Hello Sir,
The drivers in our UniField Model Two Mk2 are both made by SEAS in Norway. This company builds "off the shelf" drivers for DIY and very small manufacturers that are not willing or able to design their own units. However, SEAS is very happy to build custom versions of these same drivers, depending on the use the customers will specify. Driver X-max (excursion potential) is important in factoring in power handling and how to "load" the driver in the cabinet. A sealed box, reflex box, transmission line labyrinth, and multiple-chamber damped box (like our Quasi-Transmission line design) will all have different power handling ratings, since the box will put a load on the driver at different frequencies. Most cabinet designs will attempt to help reproduce deep bass while also lowering distortion at high levels, but the results will vary to an amazing degree.
Simply stating X-max excursion in milimeters does not give you a real indication of what that particular driver will sound like at deep bass or mid bass frequencies, nor will it give you a total picture of SPL capability. This is a complex set of variables that no single number can describe.
For instance, a Butterworth bass reflex alignment can damp the driver's cone motion at the box tuning frequency, enabling higher SPL and increasing power handling; the reflex design also will result in powerful deep bass. However, many audiophiles consider a bass reflex design to have a thick, slow bass transient response, especially in the mid-bass range.
Include me in this group. I greatly prefer a highly damped cabinet that does not use box resonance to extend or fatten the bass. The big engineering disadvantage of a bass reflex design is that below the box tuning frequency, there IS no power handling. The driver is said to be "unloaded" by the cabinet, and massive distortion can take place with an input signal like synthesizer, record rumble, or any signal that can drive the woofer to very high excursions below the tuning frequency. In my opinion, a bass reflex design is a total disaster and only small cabinets with no bass power have to resort to this type of "bass boosting." Many small monitor speakers are built with this type of design, as the engineer/listening panelists at the company believe that "any" type of bass is preferable to a thin, weak sound that is midrange-prominent.
I ask you: does the UniField Model Two Mk2 have thick, slow, or distorted bass? Will the drivers bottom out when fed signals below 20Hz? Can you damage or burn out the woofer and midrange? Is the balance between bass-midrange-treble sound balanced?
Does the speaker sound good to you? The answer lies in how big your room is, along with your amplifier power. At any normal, sane level (excluding the reproduction of organ pipes or Metallica at stage volume levels), the UniField Model Two Mk2 will not bottom out or blow up.
WOOFER-MIDRANGE DESIGN SPEC:
We have encouraged SEAS to build a cone suspension that will not allow the voice coil bobbin to hit the rear of the magnet/back plate; at any volume level, you will not hear that type of metallic distortion caused by metal-on-metal collision.
Next, we ensured that they use the highest grade of wire and enamel covering, so that high power input does not burn up the voice coil.
Naturally, we use very high power handling crossover parts that will not burn out with 1,000-watts peak signal transient input, or 200 watts r.m.s.
Finally, the four chamber Quasi-Transmission Line bass loading cabinet design controls the cone motion at high volume levels. The extremely heavy cabinet, high damping (Q=0.6) and 100% stuffing density ensures that the bass is about as good as it gets for a speaker of this size, or perhaps even a larger cabinet that is not as well designed.
However, please note that two small 7" woofer/mid drivers cannot move as much air as dedicated woofers in a very large cabinet, so there is a limit to how loud the bass can shake your pants leg and your room. The bass sounds amazing, very deep, very tight, and very exciting. By reason of physics, however, any small cabinet is limited in volume level. It does sound far more powerful than other speakers of its size, though!
Happy Listening!
