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Using ChromaVerb In Logic

Apple Logic Pro Tips & Techniques
Published June 2018
By Geoff Smith

Unlock the secrets of Logic Pro’s new ChromaVerb algorithmic reverb.

Logic has a long history of including excellent reverb plug-ins. Space Designer is a brilliant convolution reverb however, because of the huge library of impulse responses that come included, it can be a bit overwhelming, particularly if you just want to reach for a simple room reverb and tweak a few parameters. Then there’s Logic’s algorithmic reverbs such an PlatinumVerb and SilverVerb. While both are capable effects, they’re getting rather long in the tooth, so it’s great to see the addition of ChromaVerb in the 10.4 update. In this month’s Logic workshop we cover ChromaVerb’s interface and look at creating some of our own presets.

Early Reflections

Screen 1: When trying ChomaVerb for the first time it can help to listen to just the early reflections so that you can easily hear your parameter adjustments.Screen 1: When trying ChomaVerb for the first time it can help to listen to just the early reflections so that you can easily hear your parameter adjustments.First, let’s look at how ChromaVerb handles a range of different material. Create an audio track and add a synth loop, a drum beat and a vocal recording to it so that you can easily jump between parts. From the channel strip go to the first insert slot and bring up an instance of ChromaVerb. The first thing most algorithmic reverbs do is generate early reflections. These give the listener psychoacoustic cues as to the size and type of space you are creating. You can learn a lot about how a digital reverb works by listening to the early reflections in isolation. To configure ChromaVerb so that you are only hearing the early reflections, navigate to the Main tab and set the Dry slider to 0 and the Wet slider to 100. Next, click the Details tab, the Early/Late slider allows you to balance the reverb between the early reflections and the late reflections. To only hear early reflections, set this slider to its minimum value (see Screen 1). For now let’s set the Mod Depth to 0 so that the modulation section is off. Return to the Main tab; the main parameter that sets the character of ChromaVerb is the Room Type setting at the top middle of the GUI — by default this is set to the Room algorithm (see Screen 2).

Clicking on the Room Type field in the top middle of the plug-in GUI opens up a striking drop-down menu of 14 different room types. The room types are radically different to one another and worth exploring, but note that some editing parameters do nothing with certain types and make huge differences with others (again, see Screen 2).

Screen 2: ChromaVerb comes with 14 Room Types, each with a different sonic characteristic.Screen 2: ChromaVerb comes with 14 Room Types, each with a different sonic characteristic.

Reverb To Type

Now that you have heard how the Room Type defines the theme for the early reflections, set the Room Type to ‘Room’ to explore some editable parameters. Begin by adjusting the Size parameter from 0 to 100. This parameter simulates the effect of increasing the size of a room by spreading the early reflections out over time. The next parameter to try is Density. Increase this from 0 to 100 percent, and notice the difference when applied to a synth sound compared to a drum beat. On the synth part I was using, I found the effect of this parameter was very subtle and preferred it at lower values — at 100, everything felt slightly blurred and washed out. On the drum part I auditioned, the effect of the Density parameter warranted more careful consideration. A Density of 0 transformed the early reflections into a burst of short delays creating a subjectively unpleasant flamming effect. This was easily removed by increasing the Density to blur the early reflections into a more cohesive-sounding reverb effect

Now tweak the Attack parameter, increasing it to gradually ramp up the level of the early reflections on the ‘Room’ model. This doesn’t make a huge difference until you switch the Room Type to Dark Room, whereupon you will hear a much more pronounced effect. Now let’s move across to the Decay parameter and adjust it from 0.25 to 100 seconds... Surprisingly, this also has little effect on the Room model when listening to just the early reflections. However, changing the reverb type to Dense Room and altering the Decay parameter creates a much more obvious difference. After playing with the different room types for a couple of hours, listening to how they sound with different program material, I found it helpful to think of the Room Types as 14 different reverb units with subtly different configurations and parameters. You may also find it helpful to save presets matching the different Room types to the instruments/textures that you are likely to use them with.

Slapback Echo

Now that we have looked at the basic parameters that affect early reflections, let’s try our hand at creating some example patches. For our first patch we will create a preset that imitates a slapback echo recorded in a real room. Set the Early/Late slider to its minimum value so that you are just hearing early reflections. Leave the Width slider at 100 — this will make our slapback echo nice and wide, unlike a normal mono delay. Use the Output EQ to roll off the bottom and top frequencies. In the Main section choose the Chamber Room type. In order to get a tempo-synchronised slapback effect we will use the Predelay parameter. Turn Sync on and set the Predelay to 1/16th note; the Predelay will form the basis of our slap sound. Next, tweak the Size and Density parameters to taste. I settled on 44 and 56 percent, respectively. In ChromaVerb you have the option to blend from a single slap to a wall of reverb. Experiment with setting the Distance parameter to 50 and the Early/Late slider to halfway, so that you have equal Early and Late reflections. This will create more of a rhythmic wash than a single slap echo. The Decay time of the reverb as a whole can also be set to a tempo-synchronised division. Just click Sync On and try setting this to 1/4 note.

Modulated Reverb

For the second example let’s create a modulated reverb sound that adds the type of movement and width to a synthesiser pad that we might associate with a chorus effect, whilst adding the decay we normally associate with reverb. On a synth track with a synth pad part, add an instance of ChromaVerb. From the Room Type pop-up, choose Dense. The Dense and Strange Room algorithms seem particularly suited to wide, deep modulated reverberation that is perfect for synth pads. Set up a medium sized reverb in the Main page and then in the Details page set a Mod Speed of 3.90Hz and a Mod Depth of 40. This will give you a deep, rich modulation effect. The Width control is perfect for adding tons of stereo width to your modulation effects. Try setting this to 110. Now adjust the Decay time to add the right length of decay to the pad. To make the modulation effect sound more gritty and lo-fi, go to the Quality parameter on the Details page and set it to Low. Alternatively, set the Quality to Ultra to make things clear and clean.

Let’s finish by making a larger reverb that’s perfect for creating ambient textures. On a track with a simple single-line melody played on a guitar or mono synth, add an instance of ChromaVerb, set the Room Type to Reflective Hall and then crank up the Decay time to 14 seconds. The Reflective Hall mode has a beautiful soft characteristic perfect for creating long washes of sound. To accentuate the ambient nature of the track set the Dry to 0 and the Wet to 100, so you are hearing only the wet signal. Now go to the modulation section and experiment with the Mod Speed and Mod Depth parameters to further wash out the sound. When creating long reverberant tracks you can often get too much of a build-up in the bottom end; there are two ways to tackle this problem in ChromaVerb. The Damping EQ section, available in the Main view, allows you to tweak the decay time for a given frequency band. To decrease the decay time of the bottom frequencies, so they decay more quickly, drag the left hand node down. You can read the time in seconds on the right-hand side vertical axis or as a percentage of the reverb time on the left (Screen 3). On the Details page you can also use the Output EQ’s high-pass filter to remove unwanted bottom end. This works in a similar way to Logic’s Channel EQ plug-in.

Screen 3: The Damping EQ can be used to tweak the decay time of a given frequency band. To decrease the decay time of the low frequencies, drag the left node down.Screen 3: The Damping EQ can be used to tweak the decay time of a given frequency band. To decrease the decay time of the low frequencies, drag the left node down.

One Last Thing

If you’re wondering where the your trusty old PlatinumVerb plug-in has gone, then hold down the Option key and click on an empty audio FX slot. Here, in the drop-down menu you will see a ‘Legacy’ section, containing PlatinumVerb and other older Logic plug-ins.  

Published June 2018