Steve Turner

RUN

The Quad Variable LFO (QV-L) is the third eurorack product released by Five12 and has been designed to function with or without their flagship Vector Sequencer.  In my experience, despite all the deep sound design options available, it is a very easy module to get into and use to make music.  

Do not let the length and depth of this article put you off getting straight into the QV-L.  The QV-L is incredibly intuitive if you already understand LFO (low frequency oscillator) synthesis functions.  If you need some refreshers on LFOs then youcould do a lot worse than head over to Chris Meyer's Learning Modular site.  In fact, here is a link to the fundamentals.

Disclosure.  I was involved in bug identification and feature testing & was provided a QV-L prototype for this purpose.  This article is not written as a review, but rather an explanation of what the module does and informal user operational guide.  

You can also watch a 17 minute run through the basic featurs on youTube.  Like and subscribe (lol) but please, yeah, like and subscribe.   

THE BASICS 

Things you need to know before proceeding

• The QV-L user interface is divided into two sides (Side A and Side B)
• Side A: the left OLED and left three knobs. Used to manage LFO and OUTPUTS 1 & 2
• Side B: the right OLED and three knobs. Used to manage LFO and OUTPUTS 3 & 4
• When you enter Edit mode, both OLEDs are used to show parameters for the function you are editing
• The LED lit buttons have various functions which will be explained later
• CV inputs 1 to 4 can be used for external (assignable) modulation
• Output Jacks 1 to 4 may be assigned to any LFO as a source
• Gate 1 and 2 can be used for external clocking, wave reset and so on

GETTING INTO IT

Navigation

• Press Edit A to navigate forwards. 
• Press Trig A (Back) to navigate backwards
• Long press TRIG A to return to the Output (main) page
• When editing side A, press Edit B to move to the parallel page on Side B
• When editing side B, press Edit A to moove to the parallel page on Side A
• Example - if you are editing LFO 4 (Side B) and press EDIT A then you will move to LFO2 (Side A)
• Simultaneously press EDIT A and EDIT B to access Presets & Preferences (Load, Save, Init) 
• Press EDIT B from the Preset screen to see your firmware version

On the Surface

• 12hp wide, 150ma (+12), 20ma (-12)
• Dual OLED screens 
• 4 (LED lit) buttons for navigation, edit modes etc 
• 6 knobs with assignable functions (2 sets of 3)
• 4 CV Inputs (assignable) 
• 4 Output Jacks (assignable)
• 4 Output Jacks (assignable) 
• 2 Gate Inputs (assignable)
• Backplane 8 pin connector to Vector Sequencer (i2c) 

Comes with 

• 8 to 8 pin cable for backplane connectivity to the Vector 
• 16 to 16 pin power ribbon cable

Beneath the Waves

• Functions with or without a Vector Sequencer
• 48 preset memory
• 4 LFOs 
• 4 Outputs
• 8 configurable cross modulation functions for internal routing (4 per Side)
• 2 envelops (A/R) to shape LFO performance (1 per side)
• Route LFOs to external outputs (1 to 4) 
• Clocking - INTERNAL, EXTERNAL from (i) gate inputs or (ii) from Vector via backplane using i2c
• Clocking can be set per side (e.g. independent clock settings are possible for LFO1/2 and LFO 3/4)

Vector Integration

• On release, BPM SYNC is routable from the Vector to the QV-L.  
• More Vector to QV-L functions will be included in later firmwares

THE PAGES

DEEPER...

IMPORTANT: where pages of the QV-L are used to configure the same functions on Side A and Side B of the module I have collapsed those elements to single descriptions. 

Page 1 - Home

The OLEDs display all four QV-L Outputs.  You can (and should) customise the functionality of the Side A and Side B knobs as controllers for your main performance settings.  See CUSTOM A and CUSTOM B below in this document, or in the above table, regarding how to customise knob functions.  

Page 2 & 4 - LFO 1 & 2, LFO 3 & 4

This is where you configure the most generally used settings to create an LFO. 

Wave refers to the basic shape of the LFO and includes the usual suspects as well as some fun options.   At release the wave forms include SIN, TRI, forward & reverse SAW, forward and reverse Shark Fin, SQR, S&H.  There are also some evolving wave forms that shift between SIN & TRI, SAW & TRI, SAW & SQR, ascending and descending STEP, ascending THEN descending STEP, SIN to SAW to SQR, lengthening SQR, Lorenz Attractor, Perlin Noise, Logistic Modular.  That is rather a lot, and there will be more.  

SIN, TRI, SAW and SQR are common wave forms but if you need a refresher this article is a good place to start, and also this interactive page is a lot of fun.  Now, lets look at the less common wave shapes within the QV-L

Lorenz Attractor:  I am not going to pretend to be a mathemetician but instead go striaght to Wikipedia.  Here is what the hive mind says about the Lorenz system.  Alternatively, think of it as a butterfly and get on with your day.  Regardless, set LOR as your wave form and mess around with the rate and level.  You will quickly see how this algorithm can introduce constant variation to your modulation targets.

From Wikipedia - The Lorenz system is a system of ordinary differential equations first studied by mathematician and meteorologist Edward Lorenz. It is notable for having chaotic solutions for certain parameter values and initial conditions. In particular, the Lorenz attractor is a set of chaotic solutions of the Lorenz system.  In popular media the "butterfly effect" stems from the real-world implications of the Lorenz attractor, namely that in a chaotic physical system, in the absence of perfect knowledge of the initial conditions (even the minuscule disturbance of the air due to a butterfly flapping its wings), our ability to predict its future course will always fail. This underscores that physical systems can be completely deterministic and yet still be inherently unpredictable. The shape of the Lorenz attractor itself, when plotted in phase space, may also be seen to resemble a butterfly.

Perlin Noise: really cool words I dont understand

Logistic Modular:  really coool words I dont understand

Rate is the speed at which the LFO will cycle from start to end, and there are various settings including free running as Hertz, clocked (internally and externally), or sync reset from external.    

Rate as Herz  (based on MODE settings)

• Wide: 0.17 to 246 Hz  
• Slow: 0.01 to 16 Hz  
• Hz: Integers 1 to 127 Hz  

Rate as Musical Divisions (based on MODE and CLOCK settings)  

• 16th: 1 to 127  
• Beat: 1 to 127   
• Bar: 1 to 127 (where a bar equals four beats.  Let that sink in.  That LFO is older than Middle Earth) 

Shape median setting is 50 and increasing Shape will create an assymetric wave where more time is spent above 0 volts and less time below zero volts. The higher you dial Shape the more assymetric the wave becomes.  You can create some really fun LFO shapes from basic wave forms by dialing Shape. Likewise, reducing shape below fifty creates an assymetric wave favouring below zero volts.  Dial it and watch the screen.

Mode allows setting of Herz or musical division based LFO speeds.  This setting determines what is available in the Rate function.  Options are Wide, Slow, Hertz, 16th, Beat and Bar.  These settings are explained in the Rate section above.  

Phase denotes the start and end point of a complete wave cycle.  Increasing the number from zero moves the start/end point further along the wave shape.  This is very useful when you have a sync input via gate, or are clocking your LFO.

Page 3 & 5 - Outputs 1 & 2, 3 & 4

This page allows you to configure which LFO is route to an Output and add additional functions to your signal.

Source denotes the LFO (1 to 4) that will be fed to the Output.  

Op: None, Invert, Rectify, Rectify Invert, 0-5V, 5-0V, -5 to 0V, 0 to -5V defines the scope of the LFO range in voltage metrics

Offset moves your 0 point up or down in the possible output range.  If you do not also motify LEVEL then your LFO may clip at the top or bottom of the voltage range.  

Level denotes the voltage range applied to the wave shape.  Lower level will mean less of a wave movement.   

Page 6 - Modulation A1 & A2, B1 & B2.  Page 7 Modulation A3 & A4, B3 & B4 

Source sets the (guess gues guess) source for your modulation routing. 

Destination is the (guess guess guess) destination

Amount is like an attenuator on the source input.  

MOD A1 gives you 2x modulation source, destination and amount routing options.  MOD A2 gives you 2 more of the same.  So you have 4 modulation routing options per QV-L side (A or B).  

Page 8 - Reset A & Envelope A, Reset B and Envelope B 

Reeset should be self explanataory and allows you to set the reset sources for LFO1 and LFO2, as well as the Envelope.

The envelope options are Attack, Release, and Attack, Sustain, Release.  

Page 9 - Custom A & Clock A, Custom B & Clock B 

For customisation of knob functions please see the table above.  This screen allows  you to set the elements applied to each knob as well as what presents on the home screen.  

You can set clock independently per Side (A or B).   Sources are Internal, Gate 1 or 2, Vector.  You can connect the Vector to the QV-L using the supplied cable.  The Vector will always send clocking infomation so all you need to do is select the Vector as the clock source on the QV-L and you are off to the races.  Whatever that actually means.  

FIRMWARE UPDATE (HOW TO)

• Turn your rack power off and remove the QV-L from your rack
• Eject the SD card.  Give it a short lateral press and it will spring out.  Do not lose it in your case 
• Mount the SD card to your computer and view the USB drive content 
• Decompress the new firmware file, noting that the file is QVL.BIN 
• Delete the current QVL.BIN from the SD card 
• Copy the new QVL.BIN to the SD card 
• Remove the SD card from your computer and mount it back into the QV-L 
• Reconnect power ribbon to the QV-L (but do not turn on), and Install the QV-L to your eurorack 
• Turn on your eurorack power while holdin TrigA on the QV-L 
• Press TrigB to update the QV-L firmware.  
• The QV-L will restart with the new firmware loaded

CONCLUSION

Pros 

• Collapses functionality of a number of core eurorack and sound design utilities into a neat 12hp module
• Great depth and super capable, but also easy to get up and running using basic settings
• Preset storage means you don't lose your work.  Recall past settings at will
• Screens and font choice are good enough to be readable from a range of angles
• Scopes make it easy to see what you are doing, monitoring LFO movement and OUTPUTS
• Firmware updates will expand core functionality and deepen integration with the Five12 Vector Sequencer

Cons 

• You will want more than one QV-L

More information - Five12

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