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Marantz PM-84

Stereo Integrated Amplifier (1985-90)

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Marantz PM-84


Power output: 120 watts per channel into 8Ω (stereo)

Frequency response: 5Hz to 45kHz

Total harmonic distortion: 0.015%

Damping factor: 90

Input sensitivity: 0.25mV (MC), 2.5mV (MM), 150mV (line)

Signal to noise ratio: 80dB (MC), 92dB (MM), 98dB (line)

Output: 520mV (line)

Dimensions: 416 x 146 x 410mm

Weight: 18kg


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re: PM-84

Hi all,

for those who are still interested in this SK replacement, the easiest is to send me a direct message, Unfortunately I don't check this thread very often...
I've started to put all design files and replacement procedure on a shared google drive folder. I can send a link by email after you contact me. Also let me know f you have suggestions about the best way to share with the community here. :)


re: PM-84

Hi all,

I apologize for the silence, but I shortly moved to the US after I got this circuit to work, and had very little time to talk more about this...
Somehow my account seems to have been loicked, and I couldn't see your comments nor post more. I'm not sure why?

I initially wanted to get a few boards built for interested people, but I don't reasonably have time for this.
I could share the design for interested people. Maybe make a pdf and post it here.
I had initially designed the PCB with DesignSpark PCB (free software) ; I can share the files, or directly gerbers, by email for those interested, as well as photos showing how I mounted it in my PM-84II.
I haven't had time to test it in the PM-64II -- some adjustments may be necessary for bias.
The design is greatly inspired from the PM94 schematic, but with newer components.

Let me know what you think the best way to share this is! :-)

re: PM-84

Hello from Denmark

i am very interested in a pdf .. i have the marantz pm-84 with a STK3122 mk3

best regards Rune

re: PM-84

Interested in STK replace circuit for PM-84D. Can you please write to my nick at gmail?

re: PM-84

Hi everyone,

I personally own a PM84MKII for several years. I've always appreciated its sound, but was soon faced with the STK reliability problem. I alos own a PM-64MKII with similar issues.
In the past few years I had a hard time finding original STK chips... only bad copies instead.

I've developed an input stage with discret components, that mounts right in place of STK, with better cooling capacity. It is greatly inspired from the PM-94 design, with modern (but still high quality) components, adapted to the PM-84MKII.
The result is great! The sound is even improved from the original design! The reason is better components, DC-coupling eliminating the need for a capacitor at the input stage, and it is even possible to separate power supply for each channel (as in the PM-94). The PCB mounts without any mechanical adaptation. Just unsold the STK and a few passive components, then sold the PCB instead, adjust DC bias and idle current, and listen!

I'm willing to build more of my circuits for anyone interested. Feel free to contact me!
Next step I'm adapting it to the PM-64MKII !

re: PM-84

Hello from Denmark

do you still make the discrete component replacement? and what would i cost?

Best regards


re: PM-84

I'll be receiving my PM-94 soon. Can you design be adapted to the 94 also?

re: PM-84

Sounds absolute phenomenal. Very interested. This is the best Iever heard of, because the STK is in other amplifiers as well. Mostly I replace it with the Highest voltage ones STK3152 and mount it on a cooling plate between the heatsinks. The operation temp of the STK is according to Sanyo 25ÂșC.
So your solution is much better!!!! Congretulations.

This website is not affiliated with or sponsored by Marantz. To purchase PM-84/PM-84 II spares or accessories, please contact the company via their website or visit an authorised retailer.