1060, cap coupled sound

Discussion in 'Marantz Audio' started by cortico, Feb 3, 2018.

  1. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    Amp board is back in the chassis. Coupling and main filter also installed.

    Can anyone explain the purpose of the 100pf cap behind the amp board across negative and positive on both channels audio signal input?

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    Last edited: Mar 5, 2018

     

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  2. CohibaJoe

    CohibaJoe AK Subscriber Subscriber

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    This looks so GOOD!!!

    Can you take a close-up of the Jensen connections? We could use a Nice picture of this.
     
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  3. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    Thanks, Joe! The Jensen 4 pole was wired as bellow. Not sure if this is the best way:

    Rectifier (+) to Jensen (+) in
    Jensen (+) out to power amp board
    All (-) to Jensen (-) in
    Jensen (-) out to chassis strap

    The solder joints on the cap look a bit ugly, I went with a lower wire gauge and had a hard time soldering...
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    Last edited: Mar 5, 2018
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  4. Leestereo

    Leestereo Super Member

    Messages:
    2,040
    Location:
    Ottawa, ON
    Very nice work.
    The ceramic 100pF capacitors (C727/C728) are part of the input low-pass filter and it is recommended that they be replaced with C0G or film type capacitors.
     
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  5. Hipocrates

    Hipocrates Anti-Muppet

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    Nicely done! That amp deserve it!
     
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  6. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
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    Just finished to build a DBT, any advice before I proceed with first power up?
     
    Last edited: Mar 7, 2018

     

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  7. Jailtime

    Jailtime Standin' on a corner Subscriber

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    How's it sound? Sure is a nice looking rebuild you did.
     
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  8. CohibaJoe

    CohibaJoe AK Subscriber Subscriber

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    :lurk:...Have you powered this on as to Each Board being recapped?
     
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  9. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    Hi guys,

    I haven't powered the unit yet. Only the power amp and power supply board were recapped, plus the main filter and coupling.
    It shouldn't be postponed any longer, I will do it before I moved on to the preamp board.... :no:
     
  10. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    First power up went relatively well. Dim bulb tester was useful:


    A few things to note:
    The good
    -bias and clipping adjusted to spec.
    -The sound is pretty good out of the bat with headphones.
    -Right channel distortion and unbalance is eliminated.
    -VDC readings are symmetrical on both channel's output transistors.

    The bad
    -Bias trim pots are terrible to adjust, very finicky. I respected the stock 450ohm pot in parallel with a 68ohm resistor. Regretting not installing multi turn pots...
    -Noticed a hum that is not affected by volume knob or any other control, it seems to float in the background. It disappears when the jumper from preamp to main in are unplugged. When music volume goes up the hum goes unnoticed.

    The power supply is done the main amp is done, probably the hum is caused by something on the pre-amp board....

    Any thoughts?
     
    Last edited: Mar 10, 2018
  11. tonebells

    tonebells AK Subscriber Subscriber

    Messages:
    880
    Location:
    Florida
    If the top and bottom are not on they tend to pick up hum.

    Tony
     
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  12. cortico

    cortico Active Member

    Messages:
    284
    Location:
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    That could also be it. The preamp sounds good when connected to my other 1060 main amp.

    Can be a grounding issue, Hum is minimized when I short the main filter negative in with negative out.
     
    Last edited: Mar 12, 2018
  13. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    Moved on to the preamp and will power it again with cover and new ground lead dressing to see if hum improved...
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    Last edited: Mar 10, 2018
  14. ton4eff

    ton4eff Active Member

    Messages:
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    Location:
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    I also have a 1060 with a hum problem. Investigations showed that it's greatly affected by moving shielded wires from the main in connectors to input on the P700 board. The hum is somehow "inducted" by the transformer in the entire preamp (low signal) section and moving these wires at the appropriate sweet spot can kill the hum almost entirely. Maybe you have the same problem. I'm planing to go deeper with searching the cause of this inducted hum when I get around to it, because I know that fixing the main in wires in that sweet spot is not the right solution.
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  15. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    Thanks for your input. I have figured out the issues:

    -The bias was difficult to adjust because I installed a 450K ohms potentiometer instead 450ohm, ah! rookie mistake.
    -The grounding noise is gone, the addition of a star ground resolved the issue.
    (there was some residual hum that was gone after mounting top and bottom covers)
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    The sound
    OK, this little amp is sounding pretty amazing!
    The amp is running for only 8 hours. The typical warm smooth and envolving Marantz “thing” is there. I can definitely hear much clearly nuances on some familiar tracks and I have discovered cool details on tracks I am not very familiar with.

    Without wanting to sound like a "cliche", I would say that the biggest improvement is more sense of space in the sound.
    Below is a picture of the parts that came out:
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    To do list
    -Pre-amp: replace small value caps, I am not set on a cap choice yet. Order 2.2M resistors,
    -Power amp: add flyback diodes, replace ceramic input caps with films, install correct bias trim-pots.
    -Phone board: replace electrolytic, resistors, diodes and transistors
    -Tone control board: replace resistors and ceramic caps
    -Replace speaker terminals and internal speaker wiring
     
    Last edited: Mar 11, 2018
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  16. rBuckner

    rBuckner Luv 2 Restore Subscriber

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    Wow Nuno, you've done a very very nice job. I'm impressed!! :thumbsup:
     
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  17. cortico

    cortico Active Member

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    Thanks, Randy! This is really exciting.

    Well, thanks for guiding my hand finding the faulty components!
    It's been a continuous learning process. Although, I must admit that I am an extremely lucky "parts swapper"!
     
    Last edited: Mar 12, 2018
  18. CohibaJoe

    CohibaJoe AK Subscriber Subscriber

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    Very Nice:music::music:....100+ hrs at least. Please keep us posted.
     
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  19. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    The amp is already sounding very nice!

    I realized that left and right channel sound perfectly balanced when listening to the Phono input.
    When using the DAC/CD input the left channel sounds a tiny bit louder. I think I may have an issue upstream the amp...probably the interconnect cables or the DAC itself. It's an old Parasound DAC1100 it may need some service.

    Question:
    Would it be an issue if I replace the original Metal oxide 100ohm 2W resistors on the speaker switch (R311-R312) with 2W carbon films??
     

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    Last edited: Mar 17, 2018
  20. cortico

    cortico Active Member

    Messages:
    284
    Location:
    New York
    The amp has reached the 75-hour mar. The sound seems pretty much settled by now, although many say things will keep improving.

    This is my first reaction comparing the stock 1060 (original parts in) with the rebuilt 1060 in three basic comparison points:

    Equipment used:
    Parasound C/DC 1500 cd player
    Parasound D/AC 1000 DAC
    Pioneer PL-530 Turntable, Shure M97xE cartridge
    Rebuilt Jenning research speakers, fr 25-24,000Hz
    DIY Canare star quad cables and interconnects

    I have listened to favorites tracks from the albums of Diana Krall, REM, Yo La Tengo, Pink Floyd, Kings of Convenience.

    Sound signature:
    -Both amps keep the same voice, as mentioned here this is related to the design.
    -Music has a warm presentation, envolving and three-dimensional, the treble is smooth and never fatiguing.

    Sound imaging
    Stock 1060:

    The sound appears to focus between the speakers.
    The soundstage is credible when speaker position and room size are ideal.​

    Rebuilt 1060
    The sound gained more horizontality and a more depth past the speakers.
    Better soundstage sense and instrument realism.
    A clear decaying sound of the instruments, it sustains longer without blurring into the mix.
    Absolutely no background noise (hum or hiss).​

    Frequency response
    Stock 1060:

    Upper-range
    Smooth sounding but a bit recessed. Typical treble instruments have definition and sound real. Tone knob needs to compensate a bit past noon 1 o'clock)
    Mid-range
    Female voices sound really pleasant and warm. Probably a bit bloated, I have to kick back the tone knob to tame it a bit (11 o'clock)
    Lower-range,
    Bass imprints a fat sense to the sound which some people like, I also had to kick back the tone knob one notch for a more balanced sound. (11 o'clock)​

    Rebuilt 1060:
    Upper-range
    Upper range instruments sound smooth and amazing realism.
    Small nuances sound louder, more separations between treble instruments.

    Mid-range
    Mid-range is rendered very realistically without losing its warmth.
    More bite, notes seem to sustain longer, clearer note decay.
    The vocals definition is a quantum leap above, I can perfectly hear individual voices in a chorus.
    Random recording space sounds, like a chair sliding, clapping, breathing seem to be happing in my listening room or around the house.
    Lower-range
    Low frequencies improved greatly, is somewhat more extended and blends well with other rages without muddying up anything.
    More space around bass instruments, kick-drums, bass guitar, low piano notes, trombone all have its own place.
    Less boom but more fidelity and realism, I could almots divide bass into subcategories...

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    Last edited: Mar 17, 2018
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