Vintage Hi-Fi Audio Restorations: C. Nettles Marantz 4300 Quadradial Receiver

Marantz 4300 Quadradial Receiver

The Marantz 4300 was a impressively built 40W/100W Stereo+Quadradial receiver manufactured from 1972 to 1978 (est.) and encompassing the proprietary "Vari-Matrix" which allows for two to four channel emulation and output. (Customer purchased a Black Replica Faceplate for unit shown in both original Silver and Black)

P800 Regulated PS

The 4300 PS is designed quite a bit differently than the lower series 42XX quads, with a regulated 35V and 14Vdc output with two full wave rectifiers.

Uniquely Marantz mounted C803 on the P800 to the chassis as a large axial 1000MFD component, as I always try to avoid any axial capacitor this was replaced by a high temp (105C) low impedance PW capacitors 1000MFD on the actual footprint of the PCB removing long runs of wire an unnecessary connects.

Both NPN TO-220 regulators were replaced with a robust modern TIP variant with new full synthetic thermal compound as well as remaining small signal devices with new low noise TO-92L Fairchild devices with better dissipation. A new adjustment precision Bourns potentiometer was added. All electrolytic were replaced with high temp (105C) low impedance PW capacitors and high grade WIMA/Polypropylene film capacitors with an increase in operating voltage.

BEFORE

AFTER

35Vdc SE Confirmation

The 20,000MFD filter capacitors were replaced with a computer-grade Nippon Chem Con type

P700 Drivers

The 4300 has very robust and heavy built driver assemblies with a unique parallel mounting pattern. With a differential front end and tied PP output stage the P700 routes through the phase inverting stage and the BTL (Balanced Transformer-less Connection).

Unlike the original diff pairs, new matched beta differential were installed and then thermally coupled together for better DC stability.

Differential Boding

The Pre-driver and biasing/regulating devices were all replaced with modern low noise TO-92’ Fairchild devices and a high-speed ZTX TO-92 devices, new TO-220 KSA was also installed. All VD diodes replaced with modern Vishay axial diodes and new precision Bias potentiometers installed, the original offset closed frame plastic pots were removed and proper cleaned.

All new low impedance Nichicon PW and high grade WIMA/Polypropylene film capacitors installed with an increase in operating voltage.

BEFORE

AFTER

Bias Confirmation

PE01 Pre-/Buffer

The 4300 has a different approach to the gain stage here, with a tiered input/output gain stages including additional tone control pickup. The PD01 and PE01 are mounted perpendicular tongue/grove fit which soldered versus wire leaded.

In the PE01 stage all the initial input .22MFD and other 1FMD< were replaced with a high grade WIMA polypropylene film capacitors, remaining electrolytics/tantalum were all replaced with a audio grade KT/KA Nichicon with an increase in operating voltages. The Decoupling was increased in MFD with a low impedance Nichicon PW. All small signal devices were replaced with low noise, modern TO-92 Fairchild devices.

BEFORE

AFTER

PD01 Tone

The PD01 tone buffer stage electrolytics and tantalums, like above were all replaced with audio grade KA/KT and low impedance PW, Bipolars were replaced with a audio-grade Nichicon MUSE type, all with an increase in operating voltages. All small signal devices were replaced with low noise, modern TO-92 Fairchild devices.

BEFORE

AFTER

PM01 Inverter

The distal stage phase inverter had all of the electrolytic capacitors replaced with audio grade KA/KT Nichicon capacitors with an increase in operating voltage. All new small signal devices were installed with TO-92/L modern low noise Fairchild devices.

BEFORE

AFTER

P400 Phono

The gain stage NPN’s were all replaced with low noise modern Fairchild TO-92 devices matched to 1% BETA. The 100MFD decoupling electrolytic was increased to a 220MFD for better filtering and replaced with audio grade KA/KT with an increase in operating voltages along with remaining electrolytic. The ceramics and 1MFD were all upgraded to WIMA polypropylene film capacitors. New Bourns precision clipping potentiometers installed.

BEFORE

AFTER

RF & P500 Vari-Matrix / 400Hz Oscillator

Dolby and associated RF stage electrolytic and tantalum capacitors were replaced with a low impedance Nichicon PW with an increase in operating voltages.

The vars-matrix, which takes a stereo input and converted to quadraphonic output. All of the electrolytic here were replaced with a low impedance and audio grade KA/KT Nichicons with an increase in operating voltages. New high-grade WIMA PP films and all associated small signal devices were replaced with TO-92/L low noise Fairchild devices.