PRaT trumps all

[anthonyTD]

When comparing small cones with large ones, you also have to take into account the amount each cone has to move, to move the same amount of air!
A...

[SPS]

Isn't it? If the coil has too much inertia to move backwards and forwards very fast, it won't reproduce high frequencies - hence tweeters have to be small and light. Obviously you need more acceleration/deceleration to move at 20kHz than to move at 100Hz, so how is cone mass and acceleration not linked to frequency response?

Yes I agree it's linked I've always thought of that aspect as bandwidth.
I would not recommend any large driver for the higher frequencys though, many I use do have a very wide band width but there is only a much narrower band they are used at.
What's nice to see there are many differing views on the best types of drivers... we are all entitled to our opinions. More meet ups and bake offs should be the order of the day !

[Pharos]

Very often cones are not designed to work in pistonic motion, and these tend to have 'curvilinear' cones which allow gradual detachment of the cone towards the voice coil as frequency ascends.

In this situation, where the cone is behaving like a suspension for the moving central part, the effective mass is not the whole cone but a portion of it. This is how mid/woofers work.

[walpurgis]

Altec had a novel driver design called the Biflex. The cone had two suspensions. The usual outer at the cone edge and a second, separating the outer portion of the cone from the inner. This second suspension decoupling the inner and outer cone at a chosen frequency, acting like a mechanical crossover. One or two other makers copied this.

This is the 408 driver.

[Macca]

clever idea.

Re driver speed and ease of drive, isn't it also going to be dependant on the material of the cone and the size of the magnet?

Light paper cone with big magnet = fast, doesn't need much power, and heavy plastic cone with small magnet = slow, needs lots of power

[Pharos]

Yes Martin, and the magnets should be applied in the reverse way IMO, big for slow polyprop, and lesser for light paper.

Bill Woodman's 20s mid/woofer has the dome decoupling from the cone outer.

[walpurgis]

Some of the small magnet speakers rely on the 'airspring' effect from sealed cabinets. And it works. KLH, Acoustic Research, Celestion, Advent and KEF used this to good effect. It did nothing for efficiency, but did provide good bass transient response.

[Haselsh1]

It is harder to get the small driver to start and stop on a pinpoint.

Not true because here momentum comes into play and a relatively heavy 15" cone is going to have much more momentum than a relatively lighter 5" cone. This is of course also dependent on the braking effect of the amplifier and loudspeaker cable. I also think this is why one of my favourite loudspeakers is the Audio Note AZ-2 because it has a light weight paper cone. This has lower inertia so can move from a standing start quickly and can be stopped rapidly because it has low momentum. Similar to five valve per cylinder engines where the total reciprocating mass is so much less than dinner plate valves. This means they can rev much higher. Smaller lighter cones yes for a much faster response but small cones cannot shift great gobs of air.

[Pharos]

I believe that there are three categories of cabinet air loading, the middle one being 'Acoustic suspension' innovated by Acoustic Research.

And also, what the heck is "scale" as described on another thread w.r.t. small boxes, this term also leaves me in a completely dumfounded state as do PRaT.

[Yomanze]

Scale: does a system reproduce the size and ‘physical presence’ of a musical instrument. For example, very very few systems can get close the accurately reproducing the scale of a pipe organ at lower frequencies.