Marantz SR-4000

Marantz SR-4000 Receiver

Serial No. 07U170828

Professional Restoration with full Recap and Audiophile Modifications.

MSRP $420, Circa 1979

Cost Adjusted for Inflation $1800 !!!

$1175

FMI HiFiHealthCare@Gmail.com

It was 1979 and the transition from the Marantz of infamy to the beginning of the end of a legacy was upon us.

As others such as Pioneer were dipping their toes into the ‘digital’ transition that was about to take place where flashy ‘Fluroscan’ meters replaced the dancing needles of the classic analog meters we had known for so many decades before.

Soon, the classic experience of spinning a tuning wheel and watching the tuner indicator skate effortlessly across the dial in a manner befitting the movement of a fine timepiece would be replaced with the forthcoming digital tuners where a stationary display just barked out numbers as you turn a tuning dial with as much character as a wingnut.

As Philips began to take the helm of the Marantz brand in 1980, while still keeping the quality of production in Japan, they decided to keep the classic analog aesthetic alive in their receiver lineup for that year where the SR-4000 took second place only to the Top of the Line offering for that year. the SR-6000.

Where Marantz did run with the rest of the pack, like Pioneer, is they went with very similar topology under the hood such as the transition of discrete output stages to STK modules and phono circuitry moved into the application specific monolithic IC such as the upc1024 and it’s allies.

It was however, 

Styled in Marantz class and priced at about $1800 

2025 dollars.

As history would prove, the STK modules were less forgiving to clumsy mistakes such as the accidental shorting of speaker wires and the like as they would give up the white smoke as quick as a Robin giving up a worm to a chick lending to their less than favorable reputation.

If however, they were not abused they still run strong to this day until that is you go to push them anywhere near their rated power at which point they often succumb to thermal avalanche effect as their dried up heat transfer paste can no longer transfer the heat away from the device effectively.

Removing the output devices, cleaning off the old paste and applying modern high density, non-curing, non-flowing heat transfer paste is standard procedure for any restoration we do. This provides factory door reliability back to the devices after we run them through QA to insure they meet or exceed factory specification.

The SR-xx00 series gets belittled not because of what was under the hood, because as I stated the rest of the pack was making the same transitions from discrete components to monolithic packages, but Marantz gave themselves a real black eye because they really cheaped out on the cabinets which were more befitting to a Yorx or Soundesign low end product with it’s pressboard construction that literally disintegrated over time.

It is rare to see one of these without the slotted vents destroyed or on the verge!

The reality is, in comparison to their competition such as Pioneer, NAD and their allies, the Marantz had a superior assembly and attention to quality when it comes to the wiring schedule and layout. This is partly why Marantz commanded a higher price in it’s day.

We corrected the shortcomings of the cheap cabinet by building a high quality cabinet of Phillipine Mahagony

One of the biggest killers of vintage amplifiers is heat and the deterioration of heatsink compound resulting in a loss of adequate heat removal from the power devices ultimately creating an avalanche effect and destruction of the devices.

To further increase the life of the STK VAS stage, we modified the device by adding heatsink fins to the package which during testing proved to reduce the heat of the device by more than 15%. Although this may not be necessary, we believe every small thing you do to decrease heat on these devices ultimately leads to better reliability overall.

A complete re-cap of the Main Amplifier; power supplies, flat amp, tone amp and phono stage was performed. 

The devil is in the details as they say and the hardest improvement are in the last 10% but we don't stop at the low hanging fruit. As an example, we couple the main power supply rail with a robust Stacked Metal Film compliment in paralellel to lower the overall ESR and squeeze out the extra margin of filtering for the higher frequency demands.

DC offset was below 15mv on both channels and idle current was within spec at 27 watts providing feedback as to proper bias alignment of STK’s.

All calibrations were performed as per manufacturers Service Manual instructions including;

-  Tuning Meter Alignment

-  FM Tracking Alignment

-  FM IF alignment

-  Mono Distortion Alignment

-  Stereo Distortion Alignment

-  Multiplex Alignment

-  Stereo Separation Alignment

-  Muting Level Alignment

-  FM Signal Strength Meter Alignment

-  LED Power Meter Calibration

 Every restoration of course gets the full complement of control attention with the appropriate cleaning agents and preservation chemicals such as F5 and D100. Potentiometers; switches, and relays are not serviced insitu but instead they are removed where they can be properly serviced for a fix that goes beyond the next few weeks and instead instills confidence in long term performance and reliability. When all is said and done testing shows we have exceeded the manufacturers specification.