GSE XaVCF Eurorack Filter Overview [Demo #1]


fantastic more oh yeah haha more there’s a lot of weird stuff happening
down there at the bottom end ooh hello and welcome back g-man here in the
studio today I’m showing you my XaVCF a little bit later on in this video I
will show you how I made those patches at the beginning of the video
what is the XaVCF well it’s a eurorack adaptation of the Oberheim OB-Xa
filter in eurorack format as with the original synthesizer there’s two
completely different circuits in here to choose from mode one is what I’m calling
their original two pole filter it is derived from a state variable circuit
and then mode two is the original four pole filter it is a standard datasheet
configuration of the CEM3320 now this filter uses the reissue alpha AS3320
chips and these are perfect for replicas of the Curtis chips fantastic sound you
will be amazed with this one so let’s get into it as I’ve stated there’s
architecture is two completely different circuits on the one side you
will see that I’ve also derived an additional one pole bandpass from the
state variable configuration sounds fantastic and then over in mode 2 I have
pulled the output from the one pole low-pass this is just a fantastic Oberheim sound you will love that one as well so it also has two inputs so you can mix two
different VCOs together two input CVs for controlling the frequency cutoff on
this filter I have configured cv 2 to have volts per octave input so this
filter will track the cv 1 is it has more range so that if you have some
modulations signals that are a little bit weaker this will actually boost a
little bit more than what cv 2 does so I’ve also added cv 3 this is for
controlling the resonance it’s an interesting little addition that you
would not find on the original synthesizer
let’s get to demos mode one we’re gonna go through
low-pass I’m just going to use a simple sawtooth waveform coming from my 101 VCO
nothing else there so let’s hear what that sounds like without any resonance let’s add some
resonance in You start to see a little bit of a peak there more resonance there’s all kinds of stuff going on
there then flat-out this is going to hurt so I’m going to turn down the input now you’ll notice those Peaks were kind of
going in one general direction that’s because of some clipping diodes that are
in that state variable configuration so check it out again look for the peaks
going in that direction so yeah pretty cool let’s check out the
one pole turning the resonance all the way down one pole you’re gonna hear some
bleed through because even though it’s at the crossover is at zero it’s because
of the slope allowing so many of the frequencies in being one pole you could
expect that so if you don’t want any sound at 0 cutoff then follow it up with
a VCA to gate it so that no sound will come through when you don’t want it to zero resonance let’s kick it all halfway a little bit more and then all the way okay I was turning down the output
volume on my mixer it’s just because it was gonna clip out my tascam dr-05
recorder so don’t want that. now let’s go over to mode 2 and see what that sounds
like first the 4-pole it’s a bit quieter so I go ahead and turn up my input a
little bit that’s what zero resonance, then halfway still not much going on there it’s not
as wild as the mode one resonance okay let’s kick it up all the way yeah so that resonance is a little bit
more musical a little more bit more toned down let’s go to one pole you know
you wanna hear it once again you’ll hear the bleed through because even though
the frequencies at zero because the slope is so far out it’s allowing a lot
of those frequencies through past the cutoff once again if you want no sound
…at zero go ahead and chase it with a vca to gate that audio so
let’s see what this one sounds like clipping out there sorry I could probably turn down my input
again you’re starting to get those little
Peaks there more this one to me is just such a typical
Oberheim great sound now resonance up all the way it’s a lot of… there’s a lot of weird stuff happening
down there at the bottom end of the frequency in the lower frequency
spectrum once again I was turning down the level on my mixer as I neared the
top of the frequency cutoff just to watch my levels there so let’s talk
about the volts per octave tracking so I want to go back to mode 1 and you’ll
hear it in the background there actually describe what I’m doing here there’s two
ways to use your volts per octave tracking one is to patch your input turn
it up and then kick in some resonance and find a sweet spot and the volts per
octave even though you play up and down on the keyboard it will follow that
sweet spot around so I’m gonna go ahead and do that I’m running my volts per
octave through a buffer first so that will be available to my oscillator let’s find a sweet spot on the resonance OK that one’s pretty cool
and now what I’ll do is I’ll follow that around using my keyboard and you’ll see
what I mean now if I didn’t have volts per octave then
here’s what that would sound like that’s because the frequency isn’t
moving at all with the keys and that I’m pressing on my beat step pro so that’s
one way to use the tracking the other way is to use for a sine wave oscillator
so if you just turn this up it becomes a sine wave so I want to run
I could turn off my input okay resonance up all the way volts per octave up all the
way and then I will plug in a CV into that input. This is coming directly from
my beat step pro volts per octave directly in
whoa I want to turn the frequency all the way down resonance all the way up
and then the volts per octave this has to be all the way up
this will correspond with the notes on the keyboard like C-D-E-F-G-A those will be
the notes that you’re playing okay I have a little sequence programmed
into my beat step very simple but I’ll just be transposing that up and down the
keyboard cool so you can also do that in mode 2
with the 4-pole so that one sounds a little bit more tame so I can kick that
one back up same sequence okay the tracking isn’t bad on this this is an
analog device so the tracking isn’t going to be pitch perfect like anything
that’s digital so one pole you know you want to hear the one pole tracking cool
and may as well do the bandpass mode in mode one see that one’s crazy as well sorry about that! it’s a different sound cool let’s get on
with doing some patches I’m going to doing some patches the Tom Sawyer
synth sweep that I did in my first like teaser video I want to copy oh I’m
sending my volts per octave from the beatstep to and into a buffer and I’m
going to send that to CV2 we’re gonna do some pitch tracking on that and then
I’m going to plug in my 101 VCO in the one
let’s go back to two pole low pass so 101 VCO sawtooth, square wave, pulse width
modulation is coming from Batumi and then a little bit of sub oscillator see
what that sounds like so there’s that and then I’ll add my
synthesizer box into input 2 – it also has pulse width modulation and we’ll let them slightly be detuned
the Pittsburgh box also has sawtooth and sub-oscillator as well that’s how I come
up with those really big fat tones so and I’ll slightly detune them so they’re
slightly phasing here there’s that and then I need some
resonance for this to work I want to turn my volts per octave back up way up. then I want to add some delay
from the Eventide time factor this module is going to be your delays best
friend so let’s have it there’s the delay now I can also run the main pitch
through a slew limiter for a glide sound you’ll find a a sweet spot and then it
will track when this is up it’ll just track that sweet spot across the
keyboard let’s hear that in four pole and see
what happens with that I need to boost my inputs a little bit more haha. one pole it’s gonna be loud
so I’ll turn this down sweet okay that’s a lot of fun you don’t have
to use the tracking dual envelope in the CV one let’s make some bass sounds I’ve got some attack man that one pole sounds so good was
getting resonance quick attack let’s do that let’s get rid
of the delay so you can hear what’s going on let’s do short and punchy bandpass okay let’s add some LFO to that sometimes your inputs may be overloaded
so you might dial back your inputs there I’m sending a lot to it so I just
have the sawtooth and pulse coming from my 101 vco1 back to one pole on the mode 2 shorter envelope time oscillator sub-oscillator back in let’s
bring the delay back in let’s make your little sequence fantastic I still haven’t shown what the resonance
input does so let’s add that in LFO from Batumi give it (CV) a ramp wave so much fun so that’s the XaVCF thank
you for watching and be sure to LIKE comment and subscribe thank you

4 comments on “GSE XaVCF Eurorack Filter Overview [Demo #1]”

  1. impurfekt says:

    Wow. Sounds absolutely amazing!

  2. Sine Mountain says:

    um, wow.

  3. Adamski A. says:

    Sounds like a very versatile filter. Love it !!!

  4. Bud Marcom says:

    excellent

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