[As designed] Exported IR from TMA out-of-phase (and 9 dB level difference)

yyz67

Fractal Fanatic
I have been trying to use a combination of TMA and IRs saved from TMAs and occasionally get what seemed to be large cancellation, sometimes between the TMA and an IR from a TMA or between two IRs from different TMAs. I have confirmed on FW 8.00 that if I export an IR from a TMA and then put them in parallel, there is a clear cancellation (large drop in volume, though not perfect cancellation).

As has been noted by others, exported IRs are quieter than the TMA itself, and it appears that increasing the level of the saved IR by 9 dB (whether in an IR Player or CAB) brings them to the same level. I don't know if this is a bug or by design. Using the same 9 dB boosted IR (via IRP or CAB block) in parallel largely cancels the TMA.

Attached preset and IR used (FW 8.00):
Scene 1 - Original tone match​
Scene 2 - IRP using the saved IR from the TM (+9 dB)​
Scene 3 - CAB using the saved IR from the TM (+9 dB)​
Scene 4 - TMA and IRP in parallel demonstrating cancellation​
Scene 5 - TMA and CAB in parallel demonstrating cancellation​


Here's a recording stepping through the 5 scenes:

 

Attachments

  • TMA vs saved IR out of phase.syx
    48.2 KB · Views: 3
  • TM 8.00 Limelight wCab 730.syx
    10.1 KB · Views: 2
The Cab and IR Player blocks automatically "phase correct" IRs so that the peak signal is positive. A Tone Match may have the peak signal negative. When putting them in parallel this will lead to cancellation.
 
@FractalAudio thanks, I think that makes sense. I have also had an out-of-phase issue with two IRs saved from different TMs, thus being able to use multiple TMs (as TMAs and/or as IRs) seems to be a bit luck of the draw?

Would it be possible (and would you be willing) to implement a "phase correct" (or "phase invert") on/off switch either in the TMA or IR/CAB or both?
 
For now I came up with a workaround which eliminates cancellation: place a NULL Filter with phase=inverted inline with the TMA. New preset attached.
 

Attachments

  • TMA vs saved IR out of phase(2).syx
    48.2 KB · Views: 3
  • TM 8.00 Limelight wCab 730.syx
    10.1 KB · Views: 4
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