Some good ideas floating around here, sealed bass will be used but a Nola style mid using a light sensitive 170mm cone Hmm....

The accuton drivers used in Avalon speakers are certainly not cheap!

Not an area I have played with. Can you give some examples and figures?

What about the Jordan JX92S?

Over on the DIy audio boards, veteran designer Ted Jordan's JX92S has a keen following. It's a versatile 4 inch "full range" driver which can sound amazingly clear and fast, and can produce ridiculous bass for its size when in the right enclosure. I use a pair in transmission line cabinets and there is plenty of bass. It is also used in a number of commercial designs.
There are 3 problems:
They're aluminium and can get peaky at around 16K - but there are various recipes for calming the peaks. Then you have a single driver which can cover from below 50Hz to 20kHz
They're expensive - but many of the designs don't have any crossovers.
They're 5 Ohms - but someone has designed a Zobel
Personally - I love them, and I know a guy who sold his electrostatics when he heard them.

You’re right – it is “fake bass”, but isn’t all hifi sound “fake”? It is after all just an attempted reproduction of an event or performance that often never took place in the form in which it is presented. Many performances are assembled from different takes or tracks laid down at different times and assembled into the illusion of a single seamless event by editing and then enhanced by mixing and processing We know we are not at a real event listening to real musicians performing in real time, but we become complicit in the illusion through what Aristotle called the “suspension of disbelief”. We enjoy the self-deception of the pretence but we know it isn’t real.

Within the limitations of its size, the JX92S can do a wonderful job of creating the illusion of bass notes. Perhaps I should have said “ridiculously deceptive amounts of illusory bass for a speaker of its size”.

By the way I use them with a subwoofer and am looking at design using them as the mid in an open baffle with an 18 inch woofer.

The indefatigable Zaph has posted some Le(X) measurements on drivers he has tested:
http://www.zaphaudio.com/Le(x)
The vagaries of voice coil inductance variation depending on displacement are many. As far as I know, such specs are not widely available. I suspect that this is partly due to the fact that it might reveal substandard quality on behalf of driver manufacturers. There are only two ways to eliminate this source of nonlinearity: one is to make a voice coil much, much shorter than the magnetic gap, so that the coil always moves within a uniform magnetic field while constrained by its mechanics. The other way is to make the coil much, much longer than the gap, in which case the total flux remains unchanged, albeit a certain number of coil turns always remain "unused" as far as force generation is concerned. The former way is expensive, because it calls for a very large magnet. The latter is cheap. I guess most manufacturers go for the middle way, which is probably the worst because it makes force generation vary with displacement, and therefore not proportional to current alone as it should be. As far as I know, there is no way for DIYers to obtain these parameters other that measuring them for themselves, or hiring the services of consultancy firms like Klippel. There is magazine called "Voice Coil" that may be doing such tests, but it is strictly a trade publication, so I cannot know for sure. Darkmatter, is this a parameter you have looked into in your past designs?

Edited by user 30 December 2008 13:22:31(UTC)  | Reason: Not specified

Neat! It is my impression that very few manufacturers do things the hard way and shoulder the expense of using strictly underhung, linear motors in their designs. I've been told that ATC is one of them, I wonder who else is.

The recent article by Jonathan Valin comparing his Magico Minis with Quad ESLs is very interesting.

The above makes it all the more of a challenge for a rank amateur like me, to achieve the excellent results craved for when only stock drivers are available.

This is half the fun for me and makes one more resourceful.

DM

Edited by user 02 January 2009 00:14:03(UTC)  | Reason: Not specified

I couldn't agree more. I made my first speaker cabinets. They were 4 cubic feet; had sand-filled sides and baffle, with the tops, bottoms, and backs made of a sandwich of plywood - glued and screwed together. I used 2 by 2 as reinforcement. Originally they has a distributed port, but converting them to infinite baffle made little difference (they were also well and truly stuffed. With just 12 watt valve amplifiers these reproduced plucked double basses better than anything else I've had up until a fairly recent substantial upgrade.

But, 4 cubic feet is rather a big beast ...