Koss esp 9 owners manual

Page 1

Fig. 1 Model ESP-9 Studio Monitor
Stereophones with E-9 self-energizer.

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ESP-9 Electrostatic Stereophones*are a new development
employing the principle of a currentless, or electrostatic
charge on push-pull condenser plates to cause movement
of an intervening, light, conductive diaphragm. The dia-
phragm will move in conformance to the signal energy from
an amplifier to produce wide frequency response range with
low distortion.

The ESP-9 has a response range of 10 octaves, the widest
ever attained in a headset. A new cup design promotes
virtually linear response to below 20 Hz.

The ESP-9 has a signal handling capacity of 10 volts at
30 Hz with good wave form versus 6 volts for the ESP-6.
This is made possible by increasing the size of the coupling
transformers by a factor of 4, and mounting them externally
to the cup in the ES Energizer.

The ES) Energizer offers the option of self-energizing for
the bias supply, or energizing through the ac line. Choice is
made with a selector switch on the front panel. When
energized through the ac line, very precise level measure-
ments can be made. Thus the unit is ideal for audiometry
and for evaluating the spectral character of very low level
noise in equipment like tape mastering machines and record-
ing consoles. In contrast to the ESP-6 and ESP-7, both cups
are independently energized; a left cup signal is not re-
quired to supply bias to the right cup.

Page 2

Electrical Description. The usual speaker impedance is lowest in the midrange of frequencies. At the
extremes of the range, the impedance will increase 10 to 20 times or more. With electrostatic devices,
the highest impedance is in the middle of the range, with the lowest impedances at the extremes.
For these reasons it is appropriate to quote, not the internal impedance of the speaker or headphone,
but the impedance of the source into which it is designed to operate. Therefore, in the specifications
to follow, attention is called to the source impedance.

The self~energizing power source consists of a voltage tripler, the maximum voltage of which is
controlled by a zener diode circuit across the internal high impedance circuitry. Because of the long
time constants employed, the wattless drain of the power source has no perceivable effect on
the signal.

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10

SOLID LINE - ESP-9 INPUT IMPEDANCE IN OHMS
S

DASHED LINE - CONE SPEAKER INPUT IMPEDANCE IN OHMS

FREQUENCY IN CYCLES p50?! SECOND

Fig. 2 Solid line represents impedance characteristic of.ESP-9 Stereophones. Dashed line
shows impedance characteristic of a high quality speaker for comparison. (Courtesy Klipsch
and Associates.)