Leestereo's Restoration and Upgrade Of A Marantz 2325

Discussion in 'Marantz Audio' started by Leestereo, Nov 18, 2015.

  1. dgoulet

    dgoulet New Member

    Messages:
    22
    Location:
    Kelowna
    I was going to ask you Steve did you replace those grey tin film caps I see on other rebuild that lots of people are not replacing them , just curious about the sound impact,my 2325 is not working until I rebuild it so I can't tell what a 2325 sounds like
    Denis
     

     

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  2. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    Which board are you referring to? I can check my parts list. Don't remember off hand if I did or didn't.
    Steve
     
  3. dgoulet

    dgoulet New Member

    Messages:
    22
    Location:
    Kelowna
    I have some on the P-400 C-401-2 and I am reading about high end Philips orange drops I was thinking on using some on the P-700 C-701 I hear these put out fantastic sound
     
  4. Steven Tate

    Steven Tate AK Subscriber Subscriber

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  5. dgoulet

    dgoulet New Member

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    Location:
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    Ok thanks again:beerchug:
     
  6. OFrank

    OFrank New Member

    Messages:
    5
    Hello Leestereo, in your post for upgrading the P700 power amp for the Marantz 2325, you specify that H701 and H702 are a matched pair. Where do you purchase matched pairs?
    Thank you in advanced. 'O'Frank
     

     

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  7. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    OFrank, those transistors are dirt cheap. You buy at least 20 or so - more if possible - and test them on an hfe tester. The Chinese component testers you can get on the bay will digitally display the hfe or many cheap (think Harbor Freight) DMM’s have an hfe test mode. Measure a bunch of the transistors and pick two close together in hfe - say a difference of 5 or less. Less is better.
    Steve
     
  8. OFrank

    OFrank New Member

    Messages:
    5
    I am getting ready to restore my Marantz 2325. I have been reading a lot of forums (this seems to be the best) about doing the restoration. In doing my research for the P400 phono pre-amp. Everything I read and have seen on YouTube videos it spec's that the 2SC1344 and 2SC458 transistors are replaced with KSC1845 which has half the Ic of the original transistors. I have found other transistors that are a much better match to the original transistors. Therefore, I am wondering why the KSC1845 is used?

    The Fairchild BC548C is almost an exact match with a higher gain. Also, the NTE199 also seems to be a better match. Although the NTE is a higher price, the Fairchild is about the same price as the KSC1845.

    Again why is the KSC1845 used over others?

    Thank You in Advance! 'O' Frank
     
  9. catrafter

    catrafter Marantz Specialist Subscriber

    Messages:
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    Location:
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    I would hesitate to use NTE in anything I care about.
    Does the BC part have the same basing (collector in the center) as JIS parts?
    I have used KSC1845 'F' gain code to replace 2SC458 transistors many times, the lower Ic is not a factor here, low noise is.

    Tom
     
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  10. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    CBE Pinout.
    You don't know what you get with NTE, they are re branded parts from who knows where, sometimes they work, sometimes don't.
     
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  11. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I used the KSC1845's in my 2325 restoration as recommended in this thread. The phono section sounds great to me and is very quiet. But I do have a situation where the volume has to be turned up 15-20% if you go from tuner to phono. I didn't listen to the unit other than just to confirm it worked before the restoration, so I never knew if this volume difference existed before the rebuild. Your info makes me wonder if the gain difference is the cause. Regardless, I'm very happy with the sound and I have more volume available than I am willing to use.
     
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  12. Leestereo

    Leestereo Super Member

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    The transistor gain (hFE) specifications for H405/406 does not set the sensitivity of the phono circuit per se, it is the feedback loop that controls the overall gain. Also the "B" gain specification for the 2SC458L at H405/406 is 100-200, which is actually lower than that specified for the "F" gain specification of the KSC1845: 300-600.
     
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  13. Echoplex

    Echoplex AK Subscriber Subscriber

    Messages:
    173
    Phono output level will always be lower compared to tuner and tape levels due to the lower voltage output; cartridge output levels have very small voltage increments...some less than 1 mV. That will definitely show up on the volume level when trying to match output for output per se.

    But still, you’re on to something interesting with matching transistor gain output levels. Sounds like many techs here essentially found a good replacement that works well, drops the noise floor a little, but sacrifices a little output gain.

    Has anyone tried slightly different output gain transistors in those spots on P400? I wonder what they would sound like as a comparison? Too hot? Increased noise floor? I’ve never heard the originals, so haven’t experienced the notorious problems they are known for. Just curious...
     
  14. Echoplex

    Echoplex AK Subscriber Subscriber

    Messages:
    173
    Never mind...

    Thanks Leestereo for the explanation!

    In the feedback loop, how would increase gain output slightly higher, without adding more noise? Or is it possible without changing the RIAA curve?
     
  15. Leestereo

    Leestereo Super Member

    Messages:
    2,042
    Location:
    Ottawa, ON
    Decreasing the value of R412/R413 would increase gain; a small decrease from 620ohm e.g., 560ohm or 470ohm will give a small increase in gain and would not significantly impact the RIAA correction.
     
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  16. catrafter

    catrafter Marantz Specialist Subscriber

    Messages:
    6,085
    Location:
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    The phono preamp in most older gear was designed to boost the output of a typical (what ever that is) magnetic phono cartridge to a line level signal. When CD players came out, their output was around 2VRMs instead of the old .775VRMS line level standard.
    Most FM radio stations have volume limiters to keep their transmitter modulation near 100%, so it's as as loud as possible.

    It's no wonder we have to crank up the volume when we want to play a record.

    My 2 cents.

    Tom
     

     

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  17. hunter00

    hunter00 Super Member

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    2,725
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    possibly looking for one of the black 2325 marantz faceplates whoever sells them let me know if available and cost thx
     
  18. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    PM AK member wlhd1610 (Bob Speece). I think he sometimes has a beautiful laser etched black faceplate for the 2325. I have one of his for the 2245 and it is superb.
     
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  19. OFrank

    OFrank New Member

    Messages:
    5
    Your replacement for R801 is it a wire wound?
     
  20. Leestereo

    Leestereo Super Member

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