Tannoy Owners: Need help with Canterbury GR fine tuning.

I recently got a pair of Canterbury GRs which have multiple adjustment on treble level and treble roll off.  I prefer the tonal balance with -2db roll off and flat treble energy setting.   The sound is more focused and balance.   The soundstage is more focused but slightly smaller.   With the treble roll off set to flat, the soundstage is wider and taller ( imaging outside of speakers ).   The very high notes of the piano deem to have longer decay ( which I like) However, there is exaggerated sibilance of human voices and a overall a little bright.   The degree of changes are somewhat cable dependent but the same trend is observed consistently observed across different cables.   

I have played with speaker positioning and toe in.   

What do you guys use for your settings and how much toe-in?

Does biwire make a big difference?

Thank you  
I know a Tannoy dealer and he recommends toe-in such that the axis of the center of the speakers crosses 8"-10" in front of the listening position.

I have this setup on my AV systems and it sounds great
SPK1       SPK2
     \            / 
       \        /
         \    /
          /  \

That is a lot of toe-in but it seems to work well

Regards - Steve
Thanks for the suggestion.  That's also what the manual suggest.   
Do you have any soundstage wide issues using severe toe in?
Do you have any soundstage wide issues using severe toe in?
Not at all. I use the tannoys (as a stereo pair) on my A/V system and have often heard sounds from behind me - spooky.

The A/V system is in our living room, which I have not applied treatments to, so it is far from perfect, but it is spacious and 3D in nature

I've heard in-store tannoys in small rooms and they have a nice image oncce the toe-in is perfected

But the best I have heard them is when they are in a large room with about 6ft between the side walls and the speakers and 5-6 ft from the wall behind them - so a room about 20 ft wide x 18-20 ft deep would be optimum.

Seems the more space you give a pair of tannoy's the better they performs.

Also - if your room has bookshelves - place a layer of foam rubber on top of them - that helped with clarity in my previous house a lot

Hope that helps
Steve (Williewonka), is absolutely right. While I'm not using Canterburys, rather 12" HPD in massive cabinets (heavy), they perform the same magic described by Steve in my large room. The speakers are one-third of the way into the room, with nearly five feet to the sidewalls. I don't have mine toed-in to the extent Steve has, though I benefit from the same virtues described by Steve.

I also have no room treatments, though my room is furnished with carpeting, and large, heavy couches. You have not mentioned what you use for amplification, perhaps that aspect of your system may exacerbate the problem.

I hope you get it sorted out to your satisfaction.
@glai - BTW - Nice system -

What speaker cables are you using? The reason I ask is - if they have a high capacitance they can cause oscilation in solid state amps having a high current design and the Luxman amp is high current.

The capacitance might not be enough to do damage, but can cause distortions.

Look for cables with capacitance down around 10-20 pf/ft

Van den Hul makes several cables in that ballpark

Some Cardas cables have a pretty high capacitance and I know of two amps that they drove to destruction - from  Ayre and Gryphon

If you did NOT have the same problem with the speakers you had prior to the Tannoys - it could be because of an impedance issue caused by the capacitance of the cables combined with the speakers. Just high enough to push them over the edge.

Regards - Steve

RE: my comment...
Some Cardas cables have a pretty high capacitance and I know of two amps that they drove to destruction - from Ayre and Gryphon
I forgot to add - the Cardas cables WILL NOT cause the same issue when used with tube amps. 

Regards - Steve