Cube Audio F8 Neo Fullrange Driver
Cube Audio F8 Neo is the new 8″ flagship fullrange driver. Extremely powerful neodymium magnets based motor combined with 12 mm magnetic gap. The control of the speaker cone by the magnetic motor assembly is unheard of. You can expect even better controlled and bigger bass, and even more natural tonal balance. Ultimate 8″ fullrange driver is finally ready and available. Why and how do we do it? We believe that fullrange speakers can create an illusion of live music that multiway loudspeakers struggle to match. Amazing soundstage, absolute holography, magical midrange, open and direct sound that gives you the most emotional presentation possible of your favourite music. If you have ever heard a good implementation of the fullrange speaker, you know exactly what we are talking about.
We are very happy with the performance of Cube Audio 8″ drivers. Plenty of positive feedback from our happy customers, very enthusiastic reviews, but there still was this … “we should do more”. We knew that if we wanted to go into “even more fullrange regions”, we would have to increase the size of the driver. The answer was 10″ design, and it happened to be a very good choice. First of all, the size increase is meaningful enough so that it really makes a difference, but on the other hand, we had to overcome plenty of traps placed by mother nature. Physics is heartless and it really did everything it could to play with us “the hard way”.
The voice coil is completely underhung with +- 3 mm excursion in 100% magnetic field strength. Maximum excursion is +- 6 mm. Since the voice coil practically does not leave magnetic gap, with uniform field strength along all the gap height, the raw power, linearity and reduction of distortions are at their best. In order to maintain 0.01 mm tolerance of all elements, magnetic motor components are manufactured using computer controlled CNC lathes.
The full Neodymium magnet motor contains 81 magnets with a combined weight of 1480 grams and is capable of delivering 2.1 Tesla in the magnetic gap that is 12 mm high. The ultra-powerful motor and specially designed voice coil allow for unheard-of control of the cone.
Another unique solution is a lower suspension commonly called the “spider”. After listening to the prototypes with manifold, even most advanced spiders available for speaker manufacturers, we agreed that we had to develop our own solution. The issue with the spider is that by being a damper it dissipates the energy, that otherwise would be transferred into the speaker cone. It makes the speaker sound weak and dull, so we knew that it is an unacceptable way to go. We wanted a material that does not absorb energy and only transfers it.
After conducting many tests the solution was found and it turned out to be even better than we expected. It is 100 % linear within the maximum excursion of the speakers ( + – 6mm). It behaves like a spring. It does not consume the energy by damping, it just positions the voice coil in the magnetic gap. The downside of such technology is that each spider has to be milled with a precise CNC machine. Nevertheless, the advantages are obvious and totally worth it. In order to measure the actual compliance (amount of excursion under known force) of the suspensions, we designed and custom made the special device to do the measurements. You can see the graph with the measurement comparison of our suspension and classical (resin-soaked cloth) spider below.
Once we had the motor ready and capable to control heavier moving cones and suspensions mass, it was time to do the cones. Plenty of experience for experimenting with 8″ drivers came in handy. We knew where to start with. But that was basically it. 10″ is a completely different beast. For a very long time, we were not satisfied with the sound. There was a time where we didn’t have more bass than from 8″ driver which is basically pointless. Multiple times we had a prototype cone geometry that on measurements was absolutely linear and looking amazing to the point that studio monitor could be really envy, but the sound was dull and boring. Those times were very frustrating. Sometimes we thought that it is impossible to do a really amazingly sounding 10″ fullrange driver. But we never gave up and experimented more and more with even more drive every next day.
It was definitely worth it. The final design consists of 4 cones. One being the main cone and 3 whizzer cones. The smallest cone is responsible for the highest frequency range. With only one standard whizzer we never would never be able to go up to 18 kHz with a driver that in proper cabinet reaches 30 Hz region. So adding that little whizzer, solved one of the issues that we had. But there were plenty more of them. When you add a whizzer to the cone, there is additional interference between the cone and the whizzer. The mini high-frequency whizzer and the main whizzer got together really well and the sound was way better than without it. There was still a geometry issue present though. Its diameter, height, surface, geometry, stiffness, damping, coating all are a part of the final sound equation.
To achieve the right amount of sound pressure in the desired frequency region the most important of them all is geometry. There was one geometry that gave us amazing rich, colourful midrange, but on the other hand, it interfered with the main cone in such a way, that mods were pumping up mid frequencies. Since “shouty” vocals were not desired, we had to do something about it. Here’s where the third whizzer comes into play. That is a very elegant solution to change the interference mods of the whizzer and the cone. Due to changed geometry and distance, the amplitude of the modes decreased. As a result, the overall sound became sweeter, richer and more natural. At that moment we knew that this is the way to go.
Thiele / Small parameters
Fs = 39 Hz
Impedance = 10 ohms
Le = 0.008 mH
Qt = 0.36
Qes = 0.37
Qms = 21.7
Cms = 0.74 mm/N
Vas = 54 liters
Sd= 230 cm^2
Bl = 11.5 Tm
Xmax = +- 3 mm*
Xdamage = +- 6 mm
Sensitivity = 91 dB
* Voice coil remains in 100% of magnetic field.