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RNDigital D4 Plug-In

This graphic dynamics processing plug offers plenty of useful features at a good price.

The RNDigital D4 dynamics processor GUI in a Pro Tools session When was the last time you opened up a brand new piece of software and said to yourself, “Hmm, now just how do I work this thing?” With the recently released D4 Plug-In from RNDigital, I would bet that I’m not alone in saying just that. One quick glance at it made me realize: “We’ve clearly got something different here.”

After using it for just a few minutes, then over the course of just about every session since, I was damn glad to have it in my arsenal. This Mac OSX (10.2+), Windows XP- and Vista-compatible mono/stereo dynamic compression tool will run with VST, AU, or RTAS hosts up to 192 kHz. Built on the foundation of RND’s Dynamizer but with a bevy of new features, it packs a lot of options into a small interface. While, deep down, it is a compressor, don’t think of this as “multiband” — it breaks the audio up into compression zones (up to four), each with independently configurable attack, release, and ratio settings.

Installation and iLok authorization was a breeze, and RNDigital wisely provides an 84-page PDF manual. It not only features some interesting discussion on compression, but also thoroughly examines what the D4 is and isn’t — a mustread to get the most out of this tool.


The multicolored main section of the plugin is called the I/O Map. The four zones are broken up with I/O lines, each with a small, colored, input flag on the left and output flag on the right, along with a small drag circle in the middle. Each flag setting determines the max I/O levels for compression, and each zone has a moveable upper and lower threshold.

Running along the left and right side of the I/O Map is a scale that runs by default from 0 up top to -48 dB at the bottom. The setting will change (-24, -48, -80) depending on the adjustment of a Scale Control. This scale helps you make input and output level choices.

The D4 features three types of meters: peak, cloud, and attenuation. Peak and attenuation work on Input and Output as expected. Cloud meters, however, visually display the concentrated amount of “energy” at a given level and have to be seen to be appreciated and understood.

Many other small but important options lie within the nooks and crannies of D4’s GUI. There’s an Auto Limiter to prevent levels from exceeding 0 dB, I/O Trim Controls, Automatic Gain Compensation and a Zone Gain Control (ZGC). With ZGC on, audio outside of those thresholds responds the same way as audio in the zone. With ZGC off, audio outside those thresholds pass through unaffected, or 1:1 with no gain or cut applied. It’s a very creative control feature.

The Key to Success

By selecting the Key button, a whole new GUI appears in place of the I/O Map. Featuring a selectable Key Input (Left and Right, Left Channel, Right Channel, Side Chain), a variable Look-Ahead slider (up to 10.0ms), and a full Key Filter graphic interface with selectable frequency, gain and Q, it further expands the capabilities of the D4.

At the bottom of the plug-in sits a full Attack, Ratio, and Release section (from which all four bands can be grouped or independently controlled). D4 has the ability to operate with one to four bands, chosen with a small 1-4 selector located on top. There’s also the usual Load, Save, Copy, and Clear, as well as useful A and B “workspaces,” which let you quickly switch between two different settings for comparison’s sake. Also, by hitting the Help button atop the plug-in, the manual document automatically opens up — love that touch!

Jump In

The best way to get used to the D4 is to just jump in and start dragging around the Zones. My first experience was to launch it within Peak Pro 6 on a short TV spot. Within a few minutes of not knowing what I was doing, it sounded far better. I was able to punch up the level and top/mid end clarity while leaving the bottom alone. A quick A/B even gave me a “wow, this thing rocks” feeling. I then printed the spot and shipped it to the client.

After a good manual read, I was able to make more effective use of the D4’s abilities. Using it within Logic, I created some great original sounds on drum loops with 1- and 2-band applications; almost like EQ meets multi-band compression with limiting. It’s also good to explore presets like “Mastering Lifter,” “RN Snare Anti Gate” and “Vocal 1 LNF.” This preset exploration also help you understand how the plug-in operates.

Final Thoughts

Overall, D4 is a flexible, powerful sonic tool that, like multi-band compressors, can be overused if not careful. Aside of its obvious use on 2-track masters, it’s also great for sound design, looping, and mixing. For me, it’s quickly become a go-to plug-in across various instruments, and also to help punch up final tracks.

While the interface is a bit small and cluttered, it packs in a lot of useful features at a good price, making it a fair tradeoff. Also, RNDigital informed us that it is working on a video tutorial, which will be posted on its website soon, and — even better — any registered owners of the Dynamizer can upgrade to the D4 for free.

Rich Tozzoli is a producer, composer, sound designer, and the software editor for Pro Audio Review.