Review – Blue II: Bluer than Blue?

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If you’ve been thinking about picking up a Rob Papen synth but haven’t been able to decide on one, Blue II would make an excellent choice.  Find out why in this review.


by Jon K. Carroll, Nov. 2014


Noted synth programmer and sound designer Rob Paper released the original Blue in 2005. It delivered a mix of FM and subtractive synthesis, and later added Phase Distortion and wave-shaping to its arsenal of tone-shaping capabilities.

Blue II takes that basis and extends it by adding more filter modes, two more FX blocks, and the X-Y pad from its additive synthesis brother, Blade.


FM+ Subtractive = “Crossfusion Synthesis”

At least, that’s what Rob Papen calls it.

According to legend, techs working on Yamaha DX7s back in the day noted that the units coming in for service rarely had sounds in them that were not either presets originally on the unit, or standard presets available elsewhere. True or not, it demonstrates the difficulty with programming hardware FM synthesizers.

With Blue II, we are presented with a panel of six oscillators. These reflect a wide selection of waveforms, from basic analog-style waveforms like sine, saw, square and triangle, and more complex analog waveforms like rezsaw, through additive  waveforms, spectral waveforms, and even mono and stereo samples. The manual says it has “dozens” of oscillator types.  I tend to believe it but really don’t care to sit here and count them to get a precise number.

The thing is that’s all well and good. Lots of oscillator types, plus lots of filter types (36 filter modes) means a large variety of sounds, right?



Now we look into the algorithm display, where we control how the six oscillator sounds are combined. There are 32 algorithms, starting with the above, which gives you fairly straightforward subtractive synthesis.


Here is a more complex algorithm, pretty much randomly chosen. Oscillator A is frequency modulating Oscillator B. Likewise Oscillator C modulating E, and D modulating F. There are even setups where the oscillators are stacked- algorithm 26 has A modulating B modulating C modulating D modulating E modulating F… (takes a breath) giving you some really complex FM modulations.


If you prefer, you can set these using the FM Matrix, which allows you to set the precise amount of modulation from each oscillator. The handy Presets button lets you flip the Matrix through the presets shown on the Algorithm screen, and then work from there. Though the two methods can be made to work similarly, they can produce drastically different results.

Also, this window is where you can switch between Phase Modulation (the FM algorithm used in the DX7) and true  FM. Note that this makes drastically different sounds.




Blue II has a wave-shaper that can use either phase distortion or wave-shaping to reshape each oscillator’s waveform.  You draw the shape into the window and the windows to the side show you what the resultant waveform look like. In this way you can take the “stock” waveforms and reshape them into something completely new.


Envelopes, Envelopes, and More Envelopes

Of course, controlling all this by hand isn’t very entertaining. Blue II provides a comprehensive set of envelopes – one envelope per oscillator, one for each filter, and one separate Volume envelope. The envelopes are ADSR envelopes with adjustable slope (curvature) on the attack, decay and release stages. The Sustain stage also has a fade control. Adjusting the Volume envelope visually here also adjusts it in the Amp state, as they are the same envelope.


Then there are four ‘multi-env’ envelopes with up to sixteen stages, with adjustable curves in between. These are used to control things through the mod matrix.




Instead of a standard and fairly limited LFO section, Blue II provides one PWM LFO per oscillator,  one per filter, separate tremolo and vibrato LFOs, and four “free LFOs” to be assigned to any destination. Each LFO has six possible waveforms, is syncable, and features separate attack and decay face parameters along with other wave-shaping capabilities like smooth and humanize.


All this is augmented by a twenty-slot mod matrix with a quick and easy click to bypass area. The mod matrix sources include MIDI CCs, LFOs, oscillators, envelopes and other controls, with even more destinations. This same area is also where you can use Key Scale and Velocity Scale, which allows you to use the key number and velocity as scalable modulation sources.


The last modulation source is the modulation sequencer, which gives you three 32-step sequencers. Like the multi-env envelopes, these are routed to destination(s) using the mod matrix.


Arpeggiator and Step Sequencer


Blue II also features both an arpeggiator and a step sequencer, patterned after the ones in other Rob Papen synths.  They can be up to 32 steps long, and can send note values and velocity for each step.  The step sequencer gives you an adjustment at each step for both filter A and filter B, and both have a free modulation slot that can be routed using the mod matrix.


The X-Y Pad


Somewhere between being a modulation source and a performance tool is the X-Y pad, brought over from Rob Papen’s Blade additive synth. It gives you an X-Y pad with four adjustable modulations at its axes, and with four positions, a total of sixteen modulation destinations. It can either record your movements (with up to 128 editable points) or you can play it live to add motion to what you are playing. Quite a step up from that old SY-22 you have laying around!


The Sound

Alright, you say, but what does it sound like?

Given that it can combine two different forms of synthesis – namely, analog-style subtractive synthesis with digital-style FM synthesis, you can get your  typical analog and digital sounds as well as sounds that are a stunning hybrid of both, with all the breadth and shimmer and motion you care for as well as being able to produce simpler bread-and-butter sounds. FM and analog basses, pads and leads are all well within its capabilities. If you’ve been thinking about picking up a Rob Papen synth but haven’t been able to decide on one, Blue II would make an excellent choice due to its excellent all-around capability.

Systems used for evaluation:

Samsung RF710-S02us, Intel Core i7-720QM processor, 8 GB RAM, TASCAM US-1640 audio interface

Homebuilt system- Core2Quad 8300 2.66 GHz, 4 GB RAM, Realtek audio chipset + ASIO4All

HP z600, 2x Xeon E5520 2.26 GHz, 24 GB RAM, Echo AudioFire 2 audio interface

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