Pro Audio Files

How to Enhance a Mix with Sound Radix Pi


Hey, folks. Matthew Weiss here —,, and of course,

What I’m going to show you right now is a product from a company that I think is probably the most forward thinking in terms of audio digital processing. They really have conceptualized what the digital world can do in the realm of audio for its full capacity. Things that go further than what analog could ever do.

One of their flagship products is called Pi. Pi is an automated phase rotater, so I’ll break down what that is in a second, but first, I’m going to show you what it does.
So, this is without it.


And here’s with.

[music with Pi]

So, the difference is fairly subtle. However, I think that it is noticeable, and you can feel it. It’s sort of like when you flip it on, everything just kind of comes to life. In a very subtle way, but in a sort of profoundly awesome way. What it’s doing is when you have a whole bunch of overlapping frequencies, it’s very easy for things to become slightly out of phase in the way that they combine; when they sum.

So, what Pi is doing is essentially doing the work of the most brilliant summing mixer in the world that can also change time, and getting that fundamental frequency stuff aligned as closely as possible.

So, now I’m going to break down how I use it. In a mix, I will generally put it on every channel, and I will mix through it, so that’s generally the first thing that I’m doing after I use one of their other products, which is Auto-Align, which is a great product as well, and I’ll talk about that in another video.

Then, I will set the groupings for what makes sense. So, for phase coherent material, like a multi-faceted phase coherent material like drums, for example, I’ll assign that all to it’s own group, and I’ll assign the group mix mode either to “internal exclusively,” or “internal and mix.”

Generally speaking, when I have something that’s a little bit more complicated than I’m showing you now, I’ll do internal only, but for something as simple as this, if I switch between internal and mix, you probably wouldn’t hear any difference. I don’t hear any difference, and whether or not that difference is any better or worse is pretty negligible.

So, the difference between those two modes is that when you have it set to “internal only,” it means that all of these elements are being slightly adjusted through Pi, but they’re not regarding the elements that are outside of the group, so in this case, my drums are all in one group. They’re not doing anything in regards to the bass, or the guitar, or the keys. They’re only adjusting to each other.

If I switch it to “internal and mix,” the program will prioritize the drums to work best with each other, and then readjust everything to work well with everything else, which can be very useful, and I’ll give you a quick A/B. If you have a preference, then by all means – and I suggest if you’re using it, you try it yourself, but it’s pretty subtle.

Here we go.



So, pretty much isn’t making much difference, and a big part of that is because it’s a very simple mix. There’s not a lot of elements. Those differences become slightly more noticeable when you start piling up more and more stuff.

So, this next setting here is full range mode vs. low frequency mode. I’ve only used the low frequency mode a couple of times. It’s when I’m not using Pi on the entire mix – when I’m simply just trying to get a bass and a kick to work together a little bit well, or just the low end of a mix to work together a little bit better, then I’ll switch into low frequency mode, but for everything else, I’ve been using full-range. I find that it always sounds better.

Here’s a quick before and after.


In this case, actually, low frequency mode might be preferable, just because I do feel like I get a little bit more punch in the kick, and a little bit more definition in the bass, ever so slightly.

But, if I were to bring the vocals in, I would have to reassess that again. But again, that’s splitting hairs. It’s a very subtle difference, and I don’t think it would impact the end listener too much. Generally speaking, I find that I feel that full-range mode is working better most of the time.

Okay, so, over here we have this channel weight knob. So, when you’re adjusting anything involving phase, you’re adjusting several sides of the same triangle. Phase, time, and pitch are all inherently linked together. As you change one, you have to in some way, shape, or form, readjust another. So, one thing that will sometimes happen with Pi, is that because it’s using the loudest element to be the beacon for where everything is being adjusted, like the kick drum will often times default to that in the drums scenario, you might get things like the overheads starting to get a little bit washy or something like that. They bend in pitch a little bit.

Kind of like the “wow” effect on a tape machine – like an older tape machine. So, by adjusting the channel weight, you can mitigate that if it’s showing up. Most of the time, you’re going to hear it in sustaining elements, like overhead cymbals, or most commonly, you’ll hear it in a bass guitar, because the waveshape is so long, that the adjustment becomes more noticeable.

So, that’s a pretty simple thing once you kind of hear it. Like, you hear that sort of washy-ness show up, and you go, “okay, I got to change that.” It works very well.

So then, here we have the bass, and the guitar, and the keys. They’re not in groups, because they’re sort of just their own elements. The bass DI should probably be in a group with the bass. In fact, I’m going to do that real quick. Let’s put that to group two. I’ll leave it in “internal and mix,” and now let’s hear it.


I’m going to take the DI out of this, and play it again.


I actually could hear the difference in that pretty readily. You might have to play it back a couple of times, but listen to the nose of the bass. That “ehhh” kind of range. That becomes a thicker and more concentrated sound when I throw these into a group together. I guess it’s doing a micro-adjustment, and of course, I could use Auto-Align to kind of help it out.

Yeah, so that’s basically how I set up Pi. It seems like a very complicated program when you go over the literature, but in reality, it’s actually a fairly straight-forward program. There are times when I do leave it off. Sometimes, it doesn’t – it will change things in a way, where sometimes the transient might smear a little bit, or I might want the phase interaction to not be perfect, because sometimes, that creates a sense of depth or texture that I like, but I would say about 85% of the time, things sound better with this on, and so, that’s usually a pretty strong sign that it’s a good go-to default, just to have it setup to begin with.

Alright, guys. I hope you learned something. Check these guys out. Sound Radix is awesome. I love what they’re doing, and you know, probably one of the best purchases I’ve made of the year, hands down.


Matthew Weiss

Matthew Weiss

Matthew Weiss is a Grammy nominated and Spellemann Award winning audio engineer from Philadelphia. Matthew has mixed songs for Snoop, Sonny Digital, Gorilla Zoe, Uri Caine, Dizzee Rascal, Arrested Development, 9th Wonder, !llmind & more. Get in touch:

Free Video on Mixing Low End

Download a FREE 40-minute tutorial from Matthew Weiss on mixing low end.

Powered by ConvertKit
/> /> /> /> /> /> /> /> /> />