Crossover network for a multi-element electrostatic loudspeaker system

Claim 2

In an electrostatic speaker system having a pair of input terminals connectable to receive an audio signal from an audio amplifier, the combination comprising: an electrostatic driver having a pair of terminals connected to a respective pair of fixed plates which present a relatively fixed, highly capacitive impedance across said terminals; a step-up transformer having a primary winding connected in a series branch across said speaker input terminals to receive said audio signal, and a secondary winding magnetically coupled to said primary winding and electrically connected to the input terminals of said electrostatic driver to form a parallel resonant circuit therewith, the inductance of said secondary winding being selected such that the parallel resonant circuit it tuned to a selected audio frequency, and an impedance device connected in said series branch to voltage divide the audio signal with the primary winding of said step-up transformer. wherein the impedance of the primary winding of said step-up transformer increases substantially for a range of frequencies about said tuned audio frequency with the result that a majority of the audio signal within said frequency range is applied to said electrostatic driver and a majority of the audio signal outside said frequency range is applied to said impedance device.

Claim 3

The electrostatic speaker system as recited in claim 1 in which said impedance device is a resistor having a value which is substantially less than the maximum impedance of said primary winding.

Claim 4

The electrostatic speaker system as recited in claim 1 in which said impedance device is the primary winding of a second step-up transformer having a secondary winding which connects to a second electrostatic driver to form a parallel resonant circuit which is tuned to a frequency outside said frequency range.

Claim 5

An electrostatic speaker system for reproducing an audio signal generated at a pair of output terminals on an audio amplifier, the combination comprising: a first electrostatic driver having a pair of plates connectable to receive an audio signal, said first electrostatic driver being designed to operate over a first preselected audio frequency range; a second electrostatic driver having a pair of plates connectable to receive an audio signal, said second electrostatic driver being designed to operate over a second preselected audio frequency range; a first step-up transformer having a primary winding coupled to one of said audio amplifier output terminals to receive said audio signal which has frequencies in both of said preselected audio frequency ranges, and a secondary winding connected to the plates of said first electrostatic driver to form a first parallel resonant circuit which is tuned to a frequency in said first preselected audio frequency range; and a second step-up transformer having a primary winding connected in series with the primary winding of said first step-up transformer and coupled to the other of said output terminals on said audio amplifier to receive said audio signal having frequencies in both of said preselected audio frequency ranges, and a secondary winding connected to the plates of said second electrostatic driver to form a second parallel resonant circuit which is tuned to a frequency in said second preselected audio frequency range.

Claim 6

An electrostatic speaker system for reproducing an audio signal generated at a pair of output terminals on an audio amplifier, the combination comprising: a first electrostatic driver having a pair of plates connectable to receive an audio signal, said first electrostatic driver being designed to operate over a first preselected audio frequency range; a second electrostatic driver having a pair of plates connectable to receive an audio signal, said second electrostatic driver being designed to operate over a second preselected audio frequency range; a first step-up transformer having a primary winding coupled to one of said audio amplifier output terminals to receive said audio signal which has frequencies in both of said preselected audio frequency ranges, and a secondary winding connected to the plates of said first electrostatic driver to form a first parallel resonant circuit which is tuned to a frequency in said first preselected audio frequency range; and a second step-up transformer having a primary winding connected in series with the primary winding of said first step-up transformer and coupled to the other of said output terminals on said audio amplifier to receive said audio signal having frequencies in both of said preselected audio frequency ranges, and a secondary winding connected to the plates of said second electrostatic driver to form a second parallel resonant circuit which is tuned to a frequency in said second preselected audio frequency range.

Claim 7

The electrostatic speaker system as recited in claim 4 wherein a first impedance device is connected in series with the primary winding of said first step-up transformer and the primary winding of said second step-up transformer.

Claim 8

A four-way electrostatic speaker system, the combination comprising: a bass unit having a bass electrostatic driver connected to the secondary winding of a bass step-up transformer to form a parallel resonant circuit therewith which is tuned to a first audio frequency; a mid-bass unit having a mid-bass electrostatic driver connected to the secondary winding of a mid-bass step-up transformer to form a parallel resonant circuit therewith which is tuned to a second audio frequency higher than said first audio frequency; a treble unit having a treble electrostatic driver connected to the secondary winding of a treble step-up transformer to form a parallel resonant circuit therewith which is tuned to a third audio frequency higher than said second audio frequency; and a tweeter unit having a tweeter electrostatic driver connected to the secondary winding of a tweeter step-up transformer to form a parallel resonant circuit therewith which is tuned to a fourth audio frequency higher than said third audio frequency; wherein a primary winding on said bass step-up transformer is connected in series with a primary winding on said treble step-up transformer to form a first series branch, and a primary winding on said mid-bass step-up transformer is connected in series with a primary winding on said tweeter step-up transformer to form a second series branch.

Claim 9

A four-way electrostatic speaker system, the combination comprising: a bass unit having a bass electrostatic driver connected to the secondary winding of a bass step-up transformer to form a parallel resonant circuit therewith which is tuned to a first audio frequency; a mid-bass unit having a mid-bass electrostatic driver connected to the secondary winding of a mid-bass step-up transformer to form a parallel resonant circuit therewith which is tuned to a second audio frequency higher than said first audio frequency; a treble unit having a treble electrostatic driver connected to the secondary winding of a treble step-up transformer to form a parallel resonant circuit therewith which is tuned to a third audio frequency higher than said second audio frequency; and a tweeter unit having a tweeter electrostatic driver connected to the secondary winding of a tweeter step-up transformer to form a parallel resonant circuit therewith which is tuned to a fourth audio frequency higher than said third audio frequency; wherein a primary winding on said bass step-up transformer is connected in series with a primary winding on said treble step-up transformer to form a first series branch, and a primary winding on said mid-bass step-up transformer is connected in series with a primary winding on said tweeter step-up transformer to form a second series branch.

Claim 10

The four-way electrostatic speaker system as recited in claim 6 in which an impedance device is connected in series with each of said series branches.