LG21A The most reasonable finished product of the Baxandall 6N2 tube tone circuit: British Baxandall tube tone control circuit,
It has been published and used as early as in the monaural period. It uses a low-distortion tone circuit that works with negative frequency feedback. Although it is a negative feedback type tone control circuit, not all the tone control functions are performed by the β loop. It changes the frequency characteristics of the coupling part with V1, and works with the changes given by negative feedback to enhance or attenuate low and high frequencies.
The characteristic of this circuit is that the control range is very wide, and when both potentiometers are placed in the middle position, a flat response curve can be obtained. During control, the shape of the treble frequency response curve is almost unchanged, but it is translated along the frequency axis. Although the bass frequency response curve is not constant, its change is smaller than that of most continuously adjustable circuits. Baxandall type tone control circuit is the best tonal tone circuit, which is also widely used in professional stage audio equipment today.
Due to its unique working method, the tube device has the following advantages compared with discrete components and op amp tones as a tone circuit: high input impedance, large dynamic range, low thermal noise, good transient response, low distortion, good air sense, and circuit There are many advantages such as simplicity.
Double-sided epoxy board, imported metal film or domestic red robe resistor, Deweima capacitor frequency division, 500K double connected potentiometer woofer adjustment, Dutch 33μ450V filtering and decoupling, Deweima capacitor coupling, American Moroli cathode Electrolytic, high frequency ceramic socket. High voltage 250V DC power supply, filament 6.3V DC power supply. Board thickness is 2mm, board size: 115X115mm.
