not entirely, if they are lightweight enough then fine, but thats always a challenge, if you attempt to build a 2-way speaker with a large 12" woofer it's not going to sound all that great unless the driver is really lightweight, thats why most really large speakers are 3-way, but then again, there is alot more to it then size,
I'm not sure what you mean about lightweight. Are you talking about the cone's mass?
The real reason has much more to do with the width of the driver's cone. When the reproduced frequency's wavelength is less than that distance the driver begins to beam and the off-axis response goes from omnidirectional to forward firing. The higher the frequency the narrower that beam.
When you match a large driver in a two-way configuration you will have a hard time blending the off-axis response between the woofer and tweeter. This is what drives designers toward 3-way designs, so as to better control the off-axis response throughout the audio spectrum.
Cone mass affects the resonance frequency of the driver and the transient response of the driver. That has no effect on the driver's directivity.
you can get the same bass from a 6" woofer then you can get from a 15" one if its done right, just look at pro sound speakers, most of them dont have a response lower then 50hz,
Yes, and no. It is possible to make a 6" woofer produce very low bass, but in the end it is all about moving volumes of air. If you produce a downward sweeping frequency tone of constant amplitude, as frequency descends, the amount of cone displacement increases. The tweeter's movement is almost nil, but the woofer will be stroking.
A 15" requires a lot less excursion than a 6". It also better couples that low end power to the room. The 6" has to work too hard and will require a design that allows for very large cone excursions, yet remain linear in its impedance and inductance through that large excursion. That is far easier to do on a 15" woofer than a 6" woofer.
but my small polk bookshelfs have more bass then them. cabinet volume has a bit to play in bass reproduction, this is why floorstander have better bass then bookshelfs, even if they have the exact same drivers in them. like my monitor 40s are good down to 47hz, but the exat same drivers placed in a large floor cabinet are good down to 38hz. i also owned a pair of sonys well two pairs that had the exact same driver config and the floors had tons more bass then the bookshelves. there are so many factors that go into good bass and size is only one of them. if you mess with a BV calculator and increase the QTC you keep getting more bass as the cabinet volume goes up.
Most bookshelf speakers are a sealed cabinet and generally have a much higher F3 than a vented counterpart. If you increase the cabinet volume you lower the Qtc of the enclosure.
The effect of Qtc on the response of an enclosure works like this:
The higher the Qtc (smaller the box) the response curve develops a positive bump at the knee of the bass response. This tends to make the box boom.
A Qtc of .7 yields a maximally flat response. The bass extends down flat until the driver resonance and slopes off at 6 dB/Octave.
When the Qtc is less than .7 (larger box volume) the bass knee drops off earlier (higher in frequency) and the rate of the rolloff slope is gentler (less than 6 dB/Octave).
A lower Qtc will result in weaker sounding bass, not bigger, but it will extend lower in frequency because the rolloff rate is less than 6 dB/Octave. The reason a larger floor standing enclosure (with the same driver) sounds like it has more bass is more likely due to room placement (coupling with the floor and walls and corner) and the bookshelf box Qtc may be higher than optimum (just a guess).
The only real way to evaluate the two systems is to have each loudspeaker suspended in a very large room with the walls and floor/ceiling at least 32 feet away or more so as to eliminate reflections. This would be the 4∏ anechoic response curve.
Evaluations in your living room are fraught with the artifacts caused by room modes and reflections interacting with the response and the placement of the loudspeakers under test need to be the same. Some test software has the ability to gate the signal received by the test microphone, but this has two adverse effects. The first is to reduce the resolution of the data. The second is to limit how low you can measure in frequency. Both render getting low end response impossible at one or two meters. The only way around that is to measure the bass response in the nearfield (about 1/4" away).
