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AW: [Doepfer_a100] Really low A-118 (noise) signal level.

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  • ddoepfer
    ... Since end of 2011 the A-118 is equipped with a trimming potentiometer (P5) to compensate the level tolerances of the noise transistor. Until then the noise
    Message 1 of 3 , Sep 17 1:10 AM
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      > The signal-level of my A-118 is really low. About -1V -> +1V (in
      > contrast to the A-110s which have -5V -> +5V). I don't think
      > this has always been the case.
      >
      >
      > There is no trim-pot for output signal level (or anything) on the
      > A-118PCB. Is there a resistor that can be changed out to
      > increase the output?
      >
      >
      > Thanks,
      > Paul McLean
      > Denver/San Jose, USA

      Since end of 2011 the A-118 is equipped with a trimming potentiometer (P5)
      to compensate the level tolerances of the noise transistor. Until then the
      noise transistors were selected to obtain at least 5Vpp level. If the level
      is only 2Vpp probably the transistor may have changed it's noise behaviour
      over the time (and your message implies that the module had earlier a higher
      level). I see two solutions: increase the amplification of the internal
      amplifier by decreasing the value of R3 or replace the noise transistor Q1.
      Contact me directly for the position of R3 (hardware@...). There are
      four different pcb versions of the A-118 with different positions of R3.

      Best wishes
      Dieter Doepfer
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