so why do people always recommend Linkwitz
Riley filters?
When we look at a measurement like this and make sense, right?
And we look at the sum between them and assuming that we have
the necessary polarity and version, it's beautiful, right?
It seems like a perfect result, but we should really be careful
about recommending these filters when they're used on speakers,
because the acoustic result.
Will not be the electrical result.
Nine times out of 10, it'll be something slightly different.
So what I want to talk about with you today is how you can
get started playing with filters investigating the results
and while you should probably never recommend one specific
kind of filter, unless you are fully familiar with
all of the circumstances around its implementation.
So today I'm going to be doing this demo and Crosslite,
which is definitely a piece of software that I recommend,
but you can also do this in.
Free software.
So I'm going to do this demo and Crosslite, but then at
the end, I'm also going to show you how to do it in REW.
So if you want to download REW or you already have it,
you can open that up and you can do all of these steps
along with me, just in a slightly different platform.
Okay. So learning how to use filters.
It's definitely a good idea to start playing around with
them in the electrical domain.
What is the result?
If we have these 2 36, dB per octave Linkwitz Riley filters,
what does that look like?
What does it look like?
If we change the topology, the slope?
What if we change the frequency between them investigating all
those things in the electrical domain is really good, because
then you're just focusing on the combination of these two shapes.
The next step then is to look at what happens when we start
applying these to speakers.
And I'll tell you now that what I teach my students
is to start thinking about these electrical filters.
Not as specifically what you want to apply, but as the
target, this is the result that you might like to achieve.
If you like the shape, if you like the sound of this, if you
would like to create a unity class crossover, then this
is a great target to pursue.
So here in Crosslite, I've just created these
two separate channels to serve as our targets.
And so what I'm going to do now is I'm going to insert
a main and sub speaker that I downloaded from Tracebook,
because I wanted you to be able to use the exact same data.
So let me show you how I did that.
So if you go to chase book.org and you go to the
search page, then you can just search for subwoofers.
And that's what I did here.
It just grabbed one of the first ones.
And then I downloaded the CSV file.
That's just a text file that has magnitude phase and coherence
values, all of this stuff that you see in this graph here.
And then I downloaded this speaker because I measured
it and I'm familiar.
And you'll notice that these are two speakers
from two different brands.
They are not designed to work together.
And I thought that would make an interesting demo since
they are quite different.
Okay.
So I downloaded the CSV files and then I imported
them here into Crosslite.
So here's my main and sub and here they are
on top of my targets.
So let's start just working on the main speaker.
Okay.
So I know this is what, where I want to end up.
So what do I need to do?
I know this is a 36 dB per octave slope, but if I add
a 36 DB per octave filter, is that going to give me
the result that I want?
Let's try it.
So I'll change this to Linkwitz Riley 36 dB per octave.
We know we're heading towards 80 Hertz, so I'll insert that and.
This is not what we want.
We've gone a little bit too far, so I could play around
with the frequency here, but, we can get this part to match,
but not this part to match.
So maybe I like this and I could insert a filter here, but
I say, you know what, let me keep playing around with this.
What if I go to a less steep slope so I'll go
to 24 DB per octave.
And now I play around with this and I see, wow, this gets me.
Really close.
This gets me part of the way there.
And now I'm looking at this and I'm thinking, you know what?
This is not something I want to EQ because this is just
some kind of reflection.
There's a little bit of ripple here, but I am curious to see
what this would look like.
Without the ripple.
So I'm going to do two things.
Number one, I'm going to run the noise reduction
function here in Crosslite.
I've done that already.
And here's what that measurement looks like.
So a little bit less ripple here.
And now this is totally improper EQ, but I am going to just apply
some little filters here, just cause what I want to see what
this would look like without this ripple, as I mentioned.
So I'm going to put in some little filters here just to
make that ripple all go away.
And now I have a, a nice fit here.
So ideally it looks like I would have only had to use one
filter that Linkwitz Riley 24 DB per octave filter, maybe
one other parametric filter here to achieve my target.
So as you can see, we wanted a 36 DB per octave results.
But we didn't use a 36 dB per octave filter to get
there because this speaker naturally, already has
some amount of roll off.
You're never going to measure any speakers that
are just flat from DC to daylight, that they're just
flat all the way across.
And then you can add filters.
That's not the way I, our filters work.
You're always adding on top of something that's already there.
And so we can look at the math of that and that's easy
to figure out and we can do the numbers, but it's
also just fun to play with and just add things and see
what gets you to the target as efficiently as possible.
And sounds good.
All right. Let's take a look at the sub.
Let's zoom in a little bit here.
What do we need to do here?
This is sometimes some of the most challenging work because
here at the crossover frequency, we are already locked in.
By the way, it might help to have some kind of a target here.
So over here, I'm going to turn on the target today.
I'm just going to use a flat target.
That's not what I always use, and you don't have
to use the same thing, but that's what I'm using today.
So I have this target.
Here's the top of it.
And then I turn on this target Delta so that I can see where
the -6 dB down point is.
Okay.
And I see that my sub is already hitting that point.
And so what do I want to do here?
What if I use something super sharp?
Imagining the shape here and I'm thinking what if I come in
with a filter that's like super sharp and maybe just push this
part down this way a little bit.
So let's try that first.
So I put in this 48 DB per octave link what's Riley filter,
and that gets me a fit here, but now I'll still have to
work on this region and this region, and maybe that's fine,
but I've played with this a little bit earlier before
I started this video and I came up with what I think is.
A more efficient solution, which is first applying
a six DB per octave first order low-pass filter.
So answer this and I play around with this a little
bit and oops, I'm probably moving the wrong filter.
Let's see.
I need the red guy.
There it is.
There we go.
So with this first order filter, now I've got this
top getting closer here.
I'm getting closer to the bottom here and now I just
need one filter here to make a slightly better match.
And now I could keep playing around with these until
I find a closer match.
Okay.
So let's say that I'm happy with that.
And now let's look at everything together.
so here's both of my measurements now
with the targets.
Now I'm going to mute the targets.
And now I can look at the sum between these guys and I already
want to have kind of a picture in my mind of what I expect.
So at this -6 dB point, I expect 6 dB of summation,
the should hit up here, and then I'm hoping for, a nice
flatline transition across here.
That is the goal of the unity crossover.
So I turned on the sum, and I see that have
a big problem here.
And I remember that's right.
36 DB per octave target.
I'm going to need a polarity and version.
And then I take a look at the max sum here, and I know it's
a little bit difficult to see because both of these lines
are black, but I'm turning.
Max on and off max signifies the total potential
summation, if everything was perfectly phased aligned.
So I see that I still have some work to do here in the high end.
So what can I do about this?
I'll turn off the sum for a second and let's place some
markers here, just so I can see this is the crossover
region that I'm going to focus on for the moment.
And I take a look at the phase here and I see, oh, this is
a slightly problematic here.
By the way before I go down this path, I should just point
out that this some that we had, this could be good enough and
I could just move on, but if I want to keep playing with this.
I could try different filters.
I could try a different combination of filters to
see if there's something that would achieve a better
phase compatibility here.
But for the moment, I'm going to try a solution
with just a second order, all pass filter here.
And when I move this around, maybe I can find
a solution here that.
Is an, a different compromise here.
So it seems like we have a little bit better
response through the entire crossover region there.
And now when we take a look at the Psalm and we turn
the max off and on now we have a much closer result.
Okay.
So again, I'm not going to say that this is the best solution.
This is just what I came up with in the few minutes
that I've been working on it with you today.
If I spent another couple hours on this and tried
out a bunch of different variations, I might find
something that I liked better.
And then ideally I could deploy all of those as presets and
then do listening tests and find the one that I actually
liked the sound of the best.
And doesn't just look the best on the screen.
So you saw here that both with the main and the sub
the filters that I applied.
Didn't necessarily have anything to do with the target.
So I wanted to end up with this 36 dB per octave result
that gave me this nice flat result here through the
crossover region, but I just did whatever was necessary.
I was just playing around and experimenting with filters
until I got to that result.
So this is why it's probably a bad idea to ever recommend.
Just one kind of filter.
Don't tell people, just use Linkwitz-Riley filters, but you
could tell them head towards this kind of result, especially
if people are just starting out.
They've never heard of this kind of idea, but.
Yeah, totally fine.
To just start with some kind of a template, use Linkwitz-Riley
filters experiment with them in the electrical domain.
Look at the result and then play around with that
and use that as a target.
Okay.
So I promised I would also show you how to do this in
REW, in case you don't have Crosslite at home and you want
to do this work along with me.
So let's try that.
So I've got an REW open and before I actually import those
measurements, I want to show you how you can also play around
with electrical filters in REW.
So you open the EQ tab and then you can just insert filters.
Down here.
It says crossover filters and I can use the exact same thing
I was using in Crosslite here.
We see the filter prediction, and now if I want to actually
play with that, then I go over here and I click generate
measurement from filters, and then I'll do the same
thing for my low pass filter.
Generate measurement from filters.
There we go.
Now I can play around with these and look at
the result and compare phase and all that stuff.
Just like I was doing in Crosslite.
All right. Let's import those measurements.
So I'll just grab them from the finder and I'll just drop
them here and here they are.
So you can see this is this, the raw data.
And so now I would want to take the next steps to.
Change the gain between them so that they line up and they
look more like this, what I was doing in Crosslite and
then start experimenting with filters to achieve this target.
And let me just show you how to take the first steps with that.
So here over on the left, do you want to select whichever one
you want to apply the filter?
And then go to the EEQ window.
And then from here, you're going to choose a target.
So I typically choose speaker driver, and then, we're going
to choose our high pass filter, which is Linkwitz-Riley six.
And then set this at zero or three, line it up with
your measurement here.
And so now we have a target here and now we can
start applying filters in pursuit of that target.
So I think over in Crosslite we added a fourth order filter.
Let's try that.
Yeah, there we go.
So that's getting pretty close.
All of these audio analyzers and modeling and prediction
software, they all look slightly different, but the
data is all very similar.
We see a magnitude response here.
We have a target, we have a prediction, so we need some
way to practice this stuff.
REW is great.
Crosslite is great.
There's plenty of tools out there.
So pick one of them and figure out a way that you can play
with this stuff at home.
And so now that I've shown you how to get started here
in REW, maybe go back to the beginning of this video and go
through step-by-step as I was doing it in Crosslite and you
can do the same thing in REW.
Okay.
Let me know what questions come up for you.
Let me know if you have any suggestions for me
and thanks for watching.