Tube Preamplifier with ECC88

Description: A very good circuit of pre-preamplifier for amplification of signals from heads of Moving Coil. It uses the two departments of tube ECC88, association parallel, for reduction of produced noise. The circuit enters in line with existing circuit PHONO. Switches S1-2 make adaptation of entry in the impedance, of expense of head. The Positive is been careful power supply, that is completely stabilised.

The described pre-preamplifier circuit is designed specifically for the amplification of signals originating from Moving Coil (MC) cartridge heads. The circuit utilizes two ECC88 (6DJ8) vacuum tubes configured in a parallel arrangement, which effectively reduces noise and enhances the overall signal quality. This configuration is particularly beneficial for low-level audio signals, as it provides improved gain while maintaining a low noise floor.

The input stage of the pre-preamplifier is equipped with two DIL switches (S1-2) that allow for impedance matching to accommodate various cartridge outputs. This feature is crucial for optimizing the performance of the pre-preamplifier based on the specific characteristics of the connected MC cartridge. The impedance adjustment ensures that the signal integrity is preserved, allowing for a more accurate and faithful reproduction of audio signals.

The power supply section of the circuit is designed to be highly stable, providing a consistent and clean DC voltage to the vacuum tubes. This is essential for the reliable operation of the ECC88 tubes, as any fluctuations in power supply can adversely affect the performance of the amplifier. The circuit employs a combination of resistors, capacitors, and zener diodes to achieve the desired voltage regulation and filtering.

The component list indicates a variety of passive and active components used throughout the circuit. Resistors (R1-R14) are specified with precise values and tolerances, ensuring accurate signal processing. Capacitors (C1-C13) are selected for their voltage ratings and capacitance values, which are critical for coupling and decoupling applications within the circuit. The inclusion of diodes (D1-D8) provides necessary protection against reverse polarity and voltage spikes, while transistors (Q1-Q3) and operational amplifiers (IC1-IC2) are incorporated to enhance signal processing capabilities.

Overall, this pre-preamplifier circuit is a well-designed solution for audiophiles seeking to maximize the performance of their Moving Coil cartridge systems. The careful selection of components, along with the thoughtful design of the circuit topology, ensures high fidelity audio reproduction with minimal noise interference. A very good circuit of pre-preamplifier, for amplification of signals from heads of Moving Coil. It uses the two departments of tube ECC88, association parallel, for reduction of produced noise. The circuit enters in line with existing circuit PHONO. Switches S1-2 make adaptation of entry in the impedance, of expense of head. The Positive is been careful power supply, that is completely stabilised. Part List R1-5= 100ohm 1% 1/4W R9...12= 47Kohm 2W S1-2= DIL Switch R2-6= 150ohm 1% 1/4W R13-14=1Mohm 1% 1/4W J1...4= RCA Jack R3-7= 33ohm 1% 1/4W C1-2= 1uF 250V MKT R4-8= 12ohm 1% 1/4W V1-2= ECC88 - 6DJ8 Part List R1= 180Kohm C2-4= 300uF 250V D4= 24V 0.5W zener R2= 33Kohm C3= 100nF 400V MKT D5-6-7= 1N4148 R3= 27Kohm C7= 1uF 100V MKT Q1-3= TIP122C R4= 8.2Kohm C8= 2.2uF 63V MKT Q2= BD340 [MJE340] R5= 56ohm 2W C9= 22uF 100V IC1= TL071-TL081 R6= 3.3Kohm 2W C10-11-15-17= 10uF 63V IC2= LM317 R7= 18Kohm C12= 100uF 25V TR1= 4.7Kohm trimmer R8= 100Kohm C13= 4700uF 25V GR1= 400V 1A R9= 120ohm D1-2-8= 1N4007 GR2= 80V 3A C1-5-6-14-16= 100nF 250V MKT D3= 30V 0.5W zener T1=230VAC//A=100V@ B=8V/2A