Assign output won't go down to zero when assigned to Mod Wheel

  1. #1 by Andy Butler on 08-13-2018
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    Posts: 28

    Assign output won't go down to zero when assigned to Mod Wheel

    Here's problem.
    Assign output is set to Mod Wheel.
    With Mod wheel at min voltage is 0.09 V
    In order to close ATT1 (by patching to ATT1CV) it needs to go down to 0V.

    So any ATT1 Input (typically LFO for vibrato) always breaks through.

    Two other users have reported this issue. One of them also measured Voltage as 0.9V.

    My firmware is 1.2.5
    I've done the calibration....not solved problem.

    Please any other users with same problem post your voltage and firmware no.

    I've an idea that might fix....but want to see if Behringer respond before trying.
  2. #2 by Michael Lapke on 08-15-2018
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    Posts: 1,750
    Hi Andy,

    So I checked with our product developers on this for you, and here's what they're telling me in regards to your question.

    What you are describing here originates from a small DC offset on the output of the op-amps, which of course are all hardware so adjusting/changing it with a firmware update is not possible Im afraid.

    That being said, the suggestion for a way to get around it is to use Att2 to attenuate whatever signal youre interested in (assuming the ASSIGN out is used as the Att1 CV) before putting it through Att1. When using the Assign Out to control the LFO depth for vibrato and similar effects this works very well by letting you set the maximum LFO depth before its put through Attenuator 1, where the small offset wont let you fully close the attenuator.

    Hoping it's a solution that works for you.

    Michael Lapke
    Specialist, Community
    MUSIC Tribe
    BEHRINGER
  3. #3 by Stephen Scott on 08-16-2018
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    Posts: 10
    I'm on ver 1.2.5, using Arturia Keystep as controller.

    Getting 0.08V at minimum (5.09V at maximum fwiw). I've done the calibration.

    Michael, running the LFO through Att2, then into Att1 does work for me, but this obviously effectively 'wastes' one of the attenuators, so limits further patching possibilities.

    It really is not acceptable to make using the mod wheel (or aftertouch - same problem) so difficult for a very commonly used function. I too would like to see this problem resolved asap.

    How about putting a capacitor across a patch lead to remove the DC voltage. Would that help?
  4. #4 by Andy Butler on 08-17-2018
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    Posts: 28

    DC Offset

    Hi Michael,
    I've been talking to a tech support person who told me he'd passed this on to development and that they were working on it!
    Hence I didn't think to check back here until now.

    Thanks very much for your comments.

    So it's a DC Offset on an op amp output?
    Well I don't have the schematic in front of me, so bare with me if I'm talking rubbish
    but
    ...doesn't quite make sense, the calibration would be able to fix a DC offset,
    I've tried that and it doesn't work. Took the calibration points down from their 1V & 4V levels to 0.9V and 3.9V respectively. Resulted in no change in that 0.09V base level.

    Nope, for some reason that voltage can't get down to zero, and yes I guess it's hardware, but DC Offset is something different. Weird because the LFO's DAC can go negative with no problem.

    Using ATT2 isn't any kind of solution I'm afraid, it lessens the problem, but you still get some breakthrough. Indeed, that's exactly what I was doing when I first encountered the problem.

    Stephen, afraid this won't be solved with a capacitor, that'll block the whole signal.

    Anyway, if Behringer says no fix then it's time to move on....where's my soldering iron?
  5. #5 by Michael Lapke on 08-17-2018
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    Posts: 1,750
    - Stephen Scott wrote View Post
    I'm on ver 1.2.5, using Arturia Keystep as controller.

    Getting 0.08V at minimum (5.09V at maximum fwiw). I've done the calibration.

    Michael, running the LFO through Att2, then into Att1 does work for me, but this obviously effectively 'wastes' one of the attenuators, so limits further patching possibilities.

    It really is not acceptable to make using the mod wheel (or aftertouch - same problem) so difficult for a very commonly used function. I too would like to see this problem resolved asap.

    How about putting a capacitor across a patch lead to remove the DC voltage. Would that help?
    It was relayed to me that using a capacitor to AC couple the Assign out for removing the DC offset (if we understand your question) is not an appropriate fix unfortunately. This would effectively filter out DC, but the Assign out is used to generate DC control voltages so we don’t want to filter them out.

    - Andy Butler wrote View Post
    Hi Michael,
    I've been talking to a tech support person who told me he'd passed this on to development and that they were working on it!
    Hence I didn't think to check back here until now.

    Thanks very much for your comments.

    So it's a DC Offset on an op amp output?
    Well I don't have the schematic in front of me, so bare with me if I'm talking rubbish
    but
    ...doesn't quite make sense, the calibration would be able to fix a DC offset,
    I've tried that and it doesn't work. Took the calibration points down from their 1V & 4V levels to 0.9V and 3.9V respectively. Resulted in no change in that 0.09V base level.

    Nope, for some reason that voltage can't get down to zero, and yes I guess it's hardware, but DC Offset is something different. Weird because the LFO's DAC can go negative with no problem.

    Using ATT2 isn't any kind of solution I'm afraid, it lessens the problem, but you still get some breakthrough. Indeed, that's exactly what I was doing when I first encountered the problem.

    Stephen, afraid this won't be solved with a capacitor, that'll block the whole signal.

    Anyway, if Behringer says no fix then it's time to move on....where's my soldering iron?
    The developers sent me another message today stating that they are looking at finding an alternate option that could allow users to potentially lower the DC offset in step increments even further. (via a future firmware update) They reiterate that the bleed would ultimately still be present, but might potentially be able to be reduced to a level that works better for users in this kind of situation.

    We appreciate everyone's patience while our developers take the time to look into finding a way to improve this on Neutron.

    Michael Lapke
    Specialist, Community
    MUSIC Tribe
    BEHRINGER
  6. #6 by Andy Butler on 4 Weeks Ago
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    Posts: 28
    Currently waiting for tech support to send some files they promised.


    Meanwhile a hardware solution is to make a special patch cable with a diode in series. Any silicon diode should do. (well you can try *any* diode, but some I found didn't drop the voltage enough.).

    Using the new patch cable for ASSIGN to ATT1 CV will allow ATT1 to shut down completely.
    If ATT1 won't open at all swap the jacks...patch cable is unidirectional.