Are Front Wide Speakers a Matrix of Front and Surround Sides or are they something different?

Yes.

Wides first gained usage on home theatre systems with the introduction of Audyssey DSX several years ago, which used concert hall acoustics as the basis for its processing. The front L/R channels were copied to the Wides with a bit of reverb & delay added to simulate early sidewall reflections of a larger space.

By comparison, DTS Neo:X (and now Neural:X) upmixing didn't generate reverb for the Wide speakers like Audyssey did but instead relied completely on extracting common info from the Fronts and Sides (or Fronts and Surrounds in a 5.1 set-up). Think of it as a centre output between a pair of adjacent channels; those sounds would have phantom imaged there anyway.

With Atmos, Wides are fed discrete content from the rendering engine; sounds/objects tagged with the x,y,z coordinates for that location are sent to speakers at that location. Without Wides, those audio objects are sent to the Front and Side speakers, so they phantom image at the intended location.

Hence the Yes at the beginning of my reply. There isn't just one method for feeding the Wides speakers.

I have a couple of Sony HTIB that I bought years ago for bed room applications. They have an analog input on the back for external sources that upmix via PLII to 5.1. Saying that, would connecting Front Left and Side Surround out of my current AVR to the L/R analog input of the HTIB then connecting a speaker to the Center output work properly for Left Front Wide via PLII? Ditto for Right Side.

Seems logical to me. Just trying to make sure my thinking is not off base.

Could technically expand my 7.1.4 to 9.1.4 with a couple of RCA cables.

Thoughts?

I simulate both of these modes with MiniDSP units. But I find there is very little there in the (front - side) mode.

Sure. That's how some are matrix extracting Top Middles from their AVR's Top Front and Top Rear outputs. AND a couple of AVRs with PLII. You forgot that part.

I have used front wide speakers for over 10 years and find that they contribute a level of immersion so that the speakers just disappear. Without them my system sound sounds more like it is emanating from specific speakers. Audyssey claims wides are more important than heights and rear surrounds. They are right IMO.

I have used the Side Axis configuration in my Sunfire TG3, the DTS-Neo X and Audyssey DSX in my Marantz 7702. I am sure the matrixing formulas differ but the end result is the same, more complete immersion.

Yeah, I am ready to try out the Matrixing with Front and Side but also has me wondering what the surround outputs from an AVR fed a Left Front and Left Surround would be like?

Meaning if Left Front and Left Surround (Side) Pre out of my 3050 in Left and Right input of Matrix AVR 1 would equal Left Front Wide...What does Surround Left output of Matrix AVR1 output? Would that be Left Height Surround and Surround Right output of Matrix AVR 1 be Left Front Wide Height?...

This is just my OCD kicking in but I have to test this. I have the ability now to but my wife would not go for 6 more speakers being hooked up in our family room!

With an Additional 2 AVRs, I am thinking it would be possible to add Left+Right Front Wides, Left+Right Side Surround Heights (or whatever it would be called) and Left+Right Front Wide Heights (or whatever it would be called). Could also output the True Left and Right output of the Side Surrounds using the Matrix AVR1+2 Front Left outputs to take the load off of the 3050 so each Matrix AVR would be outputting to 4 speakers.

Ultimately the result would be 9.1.8. Sorta

What do you all think?

I think it would work. There is a conversation going on in the Auro thread but people considering this have large rooms, something like a datasat or a trinnov, and large amounts of discretionary income. Auro just added wide channels for their new upmixer which isn't available in the home market yet called Auromax. Try posting in the auro 3d thread and you will see what i mean.

I know this is an old thread - but very curious to how you are simulating this with your MiniDSP. I have BSS London Soundweb unit which should (at least) have the same capability as the miniDSPs but I'm not sure how I can matrix new channels.