2C-Aether Manual (Draft version)

1. Introduction

2C-Aether is a versatile digital reverb implemented as audio plug-in for running in computer based Digital Audio Workstations. 2C-Aether is designed to simulate a wide range of acoustic spaces.

2. Definitions

ERs – Early Reflections

LRs – Late Reflections. Diffuse reverberant field or reverb tail

3. The concept

2C-Aether consists of two main sections: Early Reflections and Late Reflections. The parameters in these sections work independently, so for example you can separately control acoustic space size of ERs and LRs.

Early Reflection Parmaters are color coded Green in the interface.

Late Reflection Parmaters are color coded Blue in the interface.

Input and Mix Parmaters are color coded Yellow in the interface.

For more information see 2CAudio_Aether_Manual.pdf

4. Parameters description

4.1 Early Reflections section:

Space – Select Early Reflections preset from a set of 33 internally pre-programmed acoustic spaces. This type is an internal preset data. It's not a combination of ER section parameters, however for ease of use each space type has a set of default parameter values that correspond to this type. These settings are provided for ER as well as for some LR parameters. You may think of them as quick presets.

Every space is represented as picture in the space display

Link – When a new space type is selected it default parameters can be set to change current parameters in four ways:

• None – no change to current parameters

• ER – only ER parameters are changed

LR – only LR parameters are changed

Both – both ER and LR parameters are changed

Note that these space default parameters do not represent the whole acoustic space. These parameters don’t include frequency characteristics of acoustic space. For you convenience we created a set of factory presets that represent all aspects of these acoustic spaces. You can find them under “space types” folder. They have the same names and follow the same order.

Size – The size of the acoustic space. Size sets the largest dimension of selected space type. For example for room it corresponds to room width and for a church to its height.

Absorption – Controls the amount of energy absorbed by surfaces in acoustic space. The lower the value the less energy is absorbed and the less following reflections are damped.

Position – By moving this parameter you can set different positions of virtual sound source and recording points in acoustic space. Use this control to adjust a position of virtual sound source. Different acoustic space types have different positioning schemes. This way you can adjust reflection pattern without changing acoustic space properties. So adjust this parameter until you find a reflection pattern that you like.

Shape – This is a complex parameter, that adds some variation to acoustic space. The bigger the value, the more reflection pattern becomes complex and chaotic which is a result of more complex space geometry. You may think of it as increasing the number of reflective surfaces in acoustic space. For example in empty rooms there are not much reflective surfaces, so keep it low. In halls with seats and a lot of non rectangular shaped surfaces the geometry is more complex, so use higher shape value. Anyway you can start with some acoustic space type and then play with shape.

Color – 2C-Aether implements a complex multi-stage filtering technique that simulates frequency dependent absorption of different surface materials. Each acoustic space type preset has two materials associated with it. So when you change ER Color you change the way the filters are applied to incoming signal. Negative values emphasize the effect, positive do otherwise (de-emphasize). When you play with it the ERs become darker or lighter. Zero value corresponds to selected space type natural settings.

HF Soft – High Frequency Soften. It controls the characteristics of a high-shelving filter in such a way that it softens high frequencies at the ERs output.

ER Gain – The Early Reflections gain.

ER Bypass – A small led at the bottom of ER Gain switches the ER section on/off. When it's on (green) the section is on, when it's off (red) – the entire ER section is switched off: all ER controls are disabled and ER section in DSP engine does not consume any CPU cycles. Use this mode if you don't need LR section.

ER Cross – Early Reflections input stereo cross-over. The ER section is stereo in, stereo out. It means that when crossover is set to 0 the stereo image of incoming signal is preserved throughout ER section.

For more information see 2CAudio_Aether_Manual.pdf (“Understanding Cross and Width”)

ER Width – Controls a stereo image width of ERs:

0 – mono;

<100 – reduced stereo width

100% corresponds to natural stereo width.

100..200% correspond to extra width (beyond natural).

4.2 Input EQ

Input EQ has two filters in series: Low EQ and High EQ. These filters allow you to attenuate low and high frequencies in a signal that goes to ER and LR sections.

For example you may want to use Low EQ to reduce the “booming” effect as some acoustic spaces may have a lot of resonances at low end which adds unwanted muddiness to the reverb. High EQ could be used to reduce a hiss in high frequencies when processing instruments with a lot of high pitched noise like snare Drums.

Parameters:

Low EQ Frequency

Specifies low EQ filter cut-off/mid-point frequency

High EQ Frequency

Specifies high EQ filter cut-off/mid-point frequency

Low EQ filter gain

Specifies a shelf of low shelving filter. if gain is set to minimum value (leftmost knob position) the filter acts as a low cut (high-pass) filter.

High EQ filter gain

Specifies a shelf of high shelving filter. if gain is set to minimum value (leftmost knob position) the filter acts as a high cut (low-pass) filter.

Low EQ filter Q/Slope

Specifies low EQ filter resonance.

High EQ filter Q/Slope

Specifies high EQ filter resonance.

4.3 Reverb Parameters

Size – Sets a delay length used as a reference in the reverb algorithm. This parameter works in conjunction with reverb time. For natural sounding results set reverb size proportionally to reverb time. Note: Low values produce “Small Room” metallic coloration.

Shape – Sets reverb size spread.

The physical interpretation of the above two parameters is the following. Let’s take a rectangular room. Basically if the room dimensions are equal so we can say that sound waves are travelling between side surfaces. The time it takes a sound wave to reach for another surface is a delay set by Reverb Size. The greater the delay the bigger the distance between reflecting surfaces. So the Reverb Size sets the general dimensions of acoustic space. In rectangular room the reverb delays are not spread much, but in halls and in other acoustic spaces with a lot of differently positioned reflective surfaces the reverb delays are spread across a wider range. So the more Reverb Size Spread, the more complex the reverb tail will sound.

Reverb Size and Spread affect the overall timbre of reverberation.

This parameter is conceptually similar to ER Shape.

Pre Delay – Sets additional pre-delay for the reverb tail. Note reverb tail has a built-in delay that depends on reverb size.

LR Width – Controls a stereo image width of Reverb.

• 0 – mono;

• <100 – reduced stereo width

100% corresponds to natural stereo width.

100..200% correspond to extra width (beyond natural)

Diffuse – models the effect of irregular wall surfaces in a room by changing echo density. Very low values produce sharp, discrete reflections. Higher values produce groups of reflections that are smoother but less articulated. Except for special effects, it is recommended that this control be set to a high value.

HF Soft – High Frequency Soften. Controls the characteristics of a high-shelving filter in such a way that it softens high frequencies at the LRs output.

4.4 Reverb Decay

2C-Aether offers a flexible frequency dependent decay filter that allows to set different reverb decay times in three frequency bands.

Low, Mid, High – Reverb time multipliers for low, mid and high bands respectively. The actual reverb time in a band is calculated as a product of Reverb Time and multiplier value.

Low X – Low/Mid band split frequency point

High X – Mid/High band split frequency point

Note that due to algorithm features the plug-in keeps some space (around 20%) between Low and High Split frequencies.

Low/High Q – These parameters control the slope of transition curve between Low/Mid and Mid/High bands. This is a unique feature not found in other reverbs. Using these params you can get natural as well as artificial curves.

Reverb Time – Big knob in the middle of plug-in. Reverberation time. RT60. The time it takes for reverb to decay down to -60 dB. The rightmost knob position corresponds to special mode when reverb time is set to infinite, i.e. there is no decay in reverberation volume over time. In this mode you can create evolving pad sounds.

LR Gain – The Reverb gain

LR Bypass – A small led at the bottom of LR Gain switches the LR section on/off. When it's on (green) the section is on, when it's off (red) – the entire ER section is switched off: all LR controls are disabled and LR section in DSP engine does not consume any CPU cycles. Use this mode if you don't need ER section.

LR Cross – Reverb input stereo cross-over. XOver = 0 – only the left input channel goes into reverb and vice versa, Xover = 100% - left and right channels are mixed proportionally into reverb input. The reverb section is mono in, stereo out.

For more information see 2CAudio_Aether_Manual.pdf (“Understanding Cross and Width”)

4.5 Reverb Modulation

Depth – Delay modulation reference depth. 0 – the delays modulation is off. Note that even when delays modulation is off the reverb is still modulated by special spectral technique, which is not available for control.

Period – Delay modulation reference period.

4.6 Reverb Tail Shape

Attack – Controls the slope of reverb tail build-up. 0 – there is no build-up. 1 – the most slow build-up. Small rooms have a rapid build-up, larger spaces like halls have a slower onset.

Sustain – The amount of time the reverb tail sustains (or decays slower than exponentially) at a certain level after build-up. Increasing the reverb tail sustain puts more energy into reverb. High sustain value are good to simulate Halls.

Spread – The amount of time that the reverb is stretched over. You may think of this parameter as an acoustic space depth. Long values may create an echo like effect in reverb tail.

For more information see 2CAudio_Aether_Manual.pdf (“Understanding Aether's Time Envelope Controls”)

4.7 Mixer

Gain – Input gain

Mix – Wet to Dry ratio.

4.8 Reverb Mode

Reverb can operate in to channel mode:

A) Mono input to stereo output

B) Stereo input to stereo output

This mode applies only to reverb tail. The ER section always operates in B) mode.

In A) mode the input stereo signal is mixed down into a mono signal according to crossover value. So any panning information in incoming signal is lost. If you input is mono you can use this mode safely. But if you would like to retain the spatial information of stereo input signal you should use B) mode. The B) mode has also some more benefits as it can add more reverb specialization, so we recommend to use it even for mono input signals (in this case the crossover should be set to 100%)

The B) mode takes more cpu cycles. (by about 30%)

Parameter Locks

The following parameters: Input Gain, Wet/Dry Mix and Reverb Stereo Mode can be locked by pressing on parameter's label. In lock mode parameter does not change it's value when you load presets. This is very useful in the following situations:

1) auditioning presets on send bus. If you have inserted the plug-in on a send bus you would like to keep the Wet/Dry Mix set to 100%(wet). Most of presets are programmed as inserts so if you load them the wet/dry mix will change. To prevent this just set Wet/Dry mix to 100% (or whatever other setting you need to keep) and lock it

2) Plug-in factory presets have different Reverb Stereo Mode settings, so you would like to audition presets in particular mode lock this parameter

FREQ Display

The FREQ display show frequency response of various plug-in filters:

thick blue line with a fill – decay filter

thick orange line with a fill – input filter

thin green line – ER High Frequency Soften filter

thin dark blue line - LR High Frequency Soften filter

5. Interface

5.1 Organization

For more information see 2CAudio_Aether_Manual.pdf (“Aether Interface Organization”)

5.2 Mouse Control

mouse control modifiers:

• double-click on knob: edit value mode

ctrl(cmd on mac)-click on knob – sets default parameter value

changing knob value while holding shift key – precise tune mode

double click on value box – opens edit box

note: on OSX you can also use mouse wheel to control knob. Just left-mouse click on a knob you want to control and then use mouse wheel. To fine-tune hold down shift key.

5.3 Keyboard Controls

In some hosts you can use keyboard to

A) navigate in Preset Browser

B) tune knob value

To activate keyboard control press on the preset browser window or knob you want to control.

Keyboard shortcuts are:

Preset Browser:

• pgup/down - column shift left/right


home - select first preset


end - select the last preset

left/right/up/down arrow keys (select preset)

Knobs:

up/down - change value by 2% 
left/right - change value by 0.1% (fine tune) 
pgup/down - change value by 10%

5.3 Top Bar Controls

For more information see 2CAudio_Aether_Manual.pdf (“Aether Interface Controls”)

Top bar controls:

• main – switches to main page (default)

• browser – switches to preset browser page

info – switches to info page

file – shows a file pop-up menu

preset – shows presets menu

• active preset – shows active preset name

• [+] - selects next preset from library

[-] - selects previous preset from library

A – selects A setup

B – selects B setup

A<>B – exchanges the content of A and B setups

5.4 Preset Browser

Press browser key in top bar to switch to Preset Browser page. This page contains a list of presets organized in several columns. Aether comes with more than 260 factory presets and some of them dont fit the preset list so to access them press < and > buttons located at the bottom of the page. They will shift the preset list by one column left/right.

By default only preset names are shown in the list. To view full preset name including preset category press 'F' button located in the left bottom corner.

To select a preset just click on it. You can use keyboard (this feature might not work in some hosts) to navigate the preset list (See 5.3)

Note that there might be a delay when switching between different presets. This delay is normal and is caused by reverb algorithm that needs to re-calculate acoustic space model.

At the bottom of the page you can see four essential plug-in controls that you can quickly tweak without switching to main plug-in page.

5.5 File Menu

• Save to User Bank... – use this to save current plug-in state as a preset to user bank

• Save to a folder...- use this to save current plug-in state as a preset to a specified folder

Load preset... - use this to load preset from a saved preset file

5.6 Preset Menu

Clicking on preset button in top bar will show a drop-down menu will available factory and user presets. The factory presets are organized in categories to ease navigation.

5.7 A/B setups

Plug-in supports A/B setups so you can easily monitor and compare changes you make when tweaking presets.

There are two slots A and B. Use A and B buttons to switch between A and B setups. Press A<>B button to exchange the contents between A and B setups.

Suggested Usage: Make sure A setup is selected. The load a preset from a factory library that you find suitable for your task. You want to tweak it a little bit but would also like to compare your tweaked version with the original. What is do is the following: You press A<>B button so the loaded preset goes into B setup, then you load the preset again so you have a copy now in A setup. Now you have the factory preset copied in both A and B setups. Now you can start tweaking your preset. In some time you want to check how original preset sounds and compare it to your tweakings. You just select B setup that contains original factory preset.

NOTE: A/B setups are not stored as plug-in state (in host project file)

5.8 VU meter

The VU meter has three modes:

• LR – shows Left/Right, Input(top), Output (bottom) signal peak levels

MS – shows mono/stereo, Input(top), Output(bottom) signal levels

Off – disables VU meter

5.9 Info page: Options

• Change skin – select skin to load (*)

• Display values:

  • Always - always show knob value

Never - do not show knob value

While tracking - show value one while moving knob

• Knob motion

  • Linear – Linear Knob Control mode: reacts only to vertical mouse movements

Circular – Circular Knob Control mode

Follow Host - uses host setting for knob modes

• Report Tail

  • Report tail to host - notifies host about reverb tail length so it can extend the processing region if necessary

Do not report tail to host - notifies host that plug-in has no tail

(*) Note: new skin is loaded when you re-load plug-in.

6. Product Authorization

When you load the plug-in in your host application for the first time the plug-in will automatically show info page when you can authorize the product. To authorize the product you need to enter the serial code you should have been provided when you purchased the product.

The serial has the following form:

XXXXX-XXXXX-XXXXX-XXXXX-XXXX

You should enter the serial segment by segment into four fields that are filled with X. Double-click on serial field. An edit box will appear where you can type the corresponding segment of the serial. The press Enter keyboard key. Once you entered all five segments of the serial, click on orange Enter button. The product should get authorized and status text will change to 'Authorized'.

Now you can press main button to go to the main plug-in page.

Note: Unless authorized, plug-in will not do any processing.

7. Technical specifications

Latency: 4 samples. This latency is reported to host so host should automatically compensate for it

note: for optimum performance we recommend to use host buffer size that is a multiple of 64 or at least a multiple of 4.

minimum requirements: cpu with SSE2 support, 512 MB ram, 800 Mhz cpu

comfort setup: 4-core CPU with SSE2 support running at least at 2 GHz, 2GB of RAM

Note: The algorithm highly benefits from faster RAM and larger cpu cache size.