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

in the processor, that is?

My center speaker is pretty big as center speakers go, a Paradigm cc570. But it pales in LF response compared to my front L/R. Also, I am not currently using a sub.

I have tried it with the center set to small and large. When center is set to large, the movies seem to lose a lot of overall bass. I have plenty of amp power to the center, 200w.

I would like to set the center to large to get a bigger sound right there in the middle, but perhaps you have to have an even bigger center speaker. But that is going to get really expensive.
I haven't heard a center channel yet that should be set to large (and most don't deserve to be on either).
Set it to small and let the LFE come from the sub.
Set it to small. It lacks sufficient bass extension, as you have found. There are only a very few dedicated centers worthy of being set up as "Large."
I have a center that specs down into the 30hz range and it is a stretch but I do like it better at 60hz than at 80hz, very few will actually spec at full range, even fewer can honestly acheive it.
"bigger sound right there in the middle" can be best achieved by a sub that doesn't even have to be anywhere near the middle. Set up is important but if the sub is crossed at 80hz or below and even half way blended into your system, it's gonna sound like it's in the middle.

That's gotta be alot cheaper than a center speaker that has 12" woofers
Yeah, except when a speaker (in this case, center speaker) is sitting in somewhat of a hole in the 70-80hz regigion, and someone ends up getting some more "umph" by crossing their rather large center speaker over at, like 60hz or whatever, you should most always be looking at crossing over a normal sized center speaker at "small"! Why? Yes, they don't play so low. But that's not the problem entirely. Another case, and just as important of one, is that these passive speakers can't properly deal with full range bass info efficiently enough, often leading to distrotion, clipping, and squashed dynamics. Basically, not only does the speaker have to play lower than comfortable often, when set to "larger" (or anything larger than 60-80hz really), but the amps (usually receivers) can't really control the drivers well enough in most passive crossover design models either! The passive crossover is a rather innefficient design overall. And most speakers aren't so "sensitive" as well. (some larger horn speakers help greatly).
So, the vast majority of the time (I've yet to run any center speaker as large in any setup I've ever done, and I've done hundreds!), you get better efficiency, and dynamic range from crossing over to "small". The critical part is making sure your speakers and sub(s) are coupled well (and flat ideally) at the crossover frequency, and in phase! Here in lies the problem where most people run into with speaker/sub placement and setup. They know nothing of this part...
Here's a shorter explaination, IMHO. If the speaker can't handle "full range"...45 or 50Hz to 20kHz for arguments sake, set the center channel to small on your receiver. It just makes life much easier that way.

Thats just my take on things though. It works for me.
I use full range floor standing speakers for my front LR, but I find the sound more open and transparent even for stereo if I set all the speakers to small, and let the sub handle LF.

I also have full-range floorstanders for front L/R, but I don't have a sub, so I can't set them to small.
I'm confused, how about everyone else?

Small center channel with no sub and full-range LR's = big problem.

There is no good answer except work some overtime and get a subwoofer ASAP!

Are your left and right speakers Paradigms? If they are not then you must get the "matching" center for your speakers or you're designing your system all wrong and no setting is going to cover your mistake.

So what are the rest of the speaker? Lets fix your system right not patch a problem that goes much deeper than the bass response of your center channel.

Do we have an agreement to fix it correctly from the start?
Sorry, no such agreement here, due to financial considerations!! My question is just trying to get at what the best setting might be for my setup, and so far, it seems the consensus here is that I should set it to small.

My front L/R are Legacy Signature III, which have a rather large subwoofer section and go down to about 20hz in the right room, which mine is not. But they do shake the room pretty good if you turn it up.

It does seem that movies overall sound better with the center set to "small". It seems the processor in my receiver sends the bass for the center to the front L/R since I have it set to "no sub".
Mtrot...I think what D Edwards is getting at is that what your focusing on is just a temporary solution to a situation that should really bring the best out of your setup. This is part of the reason why attention should be paid to speaker selection.

Setting the center to small may work fine for you for now, but once seen and heard how sub intergration really effects the overall performance..if you haven't already, there's a good chance you gonna want to change. If you fix things early instead of slapping a band-aid on it, you're gonna be much better off.

Since there are certain limitations holding you back, I can see how you've focused on just the settings and not the overall setup. If the band-aid approach works for now, although it wouldn't be my first choice of approaches, then do what works for you. But, keep in mind you will be selling you system short though.

"But they do shake the room pretty good if you turn it up. "

I had the same misconseption about a sub and/or front-sub combo system. I was close to spending the $2500 for a Def Tec setup. Glad I didn't. Room shake is just a added bonus to a strong sub. However, it really isn't the main point though. It bares more weight and has more effect on the entire system than you think.
Good Points CDW,

My solution would be get rid of the Paradign Center channel immediately, use phantom mode and pine for a Legacy Silver Screen I center channel. ($450 used?)

Best? you don't even have a shot at mediocre. The Paradigm and the Legacy speakers you have couldn't be more different and incompatible. (who recommended that combo anyway?) In your case no center channel is better than the combo you have.

Another cheap fix which I don't recommend but I know audio guys are, is to get the Behringer "feedback Destroyer EQ $89" and EQ the Paradigm to match the Legacy's better. But that's a longshot possible fix for you.

So start selling the Paradigm and searching for the SS1 then we can really help you when you've atleast assembled a system where our advice can matter.
D edwards,

Well, actually, I aquired the Legacy Signatures some time ago, when I acutally had some money, and before I had 2 kids in college, as I do now!

I have been aware of the Legacy center channel speakers, but they were pretty pricey. I was not aware it might be possible to get a Silver Screen in that price range.

And no, nobody suggested the Paradigm Speaker. I did that myself, as a result of poor intelligibility of center channel dialog with a PSB Image 9C speaker. The Paradigm 570 is a pretty good speaker, and is quite a bit better than the PSB. And it really seems to blend with the L/R okay to me. (I have now found out that a lot of the clarity problem was due to the center speaker cable and interconnects, but live and learn).

Also, my center speaker sits on top of my Mits RPTV. How much does the Silver Screen weigh?
Correction...Mine are the Legacy Signature II, which do not have the kevlar mid-woofer. But they seem pretty good to me. Any time I listen to other speakers of any similar price, I find myself thinking of what aspects of the sound I would be giving up.
We're not talking about $$$, were talking about Brown belt with black shoes.

If I'm correct the Paradigm is a $900 center channel? Which you should almost be able to swap for a used Silver Screen, it should be a even trade or +/- $100 at the worst.

I don't know how much the Silverscreen weighs, just know having one will make a huge difference.
I have the 570 myself and use it on large. Paradigm themselves told me to use the large setting. In fact if you are using a sub and any of you speakers do atleast 40Hz or lower. Use the large setting for those with your systems crossover but not rolled off.
Just checked the spec between the Paradigm and Silver, just out of curiosity. It looks as if the Silver is ahead by 2.5 paces.

Mtrot...unless something unforseen takes place, I would take the silver and part with the 570. A bit on the chunky side at 46lbs. 1lb over the 570. The Mits RPTV might not be to happy about that. But don't take my word, check the numbers for yourself. Numbers aren't everything(some say), but it sure is a good place to start.

Oh...and Ozz

Considering the specs only give the 570 60hz on and 30 degree off axis, you should get better results by switching the setting to small, this spareing your drivers the burdon of 20hz lower than intended. With a good sub, small setting, and a xover point at about 80hz instead of 40hz, chances are you may be more pleased with the outcome. Not sure who you spoke with at Paradigm, but it wouldn't hurt to give it a shot. Never know, you might like it.
Well, now we are getting back to my original question.

The thing is, I do NOT use a sub. And it seems when I set the center speaker to "large" in the receiver menu, I lose a lot of overall bass. I think that is because in 5.1, the center channel is full range, but the Paradigm only goes down to ~50hz. But when I set it to "small", I get a lot more overall bass.

And not only that, but when set to "large", I think because it is trying to reproduce more LF, the clarity of the center is poorer.

Perhaps I should have asked not only how big, but how GOOD a center speaker needs to be, to be set to "large".
Could part of the problem be putting the center channel on top of the RPTV? Putting the speaker on a stand in front of the RPTV just below the picture might improve performance. I favor a good sub, and crossing over the other speakers at 80Hz.

I have actually tried both small and large settings for my current setup. I have no problems with clarity or bass response with the center speaker set to large. All of my speakers are set to large and i don't use a sub. I have also used a test disc with a sound pressure meter and the 570 will do 25Hz easily in my room.(Can do 20Hz but not too audible mind you, but it will do it.)
Could be as simple as different equipment,different results.
"Could part of the problem be putting the center channel on top of the RPTV?"

Yes a little, but the main problem is a dramatic spectal balance mismatch between the main speakers and the center, further aggravated by there being no sub. Which I realize he cannot buy, and that's ok just swap the 570 for a Silver Screen should be a wash financially.

Also CDW with a sub in the system, many receivers will allow you to set the crossover at 40-60-160hz and the range can be covered at 1dB to 10dB intervals. A center like the 570 I would crossover somewhere between 50 and 60 hz.
I played around with it some more tonight, watching 5.1 movies and a Black Crows concert on HD cable.

Actually, tonight I could hear no ill effect from setting the center speaker to "large". It did't seem to cause any loss of clarity in the center speaker, nor did it seem to cause any loss of overall bass. I really liked the overall sound with that setting.

I am going to try it on some DVDs and HD DVDs as well.
Mtrot, How is your setup working out?
Actually, I am now quite pleased with the system, both on movies and music. Last night, I toggled the center speaker between "small" and "large", and I think it really sounded a bit better overall with it set to "large". I am going to leave it set that way for a while.

I now think some of the problems I alluded to in my original post about setting the center speaker to "large" must stem from my recollections from when I was using my Panny RP-91's onboard decoder. Now that I am decoding with my Sony DA4ES, setting the center to "large" is sounding real good. I don't run real high volume levels, so that may be why I don't seem to be having problems with overdriving the Paradigm, and thereby getting distortion.
Glad to hear it is working out for you. As long as you are driving the 570 with ample power you shouldn't have any problems at higher levels. I use a bryston 7bst and drive it quite hard and don't have any problems what so ever.
Keep us posted.
"A center like the 570 I would crossover somewhere between 50 and 60 hz" (Dedwards).

Besides this center speaker being a typical dynamically low-efficiency design (Reviews measure this speaker at 86db efficiency/about 88 room, and is 5 ohms minimum/under 4 ohms nominal), the reviews and Paradims website list the frequency response limits on this center channel at 60hz+/-
3db, and 65hz +/- 2db! It's basically flat down to 83hz!!
So, if you plan on crossing this speaker at 60-50 hz, you can prepare for a very very weak bass response at the crossover point!!! This is a typical fauxpa by most audio-enthusiests, and should be avoided.
Not only that, but the standard inneficiency of a passive speaker, MANDATES that you get the very demanding bass info to a powered ACTIVE WOOFER, for best results, and dynamic transparancy/impact.
People can argue all they want that their full range audiophile speakers sound faster and tighter in the bass playinf "full range". But the problem lies in the "in-efficiency" of the design! When you play DD/DTS material, that's mixed at 5x's as more demanding dynamically than any recorded music material, and things fall appart real quick with this line of thinking! You get flat sound, dynamically squashed playback, limited dynamics, clipping, and blown the amps can't supply the current and control to the drivers through the passive networks! This is standard affair for typical passive hi-fi speaker setups. That's the way it is. If all speakers were active models, with bigger woofers, that wouldn't be the case so much. Heck, even active commercial cinema setup's, with 118db horn designs, still cross over at 80hz to big 15/18" bass woofers!!!! There's a reason THX does this, cause it works!
Still, everything in a balance.
Based on those speakers he's using, and knowing he didn't have a sub right now, I'd be crossing that center over at 80hz, every time, and sending the bass to the mains, yes!
Everything else is going to sucketh. Sorry to inform you.
HOWEVER, another problem here is that many people will end up "unknowingly" placing their speakers in the room, in conjuction with their seating locations, where the bass response is going to be all over the place. They often end up putting speakers where there's a hole somewhere between 60-100 hz. Then, when they put their crossover in this reigion, and it sounds like there's a "hole in the sound"/at the crossover, THEN THEY LOWER THE CROSSOVER POINT! but the problem was in the setup all along...user error.
This is one of many many reasons audio-enthusiests read reviews or hear speakers and gear at some audio store or show, then they buy some stuff off the net, hook it up in their home, without knowing what they're doing, and get bad results so often. They then conclude that the speakers aren't so good, or the sub's not as good as something else, etc.
When it comes to home theater/audio room setup, it's all about THE TEAM! Balance...
Thanks Ozz,

I am driving all 5 channels with a Sherbourn 5/1500A, which is a 5 mono channel design @ 200 wpc. Weighs about 80 pounds.

I have the Legacys bi-wired, and they sound pretty good.

Guys, I understand a good sub will make things better, but that is not in the cards right now.

Also, we don't really crank it up loud, so I don't get too much of the sound falling apart problem.
"Also, we don't really crank it up loud, so I don't get too much of the sound falling apart problem"

This is not the problem for you here! Even if you listen at a "flee's level", well bellow the average listener, the problem lies in the dynamic ability and accuracy of the sound! Put your center speaker in a place where it's not coupling well at the crossover, or cross the speaker over where the speaker is "quickly" rolling off, and you'll have lower fidelity, even weak sound from the speaker (and thus the system)!
It's not necessarily a matter of whether or not you like to crank your system. If the system is going to have any chance to have any sense of power, dynamics, impact, and accuracy of response to the sound, you need to consider these things. Otherwise, you cross your fingers and hope for the best. Often times, it doesn't turn out so well, being there's so many speakers, so many settings, crossovers, phase issues, acoustical issues, fine-tuning adjustements, etc, that it all gets washed over...pulling the system down the toilet, sonically.
If I were you', I'd do this test:

Run the center speaker full range (mono, summed stereo), with a test CD that has test-tones at all the lower frequencies. Play them through the critical 63hz-100hz reigion, and see what kind of response you're getting from your center! If you're getting weak response (in relation to the rest of the frequencies, and at 1khz) at the 80hz point, or where you cross over, you've got a problem! That's where the critical bass reigion lies. You should be getting solid response down where you're crossing your speaker over, in this case, to your mains. See what you get.

I don't know if my receiver(Sony DA4ES) offers a choice of frequencies to "cross over" the center channel. I only saw the choices of large, small, or none for the center speaker. Unfortunately, I am not too familiar with the cross over concept and procedures.
"Unfortunately, I am not too familiar with the cross over concept and procedures" (Mtrot)

Ah, you're not alone! Most even seasoned audiophiles, who've tried and followed all kinds of gear over the years, don't know any of this either!

No worries. Try this: Simply play testones through your center speaker, with your "small" setting, and measure your levels compared to 1khz. If you measure like 6, 7, or 8+ db down at 80hz to 100hz, you seriously need to check your center speaker placement, As this is where your crossover is going to be set! Many people cross their bookshelve speakers and center channels where there's "holes" in these critical crossover reigions, and things don't end up so good. If this is the case for you, from your listening possitions (where you measure from), you need to move the speaker around till you get flat response (+/-5db, or better), and especially, no holes/dips in the response above and at the crossover point. Try this and see what I mean. If you can get solid response, you'll have solid dynamic "accurate" sound, fundamentally.
Otherwise, you pay someone, that's all your options
I have a pair of 100v3, 60v3, and a CC570.
What would you recommend i use for the speaker setting for the CC570? Large or small?
I currently use the large setting for all speakers and drive each of them with bryston 7bst's.

Your recommendation is anticipated and appreciated.
Tim Kennedy

Hi Tim

I'd use the large setting for the CC-570 since it can reproduce most of the
frequency range, and you have more than adequate
power available.

Thanks for choosing Paradigm speakers.

Gary Takeda
Paradigm Technical Support
I most DEFINITELY dissagree with the standard propensity to set speakers to "large" that are typical inefficient and low sensitivity designs inherently! (regardless of what some TECH GUYS on a telephone, who doesn't know better likely, has to say)
Some "Technical support" personnel guy at a company doesn't necessarily have the experience in setting up quality high performance home theater/mulit-channel systems for a living, and is simply giving his idea of how HE THINKS speakers that will play lower than 80hz (small) should be set!!!! This means nothing to me personally.
That said, if you have NO SUBWOOFER, then yes, you could tinker with full range settings, as you, afterall, need bass, yes. STILL, all things considered, it's not going to do proper dynamic justic to your system, by making speakers that can simply simply play down lower, ACTUALLY PLAY LOWER with dynamic DD/DTS material, and harder dynamic material! A powered speaker is much much better in this application.
This is a common problem/view-point of many speaker manufactures, who's speakers measure down to a certain frequency range, for them to recommend you cross their speakers over lower, since they'll basically play lower! HOWEVER, this accounts nothing for the inneficiency in their otherwise "hopeful" speaker designs, to ACTUALLY HANDLE THE DYNAMIC ABILITIES OF THE SOURCE MATERIAL OUT THERE!
I can't tell you how many hundreds of system's and years of experience I've professionally installed hi-end systems, only to find typical FULL RANGE loudspeakers (even the likes of BIG Dunlavy's, Thiel's, B&W's, etc), that can play down to 20hz or lower, that WILL DISTORT AND SQUASH DYNAMICS, even "clip" under dynamic demands, due to IN-EFFICIENCY of the design of the speaker system!!! This is why THX uses and recommends a higher crossover setting, for this very reason! They understand how things work.
Never-the-less, yes, if you HAVE TO, you can set speakers lower, with no subwoofer mind you, and just run things on a lower level. And still, you'll sacrifice dynamics quite a bit, even squash and flatten dynamic response, ideally, if even clipping speakers.
PEOPLE can set thigns however they want however. Afterall, it's their system's! But even as I sit and discuss proper hi-end system setup, room acoustics and calibration, with "industry professionals" who do this for a living, we all understand setting speaker to 80hz range most often, as typical full range home audio speaker systems simply aren't efficient enough to deal with the extremely high demands pressent in today's software and digital media!
Each person really needs to try themselves, with their variables, and their knowledge ability to find out however...if they're doing it themselves that is.
So, for the record, I'd not be setting mine up the way that's being recommend
Just to get a better gauge of other perspectives, how do many manufactors find the crossover point when selecting the large setting W/ a sub?

If you set the speaker to large, and have a sub or two integrated into the system, does the "brain" say send signals below ABC frequency to the sub? Or is this only the case for the "small" setting?

Reason I ask is because I've tried things both ways, "small" setting @ 80-50hz, and "large". Bass response in the sub, for the latter, deminished substantially which requires me to turn up my sub amp. Output from the speakers isn't as loud either. But I did seem to like things overall when they are set to large.

I do agree with Flrn that 80hz, in general, is a good "rule of thumb" starting point for the xover. I feel if the speakers can handle below 80hz, and the xover is adjustable, then set it lower. Maybe to 50hz or so.

Now...for technical support...the jury is still out. I would HOPE that the Manufactors TS would have a good grasp of knowledge for the product if nothing else. System performance MAY be another thing. But they SHOULD also be able to understand their product in terms of overall system performance. This would require knowledge of system setup. Therefore, if the manufactor says "go large", I think it would be worth at least giving it a shot for a week or two. If you don't like it, you can always set it back.
This is weird, but as I have continued to experiment with switching the center setting between large and small, I am finding I think I like it better overall with the center set to large.

Why? Because it seems my Paradigm 570 has a bit less "chestiness" to male voices than my Legacy Sig. IIs. I know that shouldn't be the case, considering the price ranges, but when I set the center to small, the lower midrange and bass in the center signal are routed to the front L/R Legacys, which have the poly midranges rather than the kevlars in later models.

Mind you, with center set to large, I do lose some of the total deep bass in action movies, since the center channel is full range, and the 570 just doesn't do anything down low. But I am just very keen on intelligibility of dialog in movies, and the chestiness I get with center set to small just bothers me and makes it harder to understand the dialog.

Sometimes I do switch it back to small when I want a lot of bass and I have to get the bass sent to the Legacys to get the most of it.

I don't play movies at anywhere near reference level, so I guess that is why I am not running into severe problems with overdriving the woofers on the Paradigm.

Have your tried "Hometheater Blasphemy" and run a phantom center. Your Legacy speakers have ribbon tweaters so they should be fast enough for dialog. I run phantom center and I get a decent image. In fact I seem to hear seperation of dialog when there are 2 characters next to each other on screen (though this may be a visual/psychological mind trick)

I've experimented with the whole "use your receiver to cross" thing, but I found the sound to more balanced and pleasant to the ears when running my speakers to LARGE.

If you seem to like the sound better when running the center to LARGE, then "TRUST YOUR EARS"

But I would like to see what happens if you fooled w/ your Legacy speaker placement for good imaging, then try running the "phantom center". If this works good, then maybe sell the center for a nice sub - then run LFE to the sub.

If your tweaters are at a good height compared to your RPTV, I do not see the problem w/ dialog being anchored to the screen.

Yes, I have experimented extensively with setting the receiver to no center speaker. Due to the TV, equipment rack, and the room itself, I can't move the Legacys around much at all. I have played around some with the toe-in.

Actually, I am now fairly happy with the dialog from the Paradigm.
The following applies to high resolution speakers rather than midfi gear:

Setting the center channel to "large" is better sounding regardless of how small your center speaker is because when you set your receiver/processor to "small", the receiver inserts a high-pass filter, usually steep-slope and not of the greatest quality, to remove the deep bass and protect your center channel. Having this filter in the signal path to your center will degrade sound quality noticeably if you have a very high quality center loudspeaker and equally capable electronics. Less revealing speakers and systems will not be as sensitive to the insertion of this filter because of the qualitative limitations of the speaker's own crossover along with the limited transparency of the electronics.
"Setting the center channel to "large" is better sounding regardless of how small your center speaker is because when you set your receiver/processor to "small", the receiver inserts a high-pass filter, usually steep-slope and not of the greatest quality, to remove the deep bass and protect your center channel."

Dave, thanks for the response and info. I surmise that what you describe is happening with my Sony DA4ES receiver that I am using as processor.

I noticed something else I don't like when using the center speaker, whether set to large OR small. And that is a loss of ambience details, compare to setting the receiver center channel setting to "none". I was switching back and forth, and when I am set to "none" and the sound is just from the front L/R, there is a lot more sense of space and background ambient noises in the mix(example, traffic and city sounds).

It seems like a good processor would retain that spacial information even through a center channel speaker, or would still direct it to the front L/R. Are there any processors that pull this off very well?

I am starting to get an itch for a processor, but the Sony has so dang many features I like, it will be hard to find a processor that has them, phono input and TWO multi-channel inputs(I have HDDVD and a Universal player) just to name a couple.
A good processor makes a world of difference, but I might recommend another setup technique that will help.

Set the delay on your center speaker for an additional 3-5ms. With most processors you have to lie about the distance your center is away from you (say it's 3-5 feet closer than it actually is) in your surround setup menu. Most people have either have their center channel too close relative to their mains, or haven't set up the delay properly on their processor. I have found that even when the center is equidistant from you as your mains, the soundstage depth is compromised and the center speaker doesn't blend properly. The additional 3-5ms of delay solves this, as would moving the center 3-5 feet back from what is normally considered the "proper" location.
This has been a very interesting discussion. If you guys don't mind, I would like to piggyback instead of starting my own thread. I have a Monitor Audio Gold setup, with a sub and everything set to small. The Gold Center (GRLCR) has a "rated" low frequency extension of 40 hz. I just got a Sunfire Cinema Grand (200 x 5) amp and am using my HK receiver as a pre-pro. With 6 1/2" drivers, I have no illusions that it will play loud with 40 hz information, but I am debating with the added power from my new amp, if it would make sense to use a 60 hz crossover instead of 80 hz.

Any thoughts on this?
Greg -

IMO, start with 80hz, switch to 60 hz and see which one you like best. You may could use either and it may not make a difference.
I prefer running my speakers IN LARGE. I found that LARGE took alot of the harshness and edge off the sound, and I run a humble 100watts per channel.

My speakers are rated down to 36Hz, but get in room performance down to mid 20's (subs help smooth out the peaks and valleys). My subs (also) get plugged into the LFE out and I think it sounds pretty good. (no money and no WAF for a GREAT system though :( )
It is always best to set your speakers lower if they can handle it... 80hz was invented by Lucas films...they made the law but that doesnt mean you need to follow them.
" It is always best to set your speakers lower if they can handle it..."

I agree...only if it integrates with the rest of the system for overall optimal performance.

"80hz was invented by Lucas films...they made the law but that doesn't mean you need to follow them."

Some people do have an issue with THX, Lucus and so on. But, you have to admit, like it or not 80hz is a good starting point. Agreed?
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 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 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.