I have been over this ground before, but it is worth repeating. The center channel speaker is a tough challenge. I really believe very few speaker manufacturers give it the thought and attention it deserves. For a start many loudspeakers that have good speech clarity are not good music reproducers. Why, because of cheating and a slight boost given in the 1.5 to 2.5 KHz range. This makes them tiresome for music. The lobing pattern of the vast majority of center channel speakers is in my view incorrect.
The center channel lobing pattern is crucial I have found. I found this out getting my fathers system right. He was anxious to get going with all this before Dolby 5.1. It became apparent from my researches that the center channel is actually one of the biggest challenges a speaker designer can be presented with. It has to take a lot of power, be relatively small and a very good all round performer.
There is a particular problem in most rooms in that the center speaker by necessity, ends up being too close to the front left and rights. By too close I mean less than seven feet. The result is comb filtering between the front three speakers. In other words summing and cancellations at different frequencies.
I have found that a very good speaker built round a coaxial driver is the best solution. The woofer cone acts as a wave guide to the tweeter, to result in a distribution pattern that minimizes speaker to speaker interference.
The issue has been raised as to whether this results in a sweet spot problem. The answer is no. In fact the reverse. Very uniform coverage at all seats. It seems KEF and Thiel and Tannoy have come to the same conclusion I have.
Now increasing the center speaker level does help the intelligibility issue, however it destroys the perspective. I like my sound field to be behind the plane of the front speakers. Even a small increase in center speaker level, brings the sound field forward. Now I calibrate my system with a phantom powered studio condenser microphone. I have found the 1db steps on the preamp processor to be too great! I found I had to add a potentiometer, between the center preamp output and the center channel electronic crossover.
I have found the best torture test for speech clarity in the midst of action to be the battle scenes in Master and Commander. If you can reproduce that with speaker levels correctly set and hear the dialog, then in my view your system is on the right track.
I watch a lot of opera DVDs. Having the speakers properly adjusted and seamless is essential. If not it is very tiresome.
I have made this recommendation before, but if your front left and right speakers have a good neutral balance, then this kit is probably the best $261 you could spend on your system. It is the Norwegian Loki kit. It should be very straight forward to put it together.
http://www.madisound.com/catalog/product_info.php?cPath=35_40_402_275&products_id=1688&osCsid=1158554417565fec24ab94daccaa870e
It is the driver I use for center channel use.
http://mdcarter.smugmug.com/gallery/2424008#127077128
Now my center is a TLS and is diffraction compensated. The diffraction compensation is active. However the Loki will give you the same excellent speech clarity with no shout.
If any body wants to build the TLS version, get in tough with me and I will have my construction plans copied. They are very detailed. I also have a passive solution for the diffraction compensation.
It matches my left front and right very well although the driver complement is different. Even on white noise test it matches the left and right beautifully, and the sound stage is seem less, which is crucial for opera. I also have this speaker reproduce the sound for vintage mono recordings, and it acquits itself
very well.
What this member is complaining about is a prevalent problem. The solution far from easy. To help solve it seriously consider the SEAS Loki. I don't usually whole heartedly recommend a product, but this one I do.
