Thanks for your help so far in setting up my system. Everything set up and picture is fabulous - I have an issue with the centre speaker and am keen to identify if it is indeed that or something else.
 
Have the typical 5.1 setup. Sub fed through LFE output, 2 fronts and 1 center and 2 rears.
 
Ran a test signal through them and everything had a similar deep woosh through each speaker and Sub rumbled apart from the centre speaker which kind of hissed a bit. Thought it odd but pushed on.
 
Used the function on the Yamaha receiver to setup the speakers and it keeps telling me the centre speaker is not outputting at the same level as the others and move it to within 24 metres of the microphone :)
 
I've tried the center speaker in other ports on the wall for front left and right and it appears the same on the test signal - a hiss and no apparent midrange so I think I've confirmed the wiring is okay. I also rewired a new cable into the back of it to confirm I hadn't screwed that up.
 
Ran a few bluray movies through and on standard mode on the receiver which is basic film mode, the dialog from the centre speaker is whisper quiet, sounds tinny and is massively drowned out by the effects from front L&R. Dialog is barely audible and appears to be coming out of tweeter only. The two midranges that sit alongside the tweeter dont appear to being used.
 
Took speaker back to Harveys who plugged it into a dvd player and it worked !??!!? until I put a bit of pressure on the thumbscrew plate at which point all the treble disappeared and it only had bass. This was repeatable by a few of them so they happilly swapped it out.
 
I've not tried it out yet but given it appeared to be displaying the complete opposite problem to what I saw ( no bass and all treble) ,if I plug it in and still get the same issues, whats the next best steps to identify the problem issue ?   Could it be the receiver for example?
 
Thanks