Is Room treatment different for Horn Speakers?

Yes.

Because horn speakers have a higher direct-to-reverberant sound ratio due to their relatively narrow radiation pattern, you do not want to absorb any more of the reflected sound than you absolutely have to. As a general rule of thumb, I would start out with zero absorptive acoustic treatments. If your back is up against a wall then treat the area where that first backwall reflection comes from, but don’t overdo it.  Too much absorption will suck the life out of the sound.

With some horn speakers, the optimum listening angle may be somewhat off-axis. Instead of pointing them almost straight ahead, you might try using aggressive toe-in, like 45 degrees, such that the axes criss-cross a couple of feet in front of the primary sweet spot. This will also give you good sound across a very wide listening area. You may need to spread the speakers a bit wider apart than normal if you do this.

Duke

horn speaker manufacturer

The last few days these Speakers have really blossomed. Bass right now is good. I hear some what I call "frequency specific resonance",.. I was wondering if a little dispersion would help. I understand other Cornwall owners mod their speaker horns with Dynamat, but I don't want to go there just yet.

Duke, atmosphere, rego, actually everyone above, thanks for the comments. I have the speakers as far apart as I can get them... I will try to toe them in so they cross in front of me. These speakers do sound good when I set at my desk in the corner. I am really enjoying these Cornwalls, I believe with some tweaking (acoustic and otherwise) these could be very very good. 

I have horn speakers and am in the process of considering a bass trap in the corner right net to the speakers.  I have had good luck with Vicoustic Acoustic.  

Horns may need much less toe in than conventional speakers.