The Stereo Tool stereo image manipulator offers some unique options.
The following settings and sliders are available:
ON
Turns the stereo image manipulator on or off.
DIFF
If ON, plays the difference between the input
and output signal. Useful for analyzing the effects of different settings.
fix phasing (azimuth)
These sliders can be used to repair phasing errors (AZIMUTH errors), which
are often present in tape recordings, and also on some cheap CDs.
Phasing problems causes playing a recording in mono or through a surround
system to result in very ugly artifacts. But even normal stereo playback
may sometimes sound a bit unpleasant.
The phasing
offset is automatically detected and removed by this filter.
max is the maximum tape head displacement (assuming cassette tapes) that
can be detected and resolved. Setting it to 0 disables this filter. Suggested value: 40.
diff is the maximum speed at which the filter follows detected
phasing errors. Suggested value: 0.20.
phase
Stereo phase multiplier. Moves between 0 (no
phase differences between the channels), 1
(no change) up
to 8 (8 times as much phase difference as in
the original signal).
0 is VERY useful for converting to MONO,
the resulting sound can be downmixed to mono
without any distortion or loss of sounds, which occur in normal stereo
to mono conversion. This creates a much fuller and undistorted mono
sound.
Note that "0" does not mean that the output signal is mono, because the
instrument locations are not affected by the phase slider. To get mono
sound, also put the width slider to 0.
When playing compressed audio, especially lower (< 192 kbit/s) bandwidth
MP3 files, setting phase to a high value will very strongly amplify
the already present MP3 encoding artifacts, which results in a very
poor sound quality.
width
Stereo width multiplier. Moves between 0 (all sounds in the center,
1 (no change) up to 8 (the sounds are moved 8 times further away
from the center than in the original signal, if possible of course).
Note that "0" does not mean that the output signal is mono, because the
phase differences are not affected by the width slider.
Setting width to a very high value will almost always introduce artifacts,
so it should be used with care - or not at all.
limit
Sets the maximum phase difference per frequency. Could be useful for example for FM radio stations,
this can ensure that the maximum phase difference stays below a certain level, which
reduces signal loss when a receiver switches to mono.
This setting currently introduces artifacts. It should not be used unless it is really
necessary. Changes may be made to it in later versions.
max phase
When the total phase difference between the two channels gets above this level, the
phase amplification is reduced temporarily to keep it below the level that is set here.
Some example uses:
Goal: Mono output.
Set phase and width both to 0. This results in mono sound, but without the
loss of sounds and distortions that normally occur when converting from stereo to mono.
This has been reported to be very useful for people who are deaf in one ear. With this
setting, they can listen to music using a headphone in only one ear, and still enjoy the
full sound of a stereo recording.
Goal: Stronger stereo effect.
Set width to 1 and phase to 2-3 (lower if using low quality MP3 recordings).
The instruments stay at the same position, but the phase differences
are increased, which usually results in a very pleasant sound, unless the
phase differences get too large.
The max phase slider can be used to limit the maximum phase
difference. So when a recording that already has strong phase differences
is played, nothing happens - or the phase differences are even reduced.
CENTER BASS
If there is a phase difference in the bass between the left and right
channel, and the sound is played using a single bass speaker, the bass
will get deformed and lowered in volume. If this filter is turned on,
phase differences for bass sounds are removed completely, which solves
this problem.
This occurs only very rarely. Note however that when the "phase" slider
is set to a high value, this will occur much more frequently.
When listening with headphones, this somewhat reduces the stereo effect.
angle
This slider can be used to add a phase offset
between the channels. Both -180 and +180 cause
the channels to be the opposite of each other,
0 is normal output.
Note: The phase slider is performed first!
stereo only
-100 %: Play ONLY the mono sounds.
0 %: Don't do anything
+100 %: Play ONLY the stereo sounds.
If an instrument is only present on one channel,
-100% will completely remove it. If an instrument
is present at the center, +100% will completely
remove it.
Note: The width slider is performed first!
Use 'stereo only' with care: High values can cause annoying
artifacts.
The bars display the input and output phase and width.
Use these bars to visually check the effects of what you are doing.
