Do Bigger Speakers Mean a Bigger Window?

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So, if you are after high fidelity sound, why would you buy small speakers?

I never would, never again. Moreover, the "small(er) listening room small(er) speakers" mantra has no real bearing or justification - to me, at least. Smaller rooms mayn't need speakers as large, but there are benefits to be had not converging to this tendency, that I'll get back to. Some larger speakers, certainly horn variants, need space, not least listening distance, and so naturally requires a larger listening environment, but otherwise I wouldn't shy from implementing speakers with an imposing physical stature w/large drive units/horns into more moderately sized rooms. 

It's not only about big speakers/air displacement area, but about (high) sensitivity/efficiency as well - all to add up for one important feature: headroom. Some may find it ludicrous to ask for 20dB's or even more headroom on top of the loudest SPL you'd normally be able to muster with your playback system, but to others it's the ingredient that makes it all come together; when a stereo setup with large, very efficient speakers that operates within the confines of +20dB's to spare at the highest output levels you would typically require, there's an ease, sense of scale and capacity to handle complex musical material that's very beguiling and animating for one's listening pleasure. Music simply happens differently and more convincingly, unrestrained, and it's a vital element in letting go of music as something that is re-produced. Larger speakers of that kind, all things being equal, also tend to more readily succeed in eliciting an emotional response through sheer girth and force, often understated, that has smaller and less efficient speakers sounding malnourished and strained by comparison.

Also important here is bandwidth, preferably to 20Hz with full output, but that's an aspect too late at this local hour to begin unwinding. 

All this being said: small speakers may have qualities to be floored by in some areas, but on the whole and to my needs simply don't cut it.  

Just my $0.02. 

Do Bigger Speakers Mean a Bigger Window?

Short answer is NO!

Try to have a listen to a pair of early thumbnail size minuscule 198*? Proac Tablets with decent amplification, you will shake your head in disbelief and start looking around the room for the "real" speakers.
http://www.vintageaudioworld.com/wp-content/uploads/Proac-Super-Tablettes.jpg

Also another stand mount, bigger and very expensive if you can find a used pair, is the Sonus Faber Extrema these are an end game speaker, even in the bass. 
http://shop.textalk.se/shop/1785/art85/h6759/4146759-origpic-4ffba5.jpg


Cheers George

Looks like there have been various interpretations of the OP’s question.
One thing I’ve noticed is that, yes, in generally bigger speakers sound bigger. Not just the size of the soundstage, but the size of the sonic images and the sense of actual presence.

I have had (and still own) many smaller speakers that image like demons - from my MBL 121 omnis (still have them), spendor, waveform, and others. Though mostly I’ve used a variety of floor standing speakers.
I’ve continually noticed that even when a smaller speaker is rated close to the same frequency response, the speaker with the bigger cabinet/bigger drivers just sounds bigger.

For instance right now I have the Thiel 3.7 and 2.7 speakers. The 3.7 was the last Thiel flagship floor stander, and the 2.7 is just a tiny bit smaller version. Both use the same midrange/tweeter, the difference is the 2.7 uses an 8" woofer vs the 10" woofer of the 3.7, and the 2.7’s cabinet is a bit smaller.They are rated within about 2dB difference in bandwidth in the bass. And the 2.7 rarely sounds like it isn’t going as low as the 3.7. But the 3.7 just produces BIGGER sound.  A more vast soundstage, bigger more life-sized images, more authority.
And then some smaller floor standers - e.g. a model employing two 6" woofers and tweeter I’ve used, which actually went as low or a bit lower in the bass than the Thiel 2.7s, still sounded "smaller." Acoustic guitars, for instance, where just that more miniaturized.

One sort of exception to the smaller speaker = smaller sound/image size are speakers with wider baffles. The Harbeth super HL5plus monitors I had weren’t as big as my 2.7 Thiels, but the image sizes had a similar heft, which I attribute somewhat to the wider baffle/lively cabinet, bigger midrange woofer design. (Though the Thiels still threw the bigger soundstage). Similarly the Devore Orangutan speakers that I’ve been auditioning - smaller somewhat than the Thiels but much wider baffle and larger woofer - have huge image sizes with lots of heft. (Though, neither of the Devore O speakers cast quite as large a soundstage as the Thiel 3.7s).
Anyway....just musing from my own experience.

@phusis  Yes! It just struck me after reading your post, something so obvious  yet didn't consciously occur to me til now. For me at least, a major difference is that when I listen via large speakers I can more easily forget that I am listening to reproduced sound and fall under the illusion that I listening to reality.

Right now its very warm here in the UK and I have the window open. I can hear the traffic outside, someone speaking downstairs, plus someone vacuuming the landing. These are the kind of sounds (full bandwidth/ large images) I think bigger loudspeaker are more able to reproduce in a life-like fashion.

It is difficult sometimes to describe semi conscious processes taking place in your head, and they won't be the same for everyone of course, but for me that's it - bigger speakers help me forget that I am listening to a recording / reproduced sound.

That doesn't mean that bigger is better, sometimes you might want to listen into the recording, or have other priorities such as transient speed, detail etc.

But for the sheer illusion of reality large loudspeakers are hard to beat.

I have a pair of Klipsch Heresy IIIs that, in their positions of about 7 feet apart and 9 feet from my earballs, create a large and satisfying soundstage...I thought the horns might beam somewhat but they go amazingly wide...short, fat speakers...who knew?