TM-30 Pro: Procedura guidata di feedback

Let’s face it. Feedback is annoying – for you, AND your audience.

But if you’ve got a loudspeaker, a microphone, an acoustic path between the two and enough gain, eventually you’re going to get feedback.

The trick is to set up your system so the gain you need for the performance is below the "threshold of feedback".

We refer to this as a “stable” system.

The TouchMix-30 has a remarkable Feedback Wizard that can help manage any feedback …

… but before we look at that, let’s review some best practice ideas to mitigate feedback in your setup.

Selection and placement of loudspeakers and microphones, room acoustics, and the performer’s microphone handling technique …

… can all contribute to how likely it is that feedback will happen.

Here are a few tips to deal with these factors:

First, the Main PA loudspeakers should be forward of the microphones.

The vocal stage monitors should usually have low-frequencies below 100 Hz rolled off, and should be aimed at the performer’s ear level.

As for the microphones, try to keep the microphone pointed away from monitors.

And try to avoid cupping the head of the microphone with your hands, as this can cause feedback as well.

When EQing the mics, use a high-pass filters on everything that doesn’t actually have desirable low-frequency content.

Finally, be aware that if the stage has a rear wall with a hard, reflective surface, this might contribute to feedback.

Also, avoid using excessive EQ boost on input channels or outputs.

Let’s say you’ve done all these things right but you’ve still got a feedback problem.

That’s where the TouchMix-30’s Feedback Wizard can help.

You see, Feedback doesn’t happen all at once and at all frequencies.

It occurs at frequencies where there is a narrow peak in the response of the total system.

If we can find these frequencies and use very narrow filters, then we can get lots more gain before feedback.

In other words, our system will be stable.

So let’s take a look at how the TouchMix-30 manages feedback.

First we’ll select an output channel – it could be the Main L/R or one of the Auxiliaries.

Now let’s press the “Anti-Feedback” button.

Every output of the TouchMix-30 has a 12-band Anti-Feedback filter system.

These filters are very narrow so they don’t have much effect on the overall tonal balance.

Their purpose is to eliminate feedback. You could adjust these manually, or you could start the Feedback Wizard.

If you want to zero out all the filters before you begin, touch the “Reset” button.

Also make sure the Filters switch is set to “In”.

In order to kill feedback you actually have to cause a little bit of feedback.

Many professional engineers refer to this as “ringing out the system.”

This process will result in some brief instances of feedback that could be annoying to some, …

… which is why you should be sure to do this before the audience has entered the venue.

With that in mind, it’s time to let the Wizard work its magic.

Touch the “Feedback Wizard” button and you’ll see some instructions on preparing your system.

The Feedback Wizard automates the very same process an experienced operator would use to get maximum gain before feedback.

Read and follow these instructions, then press Start.

You’ll notice the fader will begin creeping up on its own. As the gain increases, the first feedback frequency rears its ugly head.

This window will display the frequency of the feedback and the wizard will apply a filter.

If the frequency starts “taking off” too much, the wizard will bring the fader down – just like an experienced sound engineer would.

Then the wizard will start looking for the next frequency.

For most situations you won’t need to apply all twelve filters, so feel free to exit the wizard before it uses them all.

When you do, the main fader will return to its starting position. Then you can repeat this process for the other outputs.

The Feedback Wizard will only use filters that have a cut of 0.0 dB, so the Wizard can’t change any filters that you have already set.

These filters are live and editable – so you can adjust them after they’ve been created.

You can quickly toggle a particular filter on or off by tapping its label, or you can adjust its frequency and cut individually using these knobs.

You can also increase and decrease all of the filters at once by adjusting the “Filter Depth” control, or widen the filters with the “Filter Q” control.

Here’s one more thing to know. The mixer keeps looking for feedback frequencies all the time, even after you’ve stopped the Wizard.

If it detects new feedback, it will still display the trouble frequency here, but it won’t apply a new filter unless you touch the “Manual Kill” button.

Certain sounds like a synthesizer that’s holding a single note or a sustained, feedback guitar note seem like feedback to the wizard.

So the Manual Kill button keeps you in control without notching out any of your music.

The Feedback Wizard. Just another way the TouchMix-30 Pro goes beyond mixing to give you great results.