Marantz - 4140 Solid state integrated amplifier

Marantz 4140 Quadradial - Fully restored collector's item
For sale: an exceptional Marantz 4140 integrated amplifier, a true legend from the "Silver Face" era.

Sold with its rare SQ decoder!
Marantz SQA1!

This device has undergone a complete and professional restoration aimed at surpassing its original performance while ensuring reliability for the next 30 years.

This is not a simple repair, but a complete audiophile refurbishment.

Technical details of the restoration (The components)
1. Capacitors (Total Recapping): All electrolytic capacitors have been replaced. The choice of brands is geared towards performance and musicality:

Power Supply: Major upgrade with 22,000µF Nippon Chemi-Con capacitors (huge capacity for exceptional dynamics and bass control).

Audio Circuit (Signal Path): Nichicon MUSE, FG (Fine Gold) and FW audiophile capacitors, renowned for their transparency and harmonic richness.

Power Supply and Decoupling: Panasonic FM and FC capacitors with very low impedance and long life.

Connections: WIMA film capacitors for surgical precision in high frequencies.

2. Transistors (Reliability and Low Noise): Obsessive attention has been paid to transistors to guarantee absolutely silent operation:

Noise reduction: Replacement of the transistors notorious for their noise and oxidation of their pins (2SC458, 2SA640, 2SC733) with modern, very low-noise equivalents Onsemi KSC1845 & KSA992.

Safety & Stability: Unstable transistors (2SC1451) and aging standards (2SC945) on the power boards have been proactively replaced with robust Onsemi models (KSC2690/KSC2383).
Replacing the relay with a modern, low-noise relay

Input stage: Differential pairs replaced by matched pairs transistors for perfect DC Offset (0V) stability.

3. Calibration & Maintenance:

Cleaning of potentiometers, switches and contacts (DeOxit).

Complete adjustment of Bias and DC Offset to factory specifications.

Aesthetic & Functional Condition
The amplifier is in superb overall condition. The brushed aluminum front panel is very clean and the iconic blue lighting is fully functional. Plug & Play.