I considered the soffit approach but couldn't sacrifice enough floor space with such a large kit in my room so will be mounting the speakers on stands.
soffits only take up a couple of extra inches in room depth. If you think about it, it's logical: What a soffit really is, is just a large flat, heavy panel that is placed as an extension of the front face of the speaker, which is still in roughly the same position it would have been anyway. The only difference is that you need to leave a little extra space at the rear for speaker ventilation, but apart from that, there's no real difference in the location of where the speakers will be...
I'll be also be covering the RFZ's, rear, sides and above me with 100mm insulation.
Just to clarify: you cannot create a reflection free zone with absorption! It has to be created with reflection, believe it or not. Some people seem to think that just putting absorption on all first reflection points will produce a true reflection free zone: it does not. All that it does is to make the first reflections more muddy, since it absorbs practically all of the high frequencies most of the high-mids, some of the low mids, and none of the lows. So it "colors" the reflected sound. That's why true RFZ rooms have carefully angled reflective surfaces at the front of the room, in order to direct ALL first order reflections past the engineer's ears, to the rear of the room where it can be diffused (if the room is big enough) or absorbed.
For the corners, I was planning on using super chunks but I wanted to at least keep some life in the room so went with the corner slat resonators floor to ceiling.
Supechunks are great bass traps, but putting slats over them makes them selective reflectors as well, and selective absorbers. Yes, you will get some more life back into the room, but since you will be absorbing some frequencies while reflecting others, the response won't be even. The normal method for keeping highs in the room is to wrap the superchunk in plastic. The thickness of the plastic can be selected to ensure that only the lows get through to the insulation, while the highs are reflected back into the room.
My problems were mostly at 40, 80 to 130, 170 to 190 and 250 to 330 Hz so I built these to cater for that range based on the Helmholtz calculator.
Which Helmholtz calculator did you use? There are two versions of the equation, but only one is correct. The other was a misprint in an old textbook, that then got copied to other texbooks, and re-copied again. Make sure you are using the correct version of the equation.
Also, your traps are NOT tuned to hose frequencies. You are building a broad-band slotwall, with a very low Q, that absorbs across the entire range from about 10 Hz to about 2 kHz, ... theoretically! But in practice, it won't even do that. The reason for that is because the depth of your cavity is not constant: It is a triangular shape, so it varies from just a small fraction of an inch at the two edges, to maybe a foot or so in the middle (apex of the triangle), thus providing very, very, broadband absorption, not the tightly tuned high-Q response you'd need for dealing with room modes.
Then there's the other issue with cavity depth. In order for a Helmholtz resonator to absorb effectively, the depth of the cavity needs to be in the range of 1/8th wavelength to 1/12th wavelength, average 1/10th, because that's what is needed in order for air to act as a spring, efficiently. So the cavity would need to be about 34 inches deep for the slot that is tuned to 40 Hz, and 4 inches deep for the slot that is tuned to 330 Hz. While that might actually be the case at one specific point on the width of each slat, the air behind the rest of the slat is not going to be "springy" enough, so the resonance won't be efficient.
Then there's the issue of tuning: room modes are very tight, very high-Q problems, just a few Hz wide. To hit a modal problem, your device must be tuned very, very accurately. And since the slots are very narrow for low frequencies, even a tiny inaccuracy in your workmanship can mean that your slot is not tuned anywhere near where you wanted it to be. For example, let's say that you want to hit a modal issue at 201 Hz, and you have a standard wall cavity depth of 90mm (3-1/2"), so you do the math and figure out that you need a slot exactly 2mm wide, ... but when you built it, you nailed the slat just a fraction skew, so the slot is really only 1.8mm wide, instead of 2mm. You figure it's no big deal, because it looks very close to correct... However... The resonant frequency is now 191 Hz, instead of the 201 Hz that you wanted. You are off by a whopping ten percent! There's no way that such a device would be any use at all. The maximum variation that you could allow in your slot gap is 1.97mm to 2.01mm. In imperial terms, that means your slot width would need to be 3/38th of an inch, accurate to within +/- 1/128th of an inch. Can you really work that accurately? Even changes in room temperature and humidity could conceivable cause the wood of your slat to expand or contract sufficiently to de-tune the device completely....
And finally, there's the issue of cavity air volume; in order for a slot resonator to be effective at dealing with a specific tone, the internal resonant volume associated with that specific slot needs to be about 1% of the room volume. There's only a tiny fraction of that amount behind any particular slot in your device.
All of the above are the reasons why you don't generally see people using slot walls to deal with modal issues: worst case, it does nothing at all, best case, it is extremely hard to tune right, and not very effective even if you get it perfect.
Oh, and you also have to make sure that the device is positioned exactly where the pressure of the modal standing wave is at its peak, or close to its peak... so it would be useless, for example, to have a trap on the middle of the front wall that is supposed to deal with a modal issue that affects on the ceiling and floor...
- Stuart -
Works for processed compressed songs but not something natural.... so I'm now at the stage where I want to get more from my room. 
