For most people planning to buy a subwoofer, whether for the home entertainment or car stereo system, the amount of space available and the budget set aside are always a crucial factor.
Generally, subwoofers are way larger compared to tweeters and will cost you significantly more. As such, they need a little bit more space for proper installation and operation.
But have you ever stopped to think why this is so? Why are most subwoofers on the market big, heavy, and expensive?
When it comes to woofers and subwoofers, the size of the speaker unit matters a great deal! If you were to get a subwoofer with, say a couple of 8-inch drivers inside a box, you will be very disappointed with the kind of results you get. There won’t be as much power with the low-frequency sounds.
In essence, big is always better as long as you don’t expect the sub to go too high in frequency. The explanation is all in moving air. To produce the large booming sound, a sub has to move a lot of air, and this is affected by the surface area of the driver. The larger the surface, the more air it can move.
It is commonly known that bass drivers are large while low-frequency drivers are typically small. If we were to consider the energy that waves carry, a high-frequency wave has more energy and only requires a little bit of amplitude to carry greater energy.
On the contrary, low-frequency waves are not very energetic, hence require very high amplitude to carry the same amount of energy. So, for the speaker to be loud, you will need to pair a lot of low-frequency amplitude with little high-frequency amplitude.
This is to say that high-frequency drivers (tweeters) don’t have to displace a lot of air to create more pressure, and this allows them to be small in size. Furthermore, high frequencies need very fast motion, so the driver has to be very little in mass. It wouldn’t be practical for something as large and massive as a woofer to move back and forth that fast.
On the other hand, you need to move a lot of air to make your bass even louder. But if you’re just looking for a slight amount of bass, then the driver shouldn’t be too large to achieve this. A good example is in headphones; they produce enough bass just to make the listening experience enjoyable.
Another thing to note is that you don’t always need a huge driver to move a lot of air. This would be possible if you had a small driver with a lot of excursions. The only problem is that it is logistically difficult to achieve, and that’s why you typically find large subs and woofers.
Can a Tweeter Produce Low-frequency Sound?
Yes! You can produce a 20Hz tone using a tweeter without any difficulties. The same is true if you have a couple of headphones with drivers that are the same size as a 1” tweeter.
However, you’ll have a hard time hearing the tone out of the tweeter or headphones since the amplitude is just too small and the tweeter isn’t designed to have the excursion required to move that amount of air.
It could work if the 1” piston tweeter you’re using can move back and forth at 20Hz, but why would you go through all the trouble of building this when there are larger woofers that are built for this?
This is something you’ll notice in the design of good bass drivers. Take for instance a massive 15” driver; these typically don’t come with huge surrounds to enhance the inches of the excursion. Rather, they have the size to move enough air around without so much movement.
Consider powerful subs with relatively smaller drivers (like Sunfire); you will realize that the relatively smaller woofer will normally come with a big surround on the driver since it is engineered to have inches of excursion to move a lot and push just as much air around.
Ultimately, you get different design challenges and different design tradeoffs but with the same goal of producing greater sound. From this, you can see the inverse relationship between the driver size and the amount of excursion needed to produce greater bass.
Finally, the other aspect is that you feel the bass physically on your body as opposed to only hearing it. While you can hear the bass in a song while listening through headphones, the experience is not as satisfying because you miss out on the thump in your chest and the reverberation from the head to the toes.
This is only possible when listening to well-installed subwoofers in a room with a booming bass!
Why are Subwoofers Heavy and Expensive?
When it comes to weight, the large size of the subwoofer directly affects the weight. Aside from the huge driver, more material is used to build the surround, which results in a heavier unit compared to low-frequency speakers.
Meanwhile, the high price of the subwoofer has more to do with the niche industry of audio equipment. The thing is that it’s only a small fraction of the demographic that wants this type of equipment, and this makes it a challenge for audio manufacturers to recoup the cost of research and development.
Additionally, speakers are typically overpriced since the technology powering them moves slowly and the equipment is also very durable. Because of this, they don’t sell as fast compared to products like flat-screen TVs where there are significant improvements with every year that comes.
In summary, subwoofers require a huge margin for the business to make economic sense! Other factors that drive up the cost of subwoofers include size (more materials used), as well as warranty and shipping.
Typically, a subwoofer’s driver is pretty large (12”-18”) compared to the driver of a large bookshelf speaker like the Edifier R2000DB (5”). Given how low the driver goes, the housing needs to be built well so that it does not break apart after just a few months of use. Ultimately, we go back to the cost of making a subwoofer unit!
So, if you’ve ever wondered why all the subwoofers you come across during shopping have to be big and expensive, the above post offers a good idea of why this is so. Remember, big is better when you are looking for the loudest boom in a sub, but remember to be guided by the amount of space you have.