Yamaha CS1D Owner's Manual - Page 545

EXPANDER An expander is similar to a compressor except that it works on signals below the threshold level. By reducing signals below the threshold level, the expander attenuates low-level noise, effectively increasing the dynamic range and improving the signal-to-noise performance. An expander set to an infinite ratio (i.e., ∞:1) is essentially a gate. The following two graphs show typical expander curves. The one on the left shows an expander with an expansion ratio of 2:1 and a hard knee setting. The one on the right shows an expander with an expansion ratio of 2:1 and a soft knee setting of 5. Output Level (dB) +20 +10 Expansion ratio = 2:1 0 Knee = Hard -10 Threshold = -10dB -20 -30 -40 -50 -60 -70 -70 -60 -50 -40 -30 -20 -10 0 +10 +20 Input Level (dB) Output Level (dB) +20 +10 Expansion ratio = 2:1 0 Knee = SOFT 5 -10 -20 Threshold = -10dB -30 -40 -50 -60 -70 -70 -60 -50 -40 -30 -20 -10 0 +10 +20 Input Level (dB) Compressor Types Parameter Range THRESHOLD -54 dB to 0 dB (1 dB steps) OUT GAIN ±0.0 dB to +18.0 dB (0.5 dB steps) KNEE HARD, SOFT 1, SOFT 2, SOFT 3, SOFT 4, SOFT 5 ATTACK 0-120 ms (1 ms steps) RELEASE 5 ms-42.3 s (fs = 48 kHz) 6 ms-46 s (fs = 44.1 kHz) RATIO 1:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 5:1, 6:1, 8:1, 10:1, 20:1, ∞:1 (16 points) INPUT FILTER HPF (high-pass filter) or HPF/LPF LPF (low-pass filter) INPUT FILTER ON/OFF ON or OFF INPUT FILTER FREQUENCY 20 Hz-20 kHz (121 steps) THRESHOLD-This determines the level of input signal required to trigger the expander. Signals above the threshold pass through the expander unaffected. Signals at and below the threshold level are attenuated by the amount specified using the Ratio parameter. The trigger signal is sourced using the KEY IN parameter. OUT GAIN-This sets the expander's output signal level, and can be used to compensate for the overall level change caused by the expansion process. KNEE-This determines how expansion is applied at the threshold point. When set to hard, expansion at the specified ratio is applied as soon as the input signal level falls below the specified threshold. For knee settings from 1 to 5, however, expansion is applied gradually as the signal falls below the specified threshold, creating a more natural sound. ATTACK - Specify the time over which the expander will return to the normal gain after the trigger signal exceeds the threshold. If the attack time is too short, the gain will return suddenly, causing the sound to "jump out." (The gain change will be obtrusive.) However if the attack is too long, the next signal will be input before the gain has returned, causing inappropriate expansion. When setting the attack time, it is a good idea to start with a value in the range of 1-5 milliseconds. RELEASE - Specify the time over which the signal is expanded from when the expander is triggered. If the release time is short, the signal will be expanded almost instantly. If the release time is long, the release portion of the sound will not be expanded. When setting the release time, it is a good idea to start with a value in the range of 0.1-0.5 seconds. 13