THE SETUP:
This is how all my gear is hooked up, for your reference. As the diagram shows, audio from my hardware synths is routed to mixer > audio interface > PC. With this setup, if I open Live, load and configure “External Instrument” to (a) send MIDI to my synths and (b) capture their audio, and hit keys, I hear the synths' output as expected. So far so good.
THE PROBLEM:
If I mute the MIDI track though, I still hear the synths, but at only like 50% the pre-mute volume. Even if I mute all MIDI and audio tracks and turn the master fader all the way down, I still hear this quiet audio. So there is this "ghost" audio signal in addition to the "regular" audio from Live, and I don't know where it is coming from.
THE QUESTION:
Where might this "ghost" audio signal be coming from, and how can I silence it?
SOME OBSERVATIONS:
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The "ghost" audio is there even if I only have a single track in my set, so it's not a problem of me absentmindedly double-monitoring from multiple audio tracks or something.
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Changing the audio device in Live seems to make no difference that I could tell. The "ghost" audio remained.
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If I load FX in Live and hit some keys, the audio I hear is FX-ed, as expected. But when I mute and turn all tracks down again, the "ghost" audio that I keep hearing is completely dry. This fact, along with the fact that the audio remains despite everything in Live being muted/turned down, makes me think this "ghost" audio stream isn't actually coming from/through Live at all.
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The "ghost" audio is slightly offset from the "regular" audio stream. When I hit a key, I can hear the quieter "ghost" audio like maybe 10 ms before the onset of the "regular" audio. To me, this supports the theory above that the "ghost" signal isn't coming from Live, because presumably if a signal goes into/out of Live, that takes processing time which leads to latency. By contrast, if the "ghost" audio is never passing through Live, it will hit my speakers first. This is what seems to be happening.
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Most of my synths receive MIDI over USB, so I need Live to route my controllers from my MIDI interface into these synths. But one synth has MIDI DIN, so I can send MIDI directly into it without a DAW. When I completely close Live and play this synth over MIDI DIN, I can still hear the "ghost" sound. This is the most conclusive evidence that this is not a Live issue.
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If the problem isn't Live, I thought maybe it was something with my PC's native sound card. So I right clicked the speaker icon in the taskbar, clicked "Playback Devices", and enabled/disabled devices at random, but the "ghost" audio remained. So I'm out of ideas there.
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Next, I thought maybe I was doing something dumb with my audio interface (PreSonus AudioBox USB; product site; manual. The only thing I could think was that the Mixer knob (manual p. 9) was set partially to "inputs" - this would allow through some input signal (i.e., pre-Live, zero latency, for live monitoring) in addition to the playback signal (i.e., post-Live, wet). Double checked, but knob is all the way to "playback", so that doesn't explain it either.
At this point I'm completely out of ideas for where this "ghost" audio is coming from and how to silence it. Can anybody assist me here? It's definitely P-ing me O at this point.
Submitted January 26, 2018 at 12:38PM by synthphreak https://www.reddit.com/r/edmproduction/comments/7t5ae9/troubleshooting_ghost_audio_signal/?utm_source=ifttt