Arturia Flanger BL-20 User manual

USER MANUAL

Special Thanks
DIRECTION
Frederic BRUN Kevin MOLCARD
DEVELOPMENT
Samuel LIMIER
Kévin ARCAS
Rasmus KÜRSTEIN
Corentin COMTE
Alessandro DE CECCO
Raynald DANTIGNY
Alexandre ADAM
Baptiste AUBRY
Timothé BEHETY
Yann BURRER
Loris DE MARCO
Geoffrey GORMOND
Pierre-Lin LANEYRIE
Mathieu NOCENTI
Marie PAULI
DESIGN
Martin DUTASTA Clément BASTIAT Shaun ELWOOD Morgan PERRIER
SOUND DESIGN
Jean-Baptiste ARTHUS
Jean-Michel BLANCHET
Clément BASTIAT
William ROBERTSON
Léo BATTLE
TESTING
Florian MARIN Thomas BARBIER Christophe TESSA
MANUAL
Fernando MANUEL
RODRIGUES (author)
Camille DALEMANS
Holger STEINBRINK
Minoru KOIKE
Charlotte METAIS
Jose RENDON
BETA TESTING
Gustavo BRAVETTI
David BIRDWELL
Jeffrey CECIL
Dwight DAVIS
Marco CORREIA
(Koshdukai)
Ben EGGEHORN
Matthew HERBERT
Guillaume HERNANDEZ
Jay JANSSEN
Luca LEFEVRE
Terry MARSDEN
Peter TOMLINSON
Chuck ZWICKY
© ARTURIA SA – 2020 – All rights reserved.
26 avenue Jean Kuntzmann
38330 Montbonnot-Saint-Martin - FRANCE
www.arturia.com
Information contained in this manual is subject to change without notice and does not
represent a commitment on the part of Arturia. The software described in this manual is
provided under the terms of a license agreement or non-disclosure agreement. The software
license agreement specifies the terms and conditions for its lawful use. No part of this
manual may be reproduced or transmitted in any form or by any purpose other than
purchaser’s personal use, without the express written permission of ARTURIA S.A.
All other products, logos or company names quoted in this manual are trademarks or
registered trademarks of their respective owners.
Product version: 1.0
Revision date: 13 August 2020

Thank you for purchasing Arturia's Flanger BL-20...!
This manual covers the features and operation of the Flanger BL-20.
Be sure to register your software as soon as possible! When you purchased Flanger BL-20
you were sent a serial number and an unlock code by e-mail. These are required during the
online registration process.
Special Messages
Specifications Subject to Change:
The information contained in this manual is believed to be correct at the time of printing.
However, Arturia reserves the right to change or modify any of the specifications or features
without notice or obligation.
IMPORTANT:
The software, when used in combination with an amplifier, headphones or speakers, may
be able to produce sound levels that could cause permanent hearing loss. DO NOT operate
for long periods of time at a high level or at a level that is uncomfortable.
If you encounter any hearing loss or ringing in the ears, you should consult an audiologist.

Introduction
Congratulations on your purchase of Arturia's Flanger BL-20...!
Arturia's passion for synthesizers and sonic purity has given demanding musicians the best
software instruments for professional audio production.
Arturia also has a growing expertise in the audio field, and in 2017 launched the AudioFuse,
a pro studio quality audio interface that features two proprietary DiscretePRO® microphone
preamplifiers and a set of top-notch AD/DA converters. This line was recently expanded with
the launch of the AudioFuse Studio and the AudioFuse 8Pre. Arturia has also been busy
making effect plug-ins, launching in 2018 the first Arturia effects bundle, which included the
Pre 1973, the Pre TridA, and the Pre V76.
Other bundles followed, dedicated to compressors, filters, delays, and reverbs. With the
launching of these new effects, this time dedicated to modulation, Arturia consolidates its
position as a leader in audio effect plug-ins.
The ARTURIA Flanger BL-20 is one of the new modulation effects plug-ins included in the
FX Collection, and benefits from decades of experience in recreating the most iconic tools
of the past.
ARTURIA has a passion for excellence and accuracy. This led us to conduct an extensive
analysis of every aspect of one of the most sought-after flanger units of the past. But, as
has been usual and became a fundamental characteristic in all of our plug-ins, we didn't
just model the sound and behavior of this unique unit, we also added several features that
were unimaginable in the days the original was being manufactured.
Flanger BL-20 runs as a plug-in in all major formats inside your DAW.
DISCLAIMER: All manufacturer and product names mentioned in this manual are
trademarks of their respective owners, which are in no way associated or affiliated with
Arturia. The trademarks of other manufacturers mentioned are used solely to identify
the products of those manufacturers whose features and sound were studied during the
development of this plug-in. All names of equipment inventors and manufacturers have
been included for illustrative and educational purposes only and do not suggest any
affiliation or endorsement of Flanger BL-20 by any equipment inventor or manufacturer.
The Arturia team

Table Of Contents
1. WELCOME ......................................................................................................................................................................... 2
1.1. What is a modulation effect? ........................................................................................................................................ 2
1.2. What about the Flanger BL-20? ................................................................................................................................. 3
1.3. Where can we use a flanger unit like this?......................................................................................................... 4
2. ACTIVATION AND FIRST START.......................................................................................................................... 5
2.1. Activate the Arturia Flanger BL-20 license........................................................................................................... 5
2.1.1. The Arturia Software Center (ASC).................................................................................................................................................................... 5
2.2. Working with plug-ins ....................................................................................................................................................... 5
3. FLANGER BL-20 OVERVIEW................................................................................................................................ 6
3.1. Arturia's Flanger BL-20 plug-in .................................................................................................................................... 6
3.2. Understanding the Flanger BL-20 Signal Flow................................................................................................ 7
3.3. Getting hands-on with Flanger BL-20.................................................................................................................... 8
3.3.1. Flanger Basics................................................................................................................................................................................................................ 8
3.3.2. Advanced methods of using the flanger.................................................................................................................................................. 10
4. FLANGER BL-20 CONTROL PANEL.................................................................................................................. 12
4.1. Channel Configuration (Mono/Stereo/Mono-to-Stereo)............................................................................. 12
4.2. Main Control Panel ............................................................................................................................................................ 13
4.2.1. Power ................................................................................................................................................................................................................................. 13
4.2.2. Mono/Stereo ................................................................................................................................................................................................................. 14
4.2.3. Zero Cr.............................................................................................................................................................................................................................. 14
4.2.4. Mix....................................................................................................................................................................................................................................... 15
4.2.5. Regen ................................................................................................................................................................................................................................ 15
4.2.6. Control Mode................................................................................................................................................................................................................ 16
4.2.7. Manual .............................................................................................................................................................................................................................. 16
4.2.8. FCT ....................................................................................................................................................................................................................................... 17
4.2.9. Env........................................................................................................................................................................................................................................ 17
4.2.10. Auto.................................................................................................................................................................................................................................. 18
4.2.11. Reverse Sweep O/P 2............................................................................................................................................................................................ 18
4.3. Advanced Mode Control Panel .................................................................................................................................. 19
4.3.1. Hi-Pass Filter.................................................................................................................................................................................................................. 19
4.3.2. Function Generator ................................................................................................................................................................................................ 20
4.3.3. Auto Shape ................................................................................................................................................................................................................... 22
4.3.4. Stereo Offset ............................................................................................................................................................................................................... 22
5. USER INTERFACE ....................................................................................................................................................... 23
5.1. The Upper Toolbar.............................................................................................................................................................. 23
5.1.1. Save Preset..................................................................................................................................................................................................................... 23
5.1.2. Save Preset As….......................................................................................................................................................................................................... 24
5.1.3. Import............................................................................................................................................................................................................................... 24
5.1.4. Export Menu .................................................................................................................................................................................................................. 24
5.1.5. Resize Window options......................................................................................................................................................................................... 24
5.1.6. Help..................................................................................................................................................................................................................................... 24
5.1.7. Preset Selection .......................................................................................................................................................................................................... 25
5.2. Advanced Mode (Double Arrow) Button............................................................................................................. 25
5.3. The Lower Toolbar ............................................................................................................................................................ 26
5.3.1. Panic.................................................................................................................................................................................................................................. 26
5.3.2. Undo ................................................................................................................................................................................................................................. 26
5.3.3. History ............................................................................................................................................................................................................................. 26
5.3.4. Redo.................................................................................................................................................................................................................................. 26
5.3.5. Bypass.............................................................................................................................................................................................................................. 27
5.3.6. CPU meter...................................................................................................................................................................................................................... 27
5.4. The Preset browser.......................................................................................................................................................... 27
5.5. Fine-tuning parameters................................................................................................................................................. 28
5.6. Resetting your controls.................................................................................................................................................. 28
6. Software License Agreement............................................................................................................................ 29

1. WELCOME
1.1. What is a modulation effect?
Modulation effects work by modifying the sound in a certain way, usually by means of
modulation controlled by a Low-Frequency Oscillator (LFO). For example, they can add one
or more slightly delayed versions of the sound to itself, while modulating the pitch of those
versions over time.
We can obtain three main effect types with modulation: chorus, flanging, and phase shifting.
Of these three, chorus is perhaps the most sought-after one, since it allows to create "richer"
versions of the sound. Chorus effect works by taking the audio signal and mixing it with
one or more delayed, pitch-modulated copies of itself. The pitch of the added voices is
modulated by an LFO, which makes the overall effect similar to that of the flanger, except
with longer delays and less modulation.
Flanger is an effect similar to the Chorus, produced by mixing two identical signals, with one
signal delayed by a small and gradually changing amount of time and modulated through
an LFO, which produces a characteristic undulating (sweeping) effect, but with a sound
resembling the result of a comb filtering. Speeding up the LFO accentuates the modulation
effect. As we said, the effect is similar to the Chorus, but here we use shorter delays for the
delayed signal.
The flanger effect can be controlled by other sources than the LFO. For example, the unit
which is modeled here allows control by means of an envelope follower and also manually.
Also, part of the signal is usually fed-back into the input, producing a resonance effect.
The phase of the feedback signal can also be inverted, to achieve further variations of the
flanger effect. Flangers usually make great use of feedback to receive more processing. This
accentuates the notches and resonances, resulting in the harsh, metallic timbre that is one
noticeable characteristic of flangers.
Beware though that the constantly oscillating comb filter can become quickly tiring to
listeners. Flangers can be great as transitional effects and momentary ear candy to keep
the listener’s attention, but we need to be careful not to push the effect too much.
The Phaser (phase-shifter) is another modulation effect, with results somehow similar to
Flanger. It is produced by splitting the audio signal in two paths, one being treated by all-
pass filters, which preserve the amplitude of the original signal but alter its phase. Here,
we use no delayed signal. The two paths are mixed again, after the all-pass filtering,
and the frequencies that are out of phase will cancel each other, producing the phaser's
characteristic "whoosh" sweeping effect.
So, the phaser works by canceling bands of frequencies to obtain the desired effect (which
is something we already observe in the flanger, by the way). No delay is used in this effect,
which differentiates it from the other two.
Modulation effects can create a huge range of sonorities, and the results may be perceived
as a fuller, richer sound. No wonder they have been used extensively since they appeared.
Also, they have been an almost obligatory addition to almost any synthesizer since the
eighties.
2 Arturi - User M nu l Fl nger BL-20 - WELCOME

1.2. What about the Flanger BL-20?
The Arturia Flanger BL-20 is part of a new set of effects, proposing three new iconic vintage
modulation effect units.
The original hardware unit this emulation is based on is an English manufacturer's stereo
flanger rack unit that became the "flanger of choice" for many of the world's top recording
artists and prestigious recording studios since its introduction in end of the 70s.
Among it's famous users we can find names like Phil Collins, Yes, The Rolling Stones and top
ranking studios like AIR Studios, RSK, Townhouse Studios, etc.
The hardware unit is based in a vintage bucket brigade circuit that creates its unique analog
warm tone. That's why we felt it would go great together with the DIMENSION-D chorus.
Another reason to choose it is its versatility and depth. In fact, despite its appearance this
flanger is far from being "simplistic". We have 3 different modulation sources. Besides the
usual and expected LFO, we can also use a manual source or an envelope follower.
Other than that, the fact that it has 2 independent delay circuits allows for true stereo
outputs even when fed with a mono input. The stereo outputs can even be opposed to get a
2-dimensional panning effect and stereo image shift.
But that's not all. As usual, Arturia Flanger BL-20 comes equipped with some extra tools
to allow you to go beyond what you could achieve with the original unit. Here, we get a
function generator that's becoming a kind of prominent in the latest Arturia plug-ins, a stereo
width control, and a Hi-Pass filter.
Arturi - User M nu l Fl nger BL-20 - WELCOME 3

1.3. Where can we use a flanger unit like this?
The flanger effect is characterized by that undulating (sweeping, wavering, swooshing)
effect, which is caused by the comb-filtering. This kind of effect became more or less a
trademark for electric guitars. Other instruments that took this effect with great prominence
were the clavinet and the electric pianos
So, obviously any kind of electric guitar sounds are good candidates for the use of this
effect. Soloing is where it may shine the most, but also riffs, especially where the notes are
more sustained, can use it to enrich and give movement to the sound.
As a matter of fact, any kind of soloing instrument may take advantage of flanging every
now and then, if we use the effect carefully.
Pianos (mostly electric, but also acoustic) are other good candidates to the use of flanger.
We can listen to it used with great results in the track "Memories of Green" by Vangelis
(this track appeared originally in the album See You Later but was also included later in
the Blade Runner Soundtrack). Many times, the electric piano sounds are spiced up with
flanging effect.
The clavinet appeared in the 70s. We would risk to say that it is almost impossible to hear
a clavinet recorded without a flanger or phaser. These effects are to the clavinet what the
rotary speaker is to the organ.
4 Arturi - User M nu l Fl nger BL-20 - WELCOME

2. ACTIVATION AND FIRST START
The Arturia Flanger BL-20 plug-in works on computers equipped with:
Windows 7 or later and macOS 10.10 or later.
You can use the Flanger BL-20 plug-in as an Audio Unit, AAX, VST2 or VST3 plug-in (64-bit
only).
2.1. Activate the Arturia Flanger BL-20 license
Once the software has been installed, the next step should be to activate your license, so
that you can use it without limitations.
This is a simple process that involves a different software program: the Arturia Software
Center.
2.1.1. The Arturia Software Center (ASC)
If you have not already installed the ASC, go to this web page:
https://www.arturia.com/support/updates&manuals
Look for the Arturia Software Center at the top of the page, and then download the version
of the installer that you need for your system (macOS or Windows).
Follow the installation instructions and then:
• Launch the Arturia Software Center (ASC)
• Log into your Arturia account
• Scroll down to the My Products section of the ASC
• Click the Activate button
That's all there is to it!
2.2. Working with plug-ins
Flanger BL-20 can be used in all major digital audio workstations (DAWs), including Live,
Logic, Cubase, Pro Tools and others, as it comes in all the main plug-in formats. Unlike what
happens with hardware, you can load as many instances of the effect as you find useful.
Flanger BL-20 has two other big advantages over hardware:
• You can automate numerous parameters using your DAW’s automation system;
• Your settings and current plug-in state will become recorded in your project, and
you can pick up exactly where you left off the next time you open it.
Arturi - User M nu l Fl nger BL-20 - ACTIVATION AND FIRST START 5

3. FLANGER BL-20 OVERVIEW
3.1. Arturia's Flanger BL-20 plug-in
Our goal was to give the users the experience of a great tool from the past. But although we
have worked to be faithful to the unit sound, appearance and workflow, it wouldn't be an
Arturia plug-in without the addition of some extra features to enrich the user experience.
We kept the user interface simplicity. As is usual with the effect plug-ins produced by Arturia,
the Graphical User Interface (GUI) has two panels, the Main panel and the Advanced panel.
The Main panel has the main flanger controls, with just a few knobs and buttons. The
original unit has a row of knobs that allow to tune the main flanger parameters. We kept
this row of knobs, with a knob to control the mix and another to control regeneration in the
left section, and five other knobs in the right section, together with a few buttons.
But we also included a few other tools, like alternative LFO shapes, a "hi-pass" filter, a Stereo
Offset, and a Function Generator. These, as usual, go to the Advanced Control Panel [p.19].
We will take a detailed look at all of these controls, and will explain all of them in detail in
the Control Panel chapter [p.12]. Now, it's time to check out how it works and how it sounds.
Let's go!
6 Arturi - User M nu l Fl nger BL-20 - FLANGER BL-20 OVERVIEW

3.2. Understanding the Flanger BL-20 Signal Flow
The Flanger BL-20 plug-in is a stereo flanger unit. It is relatively simple, although some
routings and modulations may add an extra dose of complexity and flavor to the circuit.
This plug-in is an emulation of an old vintage unit, but it still offers a lot to the user, like the
original units did countless times during all these years.
When the plug-in is bypassed, the input signal is routed directly to the output. This is the
signal heard when we press the Power button or the Bypass button in the Lower Toolbar.
After entering the unit the signal is split in two parts. One of them will be the Dry path, while
the other is the Wet path that's going to be processed by the flanging circuit.
The first stage for the Wet signal is passing through a Hi-Pass Filter. This, if active, will filter
out the lower regions of the sound. After this stage, the signal passes through a Compressor
+ Filters stage that will level the signal, preparing it for the main flanging processing.
The flanging processing is the next stage. Two BBD (Bucket-Brigade Delay) units are in
charge of the short delay lines that will create the flanging (one for each channel). The
Rev. Sweep or the Stereo Offset switches allow to change the phase behavior of the right
channel, this way creating some changes in the stereo field. For more details about these
two very important controls, please refer to the respective entries in the Control Panel
chapter [p.12].
The short delay lines may be modulated by each or all of the three modulators available:
The LFO, the Manual/Function Generator, and the Envelope Follower. These may be summed
as modulation sources, therefore there's a mixer to sum the three signals.
After the flanger core effect, the signal is passed through an Expander + Filters circuit that
will restore the dynamics lost in the previous (Compressor + Filters) stage. After this, the
Regen (feedback) control allows to re-inject (feed back) some signal into the flanging circuit.
The Wet signal is then routed through a mix (again one for each of the stereo channels)
where it will be mixed with the Dry path that was split after the signal entered the effect unit.
The final mixed signal will then be routed to the plug-in Output.
This is the complete signal flow of the Flanger BL-20. Study the circuit, spend some time
with the controls, and we're sure you'll gain a deep understanding of how this flanger
processor works. The following section will definitely give you some help.
Arturi - User M nu l Fl nger BL-20 - FLANGER BL-20 OVERVIEW 7

3.3. Getting hands-on with Flanger BL-20
3.3.1. Flanger Basics
To get an idea of the Flanger BL-20's capabilities, we suggest you try the following:
• Load a stereo clip into an audio track in your DAW (vocal tracks, guitar tracks or
some keyboard licks are ideal for this);
• Load an instance of Flanger BL-20 as an insert in that track. Alternatively, you
can create an auxiliary channel, load the effect in it and route your dry signal to
that channel. Open the Flanger BL-20 window;
• Ensure the Default preset is loaded. This will mean that all settings are positioned
in their initial values;
• Begin playback. You'll notice a slightly flanged modulation on the sound;
• Your flanging effect is in Auto mode, which means it is being controlled by
the LFO. We have other options, but for now we'll keep using Auto. Notice
that the Rate knob is at the center position, and the little black button with a
musical figure (eight-note) is Off. This means that the LFO is running freely. Lets
synchronize it to the music. Click the small "eight-note" black button, and then
turn the knob until the label on the right reads 2. The LFO is now running in sync
with the music, and each waveform cycle lasts the duration of two whole-notes.
You may try 1, which means one whole-note, or a full 4/4 bar. The faster the LFO
frequency, the more the effect becomes audible. You can check the LFO speed
by looking at the movement of the LEDs over the three Control Mode buttons;
• Now we will try other modes. We can sum all the three modes, but for now we
will try the manual mode. This will allow us to also use the Function Generator
(we will check that later). Press the Manual button to select it, and press the Auto
button to deselect that mode;
• Now play the track again. This time, we will turn the Manual knob. By default, it
is at 50%. Turn it up to 100% and then turn it back slowly until reach 0%. Notice
how the flanging effect fades. You can also try the Mix knob, located in the upper
left part of the Main panel. Turn it up and down, to vary the balance between dry
and wet signal;
• The Regen knob controls the feedback amount. Feedback is very important for
the flanging effect. By default, that knob is at 50%. Again, try other values, and
check the effect of the feedback on the overall sound;
• Now that we already tried the Auto mode and the Manual mode, it's time to try
the Env mode. Once again, click the Manual button to deselect it, and click the
Env button to select that mode;
• Env stands for Envelope Follower. In practice, it means that the flanging effect
will be controlled by the volume contour of a sound. We can select and Internal
and External source. If you know how to deal with side-chain configurations in
your DAW, you can select another track to control the effect. In that case, you
should press the button to select "Ext Env" (the LED over it will lit). If not, we
will control it with the audio that's being processed, by leaving the button at its
default "Int Env" position;
• Now, let's play again. This time, the relevant controls are the ones under ENV,
which means Threshold and Decay. Threshold sets the gain of the input signal,
and so behaves like a modulation intensity control. The higher the value, the
more the original audio volume brings flanging to the sound. Decay controls the
time it takes to fade the effect;
8 Arturi - User M nu l Fl nger BL-20 - FLANGER BL-20 OVERVIEW

• Now that we tried all the three control modes, it's time to get a little wilder.
Flanging BL-20 has some unusual controls that can perform quite interesting
roles. Mono, when pressed, sums the Right and Left input signals (both Dry and
Wet paths) so the whole plug-in will work on a Mono source. There's little else to
say about it. But we have two other buttons deserve mention. One is right after
Mono, and is labeled "Zero Cr". The other is in the extreme right of the Main panel,
and is labeled "Reverse Sweep O/P 2". This last button has an effect even if Mono
is pressed. For now, let's put the Flanger BL-20 in Auto mode (activate the AUTO
button and deactivate the ENV button), and play it again;
• While it plays, press the Zero CR button. The red LED above it will lit. You will
notice that the stereo image expands. Usually, the delayed (flanging) signal is
summed to the dry signal, creating the expected peaks and valleys that are the
result of comb filtering. This button inverts the polarity of the Wet and delays
the Dry signal, this way creating phase cancellations, hence more comb filtering.
This increases the depth of the flanging effect;
• Now, it's time to try the Reverse Sweep button. Press the Zero Cr button to turn
it Off, and press the Reverse Sweep button to turn it On. The bright green LED
above it will lit. Now put the Rate in unsync mode (the little black button has to
be off), and turn the knob all way to the left. Turn the Depth knob all way to
the right. When you hit play, you will notice the signal slowly "floating" from one
channel to the other. This reverse sweep causes stereo widening, and will be
more noticeable with a sustained sound, like a synth pad;
• And that's pretty much it in what concerns the controls present in the Main panel.
As we showed, this effects unit has more than you could imagine at first sight.
But we're not done yet. Please read below;
Arturi - User M nu l Fl nger BL-20 - FLANGER BL-20 OVERVIEW 9

3.3.2. Advanced methods of using the flanger
Now that you have a feeling for the Flanger BL-20 main controls, let's go deeper into
flanging:
• Click the double downward facing arrows to open the "Advanced" panel;
• This panel has some extra options - from left to right, we have a Hi-Pass Filter, a
Function Generator, an LFO shape selector (labeled Auto Shape, because the LFO
is in action only when we select the Auto mode), and the Stereo Offset, which
changes the behavior of the Stereo;
• For now let's focus on the Hi-Pass filter. Let's say you want to process a bass
guitar line, but you want your bass to sound firm and steady. You may achieve
that by leaving the lows unprocessed. That's where the Hi-Pass filter enters. This
filter will cut all the frequencies below the cutoff point in the Wet signal path,
which means those will be left out of the flanging. Only the frequencies above
the cutoff point will be processed;
• Next comes the Function Generator. This is more complex. The FG works together
with the Manual button. The values of both controls are mixed (Function
Generator can sum or subtract to the Manual value). Anyway, for the FG to have
a better effect on the audio, the Manual knob should be around 50%;
• Press the Manual button in the Main panel, and put the Manual knob at a value
around 30%. Now, press the "Add To Manual" button of the Function Generator.
Notice that the graphic display window becomes brighter;
• We will need to draw some function. Let's try a kind of simple Attack-Decay
envelope. Click the FG line more or less at the end of the first quarter space (there
is a soft vertical line a little thicker at that point). You may click the magneto icon
in the lower part of the FG window to be sure that the node created is exactly at
that point;
• Now raise that node up to the top of the graphic display. You'll have now the
aimed Attack-Decay like envelope contour. Since the FG is in a constant loop, the
envelope will restart every time it reaches the end. Therefore, it's better to use it
in sync with the music. That's why Sync is the default behavior;
• Hit play. The flanger effect will follow the envelope contour, but will not be very
noticeable. It is also very slow. First, change the sync value to 1 (by default it is
8t, which means eight whole-note triplets). 1 means a whole-note (a full 4/4 bar),
which is a value more suitable to what we want;
• Now raise the Amount to 0.700. This value will add to the Manual knob value,
which means that, when the envelope is at the top, we will almost reach
maximum delay time. Hit play and listen. Adjust the values to what best suits
your musicality. Remember that you can also use negative values, in which case
the Function Generator will subtract to the Manual value;
10 Arturi - User M nu l Fl nger BL-20 - FLANGER BL-20 OVERVIEW

• Now, it's time to have some fun. Create a few more nodes in the FG line. Now,
click over the dice icon and drag the mouse up. You will get a random function.
Perform this operation a few more times, until you get a contour that you think
is good. Now hit play again. You can keep playing dice for as long as you want;
• Time to check some different LFO waveforms. Go to the Main panel again, click
the Manual button to turn it off and click the Auto button to turn it On. We are in
Auto mode again. Since we are going to try different waveforms, it's better to put
the Rate knob in sync. Click the small musical figure button to turn Sync On. The
button will lit. Turn the Rate knob until the value box that pops up shows 1. Turn
Depth all way to the right to get the maximum value. Hit play one more time;
• Now, while the music is playing, click the Auto Shape button. You will notice that
the flanger effect changes noticeably with each waveform. The original unit only
had a triangle waveform, but here we have several others, and each one works
differently. Some results may be more suitable than others. Listen carefully.
Remember to always check this when you decide to use Auto mode with this
flanger;
• Finally, it's time to check the Stereo Offset. This changes the stereo image, by
offsetting one of the channels from -100% to +100% according to the knob value.
Try it and check the effect. You may even try it with each of the waveforms. You'll
notice that the Offset reacts differently with each waveform. That's because the
result depends very much from the stereo image it begins with.
These are just some examples of what you can do with Flanger BL-20. Despite looking
simple, it offers much more than you could imagine by just the looks, especially when
tools like the Zero Crossing, the different modes combined, or the ones in the Advanced
panel come into action. As always, use your imagination, and try to find other creative and
interesting ways of using the tool.
Flanger BL-20 after playing with the Regen feature a few times. We also
have pressed the three Control Mode buttons, the External Envelope button
and the Reverse Sweep button, to show some extra options, although,
during this hands-on, we only used a single mode at a time. The selected
waveform in the Auto Shape is the square, which we found great for
getting stereo ping-pong effects.
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4. FLANGER BL-20 CONTROL PANEL
The Flanger BL-20 plug-in can be used in Mono, Stereo or Mono-to-Stereo configurations,
independently of the source material.
The Mono configuration is automatically loaded when we use the plug-in with mono tracks.
When inserted in stereo tracks, the Stereo configuration is automatically loaded as well.
When the plug-in is instantiated as Mono-to-Stereo, as in Pro Tools for example, there is also
a different configuration.
Nevertheless, when instantiated in stereo tracks, you can change the desired configuration
by pressing the Mono/Stereo button, located in the upper left side of the Main Control Panel,
right after the Power button. By default, this button is selecting the Stereo Mode, but we can
"monoize" the source signal by selecting the "Mono" mode.
♪: Not all DAWs are able to work with mono tracks, in which case you will not be able to use the
mono configuration. The same applies to the mono-to-stereo configuration.
4.1. Channel Configuration (Mono/Stereo/Mono-to-Stereo)
The difference between the different configurations consists in the following:
When instantiated in stereo channels, the plug-in loads in full mode, featuring the Mono/
Stereo button and the Reverse Sweep O/P 2 switch in the Main panel and the Stereo Offset
control in the Advanced panel.
When instantiated in mono channels, the plug-in doesn't have these three controls, since
they only act in stereo signals.
When instantiated as mono-to-stereo, we have the Stereo Offset control and the Reverse
Sweep O/P 2 switch, but the Mono/Stereo button is not present, since the source signal is
mono. Bear in mind that, when used with mono sources in the mono-to-stereo configuration,
the source signal remains mono, but the processed signal will have some stereo definition
and depth, hence the presence of the other two controls.
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4.2. Main Control Panel
The Flanger BL-20 Graphical User Interface is very simple, as it follows the original unit
control panel, which was also very simple. The Main control panel is where the main flanger
controls are located, and is the one that opens by default when we launch the plug-in.
But Arturia included some extra modulation features. These are located in a second panel,
the Advanced control panel, that opens when we click the double arrow button (the
Advanced Mode button) in the Upper Toolbar.
As is the case with the previous effects bundles, as well as with all current Arturia plug-
ins, this GUI also has an Upper Toolbar and a Lower Toolbar. The Lower Toolbar is very
important for the use of the Arturia plug-ins, as it allows the Undo and Redo functions, lists
the editing history, has a Panic button to prevent damage in case of audio accidents, allows
you to put the plug-in in Bypass (which doubles the Power button in the Main control panel),
and measures CPU consumption.
Of course, the Upper Toolbar is very important as well, since it is where we access the main
menus, perform important tasks like loading and saving presets and banks of presets, and
where we can select a preset and see the name of the current preset in use. The toolbars
and their features are covered in detail in the User Interface chapter [p.23].
We will now have a look at all the controls available, explaining what they do, what are their
ranges, and how to interpret the numbers.
Notice that each time we click a control (knob or button), or simply hover the mouse over it,
the Lower Toolbar displays the parameter name at the lower left. Also, a small pop-up box
appears at the right side of the control displaying the current parameter value. This changes
every time we move that control, updating the parameter value in real time. These values
aren't always of the same type.
Now, let’s take a look at each control in Main Control Panel.
4.2.1. Power
Power button turns the plug-in on and off. In practice, it works as a bypass button (when
turned Off), and has the exact same effect as clicking Bypass in the Lower Toolbar. By
default it is On, obviously.
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4.2.2. Mono/Stereo
This switch has two positions: Stereo and Mono. When in Stereo, we have full stereo
processing. When in Mono, the source signal is "monoized" (Left and Right inputs are
summed before processing).
♪: The Mono/Stereo switch is absent when the plug-in is instantiated in mono channels, either as
mono or mono-to-stereo, since there is no stereo signal to start with.
By default, the switch is in the Stereo position.
4.2.3. Zero Cr.
This button/switch activates the "Zero Crossing Mode". This is a mode that didn't exist in the
original unit.
When activated, it inverts the polarity of the modulated signal and delays the dry signal of
the mean delay curve, so that we have this specific zero crossing effect. The resulting effect
is an increase in the undulating characteristic of the sound.
Usually, flanging is additive. This means that the delayed signal is summed to the dry signal,
creating the expected peaks and valleys that are the result of comb filtering.
But what happens if we subtract the modulated signal, instead of adding it? Subtractive
flanger is pretty similar to additive flanging. It has to, since we are still combining two
waveforms, except that the modulated waveform is 180 degrees out of phase. This means
that there will probably happen more cancellations, hence more comb filtering.
Well, we'll just say that the result will still be a flanger effect, but a little stronger. You may
prefer thicker, wetter, etc. Better try it and listen for yourselves how it sounds. To subtract,
we need to invert the modulated wave - that's what the Zero Cross button is there for.
By default Zero Crossing is off.
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4.2.4. Mix
Mix controls the amount of modulated signal versus the dry signal. It also changes the way
the final sound behaves. At 50% (the default position, labeled as Doppler) we will notice a big
presence of the "whooshing" and "undulation" that are the main characteristics associated
with the flanger effect. At 100%, the delayed signal takes over, and the Flanger can be used
in a send track.
4.2.5. Regen
Regen(erator) is a control for the feedback amount. Feedback is where we control how
much of the delayed signal is reinjected into the audio circuit.
Feedback is very important, since it allows to increase the characteristic comb filter effect.
This effect occurs because the fed back delayed signal that is combined with the original
dry signal was modulated by the LFO, therefore changing the phase relations. The resulting
combination will produce some peaks and valleys in the sound, which graphically may
resemble a comb (hence the name "comb filter"). This filtering effect is a very important part
of the flanger "sound" we are all used to.
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4.2.6. Control Mode
Control Mode is very important for the overall behavior of this effect unit. The main section
of this control has three switches: Manual, Env (Envelope Follower), and Auto. These can be
combined together. This means we can use each one of the modes, two of them combined,
or ALL OF THEM combined. The resulting modulation will be the sum of each modulation
source.
Above the buttons, we have a row of "LED lights" that will show the combined "movement" of
the effect, accordingly to the way the different controls act on the modulation.
By default, only the Auto switch is On. This is the mode where the flanger effect is
automatically controlled by the internal LFO. By default, the LFO shape is a triangle wave,
but this can be changed as well, as we will see below. By pressing any of the other two
buttons, we activate each of the other modes. Each activated mode adds itself to the sound.
4.2.7. Manual
When this button is switched On, delay time is controlled with the Manual knob. It can also
be controlled by a function set in the Function Generator, when the “Add To Manual” button
is switched On.
In this case, the function applies unipolar modulation on delay time, which is summed with
the Manual knob’s value.
The Manual control knob is a single knob, with intensity measured in percentage, from 0%
to 100%. By default, it is positioned at 50%.
Beware that, if the Manual knob value is too high and you choose positive values for the
Function Generator Amount, or too low and you choose negative values for the Function
Generator Amount, there will be little space for the Function Generator to work. FG amount
adds to the Manual knob amount - both values will be summed. If you intend to also use the
FG, it's better to start with the Manual knob at 50%, and then choose what to do.
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