Specifications

Mid-Range Panel Design

Do not attempt to disassemble these panels. The steel frame is preventing the

panel from collapsing on itself. Removal of the cap screws that hold the panel

together will surely cause damage to the diaphragm and may pinch hands and

fingers.

The mid-range panel design (shape and size) was chosen for good dispersion

and bandwidth.

For a given speaker design, there is a direct trade off between maximum sound

pressure level, bandwidth and efficiency. In the LFT-8b, the mid-range panel

is usable from 100 Hz to 15 kHz. However, there are problems if you use the

panel over its full frequency range.

At the upper frequency limit, the panel will beam because the wavelength

becomes much shorter than the panel is wide. This is also the reason the

speaker sounds best within the vertical axis of the mid-range panel.

At the lower limit, the panels free air resonance is 90 Hz. This resonance is

damped almost 100% with felt on the back magnet channel assembly. Around

100 Hz at high sound pressure levels, the excursion limit of the diaphragm will

be exceeded and it will slap against the magnet channel. A crossover point of

180 Hz is chosen to achieve a good maximum sound pressure level and still

have the mid-range panel play vocal fundamentals and mid bass which is

desirable for a good blend with the woofer. Since the lower crossover

frequency is 6 dB per octave, the panel still has substantial output below 100

Hz.

Technical

information