What makes speaker's sound big?

Sildenafil cable co.. takes about 40 min but then the soundstage really increases. Look em up

Meh, that is low fi budget constrained. Everyone knows the best cables are good for at least 72 hours.

yes, but there are those fleeting moments..when that flylined anchovie is swimming beyond ability....count it down....three, two, one....flick the lever drag.....and bang ! Tuna in the can...

IF your reference is well recorded acoustic event in reverberant space and you were there, then moving the illusion ( fleeting as it may be ) is possible, all else is just arguing about which flavor you like. Any 70’s to ? multi-track from Alan Parsons will do..... 

yes, i fish....for tuna...

...then for all you tube types, there's Viagra Valve Ventures (VVV to the cognoscenti...)....

It takes but a short while to warm, but once it's hot there's no stopping them...🙄

Ohms (and Walsh's in general) sound big, but placement and room clutter are major considerations...  Omnis' are Not to all's tastes.

Wide baffles seem to help.
Classic-shaped Spendor and Harbeth speakers for instance sound richer and fuller than most.
And certainly the Devore O series speakers sound way bigger and richer than their size would imply. 

IMHO, you can't get a bigger sound than when a speaker completely disappears.   I've never heard a 15" driver that imaged well or disappeared and they sound flat & lifeless at low volumes.

Have a play with placement.

http://www.cardas.com/room_setup_rectangular_room.php

And "full" is still a factor of SPL at your listening location, over an extended frequency range, no matter how you achieve it, and what gets to you is a combination of direct and reflected. Larger room, and the reflected is reduced. Damped room and the reflected is reduced. Line source and there is less direct loss with distance, but less reflected energy to contribute to the arriving SPL. Larger drivers provide the ability to achieve higher SPL with less cone movement at low frequencies. Multiple small drivers can achieve the same thing. You still need to move the same amount of air, area*excursion, to achieve a similar pressure wave.

It is precisely why an array of 18 Helmholtz tubes and pipes can do marvel in modifying the sound pressures zones where they are located making possible a better synchronization of the speakers and the specificity of the room...

The measured sound pressure coming from a pair of speakers in a particular room could change much in frequencies range if we implement the H. grid with the appropriate ratio volume/ neck...

I did it with great result for my speakers point source : a soundstage filling the room and not coming from the speakers but completely encompassing them...A better timbre perception also... . In 2 listening position, different but astounding results...

The room is not only a passive set of walls where waves are boucing or absorbed or diffused only, it can be ACTIVATED with heteregenuous zones pressure distribution , modulo the varied locations of the Helmholtz pipes and tubes...

This is concrete science easy to verify....

Then your analysis is correct in a STATIC room with a definite homogenuous pressure atmosphere but you forget to say that we can compensate, increase or decrease the sound pressure levels at will with more active acoustical tools... Helmholtz bottles engines grid are only one type of these tools.... I use others also....

Acoustic is way more than what it is speak about in most audio thread by most people....

Most people have no idea because many acoustic tools are not suitable at all for a living room....

And most acoustic companies sells what is EASY and esthetical to sell, not what could be an optimal or more powerful tool but less easy tool to install with a complex set of experiments to deliver the results... Bass traps and passive surface materials are supposed to be all there is to do for most.... This is not true....


The room is not a set of walls, it is a pressure ENGINE....Helmholtz dixit.....

And "full" is still a factor of SPL at your listening location,

To conclude with your opening remark, we cannot complety change each characteristic of the different type of speakers, your post is clear and very right about that, but we can adapt them optimally to the room and adapt the room optimally to them.... That was my point....




My best to you......

I don't think anything you had posted previously had influence my response Mahgister. I think for the most part we agree.

I think I will try a pair Magneplanar 1.7i and a pair of gr research servo dipole subs

just to try something new 

OP - I am biased, but I think you will love the Maggie 1.7i speakers. I have them in my main system and I use the Maggie Base Panel with them to extend the bottom end. They create a soundstage in my room (18 ft by 23 ft with 9 ft ceiling) that is amazing. I push the 1.7i with the new Krell integrated amp (K300i) with no issues at all. I did biamp the base panel with the Son of Ampzilla amp- the more current the better for Magnapans. If you live near Greenville, SC you are more than welcome to come by for a listen!

tom8999

@ mahgister  Well, my answer was a bit short and not really explained.  Obviously, EVERYONE knows that YOUR ROOM is the most important element of ANY sound system.

Having agreed to that (I hope), we can then discuss a version of physics and psycho-acoustics.  All I can tell you from my personal experience in owning a shop for many years and having the opportunity to LISTEN to pretty much every type and combination of speakers from most boxes to hybrids like the Mark Levinson HQD system (full disclosure: we made stands for that system for Levinson), Bob Fulton's "J" system, and so forth, and trying to understand why "good stuff" sounded less than good in many of my customer's rooms, I finally realized what Mr. Winey and others had been trying to explain to me.

1.  The ROOM is more important than the "stuff" you use.  This was made clear when various "high-end" manufacturers entertained me in their showrooms and showed me how good and bad the same stuff could sound when the room was changed around or things moved.
2.  ALL BOXES DISTORT.
3.  Horns belong on the top of poles at high school football stadiums.
4.  Pure electrostatics will burn your ears out (listening fatigue) fairly quickly at any volume.

Once I HEARD all this, I realized, and then again yesterday when I turned on my system and listened for a while, that Maggies are in their own world regarding sound reproduction.  Perfect?  Don't be ridiculous.  Hard to position correctly for the best possible sound?  You know it.  Require lots of high-quality equipment?  Absolutely, as they reveal whatever you put into them.

So yes, a small room is harder to "Maggi-fi" than a big one, but it can be done by selecting the right gear and having a professional, like your dealer, I hope, set everything up for you.  May not be easy, and yes, some rooms simply do not work with them, but for the most part, you get the most accurate music reproduction from Maggies.

Don't believe me...hey, I realizes that flat-Earthers think the Mars landing is a fake...go listen yourself in the shop and THEN in your ROOM.  You might like what you hear!

Cheers!

1. The ROOM is more important than the "stuff" you use. This was made clear when various "high-end" manufacturers entertained me in their showrooms and showed me how good and bad the same stuff could sound when the room was changed around or things moved.
2. ALL BOXES DISTORT.
3. Horns belong on the top of poles at high school football stadiums.
4. Pure electrostatics will burn your ears out (listening fatigue) fairly quickly at any volume.

All your post will be very useful to others.....

thanks for that....

Only a small observation about your righfull remark that boxes distort the sound....

It is precisely the reason why especially with boxes speakers damping, isolation from vibrations and controlling internal resonance could give so much correction and compensation... It is precisely for that reason that ACTIVATING the room with the pressuring engines which are my 18 Helmholtz tubes and pipes compensate in some degree for this distortion.... Dont rectify it completely, but compensate for a specific pair of ears: mine....Musical timbre perception here is the key to feed back listenings experiments correction.....


Boxes are not perfect but could be very good for the price in a small room.... I succeeded...Cost of speakers: 50 dollars used....And i prefer my sound to some 250,000 dollars system i listen to on youtube where the room is catastrophic and nobody ever even has been conscious of this fact ....

I dont say that my speakers are better, not at all, they are trash compared to costly one, but in a controlled room they can be on par with anything very costly which is working in a non controlled room .... People cannot imagine what are acoustic laws and why they are so powerful....At best they imagine sound waves bouncing from the passive walls....It is way more complex than that... The audio superstition in the market speak the language of electronic design and his measuring concepts, the upgrading motto...This is half-truth....Worst than a lie ....

Being audiophile is more linked to acoustic consciousness than being obsessed by electronic design....All thread reflect the opposite... It is the main reason why so many people are frustrated and deceived by their system.... It was mine to begin with.... It is no more the case for me without any upgrade....



I concur with all your post....

It is very important that all those who reviewed gear in a room realize how futile it is to describe sound that make sense only for their specific ears...

It is very important that people realize that upgrading BEFORE controlling and activating a room is throwing money to sellers that dont care about  audiophile experience and the installation of a system in his 3 working dimensions but about their products first and it is normal....Anything anormal here....It is the duty of people to educate themselves in the way to install any gear in a room....


My best to you.....

Mahgister, I appreciate all the comments and think you are very correct that most of us don't fully appreciate correct room treatments, etc.

The most stunning demonstration I ever heard was at RMAF when one of the Brit reviewers did a session on equipment isolation and good stands. They also had four (2'x4' ?) Helmholtz resonator panels set for all four walls. The Wilson Audio Duettes? were stunningly set and sounded superb with the system sorted.

When the reviewer and the other guy pulled all four stands out of the room the 30+ people inside were stunned at the total collapse of what we had all just heard. Sure, there was music; but the difference was off the charts (worse).  Then they put the resonator panels back and the music came back. It was aurally incredible! No tricks, no stunts.

Sadly I've not had the patience or knowledge to recreate this in my room although I feel it is very room dependent in terms of the individual design, much like it seems your brick and pipe devices are designed.

Thanks for you kind appreciation...

I thank you for your post that will remind all readers that NO upggrade can replace the powerful controls in the three working embeddings dimensions of any audio system... Especially the acoustical one...

By the way it is possible to replicate what you listen to at no cost.... It takes only time for listenings experiments.... It is way better than to boast about a 100,000 bucks amplifier like some reviews did.... 😊

Accurate frequency response AND coherent phase from 17hz to 30khz and listen at reference volume. 

Result: BIG SOUND. 

One does not need large speakers to achieve big sound and throw an immense, deep soundstage that goes on forever. But the room size matters, distance to the speakers, room treatments as well as the specific drivers for spl potential. That's why to get the above, larger speakers are often needed for large rooms. 

Can you ditch the DDs and get that in your room? If your room is fairly lively, undamped and you can sit close, yep. Obviously, not without subs and expensive speakers. 

Not having read every response I would say that the amplifier has a hell of a lot to do with the sound..

That's what I said - the amp. Speakers should be reasonably good, of course.

I had the double and packs with the 410 subs, two of them and it’s filled the room nicely. Then I got rid of the double impacts and got the moabs speaker and that really fill the room. It shakes the furniture it makes you feel like you’re there. I think you need lots of drivers to get that affect. You just can’t have a three-way speaker with a single subwoofer and get that same feeling as you can with the Tekton s

OP, don't forget Tekton makes a stand mount Double Impact Monitor.

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.

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. Report t

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...

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....

@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.

What makes speakers sound big is big speakers.

A properly set up room and dialed in subwoofer(s)

I say olde chapPerhaps a double impact is a bit stiffCan go with a single?
If not then I recommend training

Lots of interesting answers here.

The way a speaker radiates and it's interaction with the room will determine it's image size (not the size of the loudspeaker) along with it's ability to cast a holographic image. Relating this to a live performance is difficult. It all depends where you are sitting and what type of venue you are in along with the sound system being used. 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. 

There seems to be some confusion between bi poles and di poles. Bipolar speakers radiate from both sides in phase. Dipolar loudspeakers radiate from both sides out of phase. 

@audio2design, I think what you meant to say was that dipolar loudspeaker's off axis response falls off sharply which it certainly does.
You are right. Most "line source" loudspeakers are not perfect because they act as line sources only at certain frequencies. In order to act as a line source a speaker has to be taller (or wider) than the wavelength of the lowest frequency it is to reproduce. There is one exception to this rule. If the speaker is composed of a stack of multiple drivers the drivers have to be closer to one another than the wavelength of the highest frequency they are to reproduce. This is why you always see tweeters jammed close together and woofers farther apart. 
The reason low bass is lost from Magniplanar speakers is because they are too short!  At about 6 feet tall, corresponding to a wavelength of around 200 Hz, they act as a line source only down to 200 Hz. Under 200 Hz they do not radiate as efficiently so as you move away from the speaker the bass falls off much more rapidly than higher frequencies.
Well, you might say, if the average room is 8 feet tall that means you can only get a line source down to 150 Hz. That would be wrong. It turns out that if a line source terminates both ends with a solid barrier (floor and ceiling) then it acts as a line source down to 0 Hz. If it is a continuous driver like a ribbon or ESL then it is a line source up to infinity. This is the logic behind floor to ceiling continuous drivers. Magneplaner's big mistake was not making the 20.7 8 feet tall (because their marketers told them it would not sell.) A continuous driver speaker ending at barriers is a perfect line source. A perfect dipolar line source has numerous advantages, aside from the large image size they limit room interaction as they do not radiate up, down or to the sides. The result is a very well defined image.
Speakers that radiate omnidirectionally will produce higher volumes at a given power (depending on efficiency) due to all the added reflections but this plays havoc with image definition and frequency response. Then people wind up spending a lot of money on room treatment. Wide dispersion can make a speaker sound bigger and louder but at the expense of detail and focus. 
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. Do they 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. 
Sounding big and going loud are two separate issues. This single most important characteristic determining image size is the speakers pattern of radiation, point vs line source. Other characteristics are relatively minor.
Any speaker can go loud with enough power. The problem is doing it without distortion. Isolating the main speaker from bass is a great way to limit distortion at volume. Line source dipoles have a beautifully detailed image because they limit room interaction by limiting dispersion. Horns can do the same thing for people who prefer the smaller image of a point source. I also see a lot of tweeters and midrange drivers mounted in dispersion limiting baffles but have not listened to any of them under circumstances where I can tell if this approach works. Don't see why it would not.

I have a pair of Tekton Ulfberhts. They are 7ft tall and contain quite a few drivers. They certainly sound big.

I also have a single driver LII Audio Fast 8 in a simple open baffle by itself. Amazingly they sound big also!

Both sound big in the room I have them it. It's quite striking. The room isn't everything, but it has a LOT to do with how "big" a speaker sounds.

I’m not saying the latter should trump (no pun intended) the former, but that some coexistence is necessary here.

I think that all is linked to the size of the room...In relation to the speakers...

And i then understand your point and we understand each other i think...

Thanks and my best regards to you....

Pro tip: close your eyes while listening

Hello . Horn loaded speakers. Very sensitive doesn't take a lot of wattage to get them singing.  I don't work for jbl but they have quite a few speakers with compression drivers and decent woofers that not only fill your room up but will have strong deep BASS. or you can do some research and build your own set of speskers

I have big speakers. Imho, no substitute. You need to move a lot of air. 

I asked the DIY audio community here in UK about room filing, all absorbing sound and the consensus was basically “big boxes, and the biggest box is your room so use it”.  Hence the 6 foot high backloaded horns that now grace the end of my living room.  In my son’s smaller space his 9x2 line arrays plus subs sound great - and sound great if you are sat on the futon, or bopping about. 

This is a not so well defined criteria. Some call the soundstage size an expression of BIG sound and some consider bass extension the criteria for BIG sound.
 A truly big soundstage comes from speakers with very low distortion artifacts and minimal diffraction effects. Diffraction and distortion effects are non consonant and detract from the soundstage scale. Low distortion bass extension is well understood.

Hello Martin, I just read your post and haven’t gone through the responses. Excuse me if I may repeat something already mentioned. I’ve been in this hobby for 25-30yrs. So one of the things I offer is experience. The design of the speaker is what makes it sound big. Components and cables can significantly affect the size of the sound but the largest factor is the speaker. For the most part, larger drivers do produce larger sound but there are exceptions to this rule. At times, a well designed small driver in a well designed speaker can sound very big along with a larger driver in a poor designed speaker can sound small.  My advice, if you really, really like your speakers, try higher level cabling to hear if the speakers open up. If not, try upgrading your components to items that are much more “open” sounding. If these basic attempts don’t work, then I don’t think the speakers you have are really meant to be open, big sounding.  

Hello Martin. I've always had big speakers as my listening room is rather large. I've just changed to smaller ProAc speakers on sturdy heavy stands and added two 15" sub-woofers. One on each sides. The sound is pretty big and it will fill the room quite easily. I think the only draw backs will be the SPL your small speakers will deliver. If your trying to have a rather large and loud party, this set up will probably not do as usually, the power is limited with smaller woofers. The good part is that the small footprint your bookshelf speakers will have, is going to give you a better musical stage definition. 
The previous speakers where OBs. The thing I miss the most is how quickly they reacted to the music. But I do not miss the added space they took in my listening room (living room). I will have to put them up for sale as I rather like the added space that I get with the small speakers. You can't win them all.

Big Speaker:)

the answer is yes, you need a big speaker for big sound, while you can produce a reasonable sound stage out of a smaller speaker there will be no impact or force from a mini speaker. Mini or small speakers will always sound mini or small, its just physics and anything else is just a illusion or delusion or whatever you want to call it.
A big planar speaker with a big surface area will sound bigger, an array of dynamic speakers emulating a planar speaker will sound bigger. If you combine a big sub woofer with tiny speakers you will get impact from the subwoofer but the rest of the musical spectrum will still sound small - like the small speaker where the sound comes from. Same like the other poster said: a big block engine will always sound bigger than a tiny 4 cylinder engine, even blown up to deliver hundreds of horses, if you want big than go big - and yes again bigger is better as long you have room!

well sir ,  you have good hearing  selling the speakers  i was happy to read that. Then you said 
B&W.  Keep looking about.  Speaker wire , Amp,
 Pre, all work to fix the problem.  i don't know how far from the wall the speakers can be  so i won't comment   

This is what happens , Some expert will say,,,
,,Ribbons and AMTs that spread around sound will sound bigger than a single dome tweeter.    The top two the Professional talks 
about need to be a way from the wall behind the Speakers.  start at 40 in  out  then move around  
 the 3rd tweeter is the one
you might be interested (example) Merlin VSM BM  
but again never sure  good
luck   

@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?

There is ONE major and many smaller minor factors which affect the size of the sound.

That major factor is how much volume of air (not surface area), the speaker moves per unit time.  That is pretty much it.

The minor factors are just too many to count & explain and they are mostly the icing on the cake.

dsnyder0cnn's comment about closing your eyes is quite correct. Visual ques distort our sense of hearing. If it looks big it must sound big which is in reality totally false. You can make an LS 50 sound just as big as a big Wilson. Both have a single tweeter which usually sets the volume limit. If the tweeter in the Big Wilson and the LS 50 have the same power handling and efficiency they will go to the same max volume. Both radiate the same way. The only thing missing in the LS 50 is bass. Add a sub woofer and you can get remarkably close. Close your eyes when evaluating any speaker seriously to keep your visual cortex from screwing around with your audio cortex. Some people interpret volume as size. That is just not true.
@phusis , 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. 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. 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. 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.

A bit of harmonics can add up to a big sound.  I don't call it harmonic distortion, but some do.  Mt people like it. B&W aficionados try to hate added harmonics.  I add some to bad recordings by switching out my sub-woofer crossover.  The sound is much bigger when I do that, but loses some pin point accuracy.  Many non-audiophile friends prefer this plump sound.

@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. 

Your ears have no idea how big the speakers are. It hears sound pressure.

Mikelavigne, where you said....

some good mid bass is also helpful; again the speaker driver surface in the mid bass needs to be matched to the volume of the room so it can propagate. the whole room needs to be energized.

is there a formula  one could follow in order to size the speaker system to the room?

Hi, Martin (OP) 

Much wisdom spread throughout the thread here and elsewhere online. 

My 2 cents... 

For a great condensed reference that touches on all this and much more, you may want to get a copy of Jim Smith's "Get Better Sound" 
https://www.getbettersound.com/store 

Jim is one of the best in the audio / music biz and there are many things within its pages that may help solve your issue or at least improve the quality of what you hear. It is likely to help with other considerations and improvements as well. 

Although his in-person, in-home consultations are pricey, he offers very reasonable 30 minute phone consultations. The book and the chat might be the best investments you can make (or will ever make) in your system and setup. 

Cheers, 

Ken

If you want speakers that sound big try magnepan LRS speakers.
You've never heard anything like them. Neither have most others here.