The Bongiovi Dynamic Stereo Speaker Enhancement algorithm extends the perceived width of the stereo field while maintaining important center channel information. This is most effective with L/R speakers that are close together. It works by increasing the SIDES (L-R) relative to the MID (L+R) channel which changes the phase relationships between Left, Right and Mono information in the signal as shown in the image below. When MID and SIDES gains are equal, the stereo effect is normal.
The mid/sides effect is done only to frequencies above the CROSSOVER point. All content below the crossover point is bypassed. When important MID content occurs (vocals, snare drum, gunshot etc.) the SIDES gain is decreased via a sidechain AGC (Dynamic “Sides” Level Controls). Stereo Field Control Meter The effect is displayed in real-time on the STEREO FIELD CONTROL meter. The distance between the circles indicates the relative difference between MID and SIDES including any modulation created by the AGC. When the circles are touching the stereo field is normal L/R. When the SIDES level is increased, the circles move apart and the stereo field is enhanced. If MID level is increased the circles will begin to move together as L and R channels are summed together. This indicator is disabled by clicking the switch to the right. “Efficient” Stereo Enhancement Some platforms offer an “Efficient” Stereo Enhancement mode. The algorithm is the same except the Dynamic “Sides” Level Controls are disabled. The stereo enhancement effect is achieved by statically increasing “sides” gain relative to “mid”. When the stereo meter is enabled, you will see the relative difference between MID and SIDES displayed by the circles. However, they will not move as they would when the AGC is enabled. Best practices The image above demonstrates common settings for most speakers and sound bars.
- MID gain should be kept at 0dB in most circumstances.
- The best effect is achieved when the circles move together quickly when voice and important sound effects occur. Dynamics must be enabled for this feature to work. If the circles do not move (always wide or always in the center), calibration is not correct.
- Lower the THRESH control to increase the amount the “sides” signal is modulated due to loud center channel information.
- When the Left/Right high-frequency drivers of the speaker system are close together, larger SIDES gain values may be used (+5dB to +10dB). This is because of the high correlation between Left/Right signals.
- When the Left/Right high-frequency driver are far apart (like most TV soundbars), lower SIDES gain values should be used (+1dB to +5dB).
- If the difference between MID and SIDES is too great, the sound effect will be poor.
- When Dynamics are not enabled, the “sides” signal will not be automatically reduced. Therefore, lower SIDES gain values should be used (+1 to +6dB).
Control Overview
SENSE
- This affects how the AGC detects important frequency content. Increasing SENSE makes the AGC more sensitive to high frequencies.
THRESH (threshold)
- Set the level where SIDES will be decreased relative to MID.
DYNAMICS
- Enables the dynamic restoration of center channel information.
- When unchecked, THRESH and FAST RESPONSE have no effect.
FAST RESPONSE
- Controls the speed at which the SIDES signal reacts to the MID signal to restore the center channel.
- Enabled = 90ms
- Disabled = 400ms
CROSSOVER
- All frequencies above this value will receive the stereo enhancement effect.
- All frequencies below this value pass through unaffected.
MID
- The level of the middle channel.
- This is the result of Left channel + Right channel.
SIDES
- The level of the sides channel.
- This is the result of Left channel minus Right channel.
- Boost this value to increase stereo enhancement effect.
- This control is exposed to the user. You will see this value reflected in the User Controls window.
BYPASS
- Click to disable the effect.
Only one effect may be enabled:
Dynamic Stereo Speaker Enhancement