From: liz@poppyrecords.invalid.invalid   
      
   Cursitor Doom  wrote:   
      
   > On Sat, 10 Jan 2026 18:12:35 +0000, liz@poppyrecords.invalid.invalid   
   > (Liz Tuddenham) wrote:   
   >   
   > >Cursitor Doom  wrote:   
   > >   
   > >> Hi all,   
   > >>   
   > >>  I've identified an issue with my Uher tape recorder and I'd like your   
   > >> opinion. There's a problem with the audio amplifier chain. I've   
   > >> eliminated all other possible causes like dirty heads or faulty tape   
   > >> etc etc. So when I'm listening to playback, the quality is frequently   
   > >> varying from 'pretty good' to 'really quite crappy'   
   > >   
   > >Does it become good and bad at the same places each time you play the   
   > >same tape?  If it does, the problen is in the recording.   
   >   
   > Yes it does. But that recording still had to be processed through the   
   > amp chain.   
      
   I can't follow your logic.  If the tape sounds good in some places and   
   distorted in others - and these are the the same places each time you   
   play it - the fault is clearly something to do with the tape and not the   
   amplifier.   
      
   Turn down the volume and listen carefully to the tape transport - is it   
   squealing during the distorted passages?  Does the tape each side of the   
   head block appear to be running normally or is it shuddering because of   
   patches of sticky-shed?  Rest your finger gently on the feed spool and   
   feel for any vibration, then try gently putting a bit of load on it   
   until the tape slows down a fraction.  If it is unduly sensitive to the   
   load test or stops dead with little pressure, there is some sticky gunge   
   lurking somewhere you haven't looked yet.   
      
   [...]   
   > >> in your considered opinion, is the most likely cause of this problem   
   > >> and how would you go about identifying the culprit? Distorted output's   
   > >> a lot trickier than a break in the signal path to track down!   
   > >   
   > >Make a probe to feed the signal into on a high-impedance, high-gain   
   > >amplifier and trace the signal through the machine.  Is it diistorted at   
   > >the playback head?  At the volume control?  At the line-level output?   
   > >At the loudspeaker terminals (you could have a damaged loudspeaker)?   
   >   
   > A scope would function in such a role just the same AFAICS., would it   
   > not?   
      
   Depending on the type of distortion, it might be quite difficult to see   
   on a 'scope but very obvious to hear through an amplifier.  On a 'scope,   
   distortion of 10% on a sinewave will show up if you know what you are   
   looking for -  but on complex programme material even 30%  may not be   
   detectable on a 'scope trace.  On a listening test,  as little as 2% is   
   detectable on sinewaves and 'clean' programme material - but with   
   material that has been distorted for 'musical' effect, all bets are off.   
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
   --- SoupGate-Win32 v1.05   
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