stereo widener effect

I use Audacity in mastering my projects, and it works very well. I noticed in Audacity 2.0 that there are a lot of new effects, some with exotic names that don’t always tell exactly what they’re for. Can anybody tell me if Audacity offers a stereo widener effect? Thanks.


The stereo widener effect is not shipped with Audacity.
There are two plug-ins available as Nyquist implementation.
Channel mixer and Stereo-Widener.
I prefer the former one because it can also be used for nihilation effects (vocal remover).

I added the “stereo widener by David R. Sky” to Audacity to use in the mastering process of a project, but I’m not exactly sure how to use it. I played with it for about 30-40 minutes but couldn’t get satisfactory results from it. Can anyone explain exactly how to use this plug in to get a subtle stereo widening effect?

The effect depends on how “stereo” the track is already.
Stereo tracks with nearly identical content in both channels won’t profit from the effect.
It is most distinguishable in a track that has multiple instruments, already panned in the stereo field.
Maybe there’s a organ on the left side and a guitar on the right. The widenener effect pushes towards the borders and even beyond them. But it also blurs the exact position of the instruments, i.e. the sound sources are no points anymore but rather ranges.
Do you want to widen a single instrument/voice or an already mixed-down track?
Maybe you could attach a short sample sound.

I just attempted to send a post on this subject thru with a short attached WAV file, but it appears to have not gone thru. In addition, it deleted the message as well as the one I was responding to. So let me begin this message by saying I’m using version 2.something of Audacity in Windows 7 Home Premium 64 bit SP1. I’m self-mastering 13 originally recorded songs which have already been mixed with appropriate stereo panning. I’m attempting to use the stereo widener by David R. Sky to add spaciousness to these mixes. I believe it will do the job I want, but I don’t understand the controls, and playing with them didn’t bring me much clarity. I also found nothing on this plug in in FAQ or wiki, or in the plug in section of the manual. There are 3 controls: First is Inverted Signal Volume, which defaults at -18. This drops the stereo track’s volume markedly. Why? And what happens when you adjust that volume (other than it changes the amount the volume drops)? And what happens when you restore the volume? Second is Pan Position, which defaults at 0. I think in terms of pan position as L & R. What does a pan position of 0 mean, and what happens when it’s changed? Third is Time Offset, which also defaults at 0. What happens if this is changed? I apologize for my ignorance on this subject, but I’ve been told this can make a difference in my masters, since I record in a small room. Any help and/or advice will be appreciated.


Unfortunately David Sky will not be able to explain or document his effect as he sadly passed away in 2009.
I’d recommend that you try the Channel Mixer plug-in that Robert suggested. If you have any questions with that effect, the author (myself) is still alive and kicking and able to offer support.

David’s Plug-in uses two techniques to widen the stereo field.
One uses intensity stereo (same as moving pan fader)
and the other is time delay stereo.
our ears identify the position of a sound source according to volume and time difference on each side.
The general widening effect mixes the original channel with the negative part of the second channel.
That’s the second control in the plug-in which actually should be called “Width” or “Spread”.
The first control is something like wet/dry or mix control. However, it is not balanced, i.e. 30% original + 70% processed signal.
I am not entirely sure if the plug-in does what it is supposed to do. It confuses me a bit that the calculated sound is in the end taken away from the original (wet/dry) but also shifted in time, if an offset is given.
Maybe a example calculation will give some hint.
Let’s assume the values are -12 dB and -30 (percent?), offset 0.

Old left/right channel 100%
New left channel =
old left channel - (0.25 * processed left channel).
0.25 is the equivalent to -12 dB and -30 will be -0.3 for the next calculations
Processed channel =
0.5 * (old left channel * (1 - 0.3))

  • 0.5 * (old right channel * -1.3))
    = 35% left + 65% right
    and this new left channel is multiplied by 0.25 and taken away from the original left channel.
    = 91.25% left + 16.25 inverted right.
    The calculation for the new right channel will give the same results (if there’s no fault in my calculations to begin with).
    You see that the parameter -30 doesn’t tell you much, how wide the signal will be in the end because it is also dependant on the first parameter, not to mention the influence of the time shift.
    I strongly recommend Steve’s Channel mixer.
    You can read out the results for the different presets in the debug window and can adjust the percentages to suit your needs.

Thanks to each of you for your generous and helpful responses. And Steve, I downloaded your channel mixer effect, but had a little trouble installing it. However, Audacity now seems to have found & installed it, so I will be working with it soon. Thanks again to each of you.