reproducing this sound and it is not   
   > coincidence.   
   >   
   > I guess I could make some type of acoustical amplifier to probe around   
   > the circuit to find where it is coming from but besides that is   
   > anything I should look for? Maybe this is a natural thing? I suppose   
   > there is the possibility of a resistor or cap producing the sound due   
   > to some strange effect or it could be the sum of all the minute   
   > effects from each component but most likely it is something pretty   
   > straight forward(bad tube)?   
   >   
   > Any ideas where I should start looking?   
      
   >Now - this is important to know.   
      
   >Is it singing the words or just humming?  If it's humming it probably   
   >doesn't know the words.  In that case you should start singing  a few   
   >bars and give it a chance to learn the words.  I think then it will be   
   >OK.   
      
   An old friend of mine in the UK, who used to build very fine,   
   and rather expensive tube/valve amps for an exclusive clientele, always   
   used to play the same Jethro Tull song through and amplifier that   
   had completed final test and was ready to be packed for delivery   
   to its new owner.  He even included a copy of the lyric with the amp   
   manual.  The song was "Slow Marching Band"  The lyric went   
   as follows:   
      
   "Take a hand and take a bow.   
   You played for me; that's all for now, oh, and never   
   mind the words just hum along and keep on going"   
      
   They did. In ten years that I knew him he never had an amp   
   returned for anything other than scheduled maintenance/bias checks/   
   valve replacement.   
      
   Iain   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)