Table of Contents
The Mixer window in
ECHODamp operates much like any standard audio mixer. Users will find the usual complement of controls including Volume faders, Pan knobs, Mute and Solo buttons, as well as LED meters. As with all software-based mixers, the input levels to the Mixer are adjusted with the trim controls on your hardware audio interface (please see the manual that came with your audio interface for instructions on adjusting input trim levels). In addition to these standard mixing controls, ECHODamp contains a number of additional tools for controlling echo in a VTC. These echo control tools are explained in detail in the section entitled Using ECHODamp to Control Echo in a VTC.
- Turn audio processing on and off by doing one of the following:
• Choosing Audio Enabled from the Setup menu
• Clicking the AUDIO ON/OFF button in the upper-right corner of the Mixer
• Pressing the Spacebar on your computer keyboard
- Set the Input Trims for your Microphone/Line In channels (ch. 1-2, 5-8) on your hardware audio interface. When your performers are singing or playing the loudest part of their repertoire, the LED meters should just be transitioning from the green section into the yellow (meters turn yellow at -12dBfs, orange at -1dBfs, and red at 0dBfs). If the incoming audio level exceeds 0dBfs, the Clip Indicator will light and remain on for 5 seconds. This is an indication that you are experiencing digital overs, or "clips," that can create an unpleasant sounding distortion in the sound. Turn down that channel's Input Trim on the hardware audio interface until the level drops down into the yellow for the loudest passages.
- Set the Input Trims on your audio interface for the CODEC IN channels (ch. 3-4) while using the Audio Calibration tool.
- If needed, use the Hi Pass Filter to remove low-frequency noise and rumble from your inputs. Low-frequency sound can come from a variety of sources including air conditioners, wind, breath noise, microphone handling noise, etc. The Hi Pass Filters are also excellent for reducing the low-frequency boost known as the proximity effect that occurs when some microphones are placed close to the sound source. Click the HI PASS button at the top of a channel strip to open the Hi Pass Filter and select the desired cutoff frequency and slope. You can enable and disable the Hi Pass Filter by Option/Alt-clicking the HI PASS button without actually opening the window. When the button is illuminated, the Hi Pass Filter is processing audio.
Hi Pass Filter Window
- For Stereo (L/R) inputs, pan the channels full Left (64L) and Right (64R). For multiple microphones, pan the channels as desired. For a Mono VTC, pan everything to the center (<0>).
• Double-click (or Option/Alt-click) on a Pan knob to set it to the center position.
- Adjust channel faders as desired to get the appropriate mix. Be careful that the combined signal of multiple microphones does not cause the CODEC OUT channels to clip.
• Clicking on a fader sets it to the mouse position.
• Double-click (or Option/Alt-click) on a fader to set it to 0.00 dB (Unity).
• Cmd/Ctl-clicking on a fader to set it to -inf dB (Off).
- The LINK buttons (<> or < LINK >) allow pairs of faders to move together when you drag (or click) one of them. If the two faders in the pair are not at the same level, they will maintain their proportional relationship to each other as you move them up and down. To separate the two faders, simple click the LINK button to turn that function off (button illuminates green to indicate a the faders are linked).
- MUTE buttons silence that particular channel.
- SOLO buttons silence all channels except that particular channel.
- MIX A/B buttons allow you to quickly store and recall two different Mixer settings.
• Option-click one of the two buttons to store settings (button illuminates yellow to indicate a stored setting).
• Click one of the buttons to recall stored settings (button illuminates green to indicate an active setting).
- Mixer configurations may be loaded, edited, saved, created, and deleted by choosing Load/Save Configurations... (Cmd/Ctl-L) from the File menu.
- If you have the requisite hardware configuration, you can create separate mixes for a Control Room or for a live Audience. To do so, open the Monitor Controls window by selecting Monitor Controls... (Cmd/Ctl-M) from the Setup menu.
|Monitor Controls Window
- The remaining echo control tools and windows are explained below.
- For more information on the Mixer, or on any of its functions, please see the Mixer section of this manual.
Due to the wide dynamic range and frequency content of music, there is no "magic bullet" for echo control in a musical VTC. Echo control consists of
three essential stages, with the first being Physical Echo Control. In order for any echo control system to be truly effective you must first take steps to configure the physical space and audio equipment for optimal echo rejection. Once you have done that, the specialized tools in ECHODamp allow you to easily and intuitively accomplish the remaining two stages: controlling outgoing echo (the remote site hears their echo) and controlling incoming echo (you hear your own echo). Echo control is a collaborative process between the two sites. Although ECHODamp is designed to control echo in both directions, for best results, both sites in the VTC should follow these steps rather than attempting to control all the echo from just one location. Due to the way echo control works in ECHODamp, you should deal with the outgoing echo (and have the other site do the same) before working on the incoming echo. You may, in fact, discover that after controlling the outgoing echo from both sites you don't even have incoming echo. If there is still a bit of incoming echo, then proceed to dealing with it as describe in the controlling incoming echo section, but control the outgoing echo first.
The purpose of the Downward Expander is to prevent remote site audio from entering the microphones at the local site. The Downward Expander listens to the incoming audio on its channel and determines if that audio is above a predetermined loudness level or not. If you have performed the Physical Echo Control steps, then audio coming from the remote site through the loudspeakers will approach the microphones from their "null" spot and enter the microphone channels at a considerably quieter level than the audio coming from the local performers. The Expander allows you to set a Threshold level so that remote site audio is below that level, and the local audio is above the level. Thus, the Threshold tells the Expander whether the audio entering the microphone is from the local site or coming from the remote site through the loudspeakers.
When the Expander determines that the incoming audio (Program Input) is above the Threshold, it fully opens the audio channel so that the Program Output is at the same level as the Program Input. However, if the incoming audio drops below the Threshold, the Expander reduces the level of the Program Output, thus preventing the remote site's audio from being transmitted back to them. Once the Threshold level is determined, the other controls allow you to fine-tune the performance of the Expander to get the most effective and transparent response.
Note: Downward Expanders should only be used on microphone channels. Since line level devices such as CD players and synthesizers cannot "hear" audio from the loudspeakers, the Expander should be bypassed for these channels. If you are running your microphones through a hardware audio mixer and connecting the outputs of that mixer to ECHODamp, you should engage the Expander on the channels to which the mixer is connected.
Step-By-Step Instructions for the Downward Expander
For more information on the Expander, or any of its functions, please see the Downward Expander section of this manual.
- Perform the Physical Echo Control steps first.
- Open the Downward Expander for a particular microphone channel by clicking the EXPANDER button near the top of that microphone's input channel strip.
- Have the local performers sing or play some of their repertoire while you watch the level on the Program Input meter. It's important to have them actually perform the kind of music they will be doing in the VTC so that you get accurate readings. You will want them to sing or play quiet passages, as well as loud ones, so you can ascertain the entire dynamic range they will use.
- Turn the ATTACK THRESHOLD knob (or drag the green Threshold indicator) to a point where the audio level from the local performers rises above the green Threshold indicator as soon as they make a sound.
- Turn the RELEASE THRESHOLD knob (or drag the red Threshold indicator) to a point where the audio level from the local performers remains consistently above the red Threshold indicator until they stop making sound.
- Have the remote performers sing or play some of their repertoire and make sure that the audio level from the remote site remains consistently below the green Threshold indicator. Again, have the remote site do both quiet and loud passages for comparison. Note: You may need to go back and forth a couple of times between the local and remote performers to find the right Threshold settings. Once you have the two Thresholds set:
- Adjust the RATIO knob to determine how much the Program Output is reduced when the audio drops below the Release Threshold. Turning the RATIO knob to the right causes a greater Gain Reduction, while turning the knob to the left causes less Gain Reduction. You will probably find that settings between 1:4 and 1:10 work best.
- The following controls can be used to fine-tune the performance of the Downward Expander as well as to save and recall presets.
• The ATTACK knob determines how quickly the Gain Reduction stops when the audio level rises above the Threshold. To avoid cutting off the beginnings of sounds, you will usually want this to be as fast as possible. Thus, a setting of 0.1ms to 1ms will be typical.
• The HOLD knob adjusts how long the Expander waits once the audio level has dropped below the Release Threshold before reducing the gain on the channel. Longer settings will allow for slow decays of instruments, but may start allowing some echo to enter the system
• The RELEASE knob adjusts how quickly the Gain Reduction begins once the incoming audio has remained below the Release Threshold for the duration of the Hold time. To allow for a natural-sounding decay, you will find that settings between 100ms and 500ms usually work best.
• The INPUT and OUTPUT knobs adjust the Program Input and Program Output levels respectively by +/-10dB. For most situations you can leave them at their default setting of 0dB.
•The BYPASS button allows you to turn off the Expander and let the audio pass through unaffected. When the button is illuminated, the Expander is bypassed and not processing audio.
• The PRESET button opens the Preset window for the Downward Expander, allowing you to load, edit, save, create, and delete presets for the Expander modules. The Expanders all share the same presets, so if you make changes to a preset in one Expander, those preset changes will be available to all the Expanders.
|When the Program Input level rises above the
Attack Threshold and remains above the Release Threshold,
the Program Output is unaffected.
||When the Program Input drops below the
Release Threshold for the duration of the Hold time,
the Program Output is reduced.
The purpose of the 2-Channel Ducker is to reduce the amount of your own audio returning to you as echo. If the remote site is properly configured and using the Downward Expander in ECHODamp on their microphones, you may not even need the DUCKER, or only need a very small amount of it. The 2-Channel Ducker can also be the "last resort" tool if the remote site is unable to control echo at their end.
The 2-Channel Ducker listens to your local microphones and turns down the audio coming from the remote site whenever you are singing or playing. It uses the Sidechain Delay function to wait until the round-trip latency time has passed before turning the remote audio down. Thus, the remote audio is lowered just as the echo of your sound is about to come out of your loudspeakers.
When the Ducker determines that the incoming audio from your microphones (Sidechain Input) is above the Threshold—the local performers are singing or playing—it reduces the level of the remote site audio to the loudspeakers (Program Output). However, if the incoming audio from your microphones is below the Threshold—the local performers are not singing or playing—the Ducker allows the Program Output to pass at full volume. Like the Downward Expander, you begin by determining the Threshold level. Once the Threshold level for the Sidechain Input is determined, the other controls allow you to fine-tune the performance of the Ducker to get the most effective and transparent response.
Step-By-Step Instructions for the 2-Channel Ducker
For more information on the Ducker, or any of its functions, please see the 2-Channel Ducker section of this manual.
- Perform the Physical Echo Control steps first. Determine if the remote site is using ECHODamp and its Downward Expander. If they are, you may not need the Ducker, or only need to use it very lightly.
- Run the Latency Detector to determine the round-trip latency of your VTC.
- Ensure that the Sidechain Delay in the main Mixer is not bypassed (BYPASS button is not illuminated).
- Press the SIDECHAIN buttons (the buttons will illuminate) on the inputs of the microphones you are using. This sends a copy of their signals to the Sidechain Input of the 2-Channel Ducker.
- Open the 2-Channel Ducker by clicking the DUCKER button located beneath the AUDIO ON/OFF button in the upper-left of the main Mixer window.
- Have the local performers sing or play some of their repertoire while you watch the Sidechain Input meter in the Ducker. It is important to have them actually perform the kind of music they will be doing in the VTC so that you get accurate readings. You will want them to sing or play quiet passages, as well as loud ones, so you can ascertain the entire dynamic range they will use.
- Turn the THRESHOLD knob (or drag the Threshold indicators) to a point where the audio level from the local performers is consistently above the Threshold indicators. Once you have the Threshold set:
- Adjust the REDUCTION knob to determine how much the Program Output is reduced when the Sidechain Input is above the Threshold. Turning the REDUCTION knob to the right causes a greater Gain Reduction, while turning the knob to the left causes less Gain Reduction. You will probably find that settings between 10dB and 30dB work best.
- The following controls can be used to fine-tune the performance of the 2-Channel Ducker as well as to save and recall presets.
• The ATTACK knob determines how quickly the Gain Reduction begins when the Sidechain Input level rises above the Threshold. A setting in the range of 10ms to 50ms will generally provide the smoothest response.
• The RELEASE knob adjusts how quickly the Gain Reduction stops once the Sidechain Input level has dropped below the Threshold. To allow for a natural-sounding release, you will find that settings between 50ms and 200ms usually work best.
• The INPUT and OUTPUT knobs adjust the Program Input and Program Output levels respectively by +/-10dB. For most situations you can leave them at their default setting of 0dB.
• The BYPASS button allows you to turn off the 2-Channel Ducker and let the audio pass through unaffected. When the button is illuminated, the Ducker is bypassed and not processing audio.
• The PRESET button opens the Preset window for the 2-Channel Ducker, allowing you to load, edit, save, create, and delete presets for the Ducker.
|When the Sidechain audio level is below the Threshold,there
is no reduction in the Program Output level to the loudspeakers.
||When the Sidechain audio level goes above the Threshold,
the Program Output level to the loudspeakers is reduced.
- Spacebar - Starts/Stops Audio Processing
- Cmd/Ctl-Q - Quits/Exits EchoDamp
- Cmd/Ctl-L - Opens the Mixer Configurations Load/Save window
- Cmd/Ctl-U - Opens the User Manual in the preferred Web browser
- Cmd/Ctl-A - Opens the Audio Settings window
- Cmd/Ctl-T - Opens the Calibration Tools window
- Cmd/Ctl-M - Opens the Monitor Controls window
- Opt/Alt-Shift-A - Stores current Mixer settings to the MIX A button
- Opt/Alt-Shift-B - Stores current Mixer settings to the MIX B button
- Opt/Alt-A - Selects MIX A button
- Opt/Alt-B - Selects MIX B button
- Up Arrow/Down Arrow (in the Configuration or Preset window) - Selects presets from the dropdown menu
- Enter or Return (in the Configuration or Preset window) - Selects the "Enter" button if visible
- Esc (in the Configuration or Preset window) - Selects the "Cancel" button if visible
- Click a Fader - Sets the fader to the click position
• Double-Click (or Opt/Alt-Click) a Fader - Sets the fader to 0.00 dB (Unity)
• Cmd/Ctl-Click a Fader - Sets the fader to -inf dB (Off)
- Double-Click (or Opt/Alt-Click) a Pan Knob - Sets the pan position to <0> (Center)
- Shift-Click the SIDECHAIN DELAY knob - Allows the knob to move by 1ms increments instead of the default 100ms increments
- Click the Threshold indicators in the Expander or Ducker windows - Sets the Threshold to the click position
Like most full-featured computer audio programs, ECHODamp can put a substantial load on your computer's CPU. To reduce that load and improve performance—especially on slower computers—follow these two suggestions:
- Only enable the channels you need - Turn off unused channels in the Audio Settings window to eliminate unnecessary processing
- Keep windows closed - Like any computer program, the more windows you have open, the heavier the processor load on your computer is. If you need to make settings changes in a window, close the window after you make the changes.
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Overview, Installation, Setup, and Configuration | Calibrating Your Audio | Using the ECHODamp Software
Menus and Mixer Window Reference | Secondary Windows Reference
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