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Re: A-132-3 attenuation at 0V

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  • selfoscillate
    hello monroe, i think with all knobs fully ccw the a132/3 closes completely, so there is no signal coming through. at least that is my impression when i m
    Message 1 of 5 , Jan 7, 2011
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      hello monroe,

      i think with all knobs fully ccw the a132/3
      closes completely, so there is no signal coming through.
      at least that is my impression when i'm using mine.

      best wishes

      ingo



      --- In Doepfer_a100@yahoogroups.com, Monroe Eskew <monroe.eskew@...> wrote:
      >
      > Hello,
      >
      > Curious about the new version of A-132-3. On the page for the A-132-4 it
      > says that at 0V it only attenuates -60db. Is this true for the 132-3 as
      > well, or is there negative offset built into the pc board?
      >
      > Thanks,
      > Monroe
      >
      >
      > [Non-text portions of this message have been removed]
      >
    • Monroe Eskew
      Are there any trimpots on the board of the SSM version? Thanks, Monroe ... [Non-text portions of this message have been removed]
      Message 2 of 5 , Jan 7, 2011
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        Are there any trimpots on the board of the SSM version?

        Thanks,
        Monroe

        On Fri, Jan 7, 2011 at 4:01 AM, selfoscillate <synaptic_music@...>wrote:

        >
        >
        >
        > hello monroe,
        >
        > i think with all knobs fully ccw the a132/3
        > closes completely, so there is no signal coming through.
        > at least that is my impression when i'm using mine.
        >
        > best wishes
        >
        > ingo
        >
        >
        > --- In Doepfer_a100@yahoogroups.com <Doepfer_a100%40yahoogroups.com>,
        > Monroe Eskew <monroe.eskew@...> wrote:
        > >
        > > Hello,
        > >
        > > Curious about the new version of A-132-3. On the page for the A-132-4 it
        > > says that at 0V it only attenuates -60db. Is this true for the 132-3 as
        > > well, or is there negative offset built into the pc board?
        > >
        > > Thanks,
        > > Monroe
        > >
        > >
        > > [Non-text portions of this message have been removed]
        > >
        >
        >
        >


        [Non-text portions of this message have been removed]
      • yahoo@doepfer.de
        ... It s different for the linear and exponential mode. In the linear mode the max. attenuation is much less than -60dB. In the exponential mode one never
        Message 3 of 5 , Jan 10, 2011
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          > Hello,
          >
          > Curious about the new version of A-132-3. On the page for the A-132-4 it
          > says that at 0V it only attenuates -60db. Is this true for the 132-3 as
          > well, or is there negative offset built into the pc board?
          >
          > Thanks,
          > Monroe

          It's different for the linear and exponential mode. In the linear mode the
          max. attenuation is much less than -60dB. In the exponential mode one never
          reaches -00 dB (infinite) in theory as in the exponential mode a certain
          voltage difference corresponds to an attenuation in dB (e.g. -10dB/V or
          20dB/V). In reality of course the signal disappears in the noise floor if
          the attenuation exceeds a certain value. We tried and discussed several
          control scales for the exponential mode of the new SSM2164 based VCAs. If
          the control scale is flat (e.g. -10dB/V) one obtains a smooth attenuation
          but the min. attentuation is limited unless a negative voltage is applied.
          If the control scale is steeper (e.g. -20dB/V) a min. attenuation close to
          zero is reached (e.g. -100dB for 5V range). But in this case the attenuation
          comes very fast (-20dB or 1/10 at 80% of full scale, -40dB or 1/100 at
          60%, -60dB or 1/1000 at 40%, -80dB or 1/10000 at 20%). So one has to find a
          compromise between min. attenuation and control scale. The new exponential
          VCAs (A-132-3 in exp. mode and A-132-4) have about -12V/dB which is a good
          compromise from our point of view. But it would be possible to change the
          scale by changing some resistors on board.

          Best wishes
          Dieter Doepfer
          (Back from holiday)
        • yahoo@doepfer.de
          ... No Best wishes Dieter Doepfer
          Message 4 of 5 , Jan 10, 2011
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            > Are there any trimpots on the board of the SSM version?

            No

            Best wishes
            Dieter Doepfer
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