An Unconventional Loudspeaker system Latest change 2019-01-22
For details about the Electrostatic
devices see the links on the left.
The Tweeter unit seen from the bottom side.
The ESL modules are kept in place by 'J' shaped aluminium
profiles and foam strips with glue on one side. (the type you
can buy as weather-strip)
Note the three holes for the pillars. A short piece of 8 mm
aluminium tube has been glued in the holes. The studs are made
of 8 mm alu-tube, which define the height of the tweeter above
the midrange unit, and a 2 cm longer 6 mm diameter tube which
fits in these holes. The two studs in the front carry the
cables for mains voltage and tweeter signal.
Inside the Tweeter compartment.
For the photo the rockwool damping material has been removed.
It can be seen that the housing is built from a
number of ring-shaped plates of MDF, glued together.
Left the step-up transformer, right the High
Voltage PCB. Normally both are covered with an insulating
Note the insulation strips near the connections, and the extra
free space where the electrical connections to the ESL modules
are made. We deal here with voltages far over 5 kV, and we
should not regard MDF as a good insulator at these voltages.
Note the electrolytic capacitor 1000u/63V near the
transformer. It blocks possible DC from the amplifier. The DC
resistance of the transformer's primary is only 70 milli-Ohm,
so the slightest offset voltage will create currents of
Amperes. It should once be replaced by a non-polarized type,
although the signal voltage across the capacitor is only a few
hundred milliVolts (XC @ 1 kHz = 0.16 Ohm-cap).
The High Voltage Board.
Produces around 5000 Volts for the membrane of
Note that these capacitors are rated 250 V. To my opinion that
should be 500 V at least.
The diodes are 1N4007, which can withstand 1000 Volt.