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A-107 outputting noise.

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  • isoldeandisobelle
    Hi, If I take the output (without any input)from my A-107 and feed it into my A-138B mixer, a constant noise can be heard, like the sound of a noise
    Message 1 of 10 , Feb 12, 2013
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      Hi,

      If I take the output (without any input)from my A-107 and feed it into my A-138B mixer, a constant noise can be heard, like the sound of a noise generator,this is louder on some filter presets than others.
      If this signal is fed through a VCA, then the sound is, as to be expected, much louder....the sound is also there when the filter is receiving a sound source.....any suggestions, please.


      Kind regards
    • isoldeandisobelle
      ... Hi, Any help with this? I had already returned this module to my place of purchase, who passed it on to Doepfer, as it was producing the same noise
      Message 2 of 10 , Feb 13, 2013
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        --- In Doepfer_a100@yahoogroups.com, "isoldeandisobelle" wrote:
        >
        > Hi,
        >
        > If I take the output (without any input)from my A-107 and feed it into my A-138B mixer, a constant noise can be heard, like the sound of a noise generator,this is louder on some filter presets than others.
        > If this signal is fed through a VCA, then the sound is, as to be expected, much louder....the sound is also there when the filter is receiving a sound source.....any suggestions, please.
        >
        >
        > Kind regards
        >
        Hi,

        Any help with this?

        I had already returned this module to my place of purchase, who passed it on to Doepfer, as it was producing the same ''noise'' sound but also was faulty in that every filter was not operating correctly, and was kindly replaced once tested.

        Thank you
      • Florian Anwander
        Hello it is difficult to judge for us. Maybe you should post record an example on soundcloud so we can tell you whether it is normal or not. Record first the
        Message 3 of 10 , Feb 13, 2013
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          Hello

          it is difficult to judge for us. Maybe you should post record an example
          on soundcloud so we can tell you whether it is normal or not.

          Record first the filteroutput with a simple sawtooth and then (without
          changing the level) the filter-noise without any input signal.

          Florian


          On 13.02.13 19:58 , isoldeandisobelle wrote:
          >
          >
          > --- In Doepfer_a100@yahoogroups.com, "isoldeandisobelle" wrote:
          >>
          >> Hi,
          >>
          >> If I take the output (without any input)from my A-107 and feed it into my A-138B mixer, a constant noise can be heard, like the sound of a noise generator,this is louder on some filter presets than others.
          >> If this signal is fed through a VCA, then the sound is, as to be expected, much louder....the sound is also there when the filter is receiving a sound source.....any suggestions, please.
          >>
          >>
          >> Kind regards
          >>
          > Hi,
          >
          > Any help with this?
          >
          > I had already returned this module to my place of purchase, who passed it on to Doepfer, as it was producing the same ''noise'' sound but also was faulty in that every filter was not operating correctly, and was kindly replaced once tested.
          >
          > Thank you
          >
          >
          >
          > ------------------------------------
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
        • isoldeandisobelle
          ... Hi, Thank you for your reply. Here is the soundcloud link - https://soundcloud.com/isolde-and-isobelle/a-107 First with a sawtooth and then just the filter
          Message 4 of 10 , Feb 13, 2013
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            --- In Doepfer_a100@yahoogroups.com, Florian Anwander wrote:
            >
            > Hello
            >
            > it is difficult to judge for us. Maybe you should post record an example
            > on soundcloud so we can tell you whether it is normal or not.
            >
            > Record first the filteroutput with a simple sawtooth and then (without
            > changing the level) the filter-noise without any input signal.
            >
            > Florian
            >
            >
            > On 13.02.13 19:58 , isoldeandisobelle wrote:
            > >
            > >
            > > --- In Doepfer_a100@yahoogroups.com, "isoldeandisobelle" wrote:
            > >>
            > >> Hi,
            > >>
            > >> If I take the output (without any input)from my A-107 and feed it into my A-138B mixer, a constant noise can be heard, like the sound of a noise generator,this is louder on some filter presets than others.
            > >> If this signal is fed through a VCA, then the sound is, as to be expected, much louder....the sound is also there when the filter is receiving a sound source.....any suggestions, please.
            > >>
            > >>
            > >> Kind regards
            > >>
            > > Hi,
            > >
            > > Any help with this?
            > >
            > > I had already returned this module to my place of purchase, who passed it on to Doepfer, as it was producing the same ''noise'' sound but also was faulty in that every filter was not operating correctly, and was kindly replaced once tested.
            > >
            > > Thank you
            > >
            > >
            > >
            > > ------------------------------------
            > >
            > > Yahoo! Groups Links
            > >
            > >
            > >
            > >
            >
            Hi,

            Thank you for your reply.

            Here is the soundcloud link - https://soundcloud.com/isolde-and-isobelle/a-107

            First with a sawtooth and then just the filter out as I turn through the filter presets....it is also more noticeable with something like a sine.

            Best wishes
          • Florian Anwander
            ... I don t own a A_107, but I even could imagine, that this is the normal noise level at certain filtersettings. Especially if high pass filters are placed as
            Message 5 of 10 , Feb 14, 2013
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              On 13.02.13 22:17 , isoldeandisobelle wrote:
              > Here is the soundcloud link - https://soundcloud.com/isolde-and-isobelle/a-107
              >
              > First with a sawtooth and then just the filter out as I turn through the filter presets....it is also more noticeable with something like a sine.
              I don't own a A_107, but I even could imagine, that this is the normal
              noise level at certain filtersettings. Especially if high pass filters
              are placed as last part of the filteralgorithm. Dieter may jump in here.
              Perhaps the bandpasses are generated using LP->HP instead of HP->LP.

              Florian
            • isoldeandisobelle
              Well, Ok, Thank you for your reply. If you say this is a normal level for this unit, then that is fine with me, I did not want it to be a fault that became
              Message 6 of 10 , Feb 14, 2013
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                Well, Ok, Thank you for your reply.

                If you say this is a normal level for this unit, then that is fine with me, I did not want it to be a fault that became progressively louder within time.

                Best wishes to all and thanks again for your advice.
                --- In Doepfer_a100@yahoogroups.com, Florian Anwander wrote:
                >
                > On 13.02.13 22:17 , isoldeandisobelle wrote:
                > > Here is the soundcloud link - https://soundcloud.com/isolde-and-isobelle/a-107
                > >
                > > First with a sawtooth and then just the filter out as I turn through the filter presets....it is also more noticeable with something like a sine.
                > I don't own a A_107, but I even could imagine, that this is the normal
                > noise level at certain filtersettings. Especially if high pass filters
                > are placed as last part of the filteralgorithm. Dieter may jump in here.
                > Perhaps the bandpasses are generated using LP->HP instead of HP->LP.
                >
                > Florian
                >
              • Florian Anwander
                ... I don t know whether it is normal! I do not own a 107. But, I can *imagine* that it is normal.
                Message 7 of 10 , Feb 15, 2013
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                  Am 14.02.2013 18:08, schrieb isoldeandisobelle:
                  > If you say this is a normal level for this unit, then that is fine with me,
                  I don't know whether it is normal! I do not own a 107.

                  But, I can *imagine* that it is normal.
                • isoldeandisobelle
                  Thank you for your replies Florian, perhaps Dieter will have the definitive answer.
                  Message 8 of 10 , Feb 15, 2013
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                    Thank you for your replies Florian, perhaps Dieter will have the definitive answer.

                    --- In Doepfer_a100@yahoogroups.com, Florian Anwander <fanwander@...> wrote:
                    >
                    > Am 14.02.2013 18:08, schrieb isoldeandisobelle:
                    > > If you say this is a normal level for this unit, then that is fine with me,
                    > I don't know whether it is normal! I do not own a 107.
                    >
                    > But, I can *imagine* that it is normal.
                    >
                  • ddoepfer
                    ... I don t know the definitive answer but indeed the XP filter design generates a bit more noise than other filters (the A-107 is nothing but an expanded XP
                    Message 9 of 10 , Feb 15, 2013
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                      > Thank you for your replies Florian, perhaps Dieter will have the
                      > definitive answer.

                      I don't know the "definitive answer" but indeed the XP filter design
                      generates a bit more noise than other filters (the A-107 is nothing but an
                      expanded XP filter). The reason is that the original signals of the four
                      filter stages (CEM3379 filter chip) have very low levels and have to be
                      amplified by about 100 to obtain the audio level used in the A-100. This
                      causes a higher noise floor because even the noise is amplified. And in
                      addition some filter types are composed from up to 4 filter stages. This
                      increases the noise additionally. The filter types that use only one filter
                      stage (i.e. 6, 12, 18, 24 dB low pass) should be a bit less noisy because
                      for these only one of the filter stages is used.

                      But with max. audio input level (i.e. just before clipping) the noise floor
                      should cause no problems.

                      Best wishes
                      Dieter Doepfer
                    • isoldeandisobelle
                      That is definitive enough for me, thank you very much. Yes, it is not too much of a problem, as with higher inputs the noise is all but suppressed or masked
                      Message 10 of 10 , Feb 15, 2013
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                        That is definitive enough for me, thank you very much.
                        Yes, it is not too much of a problem, as with higher inputs the noise is all but suppressed or masked and with the filter types you mentioned it is not at all so bad, only in the quieter passages that I may create does it become a bit of an issue, but then I tend to just use another filter module for those parts.

                        I was only concerned that it may have been a fault that may have got progressively louder over time.....but, your answer puts that worry aside.

                        Thank you again and best wishes.
                        --- In Doepfer_a100@yahoogroups.com, <yahoo@...> wrote:
                        >
                        > > Thank you for your replies Florian, perhaps Dieter will have the
                        > > definitive answer.
                        >
                        > I don't know the "definitive answer" but indeed the XP filter design
                        > generates a bit more noise than other filters (the A-107 is nothing but an
                        > expanded XP filter). The reason is that the original signals of the four
                        > filter stages (CEM3379 filter chip) have very low levels and have to be
                        > amplified by about 100 to obtain the audio level used in the A-100. This
                        > causes a higher noise floor because even the noise is amplified. And in
                        > addition some filter types are composed from up to 4 filter stages. This
                        > increases the noise additionally. The filter types that use only one filter
                        > stage (i.e. 6, 12, 18, 24 dB low pass) should be a bit less noisy because
                        > for these only one of the filter stages is used.
                        >
                        > But with max. audio input level (i.e. just before clipping) the noise floor
                        > should cause no problems.
                        >
                        > Best wishes
                        > Dieter Doepfer
                        >
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