TM-30 Pro: RTAs

In this video, we’re going to tell you about the TouchMix-30 Pro’s Real Time Analyzers, how they work and what you can do with them.

Let’s start by talking about what a Real Time Analyzer – or RTA – is.

An audio Real Time Analyzer breaks the audio spectrum into frequency bands – 1/3 octave bands are most typical and that’s what you’ll find on the TouchMix-30 Pro.

The RTA displays the amplitude of the signal in each frequency band so you can see, in real time, what the distribution of energy looks like.

And, of course, having an RTA display looks really cool at the mix position.

The TouchMix-30 Pro has two on-board Real-Time Analyzers.

One of these RTAs is available on any input or output EQ screen.

Simply navigate to a channel’s “EQ” tab, and touch the “RTA On” button.

When you do, you will see a display of the selected channel’s audio spectrum.

The second RTA can be displayed by pushing the RTA button to the right of the touchscreen.

This RTA offers options for source selection.

You can select the Main Left/Right signal, the signal from any Auxiliary mix

the Follow Cue (which will display whatever you have selected for the Cue buss), or the Talkback microphone input.

By selecting the Talkback input for the source, you can actually look at an RTA display of the sound in the room

using a microphone that’s plugged into the mixer’s Talkback input.

You could view both RTAs at the same time by connecting a tablet device to your TouchMix.

You could have this second screen available at the mixer, or you could take it with you as you ring out the system.

So how can you use the RTA? First, use the RTA and your ears together.

Don’t rely entirely on the RTA display. There is no “right” way that an RTA display should look.

The RTA can help you identify where a tonal imbalance or feedback ring is located on the frequency spectrum,

but it’s not a substitute for ears and good audio judgment. That said, here are some examples of how to use the RTA.

The input channel RTA is useful for working on the tone for a single source.

Let’s say you’re doing a sound check and an input – for example the bass guitar – isn’t sounding quite right.

It’s kind of “boxy” sounding but you’re not sure what to do about it.

So you watch the RTA while the bass is playing and you see that the 250 Hz band is sticking out above the other bands.

If it sticks out the most when you are also hearing the offending sounds the most, that tells you the problem is likely somewhere around 250 Hz.

Now you know where to start pulling the channel EQ.

Here’s another way to use the TouchMix-30 Pro’s RTA’s.

Let’s say that you’ve set up your system and it sounded great when you played a reference tracks.

Even the individual inputs sounded fine during sound check. But when you pull up all the faders and listen to the mix – not so much.

There’s just too much of some frequencies in the mix.

What’s happened is that multiple channels are adding together in an undesirable manner. The RTA’s can help you find and fix the problem.

Start by using the output RTA to identify where this tonal imbalance is.

Once you’ve done that, you could just adjust the output graphic EQ to get the balance you want.

But a better choice might be to find the individual channels that are contributing to this imbalance.

Let’s say that the mix sounds a bit “tubby” and the output RTA is indicating too much energy on the low end.

Note the frequencies that are over-balanced. Now go to the inputs and look for sources with a bit too much of these frequencies.

Maybe all you need to do is roll a bit of low-end off the bass and guitar channels to clean up the whole mix.

Just remember – an instrument that sounds great on its own may not blend well with other instruments.

A skilled engineer knows how to make all the instruments “sit in the mix”.

Your RTA can help you find frequency overlap problems and get your mix dialed in.

Once you’ve got your instruments balanced, you could still use the RTA to identify any tonal imbalances in the aux mixes.

Let’s say that one of the performers is complaining about a “tubby” sounding stage monitor.

Just select the performer’s output and look at what you’re sending to his wedge.

Looking at his signal you see that, yes, there’s ample low-end there and you can take some out without making the mix too thin.

Or – maybe the RTA display indicates that this monitor mix is fairly well balanced.

That could be a hint there’s something wrong with the stage monitor itself – like a blown high-frequency driver or an improperly adjusted processor.

So the RTA also can serve as a trouble-shooting tool as well.

The TouchMix-30 Pro has a powerful anti-feedback system which we cover in another video.

But, if you would prefer to handle feedback using the mixer’s 1/3 octave EQ, the RTA can help identify which EQ bands to cut.

Now, you might find yourself tempted to try balancing the system with just a noise generator, microphone and the RTA.

This isn’t recommended, because if all you do is adjust the output GEQ sliders until the RTA shows a flat response

the results with actual instruments will probably not be what you had in mind. It may look right on the screen now, but remember

your goal is to achieve a tonal balance with the real signal and ultimately, your ears will still be your guide on the mix.

The Real-Time Analyzers. Just one more way the QSC TouchMix-30 Pro goes beyond mixing to help you get great results – fast.