Pre Amp Model CR With Receiver OldSchematic

The CR (Cathode Ray) model front-end amplifier with 12AX7, 12AU7, 6BD6, 6AL5 tubes and a 5MK9 rectifier is a classic design known for its combination of clarity, warmth, and dynamics preferred by many audiophiles. This design integrates both a preamplifier and radio receiver into a single unit, offering a complete audio solution.

Main Components:

• 12AX7 Tube: Acts as the preamplifier for the radio receiver’s audio signal.
• 12AU7 Tube: Functions as the driver stage to power the speakers.
• 6BD6 & 6AL5 Tubes: Work as detector and amplifier for the radio signals.
• 5MK9 Tube: Rectifies the AC voltage for the entire circuit.
• Output Transformer: Matches the impedance between the tubes and the speakers, delivering the audio signal efficiently.
• Speaker: Converts the electrical audio signal into audible sound waves.
• Radio Tuner: Selects the desired radio station.

How it Works:

1. Radio signals are captured by the antenna and processed by the tuner.
2. The processed radio signal is then fed to the detector and amplifier stage (6BD6 & 6AL5 tubes).
3. The extracted audio signal is then sent to the preamplifier (12AX7 tube).
4. The preamplifier boosts the audio signal and provides voltage gain.
5. The amplified audio signal is then directed to the driver stage (12AU7 tube).
6. The driver stage further increases the voltage of the audio signal to power the speakers.
7. The output transformer bridges the gap between the tubes and speakers, ensuring proper impedance matching.
8. The speakers translate the final audio signal back into audible sound.

Advantages:

• Sound Quality: The combination of 12AX7 & 12AU7 tubes delivers clear, warm, and dynamic sound.
• Functionality: Combines the functionalities of a preamplifier and radio receiver in one unit.
• Aesthetics: Offers a classic design that appeals to many enthusiasts.

Disadvantages:

• Cost: Tubes and other components can be more expensive compared to solid-state amplifiers.
• Size: Tube amplifiers are generally larger and heavier than their solid-state counterparts.
• Heat: Tubes generate heat, requiring proper ventilation for optimal performance.

The CR model front-end amplifier with its array of tubes provides an attractive combination of sound quality, functionality, and aesthetics for audiophiles. While it has some drawbacks, this classic design offers a unique and captivating audio experience for those who appreciate vintage audio equipment.