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06-15-2017, 04:43 AM
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iRig Acoustic Stage Compression Issue & Work-arounds
I've found that the output of my iRig Acoustic Stage is compressed and/or limited when the volume knob is on full. I've found that the compression/limiting can be removed by setting the volume knob at halfway (and setting the level higher at the recorder or mixer).
For those who want full use of the volume knob (without the compression or limiting issue), you can put a dummy plug in the little iRigAS preamp's AUX IN jack and set the blend knob for 11 o'clock. Keep in mind that the output level will be pretty low and you'll need to compensate at the recorder or mixer. The iRigAS's output is low to begin with, compared to active systems with a 9v power supply. These compression/limiting work-arounds make it even lower. Here are some sound samples which illustrate the problem and the work-arounds. I adjusted the recorder levels so that the signal would peak at around -4db for each sample. No samples were clipped in the recording process. https://soundcloud.com/guitaniac/iri...m-work-arounds The first sample is with a dummy plug in the AUX IN and the blend knob set at 11 o'clock, volume knob on full. The second sample is with AUX IN unused and the volume knob on full. The third sample is with the AUX IN unused and the volume knob at half-way (12 o'clock). All sound samples were normalized for the same peak volume. The second sample is noticeably compressed and the Waveform appears clipped (the Audacity waveform had an obvious buzz cut). Sample one is for the work-around needed if you want full use of the volume knob without compression. Sample three shows that leaving the volume knob at halfway appears just as effective at avoiding compression. (IMO, a preamp shouldn't work this way, but the iRig Acoustic Stage is such a good value that I'll happily overlook it and be glad that there are work-arounds.) Once again, the sample #2 waveform in Audacity had an obvious buzz cut which pointed toward limiting. The Sound Cloud waveform appears much different, but you can still see and hear that its compressed compared to the other two samples. 
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