What makes speaker's sound big?

There’s a lot of talk around the hot porridge, as they say (i.e.: to beat around the bush). That is, important parameters (not least acoustics and general implementation, that needn’t be expensive) have been covered already as a basis to achieve "big sound" in some form or another, but depending on the size of the listening space true room fill and effortless physicality will not occur without the addition of ample, effective air radiation area down into the sub octaves. Spatial size and overall coverage can be had from a fairly small speaker package - surprisingly small, even - but compared to subs augmented much bigger speakers with full range bandwidth it’s mostly just puff air; true big sound has that alluring quality of immersive presence and inherent, effortless power to it, even at lower volumes. A smaller listening space will be less demanding with regard to speaker size/displacement area, but the more authentic sense of real, sonic size and girth as anything reminiscent of a live event requires a moderate to large listening room and not sitting too close to the speakers, and this in turn will place more demand on speaker capacity and displacement area. I know, big speakers aren’t popular (typically not in the eyes of the missus), but there’s no way around blunt physics - again, all in relation to the listening space needed to be covered.

@mahgister --

Not necessarily completely true...

I own 7 inches speakers box 2 way, and the Brass orchestra filled my entire 13 feet square room with soundstage OUT of the speakers at the left and at the right and imaging 3-d with clear tuba notes and Horns...The brass orchestra is in my room....Not between the speakers in reduction.... The results is less related to my speakers themselves than to acoustic controls...

13 feet sq. room - so 13 ft. per wall? I don’t doubt speakers of the size you have fits the bill in providing such an acoustically well treated space with a big, immersive sound, but I’d claim that well-implemented subs would only add to that sensation. In the quoted part above I did emphasize a more authentic sense of sonic size, and for that I maintain a fairly large (acoustically well-treated) listening room and main speakers + subs is necessitated. Moreover, while the size of sound is typically associated with soundstage presentation, for good reason, it’s not the only parameter as that which fills the listening space with a more palpable, effortless sensation of sound. For that more displacement and headroom is needed - at least in my book, and depending again on the size of the listening room.

ACOUSTIC controls is way more important than speakers size in a small room and most of the times in a moderate bigger room...It is my experience only but.....

It is not raw power of the gear or mostly the size of the drivers mostly that makes event livelier but acoustic control of the room....

Audiophilia in general is very much focused on soundstage presentation, the virtues/characteristics of which you point out above, but I’m more interested in the particular type of presentation as this homogenous, large sweet-spot sphere of sound that’s visceral, full, present, effortless and less pinpoint sharp imaging-wise. To me at least it’s more reminiscent of a live event, and in that regard makes for a very effective association, or certainly one more complementing at that as something that has actual, believable size sonically.

That is to say: proper, not over-damped acoustics (and care with speaker placement) no doubt aids soundstage presentation and size in particular and as such fits many an audiophile’s "craving" here, but the fundamentals of sound with dynamics, presence, girth and ease, to my mind equally important as a constitutive measure with regard to the size and believability of sound, needs for physics to be accommodated. I’m not saying the latter should trump (no pun intended) the former, but that some coexistence is necessary here.

@mijostyn --

... Image size has nothing to do with volume but, a big image at high volume is very impressive when distortion is low. Unfortunately, the distortion of all speakers increases logarithmically with volume. Getting low distortion at high volumes is not easy.

Image size and density(!) has everything to do with volume and coverage pattern, in addition of course to acoustics and overall implementation. Such a main speaker - certainly one that combines large air radiation area with high sensitivity and prodigious power handling - will maintain (for a speaker) low distortion at high volumes, in a domestic environment not least. Somewhat easier to achieve with dynamic drivers than planar speakers and electrostatic dittos, btw.

Wide dispersion can make a speaker sound bigger and louder but at the expense of detail and focus.

Controlled or constant directivity offered by horns doesn’t strike me as leading to lack of detail and focus, even with a large sweet spot. If anything I find it sounds rather natural.

The best use of subwoofers is to lower distortion in the main speakers particularly at volume when large cone excursions put the suspension in a non linear position in it’s range and a lot of doppler distortion is produced. That fact that most subwoofer users do not take advantage of this by using a high pass filter on the main speakers boggles the mind.

Agreed, and using actively configured speakers makes the choice of high-passing the mains the more natural decision. However, if you had ample, effective cone area to begin with, in addition to high sensitivity, cone movement would be the lesser issue - even less so when high-passing such main speakers.

Do they [i.e.: subs] make a system sound larger? I suppose if you equate low bass with size. I don’t as the image size stays the same whether or not my subwoofers are on and I use four of them.

There’s a lot of spatial information - and in effect: image size - that can be retrieved from low frequencies, classical music material in particular. Spaciousness to some, bass-iousness to others ;) Preferably this requires of subs (that is: more than one, and preferably two, four or six) to be placed symmetrically to the mains and hooked up in stereo. The stereo coupling, for it to have effect, would need to be done with a cross-over no lower than 70-ish Hz, from where (on up) high-passing will have the most advantage in relieving the mains anyway.

Sounding big and going loud are two separate issues.

Sure, but that’s not to say the two can’t go hand in hand.

This single most important characteristic determining image size is the speakers pattern of radiation, point vs line source. Other characteristics are relatively minor.

Optimal coverage pattern as a determining factor of image size isn’t exclusive to a line source. You’re trying to monopolize a line source as the sole game player here - hardly the big picture, if you would.

Any speaker can go loud with enough power. The problem is doing it without distortion.

That’s the beauty of high sensitivity; the wattages available - not least by-passing a passive cross-over when actively configured - being all the more effectively used. More power produces more heat, no way around it, and there’s only so much of it that can be dissipated before thermal issues will arise. So, any lower sensitivity speaker can’t simply "go loud [enough]," for named reason.

Line source dipoles have a beautifully detailed image because they limit room interaction by limiting dispersion.

Indeed, among other reasons as well.

Horns can do the same thing for people who prefer the smaller image of a point source.

My pro cinema horn hybrid speakers can fill a medium sized auditorium (a large auditorium with bigger horns on top) rather effortlessly. You think they sound small-ish?

@mijostyn --

Image density? That is a new one. I suppose if you put the speakers closer together you get a "denser" image, farther apart less dense but larger. Yes, the distance between the speakers can change the image size as long as the listening position stays the same.

Had you experienced larger horn-loaded speaker set-ups you'd be familiar, I can only assume, with how the term 'density' applies to the perceived sound here, although variations with regard to how to explain sound can be a factor. Technically it relates to a larger part of the sound from the point sources here being emitted directly vs what's reflected, in conjunction with prodigious air radiation area. This (i.e.: density of sound) doesn't apply equally with a line source being a line source, from my recollection, even though it shares the traits of less reflected sound and large radiation area.  

However phusis I will repeat this again and having installed and set up numerous very expensive systems, volume has nothing to do with image size. They are two separate issues.

I may have expressed myself incorrectly; by "volume" I meant sheer radiation are. 

A set of dipole line sources going at 90 dB is going to have a much bigger image than any floor standing dynamic speaker going at 90 dB. You can crank that floor stander to 110 dB and it still will not have the image size of the dipoles. As a matter of fact the image size will not change at all.

I'm a fiend for sound that mimics a live event, and the planar and electrostats I've heard - for all their qualities - never left me convinced about a presentation reminiscent of live music, certainly not as much as high efficiency horn-based speakers or even some select, less efficient, direct radiating alternatives. That's line source vs. point source(s) for you, and in this particular context lower vs. high efficiency as well. We can argue all day about "the biggest sound there is" (I don't agree with you here either), but it's all for nothing unless there's some purpose to link image size with what sounds believable overall to both you and I. It seems we're simply not in tune here..

Many would not know this because they have not experienced it. Perfect line source dipoles are rare beasts and hardly ever set up in stores or at shows. It would seem you are talking from instinct and not experience or you would know this for sure. Everyone who has listened to even an imperfect line source knows this. Just ask any Maggie owner.

What exactly am I supposed to know having listened to line source dipoles, a "perfect" one not least? I've only listened to one terminated-at-floor-and-ceiling line source, the Dali Megaline (coupled to the Dali Gravity class A amps), and it was an impressive experience as I recall, now over 20 years ago. Or else I've listened to a variety of Martin Logan's, Acoustat's and Magnepan's over the years, and none of them swayed my into their direction as anything I'd consider to own.