Review – Exploring the World of Rob Papen FX, Part 1

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Rob Papen, probably best known for his outstanding software synths, also produces FX modules, and does so with the customary aplomb we’ve come to expect in his designs.


by David Baer, Nov. 2017


If you are familiar with Rob Papen software synthesizers, especially any of the ones in his marvelous trio of Predator 2, Blue II and Blade, you will know that Papen synthesizers are something special.  The entire collection is bundled in Explorer 4, which in my estimation would be a great value at its price if it only contained those three just-mentioned instruments.  Explorer 4 is officially priced at $499 USD but can be had at any time (not awaiting a sale) for $348 just by taking advantage of a simple alternative buying strategy which is trivial to figure out.  Papen software is available in all standard formats, both 32-bit and 64-bit, and is compatible with all major DAWs.  Registration is customer-friendly and requires no dongle.

While best known for synthesizers, Rob Papen also has produced five FX plug-ins that can be purchased separately (with one exception noted shortly), but also are included in the Explorer 4 bundle.  Selling FX modules must be a tremendous challenge these days.  Just consider delays or reverbs; in the last couple of years we have seen a number of absolutely outstanding offerings in both categories introduced.  Competition is bad enough because of that, but DAW manufacturers have been continually upping their game with notable FX bundled with the main product as well.

So, as excellent as Papen FX are (and they are in fact quite good), it’s easily understood why the typical home studio producer may be lacking interest in considering the acquisition of even more FX unless something comes along that is totally unique and unlike anything seen before.  On the other hand, there may be quite a few owners of the Explorer 4 bundle who have not bothered to go beyond getting to know a few of the included synths.  If you are one of those people then this two-part article is especially for you.  You have some notable software at your disposal that you should not be overlooking.

In this installment, we will look at RP-Amod (chorus, flanger, and much more), RP-EQ (more than just another EQ plug-in) and RP-Dist (distortion with additional competencies).  In Part 2, we will complete the survey with coverage of RP-Delay and RP-Verb 2.

First, here are a few general comments that apply to all.  Most significant, perhaps, is that these are all Rob Papen products, so it should come as no surprise that there are generous numbers of factory presets to be found in each of them.  Also, again in the tradition of Papen design, every one of these effects has design nuances that are extremely well thought-out and even elegant. 

The UIs are all clear and easy to use.  For a number, but not all, there are both dark and light skins.  As I have a preference for the white versions, one of my few complaints is that two of the plug-ins have only the black skin.  But this is not a major dissatisfaction.

Finally, the documentation is quite good.  There are a few minor errors, but nothing that’s not rather obvious.  On top of that, the UIs are easy to understand, and the need to even go to the documentation is infrequent.



The first module we’ll look at is the one that cannot be purchased directly.  It is part of the Explorer 4 bundle.  Otherwise, it is a free download to anyone who has registered another Rob Papen product.

This is one of the FX that has a dark and a light skin.  Both are shown below just so you can get an idea of the contrast between these options.


There are two independent modulation units.  These can be run in several routing configurations: in parallel, serially, or in a two-band mode with cutover slopes of 6, 12 or 24 dB per octave.  One of the modulation types is no modulation – you are not required to use both modulator units.  Furthermore, you can use the two-band option with only one modulator doing its thing, if such is your desire.

The modulation types are:

No Effect

  • Chorus
  • Tape Chorus
  • Ensemble
  • Flanger
  • Tape Flanger
  • Phaser
  • Analogue Phaser
  • Tremolo

All modulations are driven by an LFO type process; the waveform choices are sine, triangle, saw up, saw down and square.  The LFO speed may be synced to host tempo.

The knobs in the second row of each modulation unit change depending upon modulation type selected.  As an example, here are the controllers for the tape flanger:

Length – Sets the delay time for the flanger effect

Width – Sets the intensity of the flanger effect

Feedback – Feedback of the flanger

Speed – Control to adjust the speed of the tape playback

LP Filter – Low pass filter frequency

HP Filter – High pass filter frequency

Pan Mod – Level of modulation to the panning of the effect signal

Both modulator units have independent volume and panning and each have their own pan modulation capability.

So there you have it: a very simple but capable plug-in that’s both effective and easy to use.  The only remaining things to mention are the factory content presets, of which there are something in the neighborhood of 200.  If you don’t have experience in effectively using modulation in your mixes, the presets provide a master class.  Many of these applications are fairly obvious once you’ve seen them in action, but there are lots of great ideas here using combinations you might not have considered trying.  One final point – if your thing is synthesizer music production, RP-Amod should especially appeal to you.





Next we look at RP-EQ, which you may not be surprised to learn is more than just an EQ.  It can also be a creative mixing effect that transcends the normal commonplace role of an EQ.  But even as just a conventional EQ, RP-EQ is definitely worthy of your attention if you don’t already have a high-end graphic EQ plug-in in your arsenal.  RP-EQ will not displace Fab Filter Pro-Q2, should you own that, nor will you likely use it in preference to Steinberg’s fancy new Frequency EQ that comes in Cubase 9.  But if you don’t already have a top-of-the-line EQ plug-in, RP-EQ could easily become your go-to choice.

Let’s start with the usual EQ function.  In stereo mode there are eight bands, all of which are bell bands.  There are no alternate band types at the low and high extremities.  One can easily get a bell curve to do much the same thing as a shelf, however, and low-cut or high-cut type filter is served by another RP-EQ feature you’ll see momentarily.  At two-tab structure exposes the details of each band.

RP-EQ has a mid-side mode.  In this case, bands 1 thru 4 are mid and 5 thru 8 are side.

The graphic depiction of the overall EQ curve is shown above the details tab.  To adjust the EQ frequencies and band widths, you may use the mouse in the graphic depiction or adjust the knobs below in the details tab.  There are two Solo buttons.  The first (Visual Solo) removes all the other curves in the graphic depiction.  The second, BW Solo, takes all other bands out of the audio manipulation (it does not, however, limit the output to just the soloed band.  One very nice feature is that you may specify frequency values by Hz or by note number.

Above the main EQ panel is a spectrum display.  You have the choice of displaying input and/or output and you may freeze the display.  All in all the eight-band main EQ function is entirely straightforward, as should be the case with something as fundamental as an EQ.

In addition to the EQ bands, RP-EQ sports a resonant high-pass and resonant low-pass filters.  There are two types of each (pedigree unspecified, just choose by ear) and slopes of 12 and 24 dB per octave.

The last purely frequency-related function resides in the small subpanel labelled “Air”.  As you might expect, it can raise the topmost region of the audible spectrum.  It uses a bell filter with a very wide bandwidth and a center frequency well above the upper limit of human hearing.  The bandwidth is so broad that the leftmost “skirt” is within the audible range.  This is a very useful function that should not be overlooked.

Next, we have a mono-stereo split function that collapses the stereo signal below a specified frequency to mono.  It’s pretty straightforward.  However, the UI is a little confusing on one point.  On the left we have a knob which is used to designate the split point.  On the right there’s a Split Range group of radio buttons.  These are basically shortcut buttons that immediately dial in a frequency.  You can also specify frequency by MIDI note.  Be sure and select the appropriate mode; it defaults to Left, but you will probably want L + R (average).

The Saturation function is a very non-EQ sort of thing to provide.  But, hey, this is a Rob Papen creation, so don’t be surprised at the inclusion of a very nice addition to have at hand.  The saturation is subtle, even at higher settings, but it is quite pleasant.


The last thing we need to talk about is the XY controller, another very unusual thing to find in an EQ.  With this, your EQ plug-in can become a first-rate creative effect.  It’s basically two combined LFOs, the movement of which can be programmed and set to play (although it can also just be driven manually).  This is the same kind of XY controller found in a number of Rob Papen synths.  The best way to see what it can do is to view a video tutorial.  You can see a demo in a Rob-Papen-created video here:

The video covers all of RP-EQ.  The XY controller demo is found at 9:35 thru 16:20.

As to factory presets, you would not expect all that many for an EQ.  But given that the on-board modulation capabilities turn this EQ into a something with much creative potential, your expectations would be fooled.  In normal Rob Papen tradition we have a boatload of presets, 340 in all if I’ve counted correctly.  Check out the ones in the XY Effects 01 category in particular for some creative ideas on how to use the XY controller.




The last FX module we’ll look at in this installment is RP-Distort – obviously a distortion module.  But once again, there’s more to this than you might be anticipating.  In addition to a complete line of distortion effects, we also have a pair of resonant filters, a compressor, and a mono-to-stereo widener.  To complement all this, we also have a four-slot mod matrix and four LFOs.

There are twenty-four permutations for routing the component modules.  The default is distortion feeds filter feeds compressor feeds widener.  But all other possible configurations of the order of these modules are available.  Naturally, any of the modules may also be bypassed.

The list of distortion types is extensive; the menu can be seen to the right.  In the distortion subpanel in the UI, what controls that appear below the distortion type selector will depend upon what type is selected.  There are twenty-seven distortion types, with seven of them also offered in versions that offer a two-band capability with a user-selected crossover frequency.  I am not going to go into detail on all the types.  The documentation has all that information for those who seriously want to study the possibilities.  For now, suffice it to say that we have a wide range of “pretty” to “assertive” to “mega-destructive” possibilities.

The distortion module contains a four-band EQ (with non-user-selectable frequency ranges).  It also contains a gate.

Of the remaining modules, we probably don’t have to spend a lot of time describing.  The operation of the two filters should be obvious from the UI.  The same can be said of the compressor.

As to the widener, the documentation does not provide any details about the technique employed other than to say that the intent is to allow for full mono-to-stereo expansion and that some kind of LFO is involved, for which the LFO speed (which cannot sync to host tempo) can be specified.  Further confusion is that we have both an Amount and Width control.  The documentation says only:

Amount: Stereo widening amount

Width: Maximum spread (between left and right channels) of the stereo

I played around with this and could not put my finger on just what the Width parameter was specifically doing, other than the LFO Speed affected that processing.  That it was definitely doing something was evident when viewing the signal in a stereo correlation meter.  The basic processing governed by Amount appears to be modest complementary EQ differences between the L and R channels.

In the end what matters is the effectiveness of the widening, and this module gets that job done nicely, even using just the Amount control while the Width is set to 0.  Adding Width with non-zero speed gets you some additional animation of the sound.  Just set by ear and don’t worry about what’s going on under the covers.  This function is good enough by itself that you may end up using RP-Distort for stereo widening and nothing else.

Modulation capabilities are robust for a plug-in of this type.  The source possibilities of the mini modulation matrix include many different MIDI sources in addition to the four LFOs.  A number of factory presets make full use of this MIDI modulation capability.  The destination choices in the mod matrix, of which there are approximately 50, include LFO controls, so you may easily control the depth of an LFO effect in real time with an external MIDI controller (assuming your DAW can easily route MIDI to effect-type plug-ins).

The preset selection is (no surprise by now) generous with over 340 provided.  They cover the full range of distortion types and routing configurations.  They make good use of the MIDI controller input possibilities.  Lastly, if you thought distortion was mostly about electric guitars, the presets show a great many other possibilities you might never have considered.

One major caution regarding the presets, however.  Put a limiter on the audio chain when you’re auditioning them if you value your ears or your monitors.  Some of these get extremely loud, especially when using the mod wheel.  This is my only serious criticism of RP-Distort.  A good deal more care should have been taken in keeping preset levels consistent and not loaded with nasty surprises, in my opinion.


Until Next Time …

That does it for this installment.  We plan to be back with the concluding part of this review in our next issue.  There we will look at RP-Delay and RP-Reverb 2.  Hope to see you then.





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