Feedback/Input signal coming from outputs

If you're receiving feedback from your output(s), or if the input signal is playing through them, this may be caused by a mixer control either on the audio interface or within its control application. In this article, we'll discuss where to find this control and how to prevent the feedback from occurring.

Some audio interfaces may have an "input/playback" mixing knob that will switch between what signals are being sent to the outputs -- this is most commonly in a recording environment to hear what is being recorded. When performing acoustical analysis, we do not want the input signal to play back through the outputs as this can cause feedback.

Pictured above: Avid's MBox Mini -- the "Mix" knob controls whether the input or the output signal is sent to the output channels. For use within Smaart, turn the knob all the way to the right (P/B).

In most cases, you want to set your audio interface to "playback" mode. Other interfaces may use the term "direct monitor" (i.e. directly monitoring the input signal), and for these we want to make sure the setting is disabled/off.

Pictured above: Focusrite Scarlett 2i2 (Gen2) -- when using with Smaart, make sure the "Direct Monitor" switch if OFF

Lastly, some interfaces come with a built in mixer to send signals to and from different sources. The Roland Octa-Capture is a common example. 

After opening the Octa-Capture Control Panel, select the button in the upper right to switch from preamp control to the Direct Mixer. In the master output section to the right, ensure that the Input Mixer master fader is set to -INF. 

This can be performed through the display on the front panel of the unit itself, though it's typically easier to manage it through the Control App.

If issues persist, or if you're having trouble finding where to change this setting on your interface, please send an email to support@rationalacoustics.com or create a ticket using the links at the top of the page.