Question on small bass drivers in tower speakers


I noticed that many speaker manufacturers have been offering tower speakers with a multiple array of smaller bass drivers in their latest designs. I understand that having a series of smaller bass drivers in a cabinet can provide very fast and accurate bass response but I often wonder how these smaller drivers fair when it comes to reproducing the lower registers of the frequency range at louder volume levels (95+db).

I've seen claims of bass response down to the low 20hz range using two 6.5" woofers from some manufacturers like Proac as an example.

My question is this, how can these small drivers be capable of reproducing such low frequency when stuffed into a box when if you look at the manufacturer website of the speaker drivers themselves and see a listed Frequency response that shows the woofer only being able to play down to 40hz at best when taking a speaker of no more then 7" in diameter into consideration?

If someone was in the market for an almost "Full Range" speaker how likely are they to be happy with a tower that only uses 6.5-7" drivers at most that claim low 20hz capabilities verses some other manufacturer who uses 8" or larger drivers with similar advertised capabilities?

Even if I take into consideration the most inert cabinet designs available for these small drivers I still find it difficult to grasp the idea that they will be able to play bass that low on the scale with any real authority.

Please add your thoughts and experiences with small driver tower speakers and if you were impressed or disappointed with their capabilities of playing low and loud despite the advertised claims ..Thanks
eniac26

Showing 4 responses by mceljo

My Focal 836v speakers have an array of three 6-1/2 inch bass drivers and they often surprise me with their bass. I actually have a subwoofer, but I don't use it often for stereo listening, it's reserved for home theater. I have my speakers fairly close to the wall which increases the bass, but there are some songs that if I had the room I'd move them out from the wall and reduce the bass slightly. They don't handle "low rider" bass with authority so they have their limits, but I certainly consider them full range.
Shadorne - It seems logical from a physics perspective that smaller drivers would be easier to control resulting in a more accurate bass response. The problem being that small drivers cannot move as much air and that's more related to volume that quality. Obviously, driver design is very important, but all things being equal it seems that the smaller driver should distort less.

My current Focal 836v speakers have three 6-1/2 inch bass drivers and can reproduce frequencies down to about 30 hz on a test CD, though at a very low volume. They will play organ music in a satisfactory way. If I compare these speakers to my Infinity IL50 that had a built in 250 watt 10 inch woofer/subwoofer they certainly can't reproduce the same volume levels, but when the IL50s were adjusted to music levels on the subwoofers they wouldn't go any lower than the Focals do. For music, the Focals have an equal low end and much higher sound quality. For home theater, the Focals require a subwoofer to be used if I want the house to shake. Most people that hear my speakers assume the subwoofer is on when listening.

It's possible to put larger drivers in a side firing configuration that maintains a lot of the WAF of the small forward firing drivers so I'd think that would be the better solution IF the large drivers were the goal.
JohnK - I need to read through that link again, but I didn't come to the same conclusions that you did. About the only thing that I gleaned was that efficient drivers are better, at least for long term durability if pushed to their limits.

How does an efficient overall speaker relate to a speaker having efficient individual drivers? My speaker is rated around 92 dB so I know it an efficient speaker, but I'm not sure if that says anything about the individual drivers.

Any thoughts?
I guess I would classify a "small" bass driver as anything under 8 inches in diameter. My speakers have three 6-1/2 inch drivers. You can easily find 8 inch subwoofers, but not very often do you find them small than that, but I did have a bass unit to go with some JBL small speakers that used dual 6 inch drivers, but it really wasn't a subwoofer, more similar to the bass unit that Bose has.