LUXKIT A3400

Commentary

Vacuum tube type control amplifier kit.

The equalizer circuit uses the K-K ・ NF type, which is close to the Marantz type, and was newly developed after ascertaining the characteristics of the Marantz Model7 and Macintosh C-22 circuits. In this A3400 circuit, the cathode resistance of the third stage is divided into 33k Ω and 3.3k Ω to prevent the amount of NF in the ultra-high band from becoming unnecessarily large. In addition, by locally applying NF from the third stage cathode to the first stage plate, the bare characteristics before the major NF is applied are improved, and the strain rate characteristics are improved.

The intermediate amplifier is a 3-pole tube 2-stage configuration. In order to suppress the gain of the A3400 and not to worsen the distortion at high output, we have adopted a B-type balancer (insertion loss is approximately -8dB) to provide an appropriate overall gain. This is because in order to achieve a low gain at the 2-stage configuration, the high feedback type inevitably reduces the negative feedback resistance, so this resistance becomes the second stage plate load and prevents the distortion at high output from worsening.
By installing a linear equalizer in this stage and switching the feedback element, frequency characteristics with a linear slope can be obtained over the whole band.

The tone control circuit uses the Lux-NF type.
Since a print switch is used for adjusting the low and high sound levels, flat characteristics are improved and stable control is possible.
This circuit is also capable of defeat.

The output circuit uses a cathode follower to keep the output impedance low.
This stage is equipped with a filter that can switch the cut-off frequency in two stages for both high and low frequencies. This is an NF type filter using a cathode follower, and it is a genuine filter that cuts at a slope of -12dB per octave.

Model Rating

Type	Tube type control amplifier kit
Output voltage	Rating : 2 V (output level + 6 dB position) Maximum : 15 v (0.3% strain rate)
Output impedance	550 Ω
Total harmonic distortion factor	0.06% or Less (Output 2 V, 55 Hz to 10 kHz)
Frequency characteristic	15 Hz to 35 kHz -1dB
Input sensitivity	Phono1 : 2 mv, 4 mv, 10 mv (switching type) Phono2:2mV Mic:2.2mV Aux1:170mV Tuner, Aux2 : 170 mV (with level set)
Input impedance	Phono1, 2 : 100k Ω, 50k Ω, 20k Ω Aux1 : 150k Ω Tuner, Aux2 : 100k Ω Mic : 50k Ω
Signal-to-noise ratio	Phono1, 2 : 64 dB Mic:66dB Tuner, Aux1, 2 : 77 dB
Tone control	LUX System NF Type with Bending Point Switching Low-pass curve point : 100 Hz, 250 Hz, 500 Hz High-frequency bending point : 2 kHz, 4 kHz, 8 kHz
Filter	Low-cut : 15 Hz, 80 Hz (-12dB/oct.) High Cut : 12 kHz, 7 kHz (-12dB/oct.)
Attachment	Linear equalizer (up tilt 2 stages, flat position, down tilt 2 stages) Microphone amplifier Headphone amplifier Phono Input Sensitivity Switching Output level switching
Vacuum tube used	12AX7x6 12AU7x1
Semiconductor used	RA1Bx4 M4E1x1 1S-1850x1 1S-1850Rx1 S1R60x2 2SF657x1 N13T1x1 2SA493x3 2SC1000x4 2SA562x2 2SC735x4 KB265x2
External dimensions	Width 435x Height 165x Depth 300 mm
Weight	9kg
Sold Separately	Assembly Manual (¥ 3,000)