YAMAHA GF-1

Commentary

This active speaker system was developed purely based on the factors of sound and music, and was developed to pursue ideal sound without compromise.

The GF-1 has a 3-way configuration consisting of a YST-type subwoofer and three multi-channel amplifiers, which is rare even for commercially available speakers.
By adopting such a configuration, we are able to develop a better speaker by eliminating the limitations that cannot be separated from conventional speaker designs.

It is equipped with a cone type unit of 27 cm in the middle and low range and 30 cm in the low range.
The cone part uses crystalline polyamide fiber Kevlar (KEVLAR #149). Since the Kevlar is organic high elasticity fiber, compared to other hard diaphragm materials, it has less metallic sound image. Compared to paper, it is light, resilient, and has good S/N feeling.

It has a dome-shaped unit of 8.8 cm in the middle range and 3 cm in the high range.
Each diaphragm is made of cast beryllium, a light, strong diaphragm with a high upper limit frequency (resonance point) developed by Yamaha. This cast beryllium has two times the tensile strength and ten times the elongation compared to evaporated beryllium. The gap between crystals is one thousandth of that of evaporated beryllium (vacuum test method), and the purity is 99.9%.
In the middle and high frequency units, the diaphragm is relatively large for smooth sound connection with the low frequency. However, the high frequency characteristics are extended by reducing the weight of the voice coil and coil inductance.

Pure gold is deposited on the surface of the diaphragm of each unit in order to further adjust the sound quality.
As a result, the medium - and high-frequency units are able to dump the slight residual beryllium noise due to the stickiness of gold, and achieve a sound without turbidity and corrosion resistance.
Gold is deposited not only on the beryllium diaphragm but also on the Kevlar cone to adjust the sound quality and to unify the sound quality of the unit.

The magnetic circuit uses columnar crystal Alnico, which is selected from three types of magnets : Alnico, wet strontium (Sr) ferrite, and neodymium for its comparative listening and characteristics.
Alnico has a magnetic flux density approximately three times that of neodymium and six times that of ferrite, so it realizes a magnet shape that does not interfere with diaphragm movement.

Each unit is designed to play not only its own band but also the widest possible range of frequencies, so that light and extended bass playback can be achieved.
For this reason, the diaphragm is lightweight and curved cone, the voice coil diameter is as small as possible, and beryllium cap is used to extend it to the high frequency range with good response.
In particular, the voice coil has been greatly reduced in weight by making it a short type, and the weight has been reduced to about 1/5 of the conventional one.
In the frame design, attention is paid to the rear acoustic stiffness. The rear acoustic stiffness is minimized by increasing the inner diameter of the magnet and opening an air vent in the frame.

To achieve rich, high-quality bass playback, the subwoofer uses Yamaha Active Servo Technology (YST). As a result, the GF-1 achieves 25 Hz (-5dB) bass playback at a 30-cm unit, while the GF-1 achieves a range of 60 Hz or less, while the normal range of 38 cm or more is required.
In the YST realizes an air woofer in which the air inside the port functions as a diaphragm. This improves the reproducibility of sound field perception and sound image localization.

The division of each channel uses a multi-channel amplifier method instead of the conventional network method, which eliminates various restrictions imposed by the LC network.
Each multi-channel amplifier has an output power of 125W, and each speaker has four channels for a high power of 500W. In addition, all components from the superwoofer to the tweeter are integrated into the same circuit and part for sound unification. The design is thorough to every detail.
Each channel filter parameter is set to an optimum value, and the level of each unit can be adjusted within ± 2.5 dB in 0.5 dB steps.

The input jacks include a line-level Canon jack and a power-amp-level speaker jack.

The concept of volume factor (VF) is introduced in the design of the enclosure, and the optimal VF value is determined by comparing and listening to various enclosure sizes.
By increasing the VF value, the internal sound pressure of the enclosure is lowered, acoustic stiffness and viscous resistance can be minimized, flexibility in unit design is increased, and the merits of the speaker unit are brought out.

The enclosure is made of American Hard Maple for its strength and beautiful sound.
The baffle surface is a laminate core type with 3 sheets of maple laminated, and the other surface is a lumber core type with vertically bonded, American walnut is attached to both sides and American walnut is attached to both sides, and the exterior surface is finished with urethane open pore finish.
The plate thickness is 28 mm on all surfaces, and the baffle surface is fixed.

In addition to the standard walnut urethane open-pore finish, there was also a special specification that used Saperi urethane and layer finish for exterior material, which is a wood of West Africa characterized by dark brown color and beautiful stripes and used as a decorative material for luxury furniture and pianos.

Model Rating

Method	Multi-Amp Drive / 4-Way / 4-Speaker YST System / Floor Type / Magnetic Protection Design
Units Used	For low band : 30 cm cone type For middle and low band : 27 cm cone type For Middle Area : 8.8 cm Dome Type For high-pass : 3.0 cm dome type
Port diameter	10.0cmx2
Playback frequency band	25 Hz to 35 kHz -5dB
Output sound pressure level (unit only)	Tweeter, Subwoofer : 94 dB Skoka, mid-woofer : 95 dB
Crossover frequency	60 Hz, 600 Hz, 4 kHz (+ 12dB/oct, -18dB/oct)
Rated output	Total : 500W/ch (125Wx4, 5 Ω, Strain 0.005%)
Input sensitivity	Line level (Canon terminal) : 2 V Power amplifier level : 20 v
Internal volume	332L
Output level adjustment	± 2.5 dB, 0.5 dB step
Power consumption	Rating : 360W No signal : 120W
Maximum external dimensions	Body : Width 710x Height 1400x Depth 630 mm Power Supply : 650 mm W x 175 mm H x 180 mm D
Weight	Body : 150 kg (3-way Part : 70 kg, Subwoofer : 80 kg) Power supply : 25 kg