Lo-D H-70HD

Commentary

Horn type tweeter unit developed as a high-range drive unit of HS-500.

The H-70HD was produced by cutting aluminum round bars one by one.
As a result, a two degree-of-freedom system with a special acoustic circuit in the relation between the diaphragm, horn and air chamber can be adopted, and flat characteristics with a deviation width of 6.5 dB up to 20 kHz can be realized.

In horn speakers, non-linear distortion occurs due to non-linearity of air caused by asymmetry of diaphragm clamp and excessive sound pressure at horn throat.
In the H-70HD, machining accuracy is improved to improve the asymmetry of the diaphragm clamp. In addition, in order to make the clamp strong and stable, a special resin plate is adopted for the lower part of the diaphragm. In addition, a duralumin spacer is used to secure the gap of 0.3 mm in the air chamber.
Air nonlinearity caused by excessive sound pressure at the horn throat is dealt with by designing the ratio of the horn throat area to the diaphragm area, the distortion factor in the case of resistance control and mass control, the horn length, etc. so that the distortion factor due to overload is 1% or less at more than twice the cutoff frequency when the output sound pressure level is 100 dB (input 0.1W).

High-purity Mylar is used for the diaphragm in consideration of lightness and durability to high temperature and humidity.
The diaphragm dome has a diameter of 14 mm φ and uses a special lightweight wire for the voice coil to reduce the weight of the vibration system.

The H-70HD is equipped with a V-shaped acoustic lens to improve the sharp directivity of horn speakers. The acoustic lens is designed to have an entrance / exit ratio of 10 : 7 and a thickness of 15 mm to achieve an excellent diffusion effect.
When an acoustic lens is attached, directivity improvement of 6 by 6 dB at 10 kHz.

Model Rating

Type	Horn type tweeter
Outer Diameter	7.3cm
Aperture diameter	6.9cm 7.0 cm (listed in separate catalog)
Baffle hole	7.4cm
Voice Coil Diameter	1.4cm
Rated input	20W (with designated network)
Output sound pressure level	104dB/W/m
Voice coil impedance	8 Ω
Playback frequency band	2 kHz to 20 kHz
Cutoff frequency	1.5kHz
fo	2.3kHz
Crossover frequency	3 kHz or more
Total flux	101,000maxwell
Magnetic flux density	11,300gauss
Depth	15.9 cm (17 cm with Acoustic Lens)
Weight	1.7 kg (With Acoustic Lens Mounting Frame 2.1 kg)
Attachment	Mounting frame Acoustic lens