DENON AU-340

Commentary

A step-up transformer designed to reduce low-frequency distortion in a wide band while taking into consideration the tendency of MC cartridges designed to have a wide band of frequency characteristics.

In order to obtain linear and excellent characteristics, the step-up transformer is divided into two coils, and a sandwich wound structure with balanced division of the primary and secondary coils is adopted. This reduces the leakage inductance and distribution capacity and improves the high-frequency characteristics. In addition, a large inductance is adopted to improve the low-frequency characteristics and distortion factor, and the characteristics in the band are designed to be flat.

Equipped with 3-stage switching function of 3 Ω, 40 Ω and PASS.
In general, frequency characteristics deteriorate when multiple taps are taken out from the same winding, but in the AU-340, good characteristics are secured for each tap by effectively connecting two types of coils on the primary side.

The core material is carefully selected Super Permalloy 0.2 mm thin plate with special heat treatment for low level use and laminated in many layers.
Since this Super Permalloy is extremely delicate, a double cushion material is placed between the transformer and shield case to float it so that the magnetic properties are not damaged by mechanical shock from the outside.

In order to block external noise, a permalloy multiple shield is used for each of the left and right transformers.

Main parts such as boards and switches are also shielded with silicon steel sheets to reduce noise.

Equipped with two input switching functions.

Uses a lightweight push switch that fully takes into account contact resistance.

Uses gold-plated input / output terminals.

High-grade pin plug of low resistance, low capacity, gold plated terminal is included.

Model Rating

Type	MC booster transformer
Boost ratio	1 : 10 (40 Ω) 1 : 33 (3 Ω)
Primary impedance	40 Ω, 3 Ω
Secondary impedance	4k Ω
Frequency characteristic	10 Hz ~ 120 kHz + 0.5 -1.0 dB
Distortion factor	0.05% (20 Hz ~ 20 kHz, 4 Ω Terminal) Measurement conditions : input 1 mv, secondary side load capacity 100 pf, load resistance 50k Ω
Channel balance	0.5 dB or less
External dimensions	Width 155x Height 70x Depth 215 mm
Weight	2.1kg
Attachment : Output code
Length	1m
Capacitance	55pF/m
Core wire resistance	0.055 Ω / m