From: info@turneraudio.com.au   
      
   In a recent post I mentioned I needed to apologize for criticizing the tone   
   stack calculator program at Duncan's amps.   
      
   Well, there is still confusion, because if I examine a stock standard Fender   
   Twin Reverb tone stack and I set the B, M and T pots at 50% rotation on the   
   amp,   
   I got +13dB at 50Hz,   
   +12dB at 100Hz,   
   0dB at 320Hz,    
   -6dB at 550Hz,    
   0dB at 1kHz,    
   +5dB 2kHz,   
   +6dB 5kHz,    
   0dB at 10kHz,   
   and the 0dB level is 2Vrms.   
      
   The response as measured seems to have a lot of bass boost, even with pots set   
   in mid position.     
      
   But the 50% rotation point means very different % of R in terms of the   
   fraction of total pot R between wiper and 0V.    
      
   The program does not allow to change the schematic connections from the Fender   
   arrangement. All R and C can have values changed, and pots can either be   
   linear, or log type B, or log type A.   
      
   The trouble is that if I set up the Fender schematic in the program, and set   
   all  the slide controls to 5, or 50%, this 50% does not mean 50% of the   
   resistance of the pot.    
   So the program designer does not allow examination of the actual pot setting   
   resistance and when changing pot settings on amp for the maximum signal   
   response flatness, and then comparing with the program, response is very   
   different.    
      
   So, I have to endorse what I originally said :- that Duncan's program has   
   severe limitations, so don't believe all you simulate, you NEED to test the   
   built circuit.   
      
   Then I tried to use the program called TINA, version Version 9.3.50.40 SF-TI   
   which was a free download. OK, its easy to use to invent a circuit and set the   
   actual pot values after measuring pot properties in an amp.   
   BUT, the free version only saves the work you do in the program and if you try   
   to save it elsewhere such as in my audio-technical/guitar-amps folder, then   
   you can't open it even using TINA. The files are .tdr, and if you try to   
   download a program to open    
   .tdr files, beware, there's malware that stops you using the PC once you get   
   so far along, and then you are forced to remove the program and then shut down   
   PC, but PC continues to remove it, and not shut down, but then PC continues   
   after removing TINA.    
   So. Basic free version of TINA isn't much good if you want to store the files   
   elsewhere than in the TINA program.   
      
   I may seem overly critical but when I analyze with a simulator, I MUST get   
   answers with simulation which are equal to what I measure, and the simulation   
   program must allow me to set or confirm ALL values, so what is on the   
   schematic IS EQUAL to how I    
   have set the amp under test.   
      
   So, I'm still not happy, things don't gel, and more time must be spent with   
   soldering iron and CRO.   
      
   My -4.7 cents worth, Patrick Turner.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)