Twisty/Turn-y Things: Single Channel Polarity/Phase Reversal

Discussion in 'Modifications and Tweaks' started by Torq, Oct 3, 2016.

  1. cskippy

    cskippy Friend

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    Ah, the cable IS wrong. I retested today and was just looking at the pins but forgot that they MIRROR each other on the other end, and to make sure, like you said, to follow pin 1-1, 2-2, 3-4, and 4-3. So channels are reversed as well as polarity between channels. Damn. I'll get it rewired and post back.
     
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  2. Garns

    Garns Friend

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    I'm getting the bits in to try this out. What really pushed me to try it is @atomicbob's comment over in the system synergy thread that this can work with a completely single ended system.

    This probably bears repeating here for those who didn't see it. The only balanced part one actually needs is a 4-pin XLR termination to the headphone. To use with a SE headphone amp, plug the phase reversal cable into the headphone, then use a balanced to SE headphone adapter to plug the other end of the phase reversal cable into your headphone amp. Finally, reverse the phase of one channel in software and you are done.

    I will be trying this with Valhalla 2.
     
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  3. johnjen

    johnjen Friend

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    I'm always interested in reading what other people hear while using this tweak.
    For me personally I have never had it NOT make a difference, and what I find interesting is to come to know what changes, others hear as well.

    JJ
     
  4. Grahad2

    Grahad2 Friend

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    Well if you're on old 2pin IEMs then it's easier, since the connector is reversible. A simple plugin that offers L, R, and L&R invert for foobar2000, then you just flip one side of the connection on the IEM side.

    So technically you get audio path of (L invertR) from the PC all the way till the driver/crossover.
     
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  5. mrflibble

    mrflibble Almost "Made"

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    I have yet to makeup the cables and try this out yet. But I have been playing with Linux and ALSA to invert one channel, here is the relevant excerpt from my ALSA configuration:

    Code:
    # Invert one channel
    pcm.invert {
      type ladspa
      slave.pcm "plug:bit_perfect"
      path "/usr/lib/ladspa"
      channels 2
     
      plugins {
        0 {
          id 1429
          label inv
          policy none
          input.bindings.0 "Input"
          output.bindings.0 "Output"
        }
       
        1 {
          id 1181
          label amp
          policy none
          input.bindings.1 "Input"
          output.bindings.1 "Output"
          input {
            controls [ 0 ]
          }
        }
      }
    }
    
    pcm.invert_plug {
      type plug
      slave.pcm "invert"
      
      hint {
        show {
          @func refer
          name defaults.namehint.extended
        }
        description "Invert One Channel"
      }
    }
    It could probably be optimized to remove the amplification of the second channel (I haven't figured that out yet), I'm using it with a value of 0 as a dummy conversion for the other channel. The bit_perfect plug is my plug for bit perfect playback, substitute your own plugin or mixer depending on your configuration.

    The configuration utilizes the LADSPA plugins, and you will need to have these installed (probably via your package manager).
     

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