DENON DL-305

Commentary

MC type cartridge using amorphous boron pipe.

A new material, amorphous boron pipe with a thickness of 0.025 mm is used for the cantilever.
Boron it is light, boron has an excellent specific rigidity (Young's modulus / density) and a melting point of 2,300 ℃, making it the most suitable element for cantilever materials. Amorphous boron is an amorphous state filled with small particles, and its fracture strength is approximately three to four times greater than that of crystal boron, which is an assembly of large crystals.
In order to use this material in the optimum condition, we have succeeded in forming ultra-thin pipes using our proprietary C. V. D. (Chemical Vapor Deposition) method, and have realized uniform and dense boron film surface.
This reduces the effective mass of the vibration system to 0.168 mg, minimizes the mechanical impedance in the high-frequency range, and enables faithful and accurate tracing with light needle pressure.

Solid diamond special elliptical needle has been adopted for the needle, achieving 0.01 mg or less.
The tip of the boron pipe that fixes the needle is tapered and installed in a precise rectangular hole made by laser beam processing.

The generator coil uses a rigid resin cross-shaped winding frame to lighten the entire vibration system and to achieve an optimum mass balance, eliminating the characteristic slack caused by split vibration. This winding frame method allows the coil to be wound symmetrically around the vibration system axis, and has the advantage of matching the characteristics of the left and right channels.

For the internal structure, rare-earth cobalt magnet and rational yoke structure are adopted in order to obtain a small size and strong magnetic field. In addition, the vibration system is supported by the one point support system proven in the DL-303 and DL-103 series, so that the coil can always be held in the center of the magnetic field, and the generation of strain in the power generation system is kept low.

Model Rating

Type	MC Type Cartridge
Output voltage	0.2 mv (1 khz, 5cm/s, horizontal direction)
Playback frequency range	20 Hz to 75 kHz
Output impedance	40 Ω (20 Hz ~ 20 kHz)
Applicable load	100 Ω or More (Transformer Approx. 40 Ω)
Channel separation	28 dB or More (1 kHz)
Channel balance	Within 1 dB (1 kHz)
Static Compliance	35x10-6cm/dyne
Dynamic Compliance	14x10-6Cm / dyne (100 Hz, record measurement)
Needle tip (tip)	0.05x0.1 mm Square Solid Diamond Special Elliptical Needle
Proper needle pressure	1.2 ± 0.2g
Dead weight	5.8g
Needle exchange	Body replacement (¥ 39,000)