Small Speakers, Big Sound?

Are todays small speakers equal too or better than larger speakers? . Has the speedy rate of technological advances on electronic Audio/Visual Components influenced  speaker size aswell? It appears to be a common perception or aspiration though by todays consumer. With hundreds of small inexpensive 5.1 sub-sat systems available , surely technology advances mean you can get a big sound from a small box?

Well, again I quote a saying I’m fond of. “You can’t change the Laws of Physics”. The “bottom end”, “bass”, “low-frequency response (LFE)” of a loudspeaker is directly proportional to is size. The bigger the speaker cabinet (resonating chamber), with a bigger surface area of its bass driver has a lower LF roll off and a higher maximum bass “sound pressure level”(SPL). confused? OK! Let’s look at sound waves. Air consists of molecules. A tiny region of air contains vast numbers of air molecules. The molecules are constantly in motion and traveling randomly at a great speed. A vibrating object, like a driver found on a speaker will produce sound waves in the air. The vibrating speaker driver produces sound waves because it moves alternately outward and inward, pushing against, then moving away from, the air next to it. The air molecules that strike the drumhead while it is moving outward rebound from it with more than their normal energy and speed, having received a push from the drumhead. The bigger the driver, the more (sound pressure level) SPL. So a tiny speaker has a small driver and minimal SPL.

This is why small speaker systems (sub-satellite systems) divert all the speaker-channel bass to the subwoofer. Small satellite speakers have an ultimate LF response (-3dB) of between 90Hz and a whopping 200Hz. when you drive your sub hard above 70-80Hz to fill this gap the sound becomes really ‘thump, wump, wump’ that destroys surround sound imaging. Better sub-sat systems are good at hiding this issue, like Bose. The have spent decades on research and developement trying to change the ‘Laws of Physics’ but you really do need big speakers to get a big sound.