User Guide

Waves IR-1 software guide page 20
Reverb Time
The Reverb Time section includes these 4 parameters:
CONVOLUTION START: Range: 0 to 1 second; Default: 0 seconds
The Convolution Start control determines the starting point of the convolution process. It
enables you to remove unwanted pre-delay at the beginning of an IR.
CONVOLUTION LENGTH: Range: 0 seconds to 6 seconds; Default: Full
This control sets the length of the process filter. By default it is set to Full, which means that
the IR-series will convolve the input with the whole Impulse Response. However, if the IR is
longer than 6 seconds then it will be cut to 6 seconds. This will be indicated in the IR
Properties display. You can also set the Convolution length manually to be shorter than the
RT60 Reverb time in order to save some CPU. This makes the Impulse Response stop at
some point down the slope, creating a “gated” reverb sound. This gating effect can be
avoided by using the Envelope to make the IR fade out earlier. The default Full setting will
only use the amount of CPU it needs for the loaded IR, so there’s nothing to gain by
manually setting it to 2 seconds for a 2 second IR. RATIO: Range: 0.25 to 4.00; Default: 1.00
The Reverb Time Fader controls the Reverb Time Ratio. The resulting reverb time will be
the original RT60 multiplied by the ratio.
RT60: (Reverb Time, 60dB) is defined as the time it takes the sound pressure level of a
sound to drop by 60dB in gain once the source has been shut off. It is actually a slope factor.
RT60 is a term that is commonly used in building construction and architecture to describe a
room’s acoustic properties.
This field shows the reverb’s current RT60. It is the original RT60 multiplied by the Reverb
Time Ratio. To determine what the original RT60 is, set the Ratio to 1.00. The original RT60 is
calculated by analysis of the loaded IR.