Sibling rivalry. Before we learn how the Z1 differs from it, let's recap B-01 tech. Its ribbon tweeter takes advantage of a UK-sourced foil which bonds an aluminium layer to a nylon-aramid substrate for 600C° thermal stability and 1/100th of a gram of moving mass. This spreads across the surface area of three typical dome tweeters. Combining such a light membrane with an ultra-strong N52 super-neodymium motor nets high 96dB sensitivity. Impedance without step-up transformer is a happy 6Ω. Without stick-slip inertia that would require a minimum input current to overcome, there's instantaneous response without lag or energy storage, so zero resonance.
Circular recesses on the bottom are for Ansuz Darkz roller-ball isolators between the B-01 and its stand. The stand too takes four between it and the floor. Front and rear baffles angle back.
Operated as a dipole, the ribbon's rear wave exits through the triangular vents in the upper cheeks which continue as flared channels set into the cab in solid Walnut. That crafty detail, the rear-slimming cross section for curved side walls and a concave spine all conspire to the B-01's high cabinet cost.
The B-01's mid/woofer exploits non-woven carbon fiber from Toray of Japan which weighs all of 22g/m². As they do in Formula One race-car wings, two very thin skins of this composite graft to a Nomex honey-comb core.
That nets a moving mass of just 5g, 8 grams lighter than Michael's previous Raidho driver yet strong enough to be stepped on. It's an exceptionally well-ventilated transducer for minimal air turbulence and reflections. It gets its own N52 motor (N52 is the currently highest-grade neodymium) with solid copper pole pieces. Losing iron reduces inductance to 0.04mH, an order of magnitude lower than conventional drivers.
One benefit is that the first port impedance peak occurs at 13Ω, the second at 11Ω. Now the amplifier delivers far more current into low frequencies than it does into the typical impedance curve of a ported speaker whose first peak could be 50Ω or higher.
Such resistance extremes burn up power and lower control for typical room boom. The Børresen 01 is far easier to place. Room interaction through its port is much reduced.
The second benefit of low inductance is that the driver accelerates faster to keep up with the ribbon tweeter.
"Instead of using iron to conduct our magnetic flux, we squeeze it together with two south magnets on the outside and two north magnets on the inside which short-circuit themselves and produce 1.1 Tesla in the gap.
"In an iron motor, just 1/10th of a millimeter of added copper reduces sensitivity so only very little can be used. Meanwhile our design gets to exploit thick sold inner and outer copper rings which remove nonlinear voice-coil behavior on the in/out strokes, hence lower our dynamic distortion which is very hard to measure but easy to hear.
"Copper also makes for an exceptional thermal conductor to dissipate heat and its reluctance to magnetic change helps keep our inductance low."
For the same reason, the voice-coil former is titanium not aluminium to avoid the breaking effect of hysteresis as the phenomenon in which the value of a physical property lags behind changes in the effect that cause it, as for instance when magnetic induction lags behind the magnetizing force.
