You can get so into the technical stuff you can even arrive at an incorrect conclusion like something is not useful.  From a practical standpoint everything is useful.  Channel Tools is a very useful plugin to have around. As someone who mixes a lot I tend not to think of it as a device for increasing apparent width but much more often for me anyway decreasing width.  It is also good for fine tuning levels of both L and R channels.
 
I am working on a mix now that is big and complex and quite a lot going on right across the stereo field.  The client supplied some extra pad like tracks.  They were nice musically but very wide.  Due mainly I would so say to the processing that was on the last stages of either a virtual or hardware instrument.  (and also in programming of course)  When put into my existing mix I felt it was just out on the sides too much.  I wanted some stereo but not so wide and I wanted that whole sound to move to the left slightly.  Channel Tools did an excellent job.  Once it got out of the way of the sides and moved to the left a little it became easier to hear.  Maximum illusion, minimum voltage. I was able to turn it down. 
 
I got a bass part that was also very wide (some wild panning) and it too did not sit well being so wide with a wide mix so I planted both channels in the centre and it too became clearer and louder, able to turn it down and still hear it etc..
 
I have also had the situation where I either recorded or received a nice pad part in a piece. It was stereo and sounded nice at the time. On further listening I discovered it was not stereo enough. It had a little width.  It was having trouble being heard.  There are better processors than Channel Tools out there that will widen a sound like this and put it well into the sides and well away from the centre.  And doing it all without using delays but much more interesting techniques that you don't need to understand.  All you need is to understand what they do to the sound.  What a good widener will do will make the pad sit well out away from the centre so it becomes very clear and easy to hear.  I was able to turn it down again. 
 
I check all mono compatibility by summing L+R and listening to a small single point source mono speaker.  The better more interesting widening processors play well with the mono check.  Once you start turning the polarity of one side of a stereo image upside down is when the mono test fails badly. eg some parts disappear all together!  That is a horrible effect in most circumstances.  I prefer to leave that alone.
 
It is also very handy to be able to flip the polartiy of one side of a stereo signal too.  I have used that correct a bad stereo effect that must have used the same technique.  And it is also nice to be able to use the delays on one side.  For a slow moving pad I have been known to add 100 mS or more to one side.  It creates a lot of width due to the time distortion going on.  And it sums great in mono too.
 

Mike, I wasn't able to draw any conclusions from your last post, but it made me think that I could do a similar test to answer the idea of the out of phase from the spreader.
 
The answer is no. It does not spread the sound out of phase.
 
In this image,

• A is the original tone
• B is the tone bounced through channel tools with Left angle at 16.3 degrees, Width at 45.8
• C is the tone bounced through channel tools with Left angle at 16.3 degrees, Width at 0.

 
You can see from this image that both left and right channel stay in phase.
 
As Craig described, it seems like the width spreader is a subtle volume boost for the signal across the 2 channels.

Hi Geoff,
 Thanks for the added info.
 
 BTW, It occured to me that the change in waveform shape as displayed in the screen shot I posted is probably the result of additive synthesis of the two different frequency sine waves as they overlap due to the "widening".
 
 

Anderton
 
You keep saying CT width is not doing what it's claiming to do, and perhaps there's where I just don't get where you're coming from. What exactly do you think it's claiming to do? If manipulating the width controls changes the perceived image from (a) to (b) or (c) in the diagram below, that certainly seems like it's affecting the width of the stereo image. What are you expecting to have happen?
 
Furthermore, if I understand what you're trying to accomplish correctly (which I'm not sure I do), using an identical mono signal in each channel is NOT how Channel Tools is intended to be used.

First, let me make clear that I love Channel Tools.  This is not an adversarial discussion.  What I'm trying to accomplish is simply to understand something that seems not possible.  I recently started giving some critical thought to issues of stereo placement and width, the sort of thing that you can do with Channel Tools or plug-ins specializing in this purpose like Waves S1 Stereo Imager or Nomad Factory BT Stereo Imager ST2S.
 
I keep using the example of one channel having zero signal because it reduces the complexity of the discussion.  However the width control works, it shouldn't work any differently than normal in the edge case where one channel is completely silent, right?  In this reduced case, we can use the CT pan to effectively produce two identical audio streams in L and R that differ only in amplitude.  With me so far?
 
Now, if we have L and R that are identical except for amplitude, then the amplitude difference governs the position of the phantom center.  I can't conceive of how it could do anything but that.  If the width control simply changes the relative amplitude of L and R, then it's just moving the phantom center.  Nothing wrong with that, but it is not truly a width adjustment, just an effective pan adjustment.
 
So, my original question was really whether or not there was something else going on that the CT documentation wasn't telling us, such as the use of a Haas delay to produce a faux stereo quality - two versions of a single channel's content.  Once you had that, then you should indeed be able to produce a sense of width.  It certainly appears that CT is doing nothing of the sort - which, again by the way, I think is a good thing.
 
 
 
 

dmbaer
So, my original question was really whether or not there was something else going on that the CT documentation wasn't telling us, such as the use of a Haas delay to produce a faux stereo quality - two versions of a single channel's content.  Once you had that, then you should indeed be able to produce a sense of width.

It can do that sort of thing using the Delay parameters.

Hi David,
 Regarding the Haas effect, one of my favorite things about Waves S-1 is that when you "rotate" the image, as opposed to panning with some other dsp, there is a slight but discernible delay that occurs. I really enjoy how making an adjustment to the "image" is easy to hear in a set of monitors.
 
 I, personally, enjoy the results so much that I no longer bother to use a panning tool, and rather instantiate Waves S-1 so as to achieve the sound I had always hoped to imagine when twisting a pan pot.
 
 With regards to the Channel Tool, I enjoy using it for it's M/S capabilities. I enjoy recording with M/S mic arrays and I also enjoy M/S processing of stereo mixes.
 
 With regards to widening, Channel Tools can do a terrific job of "widening" if we simply use the Mid and Side gain knobs, which I'm sure you know, and as Geoff has made mention of, and I think it is an awfully handy tool for that sort of work. 
 
 IMO, There are good ways to use most of the tools we have available, but I enjoy knowing what they do and what they don't do, so I have appreciated the discussion that your question inspired.

mike_mccue
I have appreciated the discussion that your question inspired.

+1

Anderton
 
It can do that sort of thing using the Delay parameters.

No argument there, but I didn't want to complicate the discussion by introducing delay - it really has nothing to do with what I've been talking about.
 
I thought of possibly a better way of stating my assertion.  Channel Tools and other stereo imager plug-ins can indeed provide width control of a stereo audio stream.  But you cannot get any "widthier" than that.  To modify width, you need stereo data to work with.  You cannot add width to a mono source or one side of a stereo source.  So, in CT, the two pan controls are what's really controlling the width.  The width controls next to them are illusory, since they are just altering the pan position beneath the covers.

dmbaer
The width controls next to them are illusory, since they are just altering the pan position beneath the covers.

This is exatly what the width does as I understand it, but it does it from within the control. It's as if you could turn the pan bot on the track to increase the intensity of one side or the other before the signal enters the plugin.
 
As far as I can tell, that's what it does exactly. It allows you to emphasize the audio entering the plugin on one side or the other. 

mike_mccue
 
Regarding the Haas effect, one of my favorite things about Waves S-1 is that when you "rotate" the image, as opposed to panning with some other dsp, there is a slight but discernible delay that occurs. I really enjoy how making an adjustment to the "image" is easy to hear in a set of monitors.
 

Hmmm, wonder what that's all about.  I have S-1 but have never bothered to use it.  Easier to just whip out Channel Tools. 
 
Could it be the Shuffling control?  The S-1 documentation doesn't really tell us what it's doing, just what it's supposed to accomplish.
 
Now, if there are messing around with timing, then that contradicts what the manual later claims about how S-1 does absolutely nothing to mess up mono compatibility.  If you introduce Hass delays or the like, you absolutely are asking for trouble there, right?  On the other hand, maybe you can get away with that in the bass EQ range, which is what shuffling is supposed to assist with.  More grist for the mill.