Finding the AUs
When you double-click a track in GB, the information for that track appears. If you click the Details triangle, even more information shows up (see the following figure).
If you click one of the popup menus, the hidden AUs are visible. The list is partly shown in the following figure. Let's take a short overview of them.
AuBandpass can accentuate the frequencies of sounds you want to "punch up." To access the control for it, you click the pencil at the rightmost side of the main dialog box. A control window then appears. In this control, the range of frequencies, and the center of that range can be set. The following figure shows the control.
AuDynamicProcessor is a complex control, but has descriptive presets available at the top of the control window. This control changes a sound's dynamic characteristics. A sound can be customized in many creative ways through custom settings of the sliders as well. See the following figure for all the ways a sound can be varied.
AUGraphic EQ is a simple way to set relative volumes of each of the 31 frequency bands (labeled at the bottom of the sliders) that comprise the entire sound. This varies from the bandpass (although it can be set up to function as a bandpass) because it simultaneously affects all of the 31 bands instead of concentrating on just one specific frequency range. The following figure shows the slider arrangement.
AUDelay is different from the standard echo effect of GB in that it is much more full-featured in the way the echo can be controlled. Wet means that the sound will be more "crowded" than the dry mix. You can even cut out which parts of the sound will be unaffected by the echo. Lower frequency sounds tend to "mud" up an echo. The following illustrates the choices available.
AUPeakLimiter is useful when a sound has specific loud areas that will overwhelm the rest of the sound. With this control, the speed at which the control will respond to limit a sound can be set through the attack and release variables. The longer an attack time, the longer time period the control will take to come into play. A long release time means that the control will be in effect for a longer time. The exact amount of limiting can be set in the pre-gain and limiting amount sliders. The peak limiter works on specific frequencies when they get above the preset limit while leaving the non-peak frequencies alone. This sounds much better than reducing a track's overall volume just because one part of the sound is a problem. The following figure shows this control.
AuHiPass does just what you think it does: It allows frequencies that are higher than the settings to pass through. This is great for getting rid of low-frequency rumbles and the like. See the following figure for the control panel.
AuHiShelf is similar to the one above, but adds a gain control for the output. Personally, I've never needed to use it, but it's nice that it is there. The following figure shows what it looks like.
AuLowPass and AuLowShelf function in the same manner as the ones above, but pass low frequencies and attenuate high ones. If you use both the high and low filters in one instrument at the same time, you can get a very specific and adjustable notch filter that allows the frequencies in the middle of the high and the low settings to pass through.
AUMultibandCompressor is similar to the compression effects that GB gives in the main controls, but with control over the frequencies that are compressed. Although most users might find the available presets in this control of the most utility, advanced users have a field day tuning their compression for an instrument. Attack and release function in the same manner as the other Audio Units we have looked at, whereas threshold is the range where compression begins. The following figure shows you what you can do with this control.
AUMatrixReverb simulates the acoustics of various venues. The presets are probably the most useful here because they are fairly wide-ranging. From an intimate room to a concert call, the reverberation caused by the selected room can be simulated. The following figure shows the choices you have in this complex control.