What are the smallest speakers that are clean and flat down to 20hz?

FYI, there’s a rule of thumb, that for any given driver, going down an octave causes 10x the linear cone travel. So, if you attempt 20 Hz with a 6" driver you’ll need it to move a foot back and forth or something ridiculous like that. :)

This is why larger is better. Those who argue they are slow or not musical have not been able to integrate them properly which has nothing to do with the quality of the driver but not managing the room acoustics and EQ properly.

You may also find this resource helpful:

http://bass-db.gforge.inria.fr/BASS-dB/

Also look for Room EQ Wizard where you fill find many bass geeks to discuss things with you.

Having adequate drivers for a subwoofer is very important, but to my ears, the quality of the EQ matters much much more. So, JL to me is one of the best off-the-shelf subwoofer makers. Of course they use a high quality sub driver, but their auto-EQ is perfect.

Personally, I do my own EQ, so I’m quite happy with Hsu VTF-15H MK II for $1,300 (including EQ). If I had all sorts of money and no time, I’d go with JL.

Best,


Erik

Clearly larger active or powered speakers or speakers with integrated powered subwoofers are best able to do it but I’m wondering more about purely passive speakers even if only in a smaller room.  I realize room acoustics play a big part.   I'm also wondering more about low end extension and  distortion levels assuming other external factors will need adjustment for truly flat response. 

I would consider looking at the DIY site from Troels Gravesen. Lots of his kits show the speaker response and the room response, followed by the final outcome.  You could find it illuminating.

http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

Best,


Erik

Headphones!

Grado made a line source array that they showed at CES one year, just for fun. It made decent bass but it had a lot of drivers in it. Seems to me it was over 6 feet tall and they won't be manufacturing it.

Otherwise you're simply going to have to have a big speaker.  My speakers go to 20Hz and have two 15" woofers. You probably can do it with one. The smaller the driver, the more excursion it needs and that's your limit. Bruce Thigpen got around that limitation with his subwoofer fan.

Click on the link below and then products (TRW-17):

http://www.eminent-tech.com/main.html

From the page:

A conventional speaker cones displacement must increase four times for each halving of frequency to maintain the same output. This is why conventional cone woofer companies are trying to develop “long throw” woofers. Although inefficient, cone woofers work fine above 40Hz. Below 40Hz however cone woofers quickly run out of travel and the output diminishes rapidly.