Wikipedia says:

An all-pass filter is a signal processing filter that passes all frequencies equally in gain, but changes the phase relationship among various frequencies.

1. What does "changes the phase relationship among various frequencies" mean and what is its musical application?
2. Where is an All-Pass Filter used?
3. Are there any All-Pass filter plugins (AU, VST, AAX)?

Wikipedia says:

An all-pass filter is a signal processing filter that passes all frequencies equally in gain, but changes the phase relationship among various frequencies.

1. What does changes the phase relationship among various frequencies mean and what is its musical application?
2. Where is an All-Pass Filter used?
3. Are there any All-Pass filter plugins (AU, VST, AAX)?

Wikipedia says

An all-pass filter is a signal processing filter that passes all frequencies equally in gain, but changes the phase relationship among various frequencies.

1. What does changes the phase relationship among various frequencies mean and what is its musical application?
2. Where is All-Pass Filter used?
3. Are there any All-Pass filter plugins(AU, VST, AAX)?

Wikipedia says:

An all-pass filter is a signal processing filter that passes all frequencies equally in gain, but changes the phase relationship among various frequencies.

1. What does "changes the phase relationship among various frequencies" mean and what is its musical application?
2. Where is an All-Pass Filter used?
3. Are there any All-Pass filter plugins  (AU, VST, AAX)?