Modulation FX from Arturia

Always busy there in beautiful Grenoble, France, Arturia have introduced a number of new FX plug-ins this year (as well as some astounding hardware and software instruments, if you have kept up with the news). The three new modulation FX model three iconic studio and stage boxes that were all the rage in the 70’s, 80’s and 90’s, and are still sought after for their iconic effects. We have a chorus unit, a very flexible flanger, and an extremely flexible phaser.
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What are They?
The Arturia Modulation FX are part of Arturia's growing range of classic gear emulations and include the Chorus Dimension-D, an emulation of the famed Roland Dimension D SDD-320 rack mount unit introduced in 1979, the Flanger BL-20 modeling the very rare B.E.L. BF-20 Stereo Flanger from the late 70’s, and the Phaser Bi-Tron plug-in that recreates (and expands) on the famous Mu-Tron Bi-Phase pedal produced by USA company Musictronics in the 70’s. Actually, as with other Arturia recreations, all the units expand the capabilities of the originals. And as with all Arturia software I’ve used, the audio and FX quality are excellent. Each of the new Modulation FX is available for $99, a “steal” compared to the going price for 30 to 40 year old used hardware.

A New Dimension
The Roland Dimension D SDD-320 was used by many 80’s acts including Brian Eno, Talking Heads, Peter Gabriel and more. It was heard in in everything from Pop to New Wave, used on about everything from basses and guitars to vocals. The Roland Dimension D was unique in that there are almost no controls, at least no knobs to vary settings.


Original Dimension-D panel at the top with Advanced panel below

The original had six buttons – well, seven if you include the power switch. That was it. It used a bucket-brigade delay system to create a chorus effect and the results were beyond expectations for such a simple looking device. The left most Mode button switches the dry signal from stereo, if the source is stereo, to mono (the processed wet signal is not changed). This changes the overall effect making the dry signal centered while allowing the processed sound to dominate the sides. The five “Dimension Mode” buttons actually provide seven different levels/types of chorusing – the red button turns off the bucket-brigade chorus effect, but includes some color and filtering from the compressor, expander and filter circuits. The buttons labeled 1, 2, and 3 each provide a different level of chorusing, from least to most respectively, while button 4 “supercharges” the effect of each of the first three buttons by injecting more wet signal in the output. So you can use Red or 1 or 2 or 3 or 1-and-4, 2-and-4, or 3-and-4. That’s it for the classic Roland Dimension D SDD-320 unit.

However, Arturia have added an Advanced Mode Control Panel accessed by clicking the Advanced Mode button in the Upper Toolbar which adds additional controls for LFO waveform (five settings to control the stereo movement patterns), a four position control for warmth (saturation level), a stereo width control and a wet/dry knob to provide parallel processing. This added panel greatly expands the sound processing capability.

And as with all Arturia plug-ins there is an upper toolbar to access the main menus to import. export, load and save presets and banks of presets (there are eight factory presets included), change the GUI window size and access the user manual. Arturia also provide a Lower Toolbar that features an output gain control I found very handy, the Undo and Redo functions, provides an editing history list, a Bypass function (that duplicates what the main Power button does, fully bypassing all processing), and a CPU meter for the plug-in (which never showed much on my system since CPU use with the Chorus Dimension-D is very low).

How does it sound?
In short, this emulation sounds like the descriptions I found of the original hardware – a 1984 article stated “The actual effect can best be described as a subtle chorus with a definite increase in 'upfrontness' and image width”. It is a very subtle chorusing effect that seems to create more of a spatial enhancement than audible ‘warbling’. It can do this for a mono input as long as you provide a stereo track for the output, and of course it enhances stereo inputs. I found the effect very pleasing on a range of tracks, even lightly applied occasionally to a full mix, such as during a chorus (no pun intended!)

Drag that Flange
The Flanger BL-20 emulates (and extends) the rare B.E.L. BF-20 Stereo Flanger which was designed by Genesis guitarist Mick Barnard, and became the go-to flanger for many bands and studios in the 80’s and beyond. An ad from a British periodical in 1980 described it as “The B.E.L. BF20 Stereo Flanger is a true stereo unit with separate circuits. Which enables flanging of a stereo mix without upsetting the stereo image – £450”. That’s about US$2,595 in today’s money. Not an impulse buy! The B.E.L. BF-20 Stereo Flanger was priced for pros, and original units are still sought after today, but only rarely found. You can hear the BF-20 on many “classic” recordings by artists such as Phil Collins, The Rolling Stones, and Yes.


Original Flanger panel at top with Advanced panel opened below

As with all Arturia FX, there is the upper and lower toolbars previously described (and 42 factory presets are included), and the double-arrow button in the Upper Toolbar that opens up an advanced panel shown in the above view, below the original “rack-mount” main panel. You can see it adds significant enhancements to the modulation capabilities.

Like the Dimension-D it used a Bucket-Brigade Delay chip (actually two of them), and also incorporated filters, compressors, expanders, and feedback paths with eight buttons and seven knobs to provide a wide range of control. On the left there is a power button that turned off the original unit and in the Arturia BL-20 totally bypasses the effects, as does using the Arturia Bypass button in the lower toolbar. Next is a Mono-Stereo button that sums the left and right input signals of the dry path leaving the processed signal stereo. The mysterious Zero CR button when activated inverts the polarity of the wet signal and delays the dry signal to enhance phase cancellations and provide more comb filtering for a different flanging “flavor”. And on the far right is another mysterious control, Reverse Sweep O/P 2. Yes, this is exactly like the original hardware – reverse sweep again changes the flanging tone and creates stereo widening as well as motion in combination with some other settings. You can probably understand why this flanger was so popular back 40 years ago.

And there is more! The Wet/Dry mix control, a Regeneration adjustment that feeds signals within the processor back in the process, and the whole Control Mode section that is just amazing. You can select how the flanging is controlled, from manual to auto-rate (with tempo sync if desired) to an envelop control . . . and you are not limited to one of these choices! It would take me too many paragraphs to describe it all – and I’m still describing the controls of the original BF-20 Stereo Flanger!

As usual Arturia have more “up their sleeve” with the advanced panel that adds some very useful features. There is a hi-pass filter to prevent the effects from flanging low frequencies which could lead to “wandering bass sounds” and a Function Generator that enables applying a number of preset curves or your own originals curves to “modulate the modulations”, and it can be tempo-synced to create fabulous repetitive flanging. The Function Generator is a very powerful and flexible way of further controlling the flanger effect as an alternative or in addition to using the LFO and/or the Envelope Follower. Flexible indeed! There is an LFO shape selector with five choices (the original unit had only a triangle waveform) and a Stereo Offset control which, depending on other settings, changes the tone and behavior of the Stereo image. The final result varies with the input signal as well as with all these control settings since stereo sources will already include some level and phase differences.

How does it sound?
Simply – Wow! I was quite surprised at the range of FX I could generate, from subtle modulations to extreme modification of the source tracks. Pretty much impossible to describe with words, but you can hear some samples on the Arturia site and you can test drive any of these FX.

And the Last But Not Least, the Bi-Tron
The real monster in these latest Arturia releases is the Mu-Tron Bi-Phase pedal which found application for decades in many studios and with many bands, including The Smashing Pumpkins for the "pumpkins sound" of their 1993 album Siamese Dream. It is actually two separate phasers that can be used independently or combined in many ways to produce an almost infinite range of phase modulation effects.


Bi-Tron with default pedal mode

The original Mu-tron had an optional pedal which provided two types of control – it could directly control the sweep generator “position” or its rate. The Arturia Phaser Bi-Tron includes a virtual pedal that you can control with a physical pedal should you wish, which can control both Sweep Gen 1’s rate and/or generate a CV signal to directly control the phase shift. In addition the pedal GUI can be switched to an Envelope Follower control panel.


Opened pedal view showing the Envelope Follower controls and small Advanced settings panel at the top

And of course there is an advanced control panel and all the usual upper and lower toolbar features. In this case the advanced window opens at the top of the GUI and has just a few extra controls, but the Phaser Bi-Tron itself has such a wide range of control already that I don’t know what more they could have added!

Basically you get two phasers with individual controls and the ability to “wire” them in various series and parallel manners. Note that using a mono source signal on stereo track (which both my DAWs can easily handle) will result in an output with a stereo image and possible motion in the stereo field, depending on settings.

This is a fairly complex “box” and the manual has good tutorials on setting it up for a number of uses. What I will say is, Wow again! I found I could get anything from subtle modulation effects to complete transformation of sounds with the more extreme settings, for example turning drum mixes into totally different tones that still played the input rhythm.

As with all Arturia FX you get a preset window (38 factory presets) where you can quickly pull up a factory preset or save/recall your own. And there are the upper and lower toolbars as previously described.

Flanger/Phasor – What?
Flanging is a fascinating effect first noticed back in the day when tape machines were used to record and edit music (although Les Paul apparently played with the effect using two disk players as early as the late 40’s – but then Les was always way ahead of everyone else!). Flanging is created when two identical signals mix together and one signal is delayed by a small and gradually changing time to produce a swept comb filter effect. In the bygone tape days when using tape machines to edit, the effect was heard when one of two source machines was slowed using a finger on the flange of a tape reel. The effect became popular in the mid-60’s and by the mid-70’s the flanging effect had been reproduced electronically.

Both flangers and phasers use constructive and destructive interference to create their effects, but there is a difference in the process and results. Flanging relies on adding the source signal to a uniformly time-delayed copy of itself, which results in an output signal with peaks and troughs which are in a harmonic series. Phasing uses what are termed all-pass filters which have a non-linear frequency-phase response, resulting in phase differences in the output signal that are a function of the input signal frequency. Different frequencies in the source signal are delayed by different amounts of time and when added to the source signal result is peaks and troughs which are not necessarily (or usually) harmonically related.

Technical Details
In my test system (PC Audio Labs Rok Box PC with Windows 7, 64 Bit, 4-Core Intel i7-4770K, 3.5 GHz, and 16 GB RAM) each of the Modulation FX had 48 samples of latency, a mere millisecond at 48 kHz one-way. They did vary in CPU resource requirements with the Chorus Dimension-D needing only 0.22% of total CPU resource as measured in REAPER, the Flanger BL-20 needing 0.3% total CPU and the Phaser Bi-Tron, as I expected, uses the most at 1.25% total CPU. Still, very light loads for such complex processing.

Conclusions
Excellent emulations of classic outboard modulation gear – three of the best. Each is unique with the Dimension-D providing the most subtle effects and both the Flanger BL-20 and the Phaser Bi-Tron able to completely re-image an instrument or mix. Definitely worth checking out if you produce any style of music other than, maybe, symphony orchestra recordings.

https://www.arturia.com/products/sof...undle/overview