Aurex HR-910
¥ 19,000 (around 1975)
Commentary
This is an electret condenser headphone with independent configuration of the main body and adapter.
Uses back electret (back electrode electret) system.
In this method, since the diaphragm and the electret are separated, the efficiency of the electret itself can be increased. Moreover, by making the diaphragm thin, the vibration mass can be sufficiently reduced.
In the HR-910, a newly developed high-voltage electret (a special polymer film bonded to a metal plate) is electrically connected to the diaphragm through a high resistance, realizing stable operation of the diaphragm.
The diaphragm is made of polyester film with evaporated aluminum and has a diameter of 51 mm, a thickness of 2.5 microns and a mass of 7 mg.
The matching impedance of the Adapter part is a 2-stage switching type, and the output can be taken from the speaker terminal of the amplifier and can be set to a through state.
The ear pad is removable and comes in 2 types, ear pad type and ear cover type.
Model Rating
Type | Electret condenser headphone |
Headphone Section | |
Drive system | Push-pull full face drive |
Capacitance | 60pF |
Diaphragm | 2.5 micron thick polyester film diameter 51 mm Metal (aluminum) double-sided deposition |
Frequency characteristic | 20 Hz to 35 kHz |
Output sound pressure level | 93dB/3V (H position) |
Maximum sound pressure level | 115dB |
Harmonic distortion factor | 0.5% (at 400 Hz standard input) |
Ear pad pressure | 250g (Ear Spacing 150 mm) |
Code | Copper foil with stereo plug 4-core bagging 2m |
Weight | 240g (cord not included) |
<Adapter part> | |
Format | Input impedance switching type |
Input impedance | 8 Ω (Low), 1k Ω (High), Speaker, Direct |
Code | 1.3m, curl cord |
External dimensions | 88 mm wide x 22 mm high x 151 mm deep |
Weight | 480g |
Attachment | Carrying case |