Marantz 4400 Stereo + Quadradial Receiver
Here were showcasing the monster Marantz Quad…the 4400 Stereo & Quadradial Receiver! The 4400 was release sometime between 1974-76 thru 78 and featured an impressive 125W and 50W/4CH output, with the addition of the Dolby Noise-Reduction and a CRT 50tB1 type. With he unique varimatrix feature, the 4400 series can emulated 4-channel output with a stereo input.
P800 Power Supply
The 4400 has one of the most involved power supply assemblies, similar to the 2500/2600/2130 scoped model which contain dangerous current and voltage levels. The P800 establishes the AF front end single-ended 35V and RF single-end 13.5V supply as well as zener regulated 14V differential scope supply. The 1A SE rails are establish via a series of full-wave rectification stages and zener control r/c circuits. The 200 and 600V supplies for the scope are established for the vertical/horizontal CRT.
The rectification stages were replaced with common-cathode and common-anode Ultra-Fast, Soft Recovery MUR type TO-220 rectifiers as well as 1A 1KV rated Ultra-Fast, Soft Recovery axial diode arrays. The two main NPN TO-220 regulators were both replaced with a modern, robust TIP devices with new synthetic Wakefield thermal compound. All small devices were with a better dissipating TO-92L type NPN Fairchild devices. The 35V adjustment was replaced with a precision grade Bourns potentiometer.
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The electrolytic capacitors were replaced with a high-temp, low impedance Nichicon PW type with an increase in operating voltages. As a standard rule at this shop we replace poor constructed Axial electrolytic with radial whenever possible as we did for the 1000MFD filter here. Films were replaced with a high-grade WIMA polypropylene film capacitors.
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35V SE Rail Confirmation
Filter Capacitors
The Full Wave Bridge rectified -/+ 43Vdc rails are generated via the two filter capacitors which were replaced with a computer-grade Nippon Chem Con type for better DC filtering and improved sub-sonic frequency responses at higher gain output. The bridge array is actually mounted on a vertical plate parallel to the filter caps. An additional 1000MFD capacitor is tied under the chassis as well, which was replaced with a low impedance type Nichicon PW 1000MFD and a WIMA polypropylene bypass film capacitor.
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-/+ Rail Confirmation
PE01 Pre-Amplifier/Buffer + PF01 Tone Control
The 4400 Pre-amplifier design is very similar to the 4300 concept and install application with a direct coupled NPN/PNP buffer amplifier stage feeding the PF01 Tone control utilizing a 2Sk30 JFET stage.
All the NPN/PNP devices were replaced with a modern, low noise TO-92 Fairchild type along with a multitude of VD varistors to standard axial Vishay 4148 type. Input films here were replaced with a high-grade WIMA polypropylene film capacitors.
Remaining electrolytic capacitors and tantalums were replaced with a audio grade KT/KA Nichicons as well as low impedance PW type for the DC filtering input stages, all with an increase in operating voltages.
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PF01
As part of the PF01 rebuild, each of the tone attenuators were removed to gain proper access for a full cleaning/treating of the potentiometers. This stage like higher-end models Marantz use a series of 2SK30 JFETs in the gain stage.
All of the small signal devices were replaced with a modern, low noise TO-92 Fairchild type devices. Electrolytic capacitors were replaced with a audio grade Nichicon KT/KA and high-grade polypropylene WIMA film capacitors all with an increase in operating voltages.
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PD01 Tone Amplifier + PH01 Filter Amplifier
The remaining AF stages are used as Hi/Lo Filter assemblies and additional gain stage circuits providing an achieved 6.19Vppk output.
The PD01 stage has a unique mount, similar to other quad Af stages where as the PCB fits via a tongue-groove perpendicular mount. All the small signal NPN/PNP devices were replaced with a modern, low noise TO-92 Fairchild type. Electrolytic capacitors and tantalums were replaced with audio grade KT/KA and audio grade BiPolars with MUSE Nichicons, all with an increase in operating voltages.
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The PH01 concept Filter amplifier is used in a plethora of Marantz variants down to the 2325 stereo receiver. The input films here replaced with a high grade WIMA polypropylene film capacitors. Remaining electrolytic were replaced with a audio grade KT/KA and low impedance PW for the DC filtering, Nichicons with an increase in operating voltages. All small signal devices were replaced with modern TO-92 Fairchild devices.
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PM01 Phase Inverter
Identical to the 4300 PI stage, it operates in connection with the power mode/output selector.
The electrolytic capacitors here were replaced with a audio grade KT/KA and low impedance PW Nichicon capacitors with an increase in operating voltages. Small signal devices were replaced with a modern, low noise TO92 type Fairchild devices.
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P400 RIAA Phono
The phono stage is similar to most of the 22/23/4XXX series Marantz receivers, incorporated as a simple gain stage amplifier and RIAA equalizer. Due to the grounding scheme, obtaining an accurate Curve Response in DUT is difficult.
The small signal devices, including the notoriously awful 2Sc458 device were all replaced with a NPN low noise Fairchild type. The VD varistor was replaced with a Vishay axial 4148 diodes in series as well as both clipping 100K adjustments were replaced with precision Bourns potentiometers. The coupling films were upgraded to a high grade MKP polypropylene film capacitors. Remaining electrolytic were replaced with a audio grade KT/KA and low Impedance PW Nichicons with an increase in operating voltages.
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P700 Drivers
The 4400 amplifier stage features a direct-coupled circuit with a multi differential gain stage and current mirror. The final 3rd-output stages developed via the 713/714 and h003/4 drivers.
The differential pairs were matched with 3% and now thermally coupled for better DC symmetry. Small signal devices were all replaced with NPN/PNP TO-92 Fairchild devices. new TO-126 pre-drivers were install with Wakefield thermal compound as well as new 4th order TO-220 drivers with new robust Fairchild devices with Wakefield thermal compound. New adjustments were installed with precision Bourns potentiometers.
Differential Mapping
All the electrolytics were replaced with a audio grade KT/KA Nichicon type with an increase in operating voltages. New high-grade WIMA polypropylene film capacitors were installed, as well as MKP films.
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BIAS Confirmation
Amplifier Isolated Square Wave Report
P500 Vari-Matrix + PL01 400H Oscillator
The Varimatrix stage is used for converting stereo signal to a multi path quad output, with the 400Hz stage dedicated as a 580mV Sine wave generator for the dubbing calibration.
In the P500 stage the small signal devices were replaced with a low noise NPN/PNP fairchild devices. The films were all replaced with a high-grade WIMA polypropylene film capacitors. Electrolytic were replaced with a audio grade KT/KA and low impedance PW Nichicons with an increase in operating voltages.
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PL01
Electrolytic were replaced with a low impedance PW Nichicon type with an increase in operating voltages.
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P600 Dual Dolby Assembly
The Dolby assembly is double for the quad receivers, with a sandwiched vertical PCB sharing a common card insert connector. All of the electrolytes here were replaced with a low impedance TO92 Nichicon PW type with an increase in operating voltages.
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P900 Scope Display
The scope circuit is oriented around a direct-coupled JFET differential stages, amplifying both DC/AC signals with a 47dB / 39dB gain. The 4400 primarily uses the 50TB1 tube but can also be replaced with a 2BP1 type
Both of the thermally coupled TO-220 devices comprised of two 2SD devices each were replaced with very robust MJE type On-Semi TO-220 device with new synthetic Wakefield thermal compound. A new .047 bypass film with a high-grade polypropylene film and finally all four adjustments were replaced with precision Bourns potentiometers.
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AUDIO NOTIZEN
