The Harman Kardon Citation I is a classic vacuum tube pre-amplifier known for its smooth, musical sound and excellent phono performance. I serviced this pre-amp for a customer as part of a reliability and preventative maintenance restoration. The goal was preserving its original character while ensuring long-term dependable operation.
Work Performed
- Capacitor Replacement
All capacitors known to be prone to failure were replaced. Aging capacitors are one of the most common causes of noise, drift, and instability in vintage tube equipment, so this step is critical for both performance and reliability. - Power Supply Rebuild
The main electrolytic filter capacitors in the power supply were replaced. This reduces hum, improves voltage stability, and ensures the preamp operates cleanly under load. - Rectifier Diode Upgrade
The original top-hat rectifier diodes were replaced with modern, reliable equivalents. This improves power supply robustness and reduces the likelihood of sudden failure from aging semiconductor components. - AC Line Safety Improvements
Proper AC line-rated RF filter capacitors were installed. These components help suppress line noise while improving safety compared to original parts that may no longer meet modern standards. - Inrush Current Limiter Added
I added an inrush current limiter was added to reduce stress on the power switch, transformer, and filter capacitors at startup. This simple addition significantly extends component life. - Control and Switch Cleaning
All controls and selector switches were thoroughly cleaned to eliminate noise, dropouts, and intermittent operation. - Functional Testing
All inputs were tested and verified for proper operation to ensure full functionality across the preamp’s features.
Results
After restoration, the Citation I is operating quietly and reliably, with stable power delivery and smooth control operation. This work reflects the type of service I provide—focused on reliability, proper component selection, and preserving the original performance of classic audio equipment.
