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

"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.

Thanks,

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

Greetings.
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.

Sincerely,
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 here...lol