http://theproaudiofiles.com // A video on analyzing stereo imaging effects.
More Analyzing Effects videos: http://bit.ly/analyzingeffects
Hey, guys. This is Eric Tarr for theproaudiofiles.com.
I’ve been working through a series of videos where I’m demonstrating techniques that you can use to analyze your audio effects plug-ins.
I’ve already worked through several different categories of audio effects, and that brings me to a group of effects that I’ll put together under the type of stereo image effects. These could be things related to mid/side processing, and also get into things that have the perceptual effect of stereo image widening, or narrowing.
In my first video, what I’m going to do is take you through my basic setup for my demonstration, and also get into some mid/side processing. In my second video then, I’m going to build off of these ideas and show you some of the cool things – mysterious things about stereo image effects. I’ll talk about some of the similarities and differences between a couple of different ones.
Next, let me take you through the basic setup of what I’m working with. It might seem a little bit confusing or unconventional at first, but I hope that it’ll make sense after I take you through it.
I’m going to be using a bunch of different test tones that I will send through these stereo image effects to analyze how they work. So, I started out by creating five different auxiliary tracks here in Pro Tools, and then inserted the signal generator plug-in.
I’m generating five different test tones, starting with 100Hz, 250Hz, 500Hz, 1,000Hz, and 2,000. Also, they all have the same exact relative amplitude of -12dB. The reason for this is I really just want some tones that are spread out across the frequency spectrum that I can use to analyze.
So after I’ve generated those tones, I bussed them from these auxiliary tracks, and printed them onto mono audio tracks. That way, each time that I send this signal through my stereo image effects, I know that the exact same signal, with the exact same amplitude and phase is going through the audio effect.
So, I’m going to go ahead and get rid of these, so they’re not confusing to you. So now, I’ve got five different audio tracks, each with a different test tone going through it.
Next, what I’ve done, is I’ve panned these at specific places across the stereo image. So for my lowest tone at 100Hz, I’ve panned it all the way over to 100% to the left. Then at 250Hz, I’ve got it panned to 50% to the left. 500 is panned to the center, 1,000 here over to 50% to the right, then 2,000 all the way over to 100% to the right.
The reason for this is that I’m going to take advantage of a frequency spectrum analyzer, and that’s – I’m going to use here the iZotope Insight plug-in. What I can do here is use the frequency decomposition from this plug-in to look at the relative amplitude of these tones on a left channel, and a right channel.
So, I’ve got these panned over here, then I’ve bussed them over to this stereo auxiliary track, where I’m going to be using a bunch of different stereo image effects. Then, after this, I buss this stereo effect out to two mono auxiliary tracks.
That way, I can insert the Insight plug-in here on the left channel and look at what information is contained in the left channel, after the effect, what frequencies show up, and what are their relative amplitudes, indicating the relative amplitude for something that’s panned all the way over here to 100 to the left, 50 to the left, something in the center, something over here 50% to the right, and then actually something that’s panned over here to 100% to the right, doesn’t show up on my left channel, but it does show up over here on my right channel.
So I’m just using the frequency decomposition in these relative frequency of these tones so that I can look at amplitude whenever I adjust them by using stereo image effects.
So, that’s the basic setup. I can even – you can hear these things. They’re being played back right now.
[sine waves play]
But hearing them is actually not very important. Main thing is just to visualize what’s taking place.
So, right now this is the basic setup where I’ve got these panned to different locations. This analyzer on the top is for the left channel, the amplitude of these tones at different locations when they’re panned for the left channel, and this is the one for the right channel.
Okay. So, next up, let’s get into some mid/side processing. All of this should make sense at this point. I’ve got a left channel and a right channel.
Let’s talk about mid/side processing, though, because there are some things to understand that might seem a little bit confusing. I’m going to go ahead and pull up this plug-in from Waves.