User Manual

Dimensions

 

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Intro
Understanding Common Reverb Controls
User Interface
Extended Features Panels
Algorithm Panel (Left)
Center Panel
Shimmer
Output Panel
Algorithms
Spring
Plate
Analog Controls
Digital Controls
Room/Concert Hall
Random Hall
Cathedral
Presets
Length
Tone
Echo Density
Block Diagram
Extended Features
Credits

 

Intro

Reverb is sort of the black arts of signal processing. Most normal signal processing is pure math, which is either right or wrong, and can be proven right or wrong.

Reverbs are different. While there are countless academic papers on modal densities, echo distributions, eigen vectors and other reverb related math and metrics, the bottom line is that the records we listen to use reverbs that are far from perfect. We still haven't seen any "academic" reverbs reach the top of the charts.

The imperfections of a well-designed reverb, and probably more important, the workarounds for those imperfections, are what gives a reverb its character. No-one can argue that a mechanical plate sounds "exactly like a concert hall", or that the modulation of the classic 224 hardware sounds "just like real life". But that's not what it is about, reverb is an artform without rights or wrongs, just like the melody you're about to write.

Dimensions is a collection of reverbs with character. Each is different. They can be lush and vibrant, or harsh and ugly. Dark or bright. Neither are recreations of famous concert halls, but all of them has have a purpose and a vibe.

 

Understanding Common Reverb Controls

Reverbs are different than most other audio processors, and they have some special terminology. A lot of the terminology was made up when the first reverb processors were built in the seventies and early eighties, and while some terms have disappeared ("mode enhancement", anyone?), others are still in use today.

Here are a few of the most common terms used today.

Time: The length of the reverb tail. Typically measured as the time to when the tail goes below -60 dB (“RT60”), but other reverb controls (see Multiplier) can change this a lot.

Size: Size is meant to emulate a room size by changing how close together the echoes in a reverb are. A large size reverb is sparser, can have more audible echoes and is more suitable for longer reverb times. A small size is denser, can have audible resonances and is more suitable for shorter times.

Predelay: The time between the dry signal and the onset of the reverb. Say you want to emulate the sound from a vocalist in a large reverberant space. If the vocalist is close to the mic but far from the walls, it will take a long time for the echo from the walls to arrive at the mic, and that is the time you set with your predelay. In practice, you use predelay to increase the intelligibility of the audio source by separate the dry audio (by 20-40 ms) from the reverb tail.

Diffusion: More diffusion makes separate echoes harder to distinguish, but will make the reverb take more space and energy in the mix. As a rule of thumb, lower diffusion will lead to clearer mixes. Vocals, strings, pads need very little diffusion. Percussion and drums need more diffusion.

Multiplier, Bass Multiplier, Time Multiplier: Instead of working with a normal EQ with a boost or cut in decibels, a reverb typically uses an EQ inside of the reverb algorithm. Boosting a frequency will not be audible as a normal EQ boost, but instead it increases the length of the reverb tail at that frequency. So instead of adding "6 dB of low shelf", we're making the reverb two times longer. Whenever you see the unit "x" instead of "dB", you know that the EQ happens inside the reverb and that it affects the length of the tail.

Damping, Treble Damping: Damping is similar to a multiplier that's less than 1x. Sometimes you set the damping with a frequency (as in Random Hall), and sometimes the frequency is fixed and you set it with a multiplier (Plate Digital).

Shape: This is often referred to as Depth or Attack, and typically affects the onset of the reverb. In Dimensions, a larger number means a slower onset.

Modulation: In the beginning, modulation was added to algorithms to make the reverb less repetitive and predictable. With very little memory and CPU in the early hardware reverbs, it was essential to add modulation to hide the deficiencies of the algorithms. Today, we've learned to love the sound of a subtle, or sometimes not so subtle, modulation, and most reverbs (except IR reverbs) uses some sort of modulation, even if it's not strictly needed.

If you feel that the reverb tail is altering the pitch too much, or just makes you sea-sick, just lower the amount of modulation.

 

User Interface

Dimensions' main controls are placed in the middle, with Time, Dry/Wet, Dark/Bright and Predelay.

To the left of the main controls you will find the Reverb Algorithm selector, and the individual controls for each algorithm. To the right you will find a Shimmer effect that can pitch shift the reverb for extra glitter, as well as some standard output controls.

On top of everything is our reverb tail visualizer. We took equal inspiration from the Fairlight CMI waveform display and Joy Division’s Unknown Pleasures cover and created something that intuitively illustrates the sound of the tail. Browse through the presets, listen to the sound, watch the visualization and you'll quickly get the hang of it!

Figure 1. Top: Output meters and reverb tail visualization. Looking at the visualization, you can see that the current reverb has a limited bandwidth since it has a sharp decline to the right side. It has a fairly flat onset, and the higher frequencies tail away faster than the low frequencies. Bottom left: the algorithm selector and individual algorithm controls. Middle: Main reverb controls. Right: Shimmer effect for your ambient extravaganza and an output section with filters, width and output volume.

 

Extended Features Panels

Next to the green Softube logo in the menu bar, you'll find the buttons to open the input, output and lower panels. They are part of Extended Features, a utility which is shared by all Softube plug-ins that contains advanced metering, levels, bypass, and other features. For more information, please see the Extended Features User Manual.

 

Algorithm Panel (Left)

On the algorithm panel you can choose between six different reverb algorithms, all described in detail in the next chapter. Here's a quick rundown of the different flavors.

 

 

Center Panel

The center panel contains the four most important controls. These are shared between all algorithms.

Predelay: Sets the amount of delay between the dry audio and the onset of the reverb.

Dark/Bright: Adjusts the overall tonal balance of the reverb via the use of a tilt filter.

Time: Sets the nominal reverb length. All algorithms can do times between 1.1 s and 36 seconds, but some algorithms can go lower or higher. The lowest possible time is indicated by the slider.

Figure 2. The shortest possible nominal reverb length is indicated by the small vertical bar across the slider.

Different settings of the individual reverb controls, especially the Bass/Treble Multipliers and Damping controls will change the reverb length drastically, so a "2.0 s" read-out doesn't mean that you always get a 2 second reverb.

 

Shimmer

Shimmer is an effect where you pitch shift the audio inside of a feedback loop, which means that you can achieve a slowly rising or falling pitch effect. Typically, the classic use case is to pitch shift by a full octave, in order to keep the harmonic integrity of the audio.

The Shimmer effect takes place before the reverbs, which means that it will only affect the incoming audio.

Amount: Sets the level of the Shimmer effect.

Pitch: Sets the amount of pitch shifting, from -12 semitones (one octave down) to +12 (one octave up).

Feedback: Sets the amount of feedback. 0% feedback means that we only go through the pitch shifter once. To get a subtle octave up effect you set Feedback to 0% and Pitch to +12.

Attack: Sets the speed of the feedback loop as well as the speed of the initial onset. The shimmer is a very slow effect and can be used without the pitch shifting to get a "bloom"-like reverb, as in the "Shimmer Bloom" preset.

High Cut: Sets the frequency at which the shimmer effect will taper off.

Full Wet: Turns off the audio that isn't affected by the Shimmer. Engage Full Wet if you only want to hear the pitch shifted audio, and not the fundamental/original audio.

 

Output Panel

High Cut: 6 dB/octave high cut filter, placed after the reverbs.

Low Cut: 12 dB/octave low cut filter, placed after the reverbs.

Width: Sets the M/S balance between the mid (mono) and sides. At its minimum setting, the output from the reverb is fully mono, in the center it's fully stereo and at its max setting you only get reverb in the sides, not the mid.

As opposed to most width controls that only allow you to boost the sides by a couple of decibels, the Width in Dimensions will completely mute the mid channel when it is at its maximum position.

Width should always be used with care with reverbs. Most reverbs are designed to have a maximum width, and altering the balance between mid and side might lead to side effects, such as resonances or unwanted echoes.

Output Gain: Sets the output level after the Dry/Wet control.

 

Algorithms

This section provides an overview of the algorithms and their controls.

 

Spring

The spring reverb in Dimensions is tailored from the spring reverb in a classic tape echo unit. It's not as springy as a typical guitar amp spring reverb, and it's not as clean as a high-end studio spring reverb. It's somewhere in between, and it's just a lovely addition to the other algorithms.

Mode: Full/Bright. Sets the tonal color of the spring. "Full" has a richer low end but can sometimes be a bit too much in a mix. If you just need the spring flavor, go for "Bright".

Bass/Treble: Low shelving filters that affects the output of the reverb.

 

Plate

The plate algorithm started as a recreation of the first commercial digital reverb unit, a big beast with Star Trek-like controls and levers. Despite the original's technical shortcomings, such as very little memory, low sample rate and limited calculations, it is one of the most beautiful reverb designs ever created, and it's been a studio staple ever since.

While developing the recreation we decided to expand on the original concept and bring in some flavor from real mechanical plates. Hence the two modes, "Digital" and "Analog". The digital mode gives you more control over the reverb tail, while the analog modes use resonance modeling to capture the sound of the plates, especially the onset, and carefully tuned internal parameters to recreate the reverb tails of the mechanical plates.

Type: Analog/Digital. Choose between the mechanical (analog) or digital plate.
 

Analog Controls

Color: Three different mechanical plates.

• Bright: A bright plate with a long decay, perfect for vocals.
• Medium: A dampened plate with a shorter decay and pronounced high frequency drop-off.
• Dark: Classic dark plate sound with a long and rumbly bass tail.
  
   

Digital Controls

Bass Mult./Bass Freq.: Low shelving filter that shortens or extends the reverb length below the cut-off frequency.

Treble Mult: High cut filter that shortens the reverb length above the cut-off frequency.

Modulation: Sets the amount of modulation in the reverb.

 

Room/Concert Hall

"Concert Hall" is one the earliest and most used reverb algorithms. First seen in the 224 hardware, it has been a part of many hardware reverbs ever since.

This algorithm is famous for its beautiful modulation, which has an ethereal and chorus-like character, which together with the extremely long reverb tails can make you give up your pop career and start doing yoga meditation soundscapes instead. Please don't. But it is the sound of Blade Runner, and that's something, right?

"Room" is a variation of the Concert Hall algorithm and was included together with Concert Hall in the first version of the 224. It's very similar but tuned for smaller sizes and has less pronounced echoes.

Shape: Originally called "Depth", adjusts the onset of the reverb.

Diffusion: Sets the amount of diffusion.

Bass Mult./Bass Freq.: Low shelving filter that shortens or extends the reverb length below the cut-off frequency.

Treble Damping: Sets the cut-off of the high frequency damping, reduces the reverb length above the cut-off frequency.

Modulation Type: Sets the type of modulation, from Light, Medium to Chorus. Corresponds to "Mode Enhancement" types 15, 2 and 1.

Modulation Amount: Sets the amount of modulation.

System Noise: The low-resolution math of the original hardware led to lots of audio artefacts in the reverb, and for many users it's a big part of its beauty. The downside is that you get noise from the quantization within the algorithm (it's not AD/DA quantization noise, but math noise). We modeled all the quantization, and if you aren't bothered by the noise and want the most authentic experience, turn on System Noise.

 

Random Hall

The original 480 hardware was released in 1986, but the Random Hall algorithm wasn't included until a later version. It's a pinnacle in reverb design, with a beautiful spatialization that just glues together with any source you have. It can also be quite difficult to use, and there are a lot of settings that don't sound good at all. But that's what presets are for!

In Dimensions, we're using the "Effect" mode of the Random Hall algorithm, that essentially decouples the Size control from the Time control.

Size: Sets the size of the reverb loop, essentially the space between the individual echoes. Larger sizes have typically less density.

Shape: Sets the onset of the reverb. A low setting of Shape has a very direct onset, while a higher setting makes the onset more spread out in time.

Spread: Sets the size of the onset. Use in tandem with Shape.

Diffusion: Sets the diffusion of the reverb.

Bass Mult./Bass Freq.: Low shelving filter that shortens or extends the reverb length below the cut-off frequency.

Treble Damping: Sets the cut-off of the high frequency damping, reduces the reverb length above the cut-off frequency.

Spin/Wander: While not technically correct, think of Spin as the "speed" of the modulation, and Wander as the "level" of the modulation.

System Noise: The low resolution math of the original hardware led to lots of audio artifacts in the reverb, and for many users it's a big part of its beauty. The downside is that you get noise from the quantization within the algorithm (it's not AD/DA quantization noise, but math noise). We modeled all the quantization, and if you aren't bothered by the noise and want the most authentic experience, turn on System Noise.

 

Cathedral

This algorithm was originally developed as a synth reverb, and different versions of it have been used in our synth plug-ins Parallels and Model 77. In Dimensions, we've improved further on the algorithm, especially its modulation, and designed it to be lush and long, and unlike Random Hall, without any real sense of room dimensions or reality.

Shape: Sets the shape of the onset, a higher value leads to a less direct onset.

Diffusion: Sets the diffusion of the reverb.

Bass Mult./Bass Freq.: Low shelving filter that shortens or extends the reverb length below the cut-off frequency.

Treble Mult./Treble Freq.: High cut filter that shortens the reverb length above the cut-off frequency.

Modulation Amount: Sets the amount of modulation, from subtle to very chorus-like.

 

Presets

Dimensions comes with a small selection of presets. But for each preset, you can easily change the reverb length (Time) and the algorithm (Reverb Algorithm) to explore more sounds.

The presets are divided into the following categories:

• All Purpose: This is our "best of" list. Start here.
• Bus: Something you put on your reverb return channel, works for pretty much anything.
• Drums: Presets with a dense character that work with percussive instruments.
• Vocals: Presets with a sparse character that works for all non-percussive instruments, such as guitar, strings, pads, vocals.
• Shimmer: Presets that use the shimmer algorithm.
   

We also use a couple of terms when describing the presets in names and tags.
 

Length

• Ambience: a very short reverb, used to give a sense of space to a dry recording.
• Short: 0.5-1.5 s reverb length.
• Long: 2-5 s reverb length.
   

Tone

Goes without saying, right?

• Dark
• Bright
   

Echo Density

• Dense: Good for percussive instruments, such as drums, horns, etc.
• Sparse: Good for non-percussive/legato instruments, such as voice, strings, pads, etc.

 

Block Diagram

This block diagram outlines the basic structure of the Dimensions plug-in.

 

Extended Features

The input and output panels are part of the Extended Features, which are available in all Softube plug-ins.

For more information about Extended Features, please see the manual: https://www.softube.com/user-manuals/extended-features

 

Credits

Maxus Widarsson – Product design
Kim Larsson – DSP programming
Niklas Odelholm – Product design, reverb modeling, presets, manual
Arvid Rosén – Reverb modeling
Oscar Öberg – Reverb modeling
Cameron Clark – Shimmer programming
Anton Eriksson – DSP programming
Anna Pohl Lundberg – Reverb visualization
Patrik Holmström – UI programming
Niels Nielsen – Presets
Johan Bremin – Quality assurance
Markus Krona – Quality assurance