Applying an effect to a separate track

[SubMatrix]

Hi, I want to apply some reverb to my track. On the audacity wiki, it is suggested that you apply the reverb as a separate track so you can individually control the reverb track and the original track. It seems to suggest duplicating the main track before applying the reverb, but I fail to see how this means youve isolated just the reverb signal to a track. It seems to be you would have two tracks- the original track, and the original track + reverb. How can i tell Audacity to take just the reverb signal and write it in a separate track?

[steve]

Let's say "Track 1" is the original, and "Track 2" is the duplicate (to duplicate the track, select track 1, then press Ctrl+D).

Select "Track 2" and from the Effects menu select G-Verb

The default settings in G-Verb s for a "Wet" mix - that is; the "Dry" original audio is turned off (-70 dB), so that only the "early reflections" and "tail" are present after applying the effect.

You now have the "Dry" sound on Track 1, and the "Wet" effect on Track 2.
You can now use the volume sliders on the left side of the tracks to adjust the levels.

Notes about G-Verb:
1) The default setting is a very long reverb - you will probably want to reduce the reverb time to around 2 seconds.
2) The reverb levels ( "early reflections" and "tail") are set rather high and may distort if your original track was quite loud. Test on a short loud section first and reduce these levels if necessary.

[SubMatrix]

Thanks for the reply. So as long as i have the dry signal level at -70, the original input signal will be nonexistant? How does this compare to, say, a dry signal level of 0 dB? (isnt 0 nothing? why all the negative business?)

[steve]

Decibel (dB) is ratio in relation to a given reference rather than an absolute measurement. In some situations it is more convenient to talk about the ratio of something above a given reference, in which case the dB will be positive. In other situations it is more convenient to talk about the ratio of something below a given reference, in which case the dB will be negative.

In the case of "sound pressure" levels (for example, how loud the sound coming from a loudspeaker is), the reference level is taken as the volume that is at the threshold of being audible - the level that is "silent", but just about to become audible. This reference level is 0dB, and any increase in loudness will be a positive increase in dB's.

When looking at signal levels, the reference level is taken to be the highest level signal before clipping (distortion), and again is represented as 0dB. Any signal below that reference can be described as being so many dB below the reference - that is, negative dB's. You will see this method used on all kinds of audio equipment, where 0dB is the maximum signal level, and signal levels are given as negative numbers that represent the number of dB's below the reference.

Strictly speaking, silence would be "minus infinity" dB, but -70dB is so quiet as to be virtually silent.

In digital audio, the magnitude (level) of each audio sample is represented by a number in the range +1 to -1
This is why in Audacity you will see the vertical scale marked with a range of +1 to -1 with 0 (zero) at the centre. The maximum possible signal that you can have in a track will reach between +1 and -1 (the top and bottom of the track) and this would be a signal level of 0dB.

For a more detailed explanation, you could look it up in Wikipedia.