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Small drivers vs big drivers

Hi,
I have a question that is always in my mind recently. I see some speakers with small  drivers (5-9 inches) that is reviewed to be able to throw out big sound stage and go down to 18hz-20hz. Some other speakers with big drivers (10-15 inches) though are commented to have 'big sound stage' but can only go as low as 30-35hz. 

To make the situation more complicated, some speakers have small drivers but there are many of them. Can many small drivers be compensate for the size limitation?

I don't know which specs determine a wide sound stage and the ability to reach low frequencies.  What is the pros and cons of each design?

Thank you!

Huy.
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bdp24's avatar
bdp24
9,821 posts
 

The ability to create a wide/big soundstage and the ability to reproduce low frequencies are two completely different matters (except that the sound of a large recording venue---cathedrals, churches, theaters---are of very, very low frequencies).

The size of the drivers in a loudspeaker, assuming you are talking about cone/dynamic drivers, has nothing to do with the speakers ability to create a wide/big soundstage. The size of a woofer, on the other hand, is very much related to how much air it can move at low frequencies. But size isn't everything, right girls? ;-)

seasdiamond
44 posts
 
Bass frequencies are generally omnidirectional and most driver’s don’t have a problem with bass dispersion.

Differences in soundstage between speakers is mostly something that happens in the upper midrange and highs, so this is mostly about the tweeter implementation (as well as how the crossover is structured with the midrange or woofer).
shadorne's avatar
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shadorne
7,477 posts
 
Large drivers with large diameter voice coils will push much more air and stay cooler and consequently remain incredibly dynamic and effortless at concert volume levels. Minimal distortion.

A small woofer with a small diameter voice coil pushes very little air and heats up very fast - they always sound dull and strained at realistic volumes. Lots of distortion.

Small Diameter = 6” with 1” voice coil
Large Diameter = 15” with 3”+ voice coil
bdp24's avatar
bdp24
9,821 posts
 

@shadorne raises an important point. During heavy excursions of its cone, a woofers voice coil heats up, changing the drivers electrical characteristics, and therefore its sound. One of the functions of the Servo-Feedback circuit in Rythmik subs is electronic compensation for the change in the woofers electrical characteristics due to voice coil temperature. No non-feedback woofer or sub is capable of that feat, one of the reasons for the uniquely clean (low distortion) sound of Rythmik subs. Sound like a sales pitch? Too bad ;-) .

The Servo-Feedback circuit also minimizes differences between the 12", 15", and 18" Rythmik woofers. Their sound characteristics are identical, the difference between them being in their maximum SPL capability. Rythmik also offers subs with 8" woofers, for those clinging to the idea that smaller woofers are "faster" than larger ones.

gregm
3,405 posts
 
@quanghuy147
To make the situation more complicated, some speakers have small drivers but there are many of them. Can many small drivers compensate for the size limitation
Yes, they can, but it's a whole different design ball-game! Generally, smaller diaphragmes are lightweitgh & therefore move faster but, being smaller, they reproduce lower frewuencies at an imperceptibly low amplitude (volume).
I don't know which specs determine a wide sound stage
The wide s-s is usually the result of efficient driving (i.e. small speakers) and a small baffle (small-sized speakers).
Numerous other design parametres are also invlovled, but let's not complicate the issue!

For difficulties in reproducing low frequencies through smaller drivers, see Shadorne above.

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