LUXMAN CL-38

Commentary

This tube control amplifier is designed by making full use of the technology and know-how accumulated in semiconductor amplifiers.

In order to improve the quality of the product, only a line amplifier is used instead of a phono amplifier.

In order to respond to the latest digital sources and to bring out rich musicality, all signal amplification systems are composed of vacuum tubes. 6CG7 is used for the first stage and 12BH7A is used for the second stage.
By using a two stage configuration with a simple amplifier connected by a cathode and plate resistor and a condenser coupling, the feedback is reduced to less than 20 dB, which is about half of the normal level. This reduces the energy of the input signal and provides sound quality that is rich in damping and tight.

A semiconductor assisted power supply circuit is used for the power supply circuit.
The high-voltage side of the power supply is supplied by separating the L/R for the line amplifier and tone compensator from the large power transformer. A ripple filter is used without a large regulator, and decoupling is done in the first and second stages. This configuration minimizes the multi-stage decoupling of the tube type and avoids the phase disturbance caused by the extensive use of capacitors.
The relay is supplied from a separate 12 v power supply, and the heater power supply is also divided into the Route 3 and rectified separately, and a constant current circuit is set for each tube to eliminate mutual interference by design and to extend the life of the tube.
In addition, a regulator is placed on each board to eliminate loop and jump noise caused by the routing of the regulator out depending on the shortest distance from the circuit.

Ground design applying the latest amplifier technology and noise reduction measures are applied.
In the CL-38, two large-size chokes are inserted into the B circuit of the power supply to stabilize the voltage. In addition, noise is cut off by using many resistors to prevent changes in sound quality caused by capacitors. In addition, a shield plate is used as necessary to eliminate noise from the power supply and the outside as much as possible.
In addition, consideration is given to clarifying the earth potential, following the well-established concept of star circuits.

Input terminals for Line 5 and input / output terminals for recorder can be mounted. Switching is a relay switch type, and deterioration due to wiring routing and loss at contacts are suppressed.
In addition, relays are also used for switching switches for recording outputs and accessory circuits.

For tone control, a seesaw tone compensator is used instead of the usual type with high and low frequency booths, and the circuit configuration is NF type with 6CG7.
In the center position, it becomes a defeat state, but it can be bypassed by a line straight switch.

FRP is used for the base that supports the amplifier, and in addition, parts are firmly fixed by a large copper plated chassis of 1.6 mm thickness, resulting in a heavyweight housing structure.
This reduces vibration from the outside.

Fixed resistance change-over type 32-point ultimate attenuator is used for the volume.

Custom-made capacitors are used for all signal capacitors, and a large carbon film type is carefully selected for the resistor to enhance the integrity.
The substrate is a 70 μ m glass-epoxy type.

Equipped with a line phase sensor, the polarity of power supply can be checked.

Model Rating

Type	Tube type control amplifier
Input Sensitivity / Impedance	CD : 170mV/40k Ω Line1, 2, 3, 4 : 170mV/40k Ω Tape Monitor : 170mV/40k Ω
Output Level / Impedance	1 V (Maximum), 10 V (Maximum) / 2k Ω
Total harmonic distortion factor	0.12% or Less (1 V, 1 kHz)
Frequency characteristic	20 Hz to 100 kHz ± 1 dB
Signal-to-noise ratio	98 dB or More (IHF-A)
Attachment	Recording output ON/OFF switch Tape monitor Tone compensator Line phase sensor
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	47W
External dimensions	Width 438x Height 155x Depth 428 mm
Weight	18.0kg