How big should center spkr be to set to "large"?

There's suppose to be a good reason for the 80Hz crossover point. I've heard the reason but have forgotten. CD, do you know the reason for the THX 80Hz crossover standard?

Is 80hz the point where sound is no longer omnidirectional?

I've have an older Pioneer VSX-711, unfortuneately it's lowest crossover point is 100Hz. I also have 6.5" woofer speakers w/ 1" tweeters (5 equal channels), and my system sounds its best set to LARGE. At 100Hz the sound was harsh/edgy and the bass was too boomy.

Yes it is a good starting point but lets look at just why that is?
I feel it was simply for the benefit of speaker manufactures, can you imagine small speakers that had good WAF if Lucas choose 60hz, 50hz? It is simply my opinion but I think that on one hand it is good to have a standard but they should be honest and claim that those numbers are more geared to the minimum acceptable performance and if you have speakers that can handle more.....by all means take advantage of the better performance.

"CD, do you know the reason for the THX 80Hz crossover standard?"

Drcruz - I've never considered why THX selected 80hz, seeing my system wasn't built around THX standards. I would suggest if its important, check out the website for THX or Tomlinson Holmans site to see if he explains his conclusion. IMO, considering I choose this as a STARTing point, vs. 250Hz or 45hz, it doesn't matter.

I'm glad to see the large setting works best for you system. Enjoy!

"Yes it is a good starting point but lets look at just why that is?"

I would assume it would have something to do with system integration...

"I feel it was simply for the benefit of speaker manufactures"

Conspiracy Theory?? : ) Just joking.

"I think that on one hand it is good to have a standard but they should be honest and claim that those numbers are more geared to the minimum acceptable performance and if you have speakers that can handle more.....by all means take advantage of the better performance."

I couldn't agree with you more. That why its a staring point. If the sub integrates better with the speaker performance at a lower cycle, then great. If you have satallites on all channels, then 80hz isn't where you wanna stop. But if it integrates at a higher cycle, then set the crossover higher. Its all about system integration, IMO.

Drcruz - Sorry I missed your other question.

"Is 80hz the point where sound is no longer omnidirectional?"

I can't say 100% its 80hz, but its in this region and lower, bass does become more omnidirectional.

Good Point CD, I pretty much feel the THX is for the "Big Box" Retail crowd and anyone with more than a basic knowledge of HT and equipment would dismiss it as only being rookie relevant.